Influence of molecular weight on PNIPAM brush modified colloidal silica particles

• DOI: 10.1039/c8sm01824c
• Publication Date: 2018-12-03T10:34:15Z
• Authors: Ben A. Humphreys; Stuart W. Prescott; Timothy J. Murdoch; Andrew Nelson; Elliot P. Gilbert; Grant B. Webber; Erica J. Wanless
• Keywords: Colloidal particle

The effect of molecular weight and temperature on the phase transition internal structure poly(N-isopropylacrylamide) brush modified colloidal silica particles was investigated using dynamic light scattering (DLS) small angle neutron (SANS) between 15 45 °C. Dry particle analysis utilising transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR) thermogravimetric (TGA) all confirmed thickness polymer shell increased as a function polymerisation time. Hydrodynamic diameter electrophoretic mobility results revealed that transitioned from swollen shells to collapsed conformation 35 dispersions were electrosterically stabilised over entire range investigated, with minimal thermal hysteresis recorded. Modelling hydrodynamic enabled calculation lower critical solution (LCST) which thickness. determined via SANS showed at low temperatures (18 25 °C) decayed radially away substrate, while block-like 60% volume fraction present 40 Radial separation evident intermediate (30 32.5 sample having greater in dense inner region these temperatures.