Amphiphilic Bottlebrush Block Copolymers: Analysis of Aqueous Self-Assembly by Small-Angle Neutron Scattering and Surface Tension Measurements

• DOI: 10.1021/acs.macromol.8b02366
• Publication Date: 2018-12-31T18:51:36Z
• Authors: Mohammed Alaboalirat; Luqing Qi; Kyle J. Arrington; Shuo Qian; Jong K. Keum; Hao Mei; Kenneth C. Littrell; Bobby G. Sumpter; Jan-Michael Y. Ca...; Rafael Verduzco; John B. Matson
• Keywords: 01 natural sciences; 0104 chemical sciences

A systematic series of 16 amphiphilic bottlebrush block copolymers (BCPs) containing polystyrene and poly(N-acryloylmorpholine) (PACMO) side chains were prepared by a combination of atom-transfer radical polymerization (ATRP), photoiniferter polymerization, and ring-opening metathesis polymerization (ROMP). The grafting-through method used to prepare the polymers enabled a high degree of control over backbone and side-chain molar masses for each block. Surface tension measurements on the self-assembled amphiphilic bottlebrush BCPs in water revealed an ultralow critical micelle concentration (cmc), 1–2 orders of magnitude lower than linear BCP analogues on a molar basis, even for micelles with >90% PACMO content. Combined with coarse-grained molecular dynamics simulations, fitting of small-angle neutron scattering traces (SANS) allowed us to evaluate solution conformations for individual bottlebrush BCPs and micellar nanostructures for self-assembled macromolecules. Bottlebrush BCPs showed an increase in a...