Time-resolved SANS analysis of micelle chain exchange behavior: thermal crosslink driven by stereocomplexation of PLA-PEG-PLA micelles

Abstract

Time-resolved small-angle neutron scattering (TR-SANS) was used to study the dynamic chain exchange behavior of the micelle mixture from poly(l-lactide)-b-poly(ethylene glycol)-b-poly(l-lactide), PLLA-PEG-PLLA, and its enantiomeric copolymer, PDLA-PEG-PDLA. The mixture of enantiomeric micelle solutions underwent a sol-to-gel transition as a consequence of temperature increase to yield a thermo-responsive hydrogel. The mechanism of gelation is hypothesized as a chain exchange process between L-micelles and D-micelles followed by the formation of stereocomplex crystals from PLLA and PDLA blocks. Stereocomplex crystals that have different physicochemical properties from PLLA or PDLA crystals re..