Thermo-Responsive Copolymers Based on Poly(N-isopropylacrylamide) and Poly[2-(methacryloyloxy)ethyl phosphorylcholine]: Light Scattering and Microscopy Experiments

Aqueous self-assembly of thermosensitive triblock copolymers based on poly(N-isopropylacrylamide) and poly[2-(methacryloyloxy) ethyl phosphorylcholine] (PNIPAM(m)-PMPCn-PNIPAM(m) and PNIPAM(m)-PMPCn-S-S-PMPCn-PNIPAM(m)) were studied using light scattering (SLS and DLS), TEM and fluorescence experiments. These techniques were used to investigate the morphological transition as a function of the temperature, below and above the LCST of the PNIPAM, at various triblock copolymer concentrations ranging from dilute to semi-dilute regimes. Below the LCST and at low concentrations, aqueous solutions show micellar behavior, while above the LCST self-assembly leading to large nanoparticles stabilized with PMPC chains. Such behavior is the onset of a gel-like phase transition observed at higher concentrations.