聚硅氧烷嵌段/接枝改性聚氨酯的表面性能

Surface properties of PDMS segmented/branched modified polyurethane copolymer

以不同结构的端羟基聚硅氧烷(PDMS)为软段,聚己内酯(PCL)为混合软段,通过与异佛尔酮二异氰酸酯(IPDI)加聚合成了一系列嵌段/接枝型硅氧烷改性聚氨酯(PDMS-PU),并采用静态接触角、接触角滞后以及XPS等表征手段分析了硅氧烷链段在聚氨酯主链中的链接方式对其表面性能的影响.结果表明:2种链接方式的硅氧烷均能有效的降低聚氨酯的表面能,引入质量分数为15%的硅氧烷,便可使得其水接触角达到110°,侧链接枝型由于硅氧烷位于侧链,自由度高,链段运动能力较强,易于形成表面富集.主链嵌段型由于硅氧烷链段两端均固定在主链上,难以发生表面重构,接触角滞后不明显,而侧链接枝型硅氧烷链段位于侧链,容易发生表面重构,使得部分极性亲水的聚氨酯硬段暴露在表面,其接触角滞后较为严重.

Series of different linkage form siloxane-modified polyurethane（PDMS-PU） were synthesized based on isophorone diisocyanate（IPDI）,double-side each containing a hydroxyl alkyl polydimethylsiloxane（PDMS）,as well as single-ended with two hydroxyl alkyl PDMS as the soft segment,poly caprolactone（PCL） as mixed soft segment.The effects of linkage form of PDMS unit on surface properties were investigated by water contact angle（CA）,contact angle hysteresis（CAH）,as well as XPS.CA results show that both the two linkage form PDMS can make surface modification of polyurethane by adding a small amount of siloxane（about15% mass fraction）.For branch-type copolymers,as the PDMS chain located on the side chain,segmental mobility of PDMS chains may get stronger,as a result,more PDMS chain would move to the surface and dominate the interface.For the segmented-type copolymer,of which both ends were fixed block in the main chain,the surface reorganization is difficult to occur,thus the CAH is not obvious.In contrary,PDMS locates in the side chain of branch-type copolymer;it is prone for the surface to be reorganized,making part of the hard segment polar hydrophilic polyurethane exposed to the surface,so the CAH is more obvious.