Telechelic polystyrene block

The chemical modification of homopolymers such as polyvinylchloride, polyethylene, poly(chloroalkylene sulfides), polysulfones,poly-chloromethylstyrene, polyisobutylene, polysodium acrylate, polyvinyl alcohol, polyvinyl chloroformate, sulfonated polystyrene block and graft copolymers such as poly(styrene-block-ethylene-co-butylene-block-styrene), poly(1,4-polybutadiene-block ethylene oxide), star chlorine-telechelic polyisobutylene, poly(lsobutylene-co-2,3-dimethy1-1,3-butadiene), poly(styrene-co-N-butylmethacrylate) cellulose, dex-tran and inulin, is described. 

Yamashita, Y, Iwaya, Y, and Ito, K. (1975) Block copolymerization. Polymerization of NCA of methyl D-glutamate by telechelic polystyrene having glycyl groups as active chain ends. Makromolekulare Chemie, 176,1207-1216. 

The quantum yield of polymerization is 6.72 and for photoinitiation < / = 2.85 x 10 . The polystyrene produced with this initiator shows photosensitivity when irradiated with UV light (A = 280 nm). This polymer, which carries two photosensitive end groups of - SC(S) N(CH3)2, behaves as a telechelic polymer and it is useful for production of ABA block copolymer. 

These results indicate that if polydienes and similar polymers can be prepared quantitatively with tertiary amine terminal groups, then they can be combined with other halogen functional polymers using established techniques to create interesting new block copolymer systems. For example, consider the reaction between telechelic pyridine terminated polybutadiene and monofunctional bromine terminated polystyrene (equation 4) -the latter has been prepared in 95% yield. >it The product would be an ABA... 

Investigations were mainly devoted to the synthesis of telechelic polymers and copolymers rather than to living radical polymerization. In particular, from 1960, Imoto et al. [234] started surveys on the synthesis of block copolymers from this method. Thus, polystyrene-i>-poly(vinyl alcohol) diblock copolymer... 

The ABA-type block copolymers B-86 to B-88 were synthesized via termination of telechelic living poly-(THF) with sodium 2-bromoisopropionate followed by the copper-catalyzed radical polymerizations.387 A similar method has also been utilized for the synthesis of 4-arm star block polymers (arm B-82), where the transformation is done with /3-bromoacyl chloride and the hydroxyl terminal of poly(THF).388 The BAB-type block copolymers where polystyrene is the midsegment were prepared by copper-catalyzed radical polymerization of styrene from bifunctional initiators, followed by the transformation of the halogen terminal into a cationic species with silver perchlorate the resulting cation was for living cationic polymerization of THF.389 A similar transformation with Ph2I+PF6- was carried out for halogen-capped polystyrene and poly(/>methoxystyrene), and the resultant cationic species subsequently initiated cationic polymerization of cyclohexene oxide to produce... 

Interestingly, K-TEMPO probes in monoionic block copolymers of type polystyrene-polyisoprene (notation PS-PI-S, where S stands for the spin probe) exhibited homogeneous dynamics, ie, a relatively narrow, monomodal distribution of rotational correlation times by contrast, the same probes in zwitterionic block copolymers of type Q-PS-PI-S (where Q stands for a quaternary ammonium group) exhibited heterogeneous dynamics, ie, a bimodal distribution of rotational correlation times (87). By comparison of results for telechelic homopolsrmeric... 

XIII). (b) Show how these CTAs can be used to synthesize functional telechelic product by combined RAFT polymerization and click chemistry. Consider for the discussion a speci c case of the synthesis of an a, w-telechelic copolymer having OH group at each end and consisting of polystyrene (PSt) and po y N,N-dimethhylacrylamide) (PDMA) blocks of approximately 50 and 90 monomer units, respectively. 

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