【作者】 何君勇；

【导师】 孙多先；

【作者基本信息】 天津大学 ， 材料学， 2004， 硕士

【摘要】 在本课题的研究中，通过硅烷偶联剂与硅溶胶颗粒表面硅羟基缩合的方法，制备了改性的纳米SiO2。详细研究了改性反应和改性后SiO2的性能变化和表征方法。运用密度、固含量、粒径测试、FT-IR、TEM分析手段证实缩合在SiO2表面的有机硅氧烷随甲基丙烯酰氧丙基三甲氧基硅烷（MEMO）/ SiO2摩尔比的增大而增大，当摩尔比超过某值后，表面覆盖结构可从单层转至多层。控制偶联剂在SiO2表面的覆盖率，可以得到亲油性和双亲性的单分散纳米 SiO2。当SiO2表面缩合含胺基有机硅氧烷时，表面电荷性质可根本改变。合成了一系列粒径、羧基含量不同的阴离子型水性聚氨酯。重点研究预聚过程，相反转过程, 聚氨酯乳液的粒径可由羧基含量和NCO/OH比例控制。讨论了水性聚氨酯作为二嵌段共聚物在水中的自乳化行为, 存在CMC值。最后详细研究了改性纳米SiO2与二嵌段水性聚氨酯复合时的结构变化，并与原位水解复合法作了对比。阴离子聚氨酯和中等改性度双亲SiO2复合时，可形成草莓型二次结构，SiO2和聚氨酯之间存在强氢键作用，作用主要在酰胺基和硅醇基之间发生，导致聚氨酯羰基从氢键的缔合态转变为游离态。聚氨酯内核疏水链段无法在水中解缔并在亲油SiO2表面自铺展形成包覆，亲油性正硅酸乙酯液体可乳化进入聚氨酯疏水内核。更多还原

【Abstract】 Modified SiO2 nanoparticles were synthesized by condensation of OH group of silica and the coupling agent. The process of modification reaction and the variation of surface properties were studied in detail. The results of density, solid content, particle size , FT-IR spectroscopy and TEM showed that the coverage of silica surface by coupling agent increased with increasing mol ratio of 3-(trimethoxy-silyl)propyl methacrylate（MEMO）/ SiO2. As the mol ratio reached some value, the surface structure of MEMO anchoring onto the surface of silica could be changed to multilayer. Lipophilic and amphibious monodispersed silica nanoparticles were obtained by controlling the degree of modification. Anionic waterborne polyurethane was prepared with different particle sizes and content of COOH. In this thesis, the prepolymer process and phase-reversion process was investigated particularly. The dispersions with different average particle size were obtained by controlling the content of COOH and the ratio of NCO/OH. Regarding as a diblock copolymer, WPU had definite CMC value and could be Self-emulsified in water.Finally, the structure transform of modified silica nanoparticle-WPU composite dispersion was investigated and characterized. The phase-reversion method was compared with in situ hydrolysis method. By the phase-reversion method, ‘Strawberry’ aggregations were formed and there were strong hydrogen bond associations between amide of polyurethane segment and silanol of silica, resulting in dissociation of hydrogen bond of carboxyl groups in polyurethane. The hydrophobic segments in the core of polyurethane could not dissociate in water and encapsulate lipophilic silica particles spontaneously, while the lipophilic liquid of TEOS could be emulsified into the hydrophobic core of polyurethane.更多还原