Macromonomers cross-polymerization

The structure analyses of two special types of dlacetylene "monomers," dlyne dimers and polydiyne macromonomers, are reviewed and preliminary results on the conversion and chromic behavior of one specific system, poly(l,8-nonadlyne) (F18N) are presented. Structure analyses of these materials before and after solid state polymerization allows a qualitative understanding of the dlacetylene polymerization. Cross-polymerized P18N has been shown to display solvatochromlc and thermochromlc behavior, even though this material Is Insoluble and Infusible. Examination of Initial optical spectroscopic data of the chromic behavior as a function of conversion, as well as consideration of the chromic behavior of conventional diacetylenes, leads to a possible explanation of the chromic behavior of crosspolymerlzed P18N. 

As in the case of PS (Section 8.2.1) polymers formed by living radical polymerization (NMP, ATRP, RAFT) have thermally unstable labile chain ends. Although PMMA can be prepared by NMP, it is made difficult by the incidence of cross disproportionation.42 Thermal elimination, possibly by a homolysis-cross disproportionation mechanism, provides a route to narrow polydispersity macromonomers.43 Chemistries for end group replacement have been devised in the case of polymers formed by NMP (Section 9.3.6), ATRP (Section 9.4) and RAFT (Section 9.5.3). 

Other approaches include the use of difunctional olefins such as 1,7-octadiene, 1,9-decadiene, or para-(3-butenyl)styrene.875 While the former method also generates chain cross-linking (thus unprocessable polymer gels), the latter leads only to LCB formation through hydrogenolysis after a secondary styrene insertion. Tandem Zr/Fe catalysis has been used as well.876 The preparation of iPP with PS branches has been achieved by co-polymerization of propylene with allyl-terminated PS macromonomers.877... 

More recently, Schubert and coworkers has made tailor made macromonomers bearing oxetane moiety which is cross-linkable in the presence of cationic species [151]. Recently developed ATRP has been recognized as a useful method to polymerize monomers bearing different functionalities such as epoxides in the side chain that could find potential applications in coatings and adhesives. Scheme 11.47 illustrates the preperation of polymers with oxetanes as pendant groups that are preserved through ATRR The resulting polymer is notably cross-linkable when small amount of cationic initiator is supplied. 

Kim et al. [46,47] reported the synthesis of fluorosilicone block copolymers of poly(perfluoroalkylethyl acrylate)-fc-poly(3-[m s(trimethylsilyloxy)-silyl] propyl methacrylates) (PFA-i>-PSiMAs) by a three-step synthetic approach. In the first step, a PFA macromonomer (PFAM) was made by free radical polymerization. Thereafter, a condensation reaction was applied to prepare the PFAM initiator (PFAMI). Finally, the PFAMI and SiMA were reacted to prepare the PFA-i>-PSiMAs block copolymers. In early studies, synthesis of fluorosilicone block copolymers was reported by Boutevin et al. [48-50]. However, two-step hydrosilylation was carried out to prepare the photo-cross-linkahle fluorinated PDMS as reported by Boutevin et al. [48]. In another study, Luo et al. [51] prepared poly(dimethylsiloxane)- -poly(2,2,3,3, 4,4,4-heptafluorobutyl methacrylate- -poly(styrene)... 

Audouin F, Knoop RJI, Huang J, Heise A (2010) Star polymers by cross-linking of linear poly (benzyl-L-glutamate) macromonomers via free-radical and RAFT polymerization, a simple route toward peptide-stabilized nanoparticles. J Polym Sci A Polym Chem 48 4602-4610... 

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