不同硅氧烷改性水性聚氨酯胶膜的性能

Diverse siloxane modified waterborne polyurethane for its latex films performance promotion

摘要:

不同结构的硅氧烷存在性能差异。因此，选取二苯基硅二醇（DPSD）、聚二甲基硅氧烷（PDMS和KF-2201）三种硅氧烷，通过化学键接改性具有代表性的阴离子型水性聚氨酯，在水性聚氨酯大分子链上键接不同结构的硅氧烷，优化水性聚氨酯大分子的化学结构，以改善其在耐水性和耐热性等性能的不足，并制备相应的乳液和胶膜。通过检测水性聚氨酯胶膜的水接触角、吸水率、热失重、表面和断裂截面形貌等指标，探究三者改性胶膜后在耐水性和耐热性的差异性。研究结果表明，改性后胶膜的表面、正常断裂截面和液氮脆断裂截面形貌明显顺滑，且存在显著的软硬段链相分离现象。XPS分析表明胶膜的Si-O链段易向表面迁移，而胶膜的软硬链段微相分离和Si-O链段的迁移性可以提升胶膜的耐水性和耐热性。因此含有Si-O键和疏水苯环的KF-2201更有助于提升胶膜的耐水性和耐热性。未改性胶膜、DPSD、PDMS和KF-2201改性胶膜的吸水率分别为16.41%、12.7%、10.19%、9.12%，以及水接触角分别为81.08?、96.37?、105.72?、110.05?，热失重95%时，温度分别为367℃、375℃、394℃、401℃。

Abstract:

Different structures of siloxanes possess different properties. Therefore, diphenylsiliconediol (DPSD) and polydimethylsiloxane (PDMS and KF-2201) were selected to modify the representative anionic waterborne polyurethane through chemical bonding. The different structures of siloxanes which could optimized the structures of waterborne polyurethane were bonded to the macromolecular chains for improving water resistance and heat resistance, and the corresponding emulsion and films were prepared. By testing the water contact angle, water absorption, thermal weight loss, surface/fracture cross-sectional morphology, and other indicators of the waterborne polyurethane films, the differences in water resistance and heat resistance of the three modified films were explored. The research results showed that the surface, normal fracture cross-section, and liquid nitrogen brittle fracture cross-section of the modified films were smoother, and there was significant phase separation of soft and hard segments. XPS analysis showed that the Si-O segments of the films were easy to migrate to the surface, while the microphase separation of the soft and hard segments and the migration of the Si-O segments of the films could improve the water resistance and heat resistance of the films. Therefore, KF-2201 containing Si-O bond and hydrophobic benzene ring was more helpful to improve the water resistance and heat resistance of the films. The water absorption rates of the unmodified films, DPSD, PDMS, and KF-2201 modified films were 16.41%, 12.7%, 10.19%, 9.12%, and the water contact angles were 81.08?, 96.37?, 105.72?, 110.05?, when the thermal weight loss was 95%, the temperature was 367℃, 375℃, 394℃, 401℃.