New super-hairy semi-rigid polymers

Abstract

Living monofunctional poly(tetramethylene oxyde) (PTMO) (THF bulk polymerization initiated at 20°C by methyl triflate) was end capped by reaction with 3-(dimethylamino)propyl isocyanide. Selective and quantitative quaternization of the tertiary amine function results in the straightforward synthesis of PTMO macromonomers of the isocyanide type with a fairly good control of molecular weight and polydispersity (M̄n ≈ 1800–4400, M̄w/M̄n ≈ 1.2). Their homopolymerization at 40°C in highly concentrated methanol solution (macromonomer weight fraction ≈0.80) initiated by NiCl2 quantitatively yields the corresponding poly(macromonomers) of high degrees of polymerization (DPw > 103) and of very unusual and maximum branching density: one graft chain per every backbone carbon atom. According to a semi-quantitative analysis of their radius of gyration, as derived from light scattering measurements (EtOAc-iPrOH 9 : 1 by vol., Et4N+CF3SO3−0.05 M), an increase of the intrinsic rigidity (persistence length) of the worm-like poly-(isonitrile) backbone induced by the PTMO branches cannot be ruled out. These super-hairy polymers may be considered as exotic comb-shaped cationic poly(amphiphiles) of potential interest as new lyotropic and thermotropic materials.