拒水型有机硅改性聚氨酯嵌段共聚物的合成与表征

以氨丙基硅氧烷偶联剂和端羟基聚二甲基硅氧烷(PDMS)为原料,合成了端氨丙基聚二甲基硅氧烷低聚物(SN2),并将其作为扩链剂,制备了有机硅-聚氨酯(Si-PU)嵌段共聚物.考察了聚氨酯预聚体的加料比(rNCO/OH)、SN2与聚氨酯预聚体的加料比(rNH2/NCO)对Si-PU嵌段共聚物溶液流变行为及其膜性能的影响.研究发现,该Si-PU共聚物的异丙醇溶液呈现较低的表观黏度及牛顿特性;成膜时,有机硅链段向表面迁移;膜表面对水的接触角达110°以上,且随着有机硅链段含量的增高而增大;共聚物膜的24 h吸水率较低(<1.5 wt%);但当有机硅链段含量过高时,吸水率反而增高.

STUDY ON THE WATER REPELLENT SILICONE-POLYURETHANE BLOCK COPOLYMERS

Amino-terminated polydimethylsiloane(SN2) was synthesized by using hydroxyl-terminated polydimethylsiloxane(PDMS) and aminopropyl siloxane coupling agent(DB-912).And the silicone-polyurethane(Si-PU) block copolymer was synthesized by using SN2 as a chain extender and polyurethane prepolymer.The effects of the SN2 and prepolymer of polyurethane feed ratio on the rheological behavior of the copolymer solution in isopropanol(IPA) and the properties of its film were studied in detail.It was found that the Si-PU block copolymer IPA solution with a concentration of 25 wt% exhibited low apparent viscosity and the characteristics of Newtonian fluid within the measuring shear rate scope.During film casting,the SN2 blocks may migrate toward the surface,which led to a surface contact angle to water over 110°.With the increasing of SN2 block content,the surface contact angles of films to water increased slightly.When the films were soaked in the water for 24 h,the water absorptions were very low,and the water-repellence was pretty good.The copolymer film showed water absorption lower than 1.5 wt%.With the increasing of SN2 block content,the water absorptions were very low and did not change a lot.However,if the content of SN2 block was too high,the water absorption of films increased obviously owing to the increase of hydrophilic groups(—NH2) which possessed good attraction for water molecules.