Qiu Zhaobin, Wang Huishan, Xu Changling
State Key Laboratory of Chemical Resource Engineering, Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, China.
J Nanosci Nanotechnol. 2011 Sep;11(9):7884-93. doi: 10.1166/jnn.2011.4714.
Biodegradable poly(epsilon-caprolactone) (PCL)/multi-walled carbon nanotubes containing carboxylic groups (f-MWNTs) nanocomposites were prepared via simple melt compounding at low f-MWNTs loading in this work. Scanning and transmission electron microscopy observations indicate a homogeneous and fine distribution of f-MWNTs throughout the PCL matrix. The effect of low f-MWNTs loading on the crystallization, mechanical properties, and controlled enzymatic degradation of PCL in the nanocomposites were studied in detail with various techniques. The experimental results indicate that the incorporation of f-MWNTs enhances both the nonisothermal crystallization peak temperature and the overall isothermal crystallization rate of PCL in the PCL/f-MWNTs nanocomposites relative to neat PCL; moreover, the incorporation of a small quantity of f-MWNTs has improved apparently the mechanical properties of the PCL/MWNTs nanocomposites compared to neat PCL. The enzymatic degradation of neat PCL and the PCL/f-MWNTs nanocomposites at low f-MWNTs loading was studied in detail. The variation of weight loss with enzymatic degradation time, the surface morphology change, the reduced film thickness, the appearance of f-MWNTs on the surface of the films, and the almost unchanged molecular weight after enzymatic degradation suggest that the enzymatic degradation of neat PCL and the PCL/f-MWNTs nanocomposites may proceed via surface erosion mechanism. The presence of f-MWNTs reduces the enzymatic degradation rate of the PCL matrix in the nanocomposites compared with that of the pure PCL film.
在本研究中，通过简单的熔融共混法，在低羧基化多壁碳纳米管（f-MWNTs）负载量的条件下制备了可生物降解的聚己内酯（PCL）/羧基化多壁碳纳米管纳米复合材料。扫描电子显微镜和透射电子显微镜观察结果表明，f-MWNTs在整个PCL基体中分布均匀且细微。采用多种技术详细研究了低f-MWNTs负载量对纳米复合材料中PCL的结晶、力学性能以及可控酶降解的影响。实验结果表明，相对于纯PCL，在PCL/f-MWNTs纳米复合材料中加入f-MWNTs提高了PCL的非等温结晶峰温度和整体等温结晶速率；此外，与纯PCL相比，加入少量f-MWNTs明显改善了PCL/MWNTs纳米复合材料的力学性能。详细研究了纯PCL和低f-MWNTs负载量的PCL/f-MWNTs纳米复合材料的酶降解情况。重量损失随酶降解时间的变化、表面形态变化、膜厚度减小、膜表面f-MWNTs的出现以及酶降解后分子量几乎不变，表明纯PCL和PCL/f-MWNTs纳米复合材料的酶降解可能通过表面侵蚀机制进行。与纯PCL膜相比，f-MWNTs的存在降低了纳米复合材料中PCL基体的酶降解速率。
