Abstract:

Pickering emulsion was obtained by using octadecyl trimethyl ammonium chloride (OTAC) in combination with nano SiO₂, and linear polysiloxane (PDMS) was synthesized with D₄ through ring-open polymerization under alkaline condition, and then cross-linking agent KH560 was added to prepare cationic water-based silicone rubber emulsion. The effects of SiO₂ and OTAC contents on Pickering emulsion were investigated. The absorption behavior of OTAC on the surface of SiO₂ was revealed by zeta potential, TEM and SEM. The structure of water-based silicone rubber was characterized with FT-IR, ²⁹Si NMR spectra. The effects of KH560 on the contact angle and Shore A hardness of the rubber film were also investigated. The emulsion possessed optimal liquidity and stability when w(SiO₂)=2.0%. When w(OTAC)=1.75%, the absorption of OTAC reached saturation on the surface of SiO₂, monomer conversion was about 89%, particle size was about 617 nm, zeta potential was close to zero, M_n and PDI for PDMS were 16036 and 1.485 respectively. When w(KH560)= 5.0%, PDMS hydrolyzed and condensed fully with KH560, and the obtained rubber film possessed optimal hydrophobicity and hardness.

Key words: Pickering emulsion, nano SiO₂, surfactants, stability, water-based silicone rubber, polymerization, preparation

摘要：

以十八烷基三甲基氯化铵(OTAC)协同纳米SiO₂制备Pickering乳液,碱性条件下引发D₄开环聚合制备线性聚硅氧烷(PDMS),然后加入交联剂KH560制备阳离子型水基硅橡胶乳液。考察了纳米SiO₂与OTAC用量对Pickering乳液性能的影响,通过zeta电位、TEM及SEM研究了OTAC在SiO₂表面的吸附状态,用FT-IR、²⁹Si NMR对水基硅橡胶的结构进行了表征,研究了KH560用量对橡胶膜对水接触角和邵氏硬度的影响。结果表明: w(SiO₂)=2.0%时,乳液流动性和稳定性最优;w(OTAC) = 1.75%时,OTAC在纳米SiO₂表面的单层吸附达到饱和,单体转化率为89%,粒径为617 nm,zeta电位接近零点,PDMS的数均分子量为16036,PDI为1.485;w(KH560)=5.0%时,KH560与PDMS充分水解缩合,硅橡胶膜憎水性和硬度显著提高。

关键词: Pickering乳液, 纳米SiO₂, 表面活性剂, 稳定性, 水基硅橡胶, 聚合, 制备