Poly dimethylsiloxane macromonomers

Narrow distribution in the backbone length as well as in the chemical composition or the branch frequency may be expected from a living-type copolymerization between a macromonomer and a comonomer provided the reactivity ratios are close to unity. This appears to have been accomplished to some extent with anionic copolymerizations with MMA of methacrylate-ended PMMA, 29, and poly(dimethylsiloxane) macromonomers, 30, which were prepared by living GTP and anionic polymerization, respectively [50,51]. Recent application [8] of nitroxide (TEMPO)-mediated living free radical process to copolymerizations of styrene with some macromonomers such as PE-acrylate, la, PEO-methacr-ylate, 27b, polylactide-methacrylate, 28, and poly(e-caprolactone)-methacrylate, 31, may be a promising approach to this end. 

The synthesis of poly(dimethylsiloxane)macromonomers was also carried out anionically. The cyclic trimer D3 of dimethylsiloxane may be polymerized anionically, using lithium trimethylsilanolate as the initiator. Deactivation of the silanolate end groups may be performed with chlorosilyl functions. Yamashita et al. 29) successfully applied the unsaturated deactivators I and II... 

Thus, Yamashita succeeded in synthesizing co-methacryloyl and co-styryl-poly-dimethylsiloxane macromonomers which have subsequently been copolymerized with styrene and methyl methacrylate. 

FIGURE 4.12 Structure of poly(lactide) and poly(dimethylsiloxane) macromonomers and macroinitiators [83]. 

Shinoda, H., and Matyjaszewski, K. (2001). Improving the structural control of graft copol5mers. Copolymerization of poly(dimethylsiloxane) macromonomer with methyl methacrylate using RAFT polymerization. Macromolecular Rapid Communications, 22(14) 1176-1181. 

Poly(methyl methacrylate)-g-poly(dimethylsiloxane) copolymers have been prepared by free radical copolymerizations of acrylate-functional siloxane macromonomers (29) with methyl methacrylate. Siloxane macromonomers (29) of between 1,000 and 20,000 molecular weight were utilized to give a range of copolymers with between 4 and 17 wt% silicone115. 

The ability of these macromonomers to participate in free-radical copolymerization was not tested. They were used28b) for the synthesis of tri- and multiblock copolymers by means of hydrosilylation, i.e. an addition reaction between vinylsilyl groups and the —Si — H functions at the chain end of poly(dimethylsiloxane)mole-cules. 

Difunctional polydimethylsiloxane macromonomers were prepared by Katz et al. 30) in a completely different way using a cationic process. The polymerization of the cyclic tetramer of poly(dimethylsiloxane) (D4) was carried out in the presence of a disiloxane containing carboxy groups. Since this compound acts as a transfer agent carboxylic groups are introduced as end groups into the polymer molecules. These groups are subsequently reacted with 2-hydroxyethyl acrylate. The obtained diunsaturated PDMS macromonomers... 

Sugimoto, H. Nishino, G. Koyama, H. Daimatsu, K. Inomata, K. Nakanishi, E., Preparation and Morphology of Transparent Polyfmethyl Methacrylate) Poly(dimethylsiloxane) Hybrid Materials Using Multifunctional Sihcone Macromonomer. J.Appl. Polym. Sci. 2012,124,1316-1322. 

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)... 

Segmented terpolymers of poly(alkyl methacrylate)-g-poly(D-lactide)/poly(dimethylsiloxane) (PLA/PDMS) were prepared by combination of a grafting through technique (macromonomer method) and controlled/living radical polymerization such as atom transfer radical polymerization (ATRP) or reversible addition-fragmentation chain transfer polymerization. In a single-step approach, the low molecular weight methacrylate monomer (methyl methacrylate... 

Poly(dimethylsiloxane) and poly(ethylene oxide) macromonomers were commercial products.PCL macromonomer was obtained in reaction of the terminal hydroxyl end-groups of PCL with methacryloyl chloride. Poly(D,L-lactide) methacrylate was obtained by using 2-hydroxyethyl methacrylate as an initiator of the D,L-lactide polymerization and stannous acrylate as a catalyst. 

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