Poly allyl group terminated

Figure 6.8 shows the MALDI spectrum of the fraction of copolymer eluted at 27.9 ml. The MALDI spectrum of a fraction of copolymer eluted at 27.9 ml is well resolved and this allows the characterisation of the end groups. All the peaks were assigned to sodium alkoxide terminated oligomers of poly(EO-co-PO) copolymers. Nevertheless vinyl/hydroxyl and allyl/hydroxyl terminated oligomers with different ratios of EO to PO and, more unlikely, cyclic species are also possible. 

After the development of catalyst-transfer condensation polymerization of polythiophene, the block copolymer of polythiophene and poly(alkyl acrylate) was prepared more easily. Vinyl-terminated polythiophene was first prepared. The vinyl group was converted to the 2-hydroxyethyl group by hydroboration, followed by esterification with 2-bromopropionyl bromide to give a macroinitiator for ATRP (Scheme 50) [142]. The allyl-terminated polythiophene was also converted to a macroinitiator for ATRP, which led to block copolymers of polythiophene and poly (aUcyl methacrylate) [143] or poly(acrylic acid) [144]. This allyl-terminated polythiophene has a bromine atom at the other end, which has an adverse effect on the purity of block copolymers prepared by ATRP. Hawker, Kim, and coworkers reported that replacement of the bromine with a phenyl group, followed by functionalization of the allyl group for the ATRP initiator unit, allowed access to narrower molecular weight distribution diblock copolymers of polythiophene and ATRP-derived vinyl block [145]. 

Sun and coworkers (181) used a different approach to prepare block copolymers. A polyoxyethylene with a terminal allyl group was reacted with acrylic acid to produce a graft copolymer polyoxyethylene-g-poly (acrylic acid). 

Since allylic groups facilitate chain-terminating six-membered cycliza-tion, polymerization of vinyl silane was attempted. Unusual hydrolytic crosscoupling of two chlorosilanes has provided an efficient route to two monomers, vinyltris(dimethylsiloxy)silane and tris(dimethylvinylsiloxy)silane. The hy-drosilation reaction under Pt catalysts of these AB3 monomers afforded hyperbranched poly(siloxysilane) polymers, with hydride or vinyl functional groups on the outer sphere. The functional groups on the surface of both polymers was modified further with a wide variety of reagents [73]. 

A new series of functionalized poly(arylene ether ketone)s and their use as modifiers for bismaleimide resins has recently been published (96). In contrast with the former work in this area, the functional groups are not terminal but randomly distributed along the backbone of the poly(arylene ether ketone). The synthesis involves the reaction of 4,4 -difluorobenzophenone and the potassium bisphenates of bisphenol-A and 2,2 -bis(3-allyl-4-hydroxyphenyl) hexafluoro-isopropane or mixtures thereof in DMAc at 155 °C as outlined in Fig. 31. The concentration of the o,o -diallylbisphenol employed in the synthesis determines the concentration of functional propenyl groups. 

Well-defined macromonomers of poly(BVE), poly(IBVE), and poly(EVE) with co-methacrylate end group [91] were prepared by living cationic polymerization of the corresponding monomers initiated by trifluoromethanesulfonic add in CH2C12 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-lu-tidine or with 41 to produce macromonomers with Mn 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. 

According to the reactants, either diblock or triblock copolymers can be obtained. For instance, PEO-fc-PDMS-b-PEO triblock copolymer and PEO-PDMS diblock copolymers were prepared in high yields by hydrosilylation of a telechelic PDMS which exhibits SiH functions (Mn = 1000) with monofunctional allyl-terminated PEO with Mn = 350 and 500 and telechelic diallyl PEO (Mn = 600), respectively [123]. Their dilute solution properties were investigated. Similarly, interesting PS-b-PDMS thermoplastics have been synthesized from a polystyrene fitted at chain end with a vinyl silane function which reacts with a PDMS bearing SiH end-groups [124]. In addition, hydrosilylation has been used to prepare original copolymers from a,co-disilyl-PDMS 25 and either a,oj-diallyl-polysulfone [125] or a,oj-diallyl poly (L-lactide) (PLLA) as follows [126] ... 

Lipase catalysts have been used for functionalization of polymers. A terminal hydroxy group of poly-(e-CL) was reacted with carboxylic acids using lipase CA catalyst to give end-functionalized polyesters.231 Lipase MM catalyzed the regioselective transesterification of the terminal ester group of oligo (methyl methacrylate) with allyl alcohol.232 In the PPL-catalyzed reaction of racemic 2,2,2-trichloroethyl 3,4-epoxybutanoate with hydroxy-terminated PEG, the... 

Nucleophilic substitution with the phenolate anion derived from EC-20 and K2C03 induced 30% substitution, along with elimination of hydrogen bromide.331 Phosphonium groups can be introduced at the polystyrene and poly(MA) terminal via reaction with EC-21,355 and methyl groups with Me3Al (EC-22).356 An allyl terminal is obtained also via an ionic pathway, where the polystyryl carbocation generated... 

A variety of CEs with tailorable physico-chemical and thermo-mechanical properties have been synthesized by appropriate selection of the precursor phenol [39,40]. The physical characteristics like melting point and processing window, dielectric characteristics, environmental stability, and thermo-mechanical characteristics largely depend on the backbone structure. Several cyanate ester systems bearing elements such as P, S, F, Br, etc. have been reported [39-41,45-47]. Mainly three approaches can be seen. While dicyanate esters are based on simple diphenols, cyanate telechelics are derived from phenol telechelic polymers whose basic properties are dictated by the backbone structure. The terminal cyanate groups serve as crosslinking sites. The polycyanate esters are obtained by cyanation of polyhydric polymers which, in turn, are synthesized by suitable synthesis protocols. Thus, in addition to the bisphenol-based CEs, other types like cyanate esters of novolacs [37,48], polystyrene [49], resorcinol [36], tert-butyl, and cyano substituted phenols [50], poly cyanate esters with hydrophobic cycloaliphatic backbone [51], and allyl-functionalized cyanate esters [52] have been reported. 

Hydroxy-terminated polymers prepared in this manner were used to build more complex macromolecular architectures such as graft copolymers [50] or block copolymers [51]. Using a 1,3-dithiepine instead of a 1,3-dioxepine as sacrificial monomer, allylic thiol polymer end groups could be obtained [52]. The poly(l,3-dithiepine) block was cleaved (sacrificed) under hydrogenation conditions using Raney-Nickel. 

It may be noted here that unsaturated terminal groups containing allylic chlorine are also thought to contribute to the instability of poly(vinyl chloride). Such groups can arise by disproportionation during polymerization ... 

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