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Materials Science » Polymers » "Polymerization", book edited by Ailton De Souza Gomes, ISBN 978-953-51-0745-3, Published: September 12, 2012 under CC BY 3.0 license. © The Author(s).

Chapter 13

Block and Graft Copolymerization by Controlled/Living Radical Polymerization Methods

By Hülya Arslan
DOI: 10.5772/45970

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Schematic representation of CRP
Figure 1. Schematic representation of CRP
Development of CRP by integration of advances in several fields of chemistry
Figure 2. Development of CRP by integration of advances in several fields of chemistry
Illustration of the dependence of ln([M]0/[M]) on time
Figure 3. Illustration of the dependence of ln([M]0/[M]) on time
Illustration of the dependency of molecular weight on conversion
Figure 4. Illustration of the dependency of molecular weight on conversion
A schematic representation of how new polymers and materials can be prepared using controlled/living radical polymerizations
Figure 5. A schematic representation of how new polymers and materials can be prepared using controlled/living radical polymerizations
Schematic presentation of Grafting-through
Figure 8. Schematic presentation of Grafting-through

Block and Graft Copolymerization by Controlled/Living Radical Polymerization Methods

Hülya Arslan1

1. Introduction

Copolymerization is a versatile synthetic tool for controlling the functionality and, therefore, tailoring of the physical and mechanical properties of macromolecules. Block copolymers are one of the most important polymeric materials in technological applications and theoretical research because of their exceptional properties due to the microphase separation [1]. Many basic characteristics of block copolymers and graft copolymers are similar. Graft copolymers also exhibit good phase separation and are used for a variety of applications, such as impact-resistant plastics, thermoplastic elastomers, compatibilizers and polymeric emulsifers. Because of their branched structure they generally have also lower melt viscosities, which is advantageous for processing. They have great potential to realize new properties because of their structural variables (composition, backbone length, branch length, branch spacing, etc.) [2,3]. Various polymerization methods have been used to synthesis block and graft copolymers, such as free radical, anionic, cationic, coordination, group transfer, coupling, changing polymerization mechanism, step growth, macroinitiators, metathesis and many books [4,5], chapters of encyclopaedia [6-10], papers [11,12] offer excellent reviews of research on synthesis block and graft copolymers by these methods.

According to literature, the most common and widely used approach is free-radical polymerization method. Free-radical polymerization is particularly interesting because of its adaptability to a wide range of functinal monomers under less stringent synthesis conditions. Unfortunately, uncontrolled nature of conventinal free-radical polymerization leads to homopolymerzation during the polymerization resulting in a product that is a mixture of homopolymer and copolymer. A major drawback of conventional radical polymerization is that almost no control over the molecular weight, molecular weight distribution and architecture of the polymer is possible, making its macroscopic properties very difficult to be tailored. Living ionic polymerizations can provide a methodology for preparation of copolymers with well-defined structures, such as controlled molecular weights and narrow molecular weight distribution, defined copolymer compositions, branching and end-group functionalities. There are various drawbacks that often retard the practical application of living ionic systems to prepare copolymers. These drawbacks are limitation of the method to certain monomers and their sensitivity to moisture, carbon dioxide, and numerous other acidic or basic compounds.

Polymer chemists have long tried to combine the advantages of both radical and ionic polymerizations in a single polymerizations process. These attempts have been principally successful by controlled/living radical polymerization (CRP) techniques. Controlled/living radical polymerization in brief is based on an understanding and integration of chemistry developed over 60 years in the fields of organic chemistry, conventional radical polymerization and living ionic polymerizations. Recently, extensive research has been carried out in the field of controlled/living radical polymerization (CRP), because it can be employed for the polymerization of numerous vinyl monomers under mild reaction conditions and these methods enable the synthesis of well-defined polymer structures with controlled molecular weight and narrow molecular weight distribution. CRP includes atom transfer radical polymerization (ATRP), nitroxide-mediated polymerization (NMP), and reversible addition-fragmentation chain transfer (RAFT) polymerization. Each of these methods relies on establishment of a rapid dynamic equilibrium between a low concentration of active propagating chains and a predominant amount of dormant chains that are unable to propagate or terminate, and is more tolerant towards functional groups and impurities. Recently, many studies have been reported in the literature about the synthesis of macromolecules with various compositions (homopolymers, random, periodic, block, graft and gradient copolymers) and novel topologies (linear, star, comb, branched, hyper branched, networks, brushes etc.) using CRP techniques [13-30]. It is observed that the significant improvement in block and graft copolymer synthesis has become with development of controlled/living radical polymerization (CRP) techniques. This chapter focuses on the preparation of block and graft copolymers via controlled/living radical polymerization (CRP) techniques which are new and efficient synthetic strategies.

2. Controlled/living radical polymerization (CRP)

CRP can be described as “A radical polymerization that can be stopped and re-initiated under external control” and shown schematically in Figure 1.

General CRP mechanism can be summarized as follows;


Figure 1.

Schematic representation of CRP

Equilibrium is established between dormant, end-capped chains, unable to propagate or terminate, and the active species. The equilibrium should be shifted towards the dormant species and exchange between active and dormant species should be fast relative to propagation. CRP distinguishes itself from conventional radical polymerization by involving a reversible activation process.

2.1. Historical evolution of CRP

Table 1 illustrate development of fundamental concepts in organic radical processes, some concepts in living ionic polymerization and advances in radical polymerizations which all have contributed to controlled/ “living” radical polymerization. The success of controlled/ “living” radical polymerization is an integration of advances in synthetic organic chemistry, living ionic polymerization and conventional radical polymerization (Figure 2) [31,32].


Figure 2.

Development of CRP by integration of advances in several fields of chemistry

Organic synthesisLiving ionic polymerizationConventional radical polymerizationControlled/ “living” radical polymerization
Kharash: First ATRA (hv)

Minisci, Vosfi: CuX/RX/Olefin
Rosantsev: Nitroxide
Kochi: Free radicals&Mt

Fischer: Persistent Radical Effect (PRE)

Many groups: ATRA (Mt)
Szwarc: Living anionic polym., block copolymers

Reversible deactivation in Cationic Ring Opening Polymerization (CROP)

Kennedy: Inifers,
Kennedy, Higashimura, Sawamoto, Sigwalt, Matyjaszewski:

Matyjaszewski, Mueller:
Exchange reactions
Bambord: Inhibition/retardation
Starks: Telomerization, block copolymers

Minoura: Cr(II)acetate/MMA

Otsu: “1st” Living radical polym., Iniferters
Solomon, Rizzardo, Cacioli: Stable Free Radical Polymerization (SFRP)-Synthesis of oligomers with nitroxide (TEMPO)
Rizzardo: Addition-fragmentation (RAFT)

Georges: TEMPO mediated styrene polym. (NMP)
Wang and Matyjaszewski: ATRP
Sawamoto: ATRP
Otsu: Iniferters
Solomon, Rizzardo, Cacioli: (SFRP)- (TEMPO)
Rizzardo: (RAFT)

Georges: TEMPO/styrene (NMP)
Wang and Matyjaszewski: ATRP
Sawamoto: ATRP

Table 1.

Evolution of controlled/ “living” Radical Polymerization [31,32]

Radical addition reactions have for a long time been considered to be very difficult to control due to termination reactions which not be avoided. Probably the first example of a successful addition of halogenated compounds to alkenes via radical intermediates (atom Transfer Radical Addition, ATRA) was provided by Kharash under photochemical conditions. This atom transfer radical process was subsequently converted to metal catalyzed reactions by Minisci, Vosfi and others during the 1960s.

In 1982 Otsu et al., for the first time, used the term living radical polymerization to describe a free radical polymerization in the presence of dithiocarbamates. In analogy to the inifer used in carbocationic systems, they proposed that dithiocarbamates acts as iniferters, i.e. agents which initiate, transfer and terminate. Unfortunately, as in the previously discussed systems, polydispersities were always relatively high, molecular weights did not evolve linearly with conversion and initiation efficiency was low. A new system for controlling radical polymerization based on nitroxides as stable free radicals is developed by Solomon, Rizzardo and Cacioli in 1986. They synthesized methyl acrylate oligomers via reversible capping of growing radical chain by using 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as a stable free radical. The reversible capping of growing chains defined the first mechanism of three general routes to controlled/ “living” radical polymerization. This route was named as “Stable Free Radical Polymerization (SFRP)” by its discovers. Three main types of techniques have been developed over the years: 1) stable free radical polymerization (SFRP) with nitroxide-mediated radical polymerization (NMP), 2) atom transfer radical polymerization (ATRP) and 3) reversible addition-fragmentation transfer polymerization (RAFT).

2.2. Equilibrium (reversible activation/deactivation) for the three major CRP processes

The reversible activation/deactivation reactions (dynamic equilibrium) in the most effective CRP process may be classified mechanistically into three types, which are (a) dissociation-combination (DC) (coupling), (b) atom transfer (AT) and (c) degenerative chain transfer (DT).

(a) Reversible deactivation by dissociation-combination (coupling). e.g. Nitroxide-mediated polymerization (NMP)

(b) Reversible deactivation by atom transfer. e.g. ATRP

(c) Degenerative chain transfer. e.g. RAFT

Each of these methods relies on establishment of a dynamic equilibrium between a low concentration of active propagating chains and a predominant amount of dormant chains that are unable to propagate or terminate as a means of extending the lifetime of the propagating chains.

2.3. General features of CRP

It is widely accepted that a controlled polymerization process should display the following features:

  1. First-order Kinetic Behavior

  2. Pre-determinable Degree of Polymerization

  3. Designed (Usually) Narrow Molecular Weight Distribution

  4. Long-lived Polymer Chain with Preserved End Functionalities

2.3.1. First-order kinetic behavior:

The polymerization rate (Rp) with respect to the log of the monomer concentration ([M]) is a linear function of time. This is due to the negligible contribution of non-reversible termination, so that the concentration of the active propagating species ([P*]) is constant.

ln[M]0[M]=kp[P] t =kpapp t  (if [P]  is constant)

kp is the propagation constant. The consequence of equation (6) and the effect of changes in P* are illustrated in below:


Figure 3.

Illustration of the dependence of ln([M]0/[M]) on time

This semi logarithmic plot is very sensitive to any change of the concentration of the active propagating species. A constant [P*] is revealed by a straight line. A steady [P*] in a CRP is established by balancing the rates of activation and deactivation and not by balancing the rates of initiation and termination as in a conventional radical polymerization. An upward curvature in the kinetic plot indicates an increase in [P*], which occurs in case of slow initiation. On the other hand, a downward curvature suggests a decrease in [P*], which may result from termination reactions increasing the concentration of the persistent radical, or some other side reactions such as the catalytic system being poisoned or redox processes on the radical.

It should also be noted that the semi logarithmic plot is not sensitive to chain transfer processes or slow exchange between different active species, since they do not affect the number of the active propagating species.

2.3.2. Pre-determinable degree of polymerization:

Degree of polymerization (DPn), i.e. the number average molecular weight (Mn) is a linear function of monomer conversion.

DPn=MnM0=Δ[M][I]0=[M]0[I]0 ( conversion)

This result comes from maintaining a constant number of chains throughout the polymerization, which requires the following two conditions:

  1. initiation should be sufficiently fast so that essentially all chains are propagating before the reaction is stopped; and

  2. an absence of chain transfer reactions that increases the total number of chains.

Figure 4 illustrates feature 2 and shows the ideal growth of molecular weight with conversion, as well as the effects of slow initiation and chain transfer on the molecular weight evolution.


Figure 4.

Illustration of the dependency of molecular weight on conversion

It is important to recognize that the evolution of molecular weight is not very sensitive to chain termination, since the number of chains remains unchanged. The effect of termination is only observable on the plot when coupling reactions, forming higher molecular weight polymers, start to play a significant role.

2.3.3. Designed, usually narrow, molecular weight distribution

Although this feature is often desirable, it is not necessarily the result of a controlled polymerization, which only requires the absence of chain transfer and termination, but ignores the effect of rate of initiation, exchange and depropagation.

In order to obtain a polymer with a narrow molecular weight distribution, each of the following requirements should be fulfilled.

  1. The rate of initiation is fast in comparison to the rate of propagation. This condition allows simultaneous growth of all the polymer chains.

  2. The exchange between species of different reactivity is fast in comparison with the rate of propagation. This condition ensures that all the active chain termini are equally susceptible to reaction with monomer allowing uniform chain growth.

  3. There must be negligible chain transfer or termination.

  4. The rate of depropagation is substantially lower than propagation. This guarantees that polymerization is essentially irreversible.

This should yield a Poisson distribution, as quantified in equation (8).


According to equation (8), polydispersity (PDI = Mw/Mn) decreases with increasing molecular weight.

2.3.4. Long-lived polymer chains with preserved end-functionalities:

This is a consequence of negligible irreversible chain transfer and termination. Hence, all the chains retain their active centers after the full consumption of the monomer. Propagation resumes upon introduction of additional monomer. This unique feature enables the preparation of block copolymers by sequential monomer addition. The significance of controlled polymerization as a synthetic tool is widely recognized and polymers having uniform predictable chain length are readily available. Controlled polymerization provides the best opportunity to control the bulk properties of target materials through control of the multitude of possible variations in composition, functionality and topology now attainable at a molecular level. Through appropriate selection of the functional (macro) initiator, copolymers formed in a controlled/"living" polymerization process can have essentially any desired topology. Further, the nature of the mechanism enables specific end functionalization and addition of a second monomer to make a block copolymer.

2.4. Potential applications of CRP processes

The development of CRP has allowed the preparation of many new materials with vastly differing properties simply by varying the topology of the polymer (i.e., comb, star, dendritic, etc.), the composition of the polymer (i.e., random, periodic, graft, etc.), or the functional groups at various sites on the polymer (i.e., end, center, side, etc.) (Figure 5) [33].


Figure 5.

A schematic representation of how new polymers and materials can be prepared using controlled/living radical polymerizations

3. Blok copolymerization

Polymers which are composed of two different monomers are usually referred to as copolymers. The sequential arrangement of these different monomers determines the type of copolymer that is formed. In the case of a random distribution of the two monomer over the polymer chain, the product is called a random copolymer. In a linear block copolymer, the monomeric residues are arranged in such a way that one block consists of monomeric residue A and another block of monomeric residue B. Block copolymers are defined as having a linear arrangement of blocks of varying monomer composition. That is, a block copolymer is a combination of two or more polymers joined end-to-end. Moreover, one can synthesize more exotic structures such as four- or six-arm starblock copolymers and comb-like block copolymers. These have branched structures.

The increasing importance and interest in block copolymers arises mainly from their unique properties in solution and in the solid state which are a consequence of their molecular structure. In particular, sequences of different chemical composition are usually incompatible and therefore have a tendency to segregate in space. Amphiphilic properties in solution and microdomain formation in solid state are directly related to this specific molecular architecture, which can be designed by using existing monomers or polymers. Block copolymers are generally applied as adhesives (e.g. surfactants and viscosity improvers), compatibilizers, thermoplastic elastomers, etc.

The concept of block copolymer synthesis started in 1956 when Szwarc discovered living anionic polymerization. A living process implies that all polymer chains start growing simultaneously; while during chain growth no termination or chain transfer takes place. Consequently, all chains grow for a similar period, and a narrow molecular weight distribution is obtained. When all monomer has been consumed, the active center persists, and upon addition of a new batch of monomer, polymerization continues to form a block copolymer. Anionic polymerization however requires very stringent reaction conditions, as the carbon-centered anion is very sensitive to traces of impurities. Industrially, anionic polymerization is therefore not frequently used. Later, block copolymer synthesis was also achieved by other living polymerization techniques, such as ring opening polymerization and cationic polymerization or by pseudo-living techniques like Ziegler-Natta catalysis. These polymerization techniques, however, suffer from a number of disadvantages: most of them do not tolerate even extremely low levels of impurities (like e.g. moisture or oxygen), and are compatible only with a limited number of monomers. Also these processes are very expensive, due to the special equipment and the reaction conditions that are needed to perform these reactions. This obviously leads to an expensive polymer product. An entirely different synthetic concept towards (multi)block copolymers makes use of the polycondensation principle. Since the early 1980s, there were several early attempts to synthesize block copolymers via regulated free-radical polymerizations. These methods utilized so-called iniferters, i.e. compounds which could serve as INItiators, transFER agents and TERminating agents. However, while useful, these techniques did not offer the desired level of control over macromolecular structure, due to poor molecular weight control, high polydispersities, and low blocking efficiency. This was attributed to slow initiation, slow exchange, direct reaction of counter radicals with monomers, and thermal decomposition of the iniferter. In the last decade, some polymerization techniques that combine the versatility of free radical polymerization with the control of anionic polymerization emerged. These techniques are referred to as controlled radical polymerizations, such as Nitroxide-Mediated Polymerization (NMP), Atom Transfer Radical Polymerization (ATRP) and Reversible Addition-Fragmentation chain Transfer (RAFT) and are based on two principles: reversible termination and reversible transfer. These techniques have enabled researchers to synthesize block copolymers under less stringent conditions than those necessary for living ionic polymerizations: it is possible to work under similar conditions as used in free-radical polymerizations. The synthesis of block copolymers by general polymerization methods such as free radical, anionic, cationic, coordination, coupling, step growth, ring opening, changing polymerization mechanism (active centers transformation reactions), have summarized several times in the literature [1,4,6-10, 34]. In this chapter we will focuses on the preparation of block and graft copolymers via controlled/living radical polymerization (CRP) techniques which are new and efficient synthetic strategies.

Block copolymers can be prepared by controlled polymerization routes in two strategies which are the sequential monomer addition strategy and the use of a difunctional initiator. In the sequential monomer addition strategy, certain experimental conditions governing the growth of the first block should be handled carefully to increase the blocking efficiency. It is essentially important to stop the polymerization of the first monomer before it is used up completely for the fact that end functionalities might be lost, resulting in the formation of dead blocks. Another feature to be considered, as in all sequential monomer additions, is the order of introducing each monomer [35]. In brief, the very active monomer should be polymerized first, which is valid for either of the controlled polymerization mechanisms. Different from sequential monomer addition technique utilized in anionic living polymerization, controlled routes allow for the polymerization of monomers A and B to be performed separately in two distinct steps, allowing chain functionalities to be preserved. The first block functions as a macromolecular initiator, a so-called macroinitiator, in the preparation of the second block.


By this way AB type diblock copolymers can be prepared. Further, the nature of the mechanism of CRP enables specific end functionalization and addition of a another monomer (C) to make ABC type triblock copolymer:


Another route involves the use of a difunctional initiator and has been employed in the preparation of ABA type symmetric triblock copolymers. In this methodology, a compound possessing two initiating sites is utilized in the formation of the middle block first, followed by the polymerization of the second monomer to synthesize the first and the third blocks. This allows the preparation of the ABA type triblock copolymer in two steps, instead of three steps:


3.1. Block copolymerization via Nitroxide Mediated Radical Polymerization (NMP)

Two basic strategies have been applied to initiate NMP. The first method involves use of a conventional initiator (e.g. AIBN, BPO) in the presence of a nitroxide and this system is called as “bimolecular NMP” (Scheme 1).


Scheme 1.

Bimolecular initiation in NMP

The second method is called as “unimolecular NMP” (Scheme 2) and it is possible when the initiator is a low molecular weight alkoxyamine. In this system the free radical initiator is not required and the C-O bond of the small molecule alkoxyamine derivative is therefore expected to be thermolytically unstable and decompose on heating to give an initiating radical [27].

Bosman et al. reported the preparation of poly(ethylene glycol)-based block copolymers by initial reaction of mono-hydroxy terminated poly(ethylene glycol) with sodium hydride followed by the chloromethyl-substituted alkoxyamine. The PEG-based macroinitiator is used in the nitroxide mediated radical polymerization of styrene to give amphiphilic block copolymer (Scheme 3) [36].


Scheme 2.

Unimolecular initiation in NMP


Scheme 3.

The synthesis of PEG-b-PS by NMP

Choi et al. reported the preparation of functional segmented block copolymers containing localized pyrene groups through convenient NMP processes for the versatile non-destructive functionalization of carbon nanotubes (CTAs). Polystyrene was employed as an organic tail to improve the solubility and dispersibility of CTA in organic mediums and polystyrene compatible polymer matrices (Scheme 4) [37].


Scheme 4.

Schematic representation for the preparation of pyrene functionalized poly(styrene-co-maleic anhydride)-b-polystyrene (PMAS)

Britze et al. reported the synthesis of poly(para-phenylene)-b-polystyrene (PPP-b-PS) block copolymers using a combination of Suzuki-polycondensation (SPC) and NMP. Alkoxyamine-functionalized poly(para-phenylene)s were initially synthesized by SPC and then its block copolymer with styrene by NMP (Scheme 5) [38].

Groison et al. reported the synthesis of well-defined P(MAA41-co-SS10)-b-P(MMA-co-St)-SG1 amphiphilic block copolymer nanoobjects via nitroxide-mediated emulsion polymerization by using water-soluble macroalkoxyamine (P(MAA41-co-SS10)-SD1) as macroinitiator (Scheme 6) [39].


Scheme 5.

Synthesis of PPP-b-PS under NMP-conditions


Scheme 6.

Synthesis of P(MAA41-co-SS10)-b-P(MMA-co-St)-SG1 amphiphilic block copolymers by using water-soluble macroalkoxyamine (P(MAA41-co-SS10)-SD1) via nitroxide-mediated emulsion polymerization

Ruehl et al. reported the synthesis of bidirectional alkoxyamine initiator (Scheme 7) and the preparation of a variety of symmetrical ABA type triblock copolymers based on styrene, n-butyl acrylate, t-butyl acrylate, isoprene and dimethylacrylamide by using bidirectional alkoxamine as bifunctional initiator for NMP [40].


Scheme 7.

Sythesis of bidirectional alkoxamine initiator for the preparation of ABA type triblock copolymer via NMP


Scheme 8.

Synthesis of Phosphonium-Containing Triblock Copolymers and Schematic Representation of Polymer Structures

Phosphonium ion-containing acrylate triblock (ABA) copolymers were synthesized by Long and coworkers using NMP [41]. The polymerization of styrenic phosphonium-containing ionic liquid monomers using a difunctional alkoxyamine initiator, DEPN2, afforded an ABA triblock copolymer with an n-butyl acrylate soft center block and symmetric phosphonium-containing external reinforcing blocks (Scheme 8).

The synthesis of amphiphilic triblock copolymer of polystyrene and poly(4-vinylbenzyl glucoside) via TEMPO-mediated living radical polymerization was reported by Kakuchi and coworkers [42]. 4-Vinyl benzyl glucoside peracetate 1 was polymerized with difunctional NMP initiator 2 and thus poly(4-vinylbenzyl glucoside peracetate) having TEMPO moieties on both sides of chain ends 3 was obtained. Then the polymerization of styrene was carried out using 3 as a difunctional nmp macroinitiator in order to obtain polystyrene-b-poly(4-vinylbenzyl glucoside peracetate)-b-polystyrene triblock copolymers (Scheme 9).


Scheme 9.

Synthesis of glycoconjugated triblock copolymer via NMP

Some of block copolymers derived using NMP is given in Table 2.

3.2. Block copolymerization via Reversible Addition Fragmentation Chain Transfer polymerization (RAFT)

The key component in controlled RAFT polymerization is the chain transfer agent (CTA) (Scheme 10). The CTAs used are thiocarbonylthio compounds and have the general structure RSC(=S)Z. Examples of RAFT agents (CTA) span all thiocarbonylthio families including dithioesters, xanthates, dithiocarbamates and trithiocarbonates. Z and R groups in the thiocarbonylthio compounds represent the activating group and homolytically leaving group, respectively. These determine the rates of addition and fragmentation. In fact, the choice of RAFT agent for a specified monomer is rather significant and affects the degree of control.

1st Segment2nd Segment3rd SegmentType of blockRef.


Table 2.

Some of block copolymers prepared using NMP


Scheme 10.

General scheme for the RAFT process

The first and most thoroughly studied route towards block copolymers via the RAFT process, employs monofunctional RAFT agents (Scheme 11). The block copolymers that have been synthesized in this way all carry the RAFT functionality at the end of the chain. In the first polymerization step, monomer is inserted between the -(C=S)S moiety and the leaving group R. After polymerization is complete, the second monomer is added, polymerization is started by addition of a fresh amount of initiator, and monomer is inserted between the -(C=S)S- moiety and the end of the first block, with the RAFT functionality remaining at the chain end. Repeating this cycle of monomer addition and polymerization, it is possible to produce block copolymers. However, with this method the blocks have to be introduced in the chain step-by-step, which obviously means that to produce an n-block copolymer, a series of n polymerization steps is needed. To avoid inefficient blocking, this procedure should be performed starting with the monomers having the highest transfer rate to the RAFT agent. For the production of multiblock copolymers, this obviously is not the preferred route.


Scheme 11.

Block copolymer synthesis via a monofunctional RAFT agent

A second route towards block copolymers via RAFT comprises the use of symmetrical, bifunctional RAFT agents as well as symmetrical trithiocarbonates (Scheme 12 (a)). The symmetry in these compounds ensures that both arms are of approximately the same length and composition. With these RAFT agents, the number of polymerization steps required for (multi)block copolymer synthesis can be reduced. Scheme ı clearly demonstrates that for the synthesis of n-block copolymers, (n+1)/2 polymerization steps are required. Note that only block copolymers with an odd number of blocks can be synthesized with these compounds. The major difference between a trithiocarbonate and a bifunctional RAFT agent is the way the monomer is inserted into the RAFT agent. Using a bifunctional RAFT agent, monomer is inserted into the RAFT agent at both sides of leaving group R, while both dithiocarboxylate moieties will remain at the chain ends. In block copolymerization, the second block is thus built at the chain ends of the first block, see Scheme 12 (a). Using trithiocarbonate, monomer is inserted between both A groups and the trithiocarbonate moiety, and the trithiocarbonate moiety remains in the middle of the chain. When chain extending the first block, the second block is built in the middle of the chain, and the first block will shift to the outside of the chain as is depicted in Scheme 12 (b). In the case of trithiocarbonates, the R-S- moiety functionsas the activating group Z. [34]

The well-defined block copolymer of poly[ethylene oxide)-b-poly(N-isopropylacrlamide) (PEO-b-PNIPAM) was synthesized by Liang and coworkers via RAFT polymerisation using monofunctional PEO macro-RAFT agent [48] (Scheme 13).


Scheme 12.

Block copolymer synthesis via a bifunctional RAFT agent

Stenzel and coworkers reported the synthesis of amphiphilic block copolymers based on 2-methacrylamido glucopyranose (MAG) and 5’-O-methacryloyl uridine (MAU) via RAFT copolymerization using monofunctional macro-RAFT agent (Scheme 14) [49].

Block copolymers of methyl methacrylate (MMA) and tert-butyldimethylsilyl methacrylate (TBDMSMA) have been synthesized by Bressy and coworkers via RAFT polymerization technique (Scheme 15) [50].

New block copolymers with narrow molecular weight distribution (MWD=1.04-1.14) based on (2,3-epithiopropylmethacrylate) (ETMA), methyl methacrylate (MMA) and n-butylmethacrylate (nBMA) have been synthesized by Petzhold and coworkers via RAFT polymerization (Scheme 16) [51]


Scheme 13.

Synthetic procedure for PEO-b-PNIPAM by RAFT


Scheme 14.

(a) Synthesis of poly(2-methacrylamido glucopyranose) as a macroRAFT agent (b) synthesis of poly(2-methacrylamido glucopyranose)-b-poly( 5’-O-methacryloyl uridine) via RAFT using monofunctional macro-RAFT agent


Scheme 15.

Block copolymerization of TBDMSMA and MMA by the RAFT process


Scheme 16.

Schematic representation of the synthesis of the diblock copolymer via RAFT polymerization

Nanogel particles and double hydrophilic block copolymers were prepared by Hawker and co-workers using hydrophilic as well as amphiphilic poly(dimethylacrylamide) (PDMA) chain transfer agents (CTA) in RAFT precipitation polymerization (Scheme 17) [52].


Scheme 17.

Precipitation RAFT polymerization of NIPAM using a PDMA macroCTA followed by cross-linking with BIS

Guan et al. reported the synthesis of poly(dimethylsiloxane)-b-poly(2,2,3,3,4,4,4-heptafluorobutyl methacrylate)-b-poly(styrene) (PDMS-b-PHFBMA-b-PS) triblock copolymers by two-step RAFT polymerization [53]. For this purpose, firstly xanthate-capped PDMS was prepared as the PDMS-macro-RAFT agent. Then triblock copolymers were prepared by two step RAFT polymerization using the PDMS-macro-RAFT agent (Scheme 18).

Zhang and co-workers reported the synthesis of polystyrene-b-poly(acrylic acid)-b-polystyrene (PS-b-PAA-b-PS) tri block copolymers by RAFT polymerization using S,S’-Bis(α,α’-dimethyl-α’’-acetic acid)-trithiocarbonate (BDATC) as chain transfer agent (Scheme 19) [54].

Qupicky and co-workers reported the synthesis of dually responsive (temperature- and redox-responsive) multiblock copolymers of poly(N-isopropylacrlamide) (PNIPAAM) and poly(dimethylaminoethylmethacrylate) (PDMAEMA) by RAFT polymerization [55]. Well-defined bis(dithioester)-functionalized PNIPAM 3 and PDMAEMA 4 were prepared using 1,4-bis(thiobenzoylthiomethyl)benzene 1 and 1,4-bis(2-(thiobenzoylthio)prop-2-yl)benzene 2 as RAFT agents, respectively. Multiblock copolymers were synthesized in a single aminolysis/oxidation step from the bis(dithioester)-terminated PNIPAAM and PDMAEMA (Scheme 20).


Scheme 18.

The synthesis of PDMS-b-PHFBMA-b-PS triblock copolymers by two-step RAFT polymerization

Baum and Brittain reported the synthesis of surface immobilized diblock copolymer brush (Si/SiO2//PS-b-PDMA) using RAFT [56]. Styrene, methyl methacrylate, and N,N-dimethylacrylamide brushes were prepared under RAFT conditions using silicate surfaces that were modified with surface-immobilized azo initiators. Films with controlled thicknesses were produced. RAFT was also used to synthesize PS-b-PDMA and PDMA-b-PMMA block copolymer brushes that displayed reversible surface properties upon treatment with block-selective solvents. (Scheme 21).


Scheme 19.

The synthesis of PS-b-PAA-b-PS tri block copolymers by RAFT polymerization


Scheme 20.

The synthesis of dually responsive multiblock copolymers of PNIPAM and PDMAEMA by RAFT polymerization

Some of block copolymers derived using RAFT polymerization is given in Table 3.


Poly(2-methacryloxyethyl glucoside) (PMAOEGlc), poly(methyl 6-O-methacryloyl-D-mannoside) P(6-O-MAMMan), poly(methyl 6-O-methacryloyl-D-glucoside) P(6-O-MAMGlc), Poly(N-isopropylacrylamide) (PNIPAAM), Poly(D-glucofuranosyl)-6-methacrylamido hexanoate (PMAGlcC5), Poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA), poly(acryloyl glucosamine) (PAGA), poly(vinyl acetate) (PVAc), poly(vinyl pivalate) (PVPv), poly(vinyl benzoate) (PVBz), poly(2-hydroxyethyl methacrylate) (PHEMA).

Scheme 21.

Synthesis of surface immobilized diblock copolymer brush (Si/SiO2//PS-b-PDMA) using RAFT.

1st Segment2nd Segment3rd SegmentType of blockRef.

Table 3.

Some of block copolymers prepared using RAFT polymerization

3.3. Block copolymerization via Atom Transfer Radical Polymerization (ATRP)

Of the several controlled/”living” free radical polymerization techniques, ATRP seems to be the most versatile, being able to polymerize a variety of monomers, method to prepare block and graft copolymers. ATRP enables the synthesis of a wide range of (co)polymers with controlled molecular weight, narrow molecular weight distribution, and range of architectures and functionalities.

The synthesis of well-defined AB type diblock copolymers from styrene (S) and methyl acrylate (MA) via ATRP was reported by Schubert and co-workers [64]. Both synthetic routes starting with styrene as first block or methyl acrylate as first block are shown in Scheme 22.

1st Segment2nd Segment3rd SegmentType of blockRef.
AB (brushes)

Table 4.

Block copolymers prepared using ATRP


Scheme 22.

Schematic representation of synthetic strategy to block copolymers from styrene and methyl acrylate

The synthesis of ABA type triblock copolymers of poly(2-(dimethylamino)ethylmethacrylate)-b-polycaprolactone-b-poly(2-(dimethylamino) ethylmethacrylate) (PDMAEMA-b-PCL-b-PDMAEMA) via ATRP of DMAEMA using difunctional polycaprolactone (Br-PCL-Br) as macroinitator was reported by Jhurry and Motala-Timol (Scheme 23) [65].


Scheme 23.

Synthesis of triblock PDMAEMA-b-PCL-b-PDMAEMA copolymer

Huang et al. reported the preparation of amphiphilic triblock PMMA-b-PDMAEMA-b-PMMA and poly(methyl acrylate)-b-poly(methyl methacrylate)-b-poly(hydroxyethyl methacrylate) (PMA-b-PMMA-b-PHEMA) copolymer brushes grown from a surface via sequential low-temperature ATRP (Scheme 24) [66]


Scheme 24.

Synthesis of triblock copolymer brushes from gold surfaces by sequential ATRP.

Recently many studies on the synthesis of block copolymers via ATRP in the literature have been reported due to its advantages. Some of them are listed in Table 4.

4. Graft copolymerization

Graft copolymers are another class of segmented copolymers. As informed previously, many basic characteristics of block copolymers and graft copolymers are similar and no major difference exists between block copolymer synthesis and graft copolymer synthesis. The location of sites and functions are at the chain ends or on the chains, respectively:


“Grafting” is a method wherein monomers are covalently bonded (modified) onto the polymer chain. Graft copolymers can be obtained with three general approachs [80]:

  1. Grafting-onto: A preformed polymer with a reactive end-group is used a precursor, and then attached to the backbone. This method involve reaction of functional groups (Y) located at chain ends of one kind of polymer with another functional groups (X) which distributed randomly on the main chain of the other polymer (backbone).

  2. Grafting-from: The monomer is grafted from the backbone. “Grafting-from” is significantly more versatile than “grafting-onto”.

  3. Grafting-through in other words grafting via surface-attached monomers (macromonomers): In this approach, polymerizations are carried out at the presence of polymers (backbone) onto which functionalized monomers have been attached. The surface-attached monomers are incorporated into growing polymer chains in the same way as the monomers in solution (the monomers in solution are usually different from the surface-attached ones).

4.1. Graft copolymerization via NMP

Hua et al. prepared polystyrene grafted chitosan [81] (Scheme 25) and poly(sodium 4-styrenesulfonate) grafted chitosan [82] (Scheme 26) via NMP using chitosan-TEMPO macroinitiator.


Figure 8.

Schematic presentation of Grafting-through


Scheme 25.

Synthesis of Chitosan-g-PSt by NMP


Scheme 26.

Synthesis of Chitosan-g-PSS by NMP

Jaymand reported the synthesis and characterization of novel type poly(4-chloromethyl styrene-graft- 4-vinylpyridine)/TiO2 nanocomposite via NMP [83]. Firstly, poly(4-chloromethyl styrene)/TiO2 nanocomposite carrying TEMPO groups (PCMS-TEMPO/TiO2) was synthesized (Scheme 27) and then the controlled graft copolymerization of 4-vinylpyridine was initiated by PCMS-TEMPO/TiO2 as a macroinitiator (Scheme 28).


Scheme 27.

Synthesis of PCMS-TEMPO/TiO2 macroinitiator


Scheme 28.

Nitroxide-mediated living radical polymerization of 4-vinylpyridine onto PCMS-TEMPO/TiO2 macroinitiator

4.2. Graft copolymerization via RAFT polymerization

Neoh and co-workers reported the preparation of graft copolymers of poly(ethylene glycol)methyl ether methacrylate (PEGMA) with poly(vinylidene fluoride) (PVDF) [84] and poly(acrylic acid) (PAAc) with poly(vinylidene fluoride) (PVDF) [85] via RAFT polymerization. The peroxides generated on the ozone-pre-treated PVDF facilitated the thermally initiated graft copolymerization of PEGMA and PAAc in the RAFT-mediated process respectively (Scheme 29).


Scheme 29.

Schematic illustration of the processes of PEGMA graft copolymerization with the ozone-preactivated PVDF backbone by RAFT-mediated polymerization and the preparation of the PVDF-g-PEGMA MF membrane by phase inversion.

Perrier and co-workers performed grafting of styrene from cellulose substrate via RAFT polymerization [86]. The hydroxyl groups of cellulose fiber were converted into thiocarbonyl-thio chain transfer agent, and were further used to mediate the RAFT polymerization of styrene (Scheme 30).

Stenzel and co-workers prepared stimuli-responsive glycopolymer brushes composed of N-acryloyl glucosamine (AGA) and NIPAAM using RAFT polymerization [87]. The RAFT agent was immobilized on the surface of a treated silicon waver via covalent attachment using the Z-group (Scheme 31)

Hua et al. reported the controlled grafting modification of chitosan via RAFT polymerization using chitosan-RAFT agent. The chitosan was first modified with S-1-dodecyl-S’-(α,α’-dimethyl-α’’-acetic acid)trithiocarbonate (DDACT) to serve as RAFT agent, and then the controlled grafting polymerization of acrylic acid were performed [88]. Morimoto et al. reported the grafting of NIPAAM on polysaccarides by RAFT polymerization [89]. Mespouille et al. also reported the grafting of NIPAAM on aliphatic polycarbonates by RAFT polymerization [90]. Synthesis of poly(tert-butl methacrylate) graft-poly(dimethylsiloxane) graft copolymers via RAFT polymerization was reported by Hou and co-workers [91].


Scheme 30.

Synthesis of cellulose chain transfer agent for RAFT polymerization and their use to mediate styrene polymerization

4.3. Graft copolymerization via ATRP

In recent year’s chemical modification and particularly surface modification of natural polymers such as collagen, cellulose, chitosan etc. has become a popular method for providing a material with desirable properties for practical applications. Particularly ATRP has been proven to be versatile for the grafting of vinyl monomers on to natural polymers.

El Tahlawy & Hudson prepared chitosan macroinitiators by acetylation of chitosan with 2-bromo-isobutyryl bromide (EBİB) in the presence of pyridine as a base. Then chitosan macroinitiator was used to polymerize a methoxy-poly(ethylene glycol)methacrylate (MeO(PEG)MA) monomer [92]. Using a similar approach, Li et al. proposed the controlled synthesis of chitosan beads grafted with polyacrylamide via surface-initiated ATRP [93]. The bromide-end groups were immobilized on the surfaces of chitosan beads through reaction of –NH2 or –OH groups with EBİB (Scheme 32).


Scheme 31.

Synthesis of stimuli-responsive glycopolymer brushes using RAFT polymerization via Z-group approach

Arslan et al. reported the synthesis of brush type graft copolymers of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxyoctanoate) (PHO) with methylmethacrylate, (MMA), styrene, (S), and n-butylmethacrylate, (n-BuMA) by using ATRP via ‘‘grafting from’’ technique [94,95]. Firstly PHB and PHO were chlorinated by passing chlorine gas through their solution in CHCl3/ CCl4 (75/25 v/v) mixture and CCl4, respectively, in order to prepare chlorinated PHB, PHB-Cl, and chlorinated PHO, PHO-Cl, with different chlorine contents. Then ATRP of vinyl monomers was initiated by using PHA-Cl as macro initiators in order to obtain brushes containing PHAs (Scheme 33).


Scheme 32.

Schematic presentation of the immobilization of surface initiator and polymerization of vinyl monomers via ATRP


Scheme 33.

The synthesis of PHA-g-PMMA, PHA-g-PS, PHA-g-PBMA brush type graft copolymers via ATRP

Recently many studies on the synthesis of graft copolymers via ATRP in the literature have been also reported. Some of them are listed in Table 5.

5. Block and graft copolymerzation by combined techniques

In some cases, different controlled polymerization systems are combined to produce block and graft copolymers (see Table 6).

Lu et al reported the synthesis of block and graft copolymers of β-pinene and styrene by combination of living cationic polymerization and atom transfer radical polymerization methods (Scheme 34) [105].

Block copolymer synthesis via a combination of ATRP and RAFT using click chemistry was reported by Webster and co-workers (Scheme 35) [106].

1st Segment2nd SegmentRef.

Table 5.

Graft copolymers prepared using ATRP


Scheme 34.

Synthesis of poly(β-pinene)-b-polystyrene by combination of living cationic polymerization and atom transfer radical polymerization methods


Scheme 35.

Concept of combination of ATRP and RAFT using click chemistry.

Combined polymerization techniques Obtained composition References
Ring opening-ATRP
ATRP-cationic polym.
ATRP-macromonomer method
RAFT/MADIX-click Chemistry
NMP-iniferter technique
RAFT-click Chemistry
Ring opening-NMP
Dendrimer-like star block
AB type diblock
Bottle brush

Table 6.

Some examples of polymers obtained by combination of different controlled polymerization mechanisms

6. Conclusion

The synthesis of block and graft copolymers can be achieved via different techniques such as free radical, anionic, cationic, coordination, coupling, step growth, ring opening, changing polymerization mechanism (active centers transformation reactions). CRP enables the synthesis of a wide range of (co)polymers with controlled molecular weight, narrow molecular weight distribution, and wide range of architectures (i.e., comb, star, dendritic, etc.), composition (i.e., random, periodic, graft, etc.) and functionalities at moderate experimental conditions.


It is a pleasure to acknowledge for their contributions to my graduate students, at the Bülent Ecevit University.


1 - Lodge T.P2003Macromol. chem. phys. 204265273
2 - J. Ueda, M. Kamigaito, M. Sawamoto, 1998Macromolecules 312067626768
3 - H. Shinoda, P. J. Miller, K. Matyjaszewski, 2001Macromolecules 341031863194
4 - A. Noshay, J. E. Mc Grath, 1977Block Copolymers: Overview and Critical Survey, Academic Pres, New York.
5 - R. J. Ceresa, (ed, 1976Block and Graft Copolymerization, Vols. 1 and 2, Wiley, London.
6 - B. Hazer, 1989Handbook of Polymer Science and Technology, 1Synthesis and Properties, Edited by Nicholas P. Cheremisinoff, by Marcel Dekker Inc. 133176
7 - B. Hazer, 1997Handbook of Engineering Polymeric Materials, Edited by Nicholas P. Cheremisinoff, by Marcel Dekker Inc. 725734
8 - Y. Yağcı, M. K. Mishra, 1996Polymeric Materials Encyclopaedia, 1Salamone J. (ed.), by CRC Press Inc. USA, 789796
9 - A. Fradet, 1996Polymeric Materials Encyclopaedia, 1Salamone J. (ed.), by CRC Press Inc. USA, 797807
10 - M. K. Mishra, Y. Yağcı, 1996Polymeric Materials Encyclopaedia, 1Salamone J. (ed.), by CRC Press Inc. USA, 808814
11 - M. Ueda, 1999Prog. polym. sci. 24699730
12 - A. Bhattacharya, B. N. Misra, 2004Prog. polym. sci. 29767814
13 - H. Arslan, N. Yesilyurt, B. Hazer, 2007Journal of applied polymer science 10617421750
14 - H. Arslan, N. Yesilyurt, B. Hazer, 2008Macromol. symp. 2692333
15 - Y. Cai, M. Hartenstein, A. H. E. Müller, 2004Macromolecules 3774847490
16 - M. Zhang, T. Breiner, H. Mori, A. H. E. Müller, 2003Polymer 4414491458
17 - T. Sarbu, K. Lin, J. Spanswick, R. R. Gil, D. J. Siegwart, K. Matyjaszewski, 2004Macromolecules 3796949700
18 - I. S. Chung, K. Matyjaszewski, 2003Macromolecules 3629952998
19 - Y. Shen, S. Zhu, F. Zeng, R. Pelton, 2000Macromolecules 3353995404
20 - V. Coessens, T. Pintauer, K. Matyjaszewski, 2001Progress in polymer science 26337377
21 - X. Yuan, J. Lu, Q. Xu, L. Wang, 2005Polymer 4691869191
22 - S. Muthukrishnan, G. Jutz, X. Andre, H. Mori, A. H. E. Müller, 2005Macromolecules 38918
23 - S. Muthukrishnan, H. Mori, A. H. E. Müller, 2005Macromolecules 3831083119
24 - I. Ydens, P. Degee, P. Dubois, J. Libiszowski, A. Duda, S. Penczek, 2003Macromol. chem. phys. 204171179
25 - K. L. Beers, K. Matyjaszewski, 2001J. macromol. sci.-pure appl. chem. A387731739
26 - Z. Zhang, S. Ying, Q. Zhang, X. Xu, 2001J. polym. sci.: part A: polym. chem. 3926702676
27 - C. J. Hawker, A. Bosman, Harth. E. W.and, 2001Chem. rev.10136613688
28 - J. Nicolas, B. Charleux, O. Guernet, S. Magnet, 2005Macromolecules 3899639973
29 - S. G. Boyes, A. M. Granville, M. Baum, B. Akgün, B. K. Mirous, W. J. Brittain, 2004Surface science 570112
30 - C. E. Lipscomb, M. K. Mahanthappa, 2009Macromolecules 4245714579
31 - K. Matyjaszewski, 2002General Concepts and History of Living Radical Polymerization, In Handbook of Radical Polymerization; Matyjaszewski, K., Davis, T.P., eds. John Wiley and Sons, Inc.:Hoboken, 383386
32 - K. Matyjaszewski, J. Spanswick, 2005Controlled/living radical polymerization, Materials Today 832633
33 - T. E. Patten, K. Matyjaszewski, 1998Adv. Mater. 10901915
34 - R. Bussels, 2004Multi)block copolymer synthesis via controlled radical polymerization in aqueous dispersions / by Raf Bussels, Eindhoven:Technische Universiteit Eindhoven, Proefschrift.- 9-03862-825-0DATA LIBRARY TECHNISCHE UNIVERSITEIT EINDHOVEN.
35 - A. E. Müftüoğlu, M. A. Taşdelen, Y. Yağcı, M. K. Mishra, 2009Handbook of Vinyl Polymers: Radical Polymerization, Process and Technology CRC Press Taylor &Francis Group, New York, Ch11: 307344
36 - Bomsan A. W, Frechet J. M. J, Hawker C. J2001Polym. mater. sci. eng., 84376
37 - H. Choi, M. Park, S. Lee, S. C. Hong, 2008European polymer journal 4430873095
38 - A. Britze, J. Jacob, V. Choudhary, V. Moellmann, G. Grundmeier, H. Luftmann, D. Kuckling, 2010Polymer 5152945303
39 - E. Groison, S. Brusseau, F. D’Agosto, S. Magnet, R. Inoubli, L. Couvreur, B. Charleux, 2012ACS Macroletters 14751
40 - J. Ruehl, A. Nilsen, S. Born, P. Thoniyot, L. Xu, S. Chen, R. Braslau, 2007Polymer 4825642571
41 - S. Cheng, F. L. Beyer, B. D. Mather, R. B. Moore, T. E. Long, 2011Macromolecules 4465096517
42 - A. Narumi, T. Matsuda, H. Kaga, T. Satoh, T. Kakuchi, 2002Polymer 4348354840
43 - S. Thakur, N. A. Cohen, E. S. Tillman, 2008Polymer 4914834189
44 - C. Detrembleur, A. Debuigne, C. Jerome, T. N. T. Phan, D. Bertin, D. Gigmes, 2009Macromolecules 4286048607
45 - M. Maric, B. H. Lessard, V. Consolante, E. J. Y. Ling, 2011Reactive&Functional Polymers 7111371147
46 - E. Beaudoin, P. E. Dufils, D. Gigmes, S. Marque, C. Petit, P. Tordo, D. Bertin, 2006Polymer 4798106
47 - H. Okamura, Y. Takatori, M. Tsunooka, M. Shirai, 2002Polymer 4331553162
48 - J. Yan, W. Ji, E. Chen, Z. Li, D. Liang, 2008Macromolecules 4149084913
49 - S. Pearson, N. Allen, M. H. Stenzel, 2009J.of polym. sci.:part A:polymer chem., 4717061723
50 - M. N. Nguyen, C. Bressy, A. Margaillan, 2009Polymer 5030863094
51 - Sordi M. L. T, Riegel I. C, Ceschi M. A, Müller A. H. E, Petzhold C. L2010Eur. polym. j. 46336344
52 - Z. S. An, Q. H. Shi, W. Tang, C. K. Tsung, C. J. Hawker, G. D. Stucky, 2007J. am. chem. soc. 1291449314499
53 - C. Guan, Z. Luo, J. Qiu, P. Tang, 2010Eur. polym. j. 4615821593
54 - L. Zheng, Y. Chai, Y. Liu, P. Zhang, 2011e-Polymers 3918
55 - Y. You, Q. Zhou, D. S. Manickam, L. Wan, G. Mao, D. Qupicky, 2007Macromolecules 4086178624
56 - M. Baum, W. J. Brittain, 2002Macromolecules 35610615
57 - L. Albertin, M. H. Stenzel, C. Barner-Kowallik, L. J. R. Foster, T. P. Davis, 2005Macromolecules 3890759084
58 - Z. Öztürk, H. Komber, S. Gram, D. Schmaljohann, A. H. E. Müler, B. Voit, 2007Macromolecular chemistry and physics 20810351049
59 - L. Liu, C. Wu, J. Zhang, M. Zhang, Y. Liu, X. Wang, G. Fu, 2008J. polym. sci.: part A: polymer chemistry 4632943305
60 - A. E. Smith, X. Xu, S. E. Kirkland-York, D. A. Savin, C. L. Mc Cormick, Macromolecules, 2010
61 - L. Zhang, J. Bernard, T. P. Davis, C. Barner-Kowallik, M. H. Stenzel, 2008Macromolecular Rapid Communications 29123129
62 - C. E. Lipscomb, M. K. Mahanthappa, 2009Macromolecules 4245714579
63 - L. Albertin, M. Stenzel, C. Barner-Kowallik, L. J. R. Foster, T. P. Davis, 2004Macromolecules 3775307537
64 - A. Can, E. Altuntas, R. Hoogenboom, U. S. Schubert, 2010Eur. polym. j. 4619321939
65 - S. Motala-Timol, D. Jhurry, 2007Eur. polym. j. 4330423049
66 - W. Huang, J. Kim, G. L. Baker, M. L. Bruening, 2003Nanotechnology 1410751080
67 - D. A. Shipp, J. Wang, K. Matyjaszewski, 1998Macromolecules 3180058008
68 - Y. Nakagawa, P. J. Miller, K. Matyjaszewski, 1998Polymer 392151635170
69 - K. Ohno, Y. Tsujii, T. Fukuda, 1998J. of polym. sci.: part A: polym. chem. 3624732481
70 - M. Cassebras, S. Pascual, A. Polton, M. Tardi, J. Vairon, 1999Macromol. rapid commun. 20261264
71 - X. Wang, N. Luo, S. Ying, Q. Liu, 2000Eur. polym. j. 36149156
72 - S. B. Lee, A. J. Russell, K. Matyjaszewski, 2003Biomacromolecules 413861393
73 - C. Strissel, K. Matyjaszewski, O. Nuyken, 2003Macromol. chem. phys. 20411691177
74 - M. Licciardi, Y. Tang, N. C. Billingham, S. P. Armes, 2005Biomacromolecules 610851096
75 - C. Xu, T. Wu, J. D. Batteas, C. M. Drain, K. L. Beers, M. J. Fasolka, 2006Applied surface science 25225292534
76 - R. Paris, Fuente. J. Luis la, 2008Eur. polym. j. 4414031413
77 - E. K. Oikonomou, E. K. Pefkianakis, G. Bokias, J. K. Kallitsis, 2008Eur. polym. j. 4418571864
78 - F. Suriano, O. Coulembier, P. Degee, P. Dubois, 2008J. of polym. sci.: part A: polym. chem. 4636623672
79 - G. Pasparakis, C. Alexander, 2008Angew. chem. int. ed. 4748474850
80 - R. C. Advincula, W. J. Brittain, K. C. Caster, J. Ruhe, 2004Polymer Brushes: Synthesis, Characterization, Applications (John Wiley &Sons, New York).
81 - D. Hua, W. Deng, J. Tang, J. Cheng, X. Zhu, 2008International journal of biological macromolecules, 434347
82 - J. Jiang, D. Hua, J. Jiang, J. Tang, X. Zhu, 2010Carbohydrate polymers 81358364
83 - M. Jaymand, 2011Polymer 5247604769
84 - Y. Chen, L. Ying, W. Yu, E. T. Kang, K. G. Neoh, 2003Macromolecules 3694519457
85 - L. Ying, W. H. Yu, E. T. Kang, K. G. Neoh, 2004Langmuir 2060326040
86 - D. Roy, J. T. Guthrie, S. Perrier, 2005Macromolecules 381036310372
87 - M. H. Stenzel, L. Zhang, W. T. S. Huck, 2006Macromol. rapid commun. 2711211126
88 - D. Hua, J. Tang, J. Cheng, W. Deng, X. Zhu, 2008Carbohydrate polymers 7398104
89 - N. Morimoto, X. Qiu, F. M. Winnik, K. Akiyoshi, 2008Macromolecules 4159855987
90 - L. Mespouille, F. Nederberg, J. L. Hedrick, P. Dubois, 2009Macromolecules 4263196321
91 - J. Li, L. Yi, H. Lin, R. Hou, 2011Journal of polymer science part A: polymer chemistry 4914831493
92 - K. Tahlawy, S. M. Hudson, 2003Journal of applied polymer science 89901912
93 - N. Li, R. Bai, C. Liu, 2005Langmuir 211178011787
94 - H. Arslan, N. Yeşilyurt, B. Hazer, 2007J. of app. polym. sci. 10617421750
95 - H. Arslan, N. Yeşilyurt, B. Hazer, 2008Macromol. symp. 2692333
96 - Munro N. H, Hanton L. R, Moratti S. C, Robinson B. H2009Carbohydrate polymers 77496505
97 - T. Meng, X. Gao, J. Zhang, J. Yuan, Y. Zhang, J. He, 2009Polymer 50447454
98 - Y. Liu, V. Klep, B. Zdyrko, I. Luzinov, 2004Langmuir 2067106718
99 - S. Muthukrishnan, M. Zhang, M. Burkhardt, M. Drechsler, H. Mori, A. H. E. Müler, 2005Macromolecules 3879267934
100 - C. Gao, S. Muthukrishnan, W. Li, J. Yuan, Y. Xu, A. H. E. Müler, 2007Macromolecules 4018031815
101 - J. Wang, Y. Xu, H. Xu, F. Zhang, Y. Qian, B. Zhu, 2008J. of app. polym. sci. 10929142923
102 - Y. Wang, X. Pei, X. He, Z. Lei, 2005Eur. polym. j. 41737741
103 - F. J. Xu, Q. J. Cai, E. T. Kang, K. G. Neoh, 2005Langmuir 2132213225
104 - L. G. Bach, Md R. Islam, Y. T. Jeong, Y. S. Gal, K. T. Lim, 2012Applied surface science 25828162822
105 - J. Lu, H. Liang, A. Li, Q. Cheng, 2004European polymer journal 40397402
106 - M. J. Nasrullah, A. Vora, D. C. Webster, 2011Macromol. chem. phys. 212539549
107 - J. L. Hedrick, M. Trollsas, C. J. Hawker, B. Atthoff, H. Claesson, A. Heise, R. D. Miller, 1998Macromolecules 3186918705
108 - A. B. Düz, Y. Yağcı, 1999European polymer journal 3520312038
109 - H. Shinoda, P. J. Miller, K. Matyjaszewski, 2001Macromolecules 3431863194
110 - M. A. Tasdelen, Y. Yagci, A. L. Demirel, T. Biedron, P. Kubisa, 2007Polymer bulletin 58653663
111 - S. Wang, Z. Cheng, J. Zhu, Z. Zhang, X. Zhu, 2007Journal of polymer science: part A: polymer chemistry 4553185328
112 - D. Quemener, M. Le Hellaye, C. Bissett, T. P. Davis, C. Barner-Kowallik, M. H. Stenzel, 2008Journal of polymer science: part A: polymer chemistry 46155173
113 - D. Gromadzki, R. Makuska, M. Netopilik, P. Holler, J. Lokaj, M. Janata, P. Stepanek, 2008European polymer journal 445971
114 - X. Xue, J. Zhu, Z. Zhang, Z. Cheng, Y. Tu, X. Zhu, 2010Polymer 5130833090
115 - G. J. M. Habraken, M. Peeters, P. D. Thornton, C. E. Koning, A. Heise, 2011Biomacromolecules 1237613769
116 - D. Zehm, A. Laschewsky, H. Liang, J. P. Rabe, 2011Macromolecules 4496359641