复合树脂中硅烷偶联剂γ-MPS水解与缩合机制的研究

Study of hydrolysis and condensation mechanisms of a silane coupling agent γ-MPS used for dental composite resin

目的:研究复合树脂中最常用的硅烷偶联剂γ-MPS水解与缩合的机制。方法:应用傅立叶变换红外光谱(FT-IR)法对γ-MPS及其水解液在不同状态时的特征吸收谱带进行分析。结果:(1)γ-MPS水解后其分子结构中Si-O-CH3基团消失,水解产物中出现具有反应活性的Si-OH基团,C=O基的伸缩振动向低频率发生位移。(2)γ-MPS水解液放置1h时,溶液中已有线性硅氧烷醇齐聚物存在。(3)随γ-MPS水解液放置时间延长,Si-OH吸收强度减弱,而Si-O-Si吸收强度增强;同时C=O基的伸缩振动向高频率发生位移,表明γ-MPS水解液在不断进行缩合。结论:本研究从分子水平上揭示了硅烷偶联剂γ-MPS水解液随放置时间变化,其分子间发生缩合的规律,为有效合理地使用γ-MPS偶联剂提供理论依据。

Objective:To study the mechanisms of hydrolysis and condensation of a silane coupling agent γ-MPS widelyused for dental composite resin. Methods: The IR bands of γ-MPS and its hydrolyzates in various states were analyzed byusing Fourier Transform Infrared Spectroscopy. Results: (1) The Si-O-CH3 group disappeared after g-MPS hydrolyzedand the reactive Si-OH group yielded in the hydrolyzates. In addition, the stretching mode of C=O group shifted towardslower frequency. (2) The linear oligomeric siloxanols were detected in γ-MPS hydrolyzates when it stored for 1h. (3)When the hydrolyzates stored for a longer time, the absorption intensity of Si-OH group decreased and that of Si-O-Siincreased gradually. Concomitantly, the band of C=O stretching mode shifted to higher frequency. All these indicated thatthe hydrolyzates of γ-MPS condensed continuously. Conclusion: This study could reveal the regularity of intermolecularcondensation in g-MPS hydrolyzates with the change of time, and could provide theoretical basis for applying the silanecoupling agent γ-MPS rationally.