Bio-based core–shell casein-based silica nano-composite latex by double-in situ polymerization: Synthesis, characterization and mechanism
Bio-based core–shell casein-based silica nano-composite latex by double-in situ polymerization: Synthesis, characterization and mechanism
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DOI：
10.1016/j.cej.2013.04.079
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发表时间：
2013-07
影响因子：
15.1
通讯作者：
Qunna Xu;Jianzhong Ma;Jianhua Zhou;Yuyu Wang;Jing Zhang
中科院分区：
文献类型：
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作者：
Qunna Xu;Jianzhong Ma;Jianhua Zhou;Yuyu Wang;Jing Zhang
以酪蛋白、己内酰胺、丙烯酸酯、四乙氧基硅烷和硅烷偶联剂为原料，采用双原位乳液聚合法合成了酪蛋白基二氧化硅纳米复合乳胶作为生物基成膜材料。本研究的目的是解决酪蛋白膜硬、脆、耐水性差等缺陷的问题。为了研究二氧化硅对乳液和薄膜性能的影响，分别通过傅里叶变换红外光谱（FT-IR）、透射电子显微镜（TEM）、热重分析（TG）、扫描电子显微镜（SEM）、原子力显微镜（AFM）和X射线光电子能谱（XPS）对所得纳米复合材料和控制系统（不含二氧化硅）进行表征。傅立叶变换红外光谱表明纳米二氧化硅颗粒与基质成功结合，以及预期的聚丙烯酸酯接枝到酪蛋白链上。所得复合乳胶的形貌表现出明显的核壳结构，平均尺寸约为 80 nm，壳厚度的增加表明二氧化硅被包裹在颗粒的外层，这通过 TEM 结果得到了验证。热重分析表明，与对照系统（不含纳米二氧化硅）相比，酪蛋白基二氧化硅纳米复合材料的热稳定性增强。 SEM、AFM 和 XPS 结果证实，大量二氧化硅均匀分散在薄膜外层附近，并且酪蛋白基二氧化硅复合材料中无机相和有机相之间表现出良好的相容性。此外，与不含二氧化硅的乳胶膜相比，含有二氧化硅的杂化乳胶膜表现出更高的疏水性、更低的吸水性、增强的拉伸强度和降低的柔韧性。
Casein-based silica nano-composite latex as bio-based film-forming material was synthesized from casein, caprolactam, acrylate, tetraethoxysilane and silane coupling agent via double-in situ emulsion polymerization. The objective of this study was to solve the problem of casein film deficiencies, such as hard, brittle and poorer water resistance. To investigate the influences of silica on properties of the latexes and films, the resultant nano-composite and the control system (without silica) were both characterized by flourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), thermogravimetry (TG), scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), separately. FT-IR spectra suggested the successful incorporation of nano-silica particles with the matrix as well as the expected grafting of polyacrylate onto casein chains. Morphology of resultant composite latex exhibited evident core–shell structure with the average size of around 80 nm, and the improved shell thickness indicated the encapsulation of silica on the outer layer of the particle, which was verified by TEM results. TG analysis demonstrated the enhanced thermostability of casein-based silica nano-composite, in comparison with the control system (without nano-silica). SEM, AFM and XPS results confirmed that the substantial silica dispersed uniformly near the outer layer of the films, and showed good compatibility between the inorganic and organic phases in the casein-based silica composite. Additionally, compared with the latex film without silica, the hybrid latex film containing silica showed higher hydrophobicity, lower water absorption, enhanced tensile strength and decreased flexibility.