Hydrolysis-Induced Self-Assembly of High-χ–Low-<i>N</i> Bottlebrush Copolymers
Mingqiu Hu, Xindi Li, Javid Rzayev, Thomas P. Russell
Abstract
Densely grafted bottlebrush statistical copolymers (BSCPs) and bottlebrush block copolymers (BBCPs) were synthesized with polystyrene (PS) and poly(solketal methacrylate) (PSM) side chains grafted to a polynorbornene backbone. The PSM chains could be hydrolyzed into poly(glycerol monomethacrylate) (PGM), significantly increasing the segmental interaction parameter (χ). Self-assembly of the polymers was studied with small-angle X-ray scattering before and after hydrolysis. The well-known rapid self-assembly of BBCPs by thermal annealing was retarded after hydrolysis, due to a large χ between the segments of the brushes. Utilizing the well-ordered lamellar morphology before hydrolysis, we developed a solid-state hydrolysis method to achieve high-χ BBCPs with long-range order. Analysis of the Porod scattering invariant showed that for high-χ BBCPs, the density of each phase deviated from the density of linear homopolymer melts due to multiple restrictions placed on the configuration of the brushes.