ab8b01135_si_001.pdf (681.21 kB)
Hydrolytic Degradation of PCL–PLLA Semi-IPNs Exhibiting Rapid, Tunable Degradation
journal contribution
posted on 2018-11-28, 00:00 authored by Lindsay
N. Woodard, Melissa A. GrunlanAccelerating the
rate of polyester hydrolytic degradation is of
interest for numerous biomedical applications. Poly(ε-caprolactone)
(PCL) and poly(L-lactic acid) (PLLA) have been extensively studied
as thermoplastic homo- and copolymers as well as PCL–PLLA blends.
PCL–PLLA semi-interpenetrating networks (semi-IPNs) prepared
with thermoplastic PLLA embedded in a cross-linked PCL diacrylate
(PCL–DA) network were previously shown to exhibit uniquely
accelerated degradation behavior that increased with PLLA content.
Herein, their properties before and during degradation were further
investigated to reveal the origin of this behavior and to better understand
the semi-IPNs’ degradation mechanism. Initially, semi-IPNs
exhibited restricted spherulite size and irregularity, as well as
a phase-separated morphology and a PLLA-rich surface. Under accelerated
conditions (1 M NaOH, 37 °C), degradation was revealed to be
initiated in PLLA regions. It was also found that the PCL–DA
cross-linking and PCL–PLLA phase separation played the largest
roles in degradation rates and that semi-IPNs underwent faster rates
of degradation than an analogous blend largely due to the reduced
crystallinity of PCL–DA. Nonaccelerated conditions (PBS [pH
= 7.4], 37 °C) up to 56 weeks, which had never before been studied
for polyester semi-IPNs, revealed similar trends in degradation rates.