CT/SF/CNC/CaCO_(3)仿生复合膜制备及其特性

Preparation and comprehensive properties of bionic CT/SF/CNC/CaCO_(3) biocomposite flims

基于天然甲壳纲生物壳体组成成分与多层级排列结构的仿生启示,以可再生生物质甲壳素(CT)、丝素蛋白(SF)、纤维素纳米晶(CNC)和无机纳米碳酸钙(CaCO_(3))为4种主要原料,采用溶液蒸发诱导自组装和流延法制备具有“三明治”结构的CT/SF/CNC/CaCO_(3)仿生复合膜,通过扫描电镜、紫外-可见光吸收光谱、傅里叶变换红外光谱、X射线衍射仪、热重分析仪和万能力学试验机等分析手段对复合膜的微观形貌、透明性、化学基团、结晶性、热稳定性和力学性能分别进行分析表征。结果表明:不同条件下制备的CT/SF/CNC/CaCO_(3)仿生复合膜以及将4个复合组元直接混合制备所得的复合膜中均未出现CNC彩虹色区域。复合膜的透过率随纳米碳酸钙质量分数的升高而降低,且增加基体层或者CNC层的厚度会进一步降低复合膜的透明度,四组元直接混合后制备的复合膜透明性较低,且脆性大。纳米碳酸钙的存在影响了丝素蛋白与甲壳素间的结合作用。“三明治”结构的形成以及CNC、纳米碳酸钙的引入可协同提升复合膜的热稳定性能和力学性能,但过多或过少的纳米碳酸钙均不利于复合膜强度和韧性的提升。质量分数0.10%的纳米碳酸钙且2倍CNC厚度的CT/SF/CNC/CaCO_(3)仿生复合膜具有优异的综合力学和热稳定性能,其拉伸强度和断裂伸长率分别为13.4 MPa和141%,且第2热降解阶段的最大热降解温度提升10.5℃。

With the increasing shortage crisis of petrochemical resources as well as the environmental pollution caused by traditional petroleum-based polymers,the developing trend for the materials industry further tends to be composable,functional,green and low-carbon.Based on the biomimetic inspiration of natural crustacea shell composition and multilayer arrangement structure,renewable biomasses including chitin(CT),silk fibroin(SF) and cellulose nanocrystal(CNC),as well as inorganic nano-calcium carbonate(CaCO_(3)) were used as four main raw materials.The three natural polymers have the important advantages of abundant amount,low cost,excellent biocompatibility,and environmental-friendly properties.Nano-calcium carbonate is an inorganic functional material with large specific surface area,strong chemical stability,non-toxicity and odorless property.The CT/SF/CNC/CaCO_(3) biocomposite films with a sandwich structure were prepared by combining the solution evaporation-induced self-assembly with the facile casting method.The target properties including micro-morphology,transparency,chemical groups,crystallinity,thermal stability,and mechanical properties were characterized by the scanning electro-microscope,ultraviolet-visible spectrophotometry,Fourier transform infrared spectroscopy,X-ray diffraction,thermalgravimetric analyzer and universal mechanical testing machine.The results showed that the CT/SF/CNC/CaCO_(3) biocomposite films prepared under different conditions cannot be observed rainbow-colored areas derived from CNC special optical property.The transparency of the biocomposite films decreased with the increase in mass fraction of the nano-calcium carbonate.Increasing the thickness of the matrix layer or CNC layer would reduce the transparency of the biocomposite films.The biocomposite films made from direct mixing with the four components displayed the lowest transparency and the highest brittleness.The presence of nano-calcium carbonate affected the binding between silk fibroin and chitin.The construction of the sandwich laminated structure as well as the introduction of CNC and nano calcium carbonate can synergistically improve the thermal stability and mechanical properties of biocomposite films,but too much or too little nano calcium carbonate was not conducive to the improvement of the strength and toughness.The CT/SF/CNC/CaCO_(3) biomimetic biocomposite films with 0.10% mass fraction of nano-calcium carbonate and the twice thickness of CNC exhibited the excellent mechanical properties and thermal stability.Its tensile strength and elongation at break were 13.4 MPa and 141%,respectively,and the maximum temperature of thermal degradation temperature in the second stage increased by 10.5 ℃.This study provides the information support and the theoretical reference for the development and application of novel functional biocomposite membranes in the fields of green food packaging,high-strength and high-toughness films,flexible devices and sensor carriers,barrier materials and biological tissue engineering materials.