Monitoring Collapse of Uniform Cylindrical Brushes with a Thermoresponsive Corona in Water.

We generated rod-like micelles of uniform length by living crystallization-driven self-assembly of a polyferrocenylsilane (PFS) block copolymer PFS 26 - b -POEGMA 163 in a methanol-ethanol mixture and then transferred these micelles to water. The corona chains consisted of poly(oligoethylene glycol methacrylate) that had a lower critical solution temperature (LCST) of 40.5 °C in water. We used a combination of static (SLS) and dynamic (DLS) multiangle light scattering to determine the dimensions of these cylindrical brush micelles in solution. Measurements carried out in dilute solution in water over a series of temperatures from 23 to 50 °C showed that the collapse transition was broad and continuous, upon both heating and cooling. This response is different from the collapse transition of POEGMA 163 homopolymer in water, which occurs over a very narrow temperature range. Thus, we show that the collapse transition of a cylindrical brush has important features in common with the collapse of a brush of thermoresponsive polymers on a planar surface.