新型室温酯化法接枝聚合物改性SiO_2纳米微粒

提出了一种在室温、大气环境等温和条件下通过酯化反应将端羧基聚合物链接枝到纳米SiO2微球表面从而制备有机/无机复合纳米微粒的新方法.该方法通过以下两个步骤得以实现,即第一,用3-环氧丙基三甲氧基硅烷对纳米SiO2微球表面进行改性处理,接着将引入到纳米SiO2表面的环氧基团转化为烷羟基基团;第二,通过引入到纳米SiO2微球表面的烷羟基与聚合物中的端羧基在室温下发生酯化反应,从而将聚合物接枝到纳米SiO2表面制得复合微球.利用XPS、FTIR、TEM和TGA等测试手段对纳米SiO2的改性过程以及聚合物接枝后得到的复合微球进行了表征.研究结果表明,该室温酯化接枝方法具有较高的接枝率,接枝到无机纳米微粒表面的聚合物占复合微球质量的55wt%～70wt%;接枝聚合物后,纳米SiO2微球的粒径从40nm增加到64～75nm,从而得到了以SiO2为核、以聚合物为壳的有机-无机复合微球.

SiO2 NANOPARTICLES MODIFICATION WITH POLYMER USING AN ESTERIFICATION METHOD AT ROOM TEMPERATURE

A novel method for grafting polymer onto the surface of nano-SiO₂ particles via the esterification reaction at room temperature,atmosphere,etc.was developed and organic/inorganic composite nano-particles were prepared.The method was carried out via two steps.First,the nano-SiO₂ was modified with 3-glycidoxypropyl trimethoxysilane,and then the introduced epoxy groups at the surface of the nano-SiO₂ particles were converted into alkyl-hydroxyl groups.Secondly,the polymer was grafted onto the nano-SiO₂ surface via the esterification reaction between the alkyl-hydroxyl groups and the carboxyl groups at the polymer terminal at room temperature.The modification of the nano-SiO₂ and the resulting composite particles were characterized by XPS,FTIR,TEM and TGA.Results showed that the method has higher grafting efficiency,and the grafted polymer accounted for 55 wt%~70 wt% of the total composite particles.As a result,the particle size increased from 40 nm to 64~75 nm upon the polymer grafting.Consequently,the core-shell composite particles with polymer chains on the outside and SiO₂ in the core were obtained.