Multi-scale phase separation in poly(d,l-lactide-co-glycolide) and palmitic acid blends using neutron and X-ray scattering†

Abstract

In this work neutron and X-ray scattering are used to quantitatively characterize multi-scale phase separation in a model blend of poly(D,L-lactide-co-glycolide) or poly(D,L-lactide), both synthetic biodegradable polymers, and palmitic acid. We find that phase separation occurs on two different length scales from tens of nanometers to microns. Moreover, the large-scale phase separation mechanism is sensitive to the lactide to glycolide ratio of the polymer matrix and can limit the growth of nanoscale domains of the dispersed palmitic acid. The multiscale structure in these composite materials is directly tied to function in pharmaceutical applications where phase separation and small molecule crystallization are factors that determine controlled release behaviors and drug efficacy.