Optimization of synthesis and thermoresponsive characteristics of Hydroxypropyl Cellulose nanogels

Hydroxypropyl cellulose (HPC) nanogels with thermoresponsive properties were synthesized through a novel polymerization pathway. This study determined the optimal concentrations of surfactant and reaction temperature by evaluating the solution dispersity across various HPC molecular weights. An inverse relationship was observed between the molecular weight of HPC and the required concentration of the surfactant dodecyltrimethylammonium bromide (DTAB); polymers with higher molecular weights needed less surfactant. Nanogels were formed at double the lower critical solution temperature (LCST) of the polymer, with divinyl sulfone (DVS) employed as a crosslinking agent to establish the polymer network. This novel synthesis method ultimately resulted in nanogels with a low polydispersity index. Dynamic light scattering (DLS) was used to assess the influence of crosslinker concentration on thermoresponsive behavior, revealing a consistent decrease in average size as the crosslinker molarity increased. Additionally, small-angle neutron scattering (SANS) was utilized to investigate how the internal structural changed with the temperature, highlighting marked deviations from the typical fuzzy sphere morphology. This study of the morphology of HPC nanogels as a function of temperature and molecular weight allows us to better understand the distribution of the polymeric network, investigate the phase transition, and determine the effect of molecular weight on the final size of the nanogels.