Synthesis and properties of polymer brush consisting of poly(phenylacetylene) main chain and poly(dimethylsiloxane) side chains

A novel polymer brush consisting of poly(phenylacetylene) (PPA) main chain and poly(dimethylsiloxane) (PDMS) side chains was synthesized by the polymerization of phenylacetylene-terminated PDMS macromonomer (M-PDMS). The macromonomer was prepared by the esterfication of monohydroxy-ended PDMS (PDMS-OH, degree of polymerization (DP) = 42) with p-ethynylbenzoic acid. The polymerization of M-PDMS using [(nbd)RhCl]2/Et3N catalyst led to polymer brush, poly(M-PDMS), with Mn up to 349 000 (DP of main chain 104). Poly(M-PDMS) with narrow molecular weight distribution (Mn = 39 900, Mw/Mn = 1.11) was obtained with a vinyl-Rh catalyst, [Rh{C(Ph)CPh2}(nbd){P(4-FC6H4)3}]/(4-FC6H4)3P. Poly(M-PDMS)s were brown to orange viscous liquids and soluble in organic solvents such as toluene and CHCl3. The UV-vis absorptions of poly(M-PDMS) were observed in the range of 350-525 nm, which are attributable to the PPA main chain.