Synthesis of poly[dimethylsiloxane-block-oligo(ethylene glycol)methyl ether methacrylate]:an amphiphilic copolymer with a comb-like block

摘要

AB amphiphilic comb-like block copolymers of poly(oligo[ethylene glycol] methyl ether methacrylate)and polydimethylsiloxane were synthesised with a methodology based on atom transfer radical polymerization(ATRP).The anionic ring opening polymerisation of hexamethylcyclotrisiloxane followed by reaction with 3-(chlorodimethylsilyl)propyl 2-bromo-2-methylpropanoate propyldimethylchlor-osilane gave suitable macroinitiators for the ATRP of oligo[ethylene glycol] methyl ether methacrylate.The latter synthetic procedure was optimised by performing a number of syntheses varying the reaction solvent,catalytic complex and the temperature used.Copolymers with relatively high polydispersity indices(M_w/M_n>1.3)could be synthesised at room temperature by employing a Cu(I)Br:N,N,N',N',N"-pentamethyldiethylenetriamine complex in n-propanol with Cu(II)Br.The optimum reaction conditions employed a Cu(I)Cl:N-(n-propyl)-2-pyridyl(methanimine)complex with an n-propanol/water mixture or toluene as solvent at 90 degC.This gave block copolymers of the desired molecular weights and polydispersity indices of less than 1.1.The block copolymers were characterised with ~1H NMR and ~13C NMR spectroscopy and size exclusion chromatography.