Small-angle x-ray scattering to discern microstructure of semicrystalline polyanhydrides for drug delivery.
Polyanhydride copolymers based on 1,6-bis(p-carboxyphenoxy)hexane (CPH) and sebacic acid (SA) are bioerodible, semicrystalline polymers that have been used for drug delivery. In addition to their semicrystallinity, these materials also exhibit microphase separation in the amorphous phase. This complex phase behavior, combined with the disparity in the erosion rates of the two different chemical moieties, leads to a complex erosion kinetics that can be used to tailor drug release kinetics. Thus, accurate design of drug delivery devices requires a detailed description of the microphase separation. Here, we employ in situ synchrotron small-angle X-ray scattering (SAXS) to explore the microstructure of these materials. First, we examine the crystallization kinetics of the homopolymers and CPH-SA copolymers. Next, we perform experiments on poly(CPH)/poly(SA) homopolymer blends in the miscible melt in order to discern the segment-segment interaction parameter, {chi}{sub CPH-SA}. This parameter predicts the enthalpy of mixing poly(CPH) and poly(SA) at the monomer level and can be used to predict the phase behavior of the blend. It also offers insights into the thermodynamics that drive the microphase separation in the copolymers. The homopolymer phase diagram has an upper-critical solution temperature and compares well with cloud point data obtained from optical microscopy and predictions of the interaction parameter from molecular simulation.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- SC
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 942090
- Report Number(s):
- ANL/IPNS/CP-113427
- Journal Information:
- Adv. X-ray Anal., Journal Name: Adv. X-ray Anal. Journal Issue: 2005 Vol. 48
- Country of Publication:
- United States
- Language:
- ENGLISH
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