Li Kai, Huang Junchao, Gao Huichang, Zhong Yi, Cao Xiaodong, Chen Yun, Zhang Lina, Cai Jie
College of Chemistry and Molecular Sciences, Wuhan University , Wuhan, 430072, People's Republic of China.
School of Materials Science and Engineering, South China University of Technology , Guangzhou, 510641, People's Republic of China.
Biomacromolecules. 2016 Apr 11;17(4):1506-15. doi: 10.1021/acs.biomac.6b00109. Epub 2016 Mar 14.
Incorporation of nanofillers into aliphatic polyesters is a convenient approach to create new nanomaterials with significantly reinforced mechanical properties compared to the neat polymers or conventional composites. Nanoporous cellulose gels (NCG) prepared from aqueous alkali hydroxide/urea solutions can act as alternative reinforcement nanomaterials for polymers with improved mechanical properties. We report a simple and versatile process for the fabrication of NCG/poly(L-lactide-co-caprolactone) (NCG/P(LLA-co-CL) nanocomposites through in situ ring-opening polymerization of L-lactide (LLA) and ε-caprolactone (ε-CL) monomers in the NCG. The volume fraction of the NCG in the nanocomposites was tunable and ranged from 4.5% to 37%. Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) results indicated that P(LLA-co-CL) were synthesized within the NCG and partially grafted onto the surface of the cellulose nanofibrils. The glass-transition temperature (Tg) of the NCG/P(LLA-co-CL) nanocomposites could be altered by varying the molar ratio of LLA/ε-CL and was affected by the volume fraction of NCG. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) images confirmed that the interconnected nanofibrillar cellulose network structure of the NCG was finely distributed and preserved in the P(LLA-co-CL) matrix after polymerization. The dynamic mechanical analysis (DMA) results showed remarkable reinforcement of the tensile storage modulus (E') of the P(LLA-co-CL) nanocomposites in the presence of NCG, especially above the Tg of the P(LLA-co-CL). The modified percolation model agreed well with the mechanical properties of the NCG/P(LLA-co-CL) nanocomposites. The introduction of NCG into the P(LLA-co-CL) matrix improved the mechanical properties and thermal stability of the NCG/P(LLA-co-CL) nanocomposites. Moreover, the NCG/P(LLA-co-CL) nanocomposites have tunable biodegradability and biocompatibility and potential applications in tissue engineering repair, biomedical implants, and packing.
将纳米填料掺入脂肪族聚酯中是一种便捷的方法，可用于制备新型纳米材料，与纯聚合物或传统复合材料相比，其机械性能得到显著增强。由氢氧化碱/尿素水溶液制备的纳米多孔纤维素凝胶（NCG）可作为聚合物的替代增强纳米材料，从而改善其机械性能。我们报道了一种简单通用的方法，通过在NCG中原位开环聚合L-丙交酯（LLA）和ε-己内酯（ε-CL）单体来制备NCG/聚（L-丙交酯-共-己内酯）（NCG/P(LLA-co-CL)）纳米复合材料。纳米复合材料中NCG的体积分数可调，范围为4.5%至37%。傅里叶变换红外光谱（FT-IR）、X射线衍射（XRD）和差示扫描量热法（DSC）结果表明，P(LLA-co-CL)在NCG内部合成，并部分接枝到纤维素纳米原纤表面。NCG/P(LLA-co-CL)纳米复合材料的玻璃化转变温度（Tg）可通过改变LLA/ε-CL的摩尔比来改变，并受NCG体积分数的影响。原子力显微镜（AFM）和扫描电子显微镜（SEM）图像证实，NCG相互连接的纳米原纤纤维素网络结构在聚合后精细地分布并保留在P(LLA-co-CL)基体中。动态力学分析（DMA）结果表明，在存在NCG的情况下，P(LLA-co-CL)纳米复合材料的拉伸储能模量（E'）显著增强，尤其是在P(LLA-co-CL)的Tg以上。改进的逾渗模型与NCG/P(LLA-co-CL)纳米复合材料的力学性能吻合良好。将NCG引入P(LLA-co-CL)基体中改善了NCG/P(LLA-co-CL)纳米复合材料的机械性能和热稳定性。此外，NCG/P(LLA-co-CL)纳米复合材料具有可调的生物降解性和生物相容性，在组织工程修复、生物医学植入物和包装方面具有潜在应用。
