Copolymer , graft living

Keywords Review, Copolymer, Controlled/living radical polymerization, Block, Graft, Gradient, Statistical... 

Another kind of amphiphilic block copolymer-grafted MWCNTs was prepared by sequential ATRP of styrene and fBA using CNT-Br-1 as the initiator, followed by hydrolysis of the poly(tert-butyl acrylate) (P BA) block into PAA," as shown in Figure 5.12. The polymer amount of the second block can also be adjusted by the feed ratio of fBA to polystyrene (PS)-grafted MWCNTs, demonstrating the living characteristics of the block copolymerization. The core-shell amphiphilic nano-object can self-organize into a film at the interface of chloroform and water. 

Preparation of PVA graft copolymers by living cationic polymerization. Scheme 2.28... 

Considerable progress has been made in the synthesis of tailor-made block copolymers, and to some extend also to the corresponding graft copolymers, by living ionic polymerization, controlled free-radical polymerization and quite recently by non-covalent coupling techniques. Numerous examples of linear water-soluble A-B and A-B-A structures were described in addition to the possibility of functionalization of these copolymers with specific groups, such as reactive double bonds, ionic groups, fluorescence labels, either at the chain ends and/or at the junction of the blocks. 

Similarly, grafting living polynorbornene onto polymers that contain carbonyl groups formed by conventional polycondensation reactions leads to triblock copolymers, (100), having properties totally different from those of the homopolymers [67],... 

In conclusion, by overcoming the disadvantage of the previous synthetic methods for the preparation of hyperbranched polymers, we designed an all-new Seesaw-type macromonomer strategy to construct perfect hyperbranched model samples with uniform subchains. In onr stndy, we successfully prepared various kinds of Seesaw-type macromonomers, snch as homopolymers, triblock copolymers and diblock copolymers. Using these maCTomonomers as precursors, we have further prepared a series of perfect hyperbranched homopolymers, block copolymers, graft copolymers and hetero-snbchain copolymers by a combination of controlled/ living polymerization and click chemistry. Various solution properties of these novel hyperbranched (co) polymers in dilnte and semidilute solntions have been studied in detail. More specifically, the main achievements of this work are as follows ... 

Hong, S.C., Jia, S., Teodorescu, M. et al. (2002) Polyolefin graft copolymers via living polymerization techniques Preparation of poly(n-butyl acrylate)-gra/t-polyethylene through the combination of Pd-mediated living olefin polymerization and atom transfer radical polymerization. Journal of Polymer Science, Part A Polymer Chemistry, 40,2736-2749. 

Group-Transfer Polymerization. Living polymerization of acrylic monomers has been carried out using ketene silyl acetals as initiators. This chemistry can be used to make random, block, or graft copolymers of polar monomers. The following scheme demonstrates the synthesis of a methyl methacrylate—lauryl methacrylate (MMA—LMA) AB block copolymer (38). LMA is CH2=C(CH2)COO(CH2) CH2. 

Many block and graft copolymer syntheses involving transformation reactions have been described. These involve preparation of polymeric species by a mechanism that leaves a terminal functionality that allows polymerization to be continued by another mechanism. Such processes are discussed in Section 7.6.2 for cases where one of the steps involves conventional radical polymerization. In this section, we consider cases where at least one of the steps involves living radical polymerization. Numerous examples of converting a preformed end-functional polymer to a macroinitiator for NMP or ATRP or a macro-RAFT agent have been reported.554 The overall process, when it involves RAFT polymerization, is shown in Scheme 9.60. 

Graft copolymers made by living polymerization processes are often called polymer brushes because of the uniformity in graft length that is possible. The basic approaches to graft copolymers also have some analogies with those used in making block and star copolymers. 

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