Surface-modified halloysite nanotubes reinforced poly(lactic acid) for use in biodegradable coronary stents

Poly(lactic acid) (PLA) was reinforced halloysite nanotubes (HNTs) in this study. To improve dispersion and interfacial adhesion of HNTs within the PLA matrix, HNTs were surface modified with 3-aminopropyltriethoxysilane (ASP) prior to compounding with PLA. PLA/ASP-HNTs nanocomposites were characterized by differential scanning calorimetry (DSC), Fourier transfer infrared spectroscopy (FTIR), surface wettability, thermogravimetric analysis, transmission electron microscopy (TEM), and tensile testing. The hemocompatibility and cytocompatibility of PLA and PLA composites were investigated and the in vitro degradation process of PLA/ASP-HNTs composites was investigated for a period of 6 months by gel permeation chromatography, FTIR, weight loss measurement, DSC, and tensile testing. PLA and all PLA composites were blood compatibile and non-cytotoxic. TEM analysis revealed that HNTs agglomeration in PLA matrix was reduced by surface treatment with ASP. ASP-HNTs had better reinforcing effect than unmodified HNTs evidenced by tensile testing. ASP-HNTs appeared to increase the hydrolytic degradation process as measured by weight measurement. PLA/ASP-HNTs composites displayed 12.1% weight loss and 30.6% average molecular weight reduction while retaining 74% of Young's modulus by the 24th week of degradation. Based on this data, the reinforcement of PLA using ASP-HNTs may prove beneficial for applications such as biodegradable stents. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46521.