水性含氟聚氨酯纳米SiO2复合乳液的研究
基于两步法原理，以正硅酸乙酯为前躯体，盐酸为催化剂，水和无水乙醇为溶剂，制备硅溶胶。再将硅溶胶与 APTES 封端的聚氨酯进行混合，制备出水性聚氨酯/SiO2有机无机杂化材料。硅溶胶的加入提高了水性聚氨酯的耐低温性能、耐热稳定性、耐水性、疏水性和拉伸强度，断裂伸长率、玻璃化温度下降。
关键词：水性聚氨酯/ SiO2杂化材料，溶胶凝胶法，γ-氨基丙基三乙氧基硅烷，正硅酸乙酯
Study on waterborne fluorinated polyurethane nanometer SiO2 composite emulsion
Abstract:
Hybridized waterborne polyurethane by nanomaterial is an important method in the modification of waterborne polyurethane. In the previous researches， nanoparticles were directly added into waterborne polyurethane， which resulted in nanoparticle’s agglomeration and incompatibility between nanoparticles and polyurethane， and influenced the properties hybrid materials. In the thesis， waterborne polyurethane/SiO2 organic-inorganic hybrid materials based on sol-gel technology were prepared by using tetraethoxysilane(TEOS) as precursor， silane coupling agent 3-aminopropyltriethoxylsilane (APTES) as bridging agent between polyurethane and nanoparticles， respectively. Thus， nanoparticles were chemically bonded with polyurethane backbone. The effects of TEOS content on the structure and properties of hybrid materials were investigated.
Waterborne polyurethane/SiO2 organic-inorganic hybrid materials were prepared by two methods. The first one is as follows: waterborne polyurethane/SiO2 materials were prepared by the hydrolization and condensation of TEOS or/and APTES endcapping the WPU molecular chain. The hybrid emulsions exhibit excellent storage stability. The hybrid was characterized by SEM， EDS， TEM， FTIR and XPS. The effect of TEOS on surface wettability， water resistance， mechanical strength and thermal properties of the hybrid was also evaluated by contact angle measurement， water absorption test， mechanical test， TGA and DSC， respectively. The result showed that well dispersed nano-silica in WPU was synthesized， with a typical diameter of about 50 nm. And the results indicated that the addition of nanosilica affected the crystallinity ofpolyurethane. Additionally， chemical interaction occurred between WPU and silica. Also， an increase in advancing contact angle， water resistance， tensile strength， thermal stability was obtained with the addition of TEOS， while elongation at break and glass transition temperature deceased.
Another method was based on the principle of two-step method. Silica sol was prepared firstly with TEOS as precursor， hydrochloric acid as catalyst， water and absolute ethyl alcohol as solvent. Then waterborne polyurethane/SiO2 organic-inorganic hybrid materials were prepared by the hybrid reaction between silica sol and polyurethane endcapped by APTES. The results indicated that the addition of silica sol into polyurethane enhanced the hybrid material’s resistance to low temperature， thermal stability， water resistance and hydrophobicity. Elongation at break and glass-transition temperature decreased.
Key Words: WPU/SiO2 hybrid materials， sol-gel， APTES， TEOS
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