Synthesis and solution properties of a temperature-responsive PNIPAM-b-PDMS-b-PNIPAM triblock copolymer

摘要

In this paper, we report the synthesis and self-assembly of a novel thermoresponsive PNIPAM(60)-b-PDMS70-b-PNIPAM(60) triblock copolymer in aqueous solution. The copolymer used a commercially available precursor modified with an atom transfer radical polymerization (ATRP) initiator to produce an ABA triblock copolymer via ATRP. Small-angle neutron scattering (SANS) was used to shed light on the structures of nanoparticles formed in aqueous solutions of this copolymer at two temperatures, 25 and 40 A degrees C. The poly(dimethylsiloxane) block is very hydrophobic and poly(N-isopropylacrylamide) (PNIPAM) is thermoresponsive. SANS data at 25 A degrees C indicates that the solutions of PNIPAM-b-PDMS-b-PNIPAM copolymers form well-defined aggregates with presumably core-shell structures below cloud point temperature. The scattering curves originating from nanoparticles formed at 40 A degrees C in 100% D2O or 100% H2O were successfully fitted with the Beaucage model describing aggregates with hierarchical structure.