142 Advances in Polymer Science Editorial Board: A. Abe. A.-C ...

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54 B. Charleux, R. Faust idenced by SEC. Moreover, 1 H and 13 C NMR analyses showed quantitative reaction with the malonate ion and high structural integrity. Particularly, polymerization or side reaction of the vinyl ether function of the quencher could not be detected. The vinylic protons of this vinyl ether end group were recognized together with the other ones of the capping agent. The end functionality was determined using 1 H NMR spectroscopy. According to calculation, each polymer chain carried one vinyl ether terminal. The same synthetic method was successfully applied with 2-(benzoyloxy)ethyl vinyl ether (BzOVE) which was polymerized using the HI/I 2 initiating system in toluene at –15 °C. Quantitative termination was performed with 36 used in 10–20-fold excess. More recently, the same quencher 36 was used to prepare poly(vinyl ether)s block copolymers with a polymerizable vinyl ether end group [90]. Sequential living cationic polymerization of AcOVE and IBVE was carried out with the HI/ZnI 2 system in toluene at –15 °C. After quenching with 36, well-defined block copolymer macromonomers were obtained: H- (poly(AcOVE)) m-(poly(IBVE)) n-C(COOC 2H 5) 2-CH 2CH 2-O-CH=CH 2 with m= 5/n=15 and m=10/n=30. Further living cationic polymerization of those macromonomers bearing a vinyl ether end group will be described in Sect. 3.3.2. A hydroxy function is also able to react quantitatively with living end of poly(vinyl ether)s resulting in an acetal end group which, however, has poor stability in acidic media. A proton trap should be added in order to scavenge the protons released during the coupling process. Various end-capping agents with a primary alcohol and a polymerizable double bond were used to produce poly(vinyl ether) macromonomers. The more widely used was 2-hydroxyethyl methacrylate (HEMA, 37) [91–94] but some alcohols with an allylic or olefinic group were also reported such as allyl alcohol (38) [91], 2-[2-(2-allyloxyethoxy)ethoxy] ethanol (39) [92] and 10-undecen-1-ol (40) [92]. Another capping agent with a methacrylate ester group, 2-(dimethylamino)ethyl methacrylate (41) with a tertiary amine as the coupling nucleophilic function [91] was also reported. In that case, capping results in the formation of a quaternary ammonium salt. (37) (38) (39) (40) (41)
Synthesis of Branched Polymers by Cationic Polymerization 55 Well-defined macromonomers of poly(BVE), poly(IBVE), and poly(EVE) with w-methacrylate end group [91] were prepared by living cationic polymerization of the corresponding monomers initiated by trifluoromethanesulfonic acid in CH 2 Cl 2 at –30 °C in the presence of thiolane as a Lewis base. After complete conversion, the polymers were quenched with 37 in the presence of 2,6-lutidine or with 41 to produce macromonomers with M n up to 10,000 g mol –1 , with narrow MWD, bearing one polymerizable methacrylate function per molecule. The same polymers were also quenched with 38 in the presence of 2,6-lutidine to give poly(vinyl ether)s with an allylic terminal group. A vinyl ether with a mesogenic side group, 3-[4-cyano-4'-biphenyl)oxy]propyl vinyl ether, was polymerized at 0 °C in CH 2 Cl 2 with trifluoromethanesulfonic acid as an initiator in the presence of dimethylsulfide [92]. 3-[4-cyano-4'-biphenyl)oxy]propyl vinyl ether Three macromonomers were obtained after quenching with 37, 39, and 40 respectively. All had a well defined structure as evidenced by SEC and NMR analyses, with DP n close to 6 and narrow MWD (M w /M n =1.09–1.13) and with F n very close to 1. Macromonomers of poly(octadecyl vinyl ether) were prepared by cationic polymerization although this technique is difficult since the corresponding ODVE monomer has a high melting point and poor solubility at low temperature [93]. The polymerization was initiated by the trimethylsilyl iodide/1,1-diethoxyethane system in the presence of ZnI 2 (initiator solution was prepared at – 40 °C) and was carried out in toluene at 0 or 10 °C. Linearity of M n with conversion was observed up to 6000 g mol –1 . At higher M n , deviation was observed and this was assigned to transfer to the monomer. However, although transfer leads to dead chains with a terminal unsaturation, it was shown that upon addition of 37 as a capping agent, all the chains were quenched irrespective of their end group. Actually, the dead chains could also react with the alcoholic quencher after their protonation by HI released in the reaction of the same quencher with the active chains. Thus, although controlled polymerization was not achieved, quantitative end-functionalization of poly(ODVE) with 37 could be obtained. Short macromonomers (M n
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142 Advances in Polymer Science Edi
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Branched Polymers I Volume Editor:
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Volume Editor Dr. Jacques Roovers I
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Preface While books have been writt
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Contents Synthesis of Branched Poly
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Synthesis of Branched Polymers by C
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Poly(macromonomers): Homo- and Copo
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Poly(macromonomers), Homo- and Copo
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Dendrimers and Dendrimer-Polymer Hy
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Author Index Volumes 101-142 Author
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Author IndexVolumes 101-142 231 Dun
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Author Index Volumes 101-142 233 Ka
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Author Index Volumes 101-142 235 Og
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Author Index Volumes 101-142 237 Su
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Subject Index Addition-fragmentatio
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Subject Index 241 Microphases 11z,
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