表面能连续可调的反应性超支化聚硅氧烷的制备与性能

Preparation and properties of reactive hyperbranched polysiloxane with continuously adjustable surface energy

针对不同应用场景对聚硅氧烷性能要求的变化,通过改变含环氧基和苯基的硅氧烷单体投料比,以水解缩合的方式制备一系列表面能连续可调的高固含量超支化聚硅氧烷。结合电导率测试、核磁共振氢谱、硅谱、凝胶渗透色谱三联检测仪确定在pH=1的条件下反应4 h可以得到水解程度为96.1%,支化度为51.2%,Mark-Houwink常数α在0.3左右,具有近似球形结构的超支化聚硅氧烷。通过接触角测试计算表面能发现,随苯基硅氧烷摩尔分数的提升,疏水性提高,表面能在36.5~46.7 mJ·m^(-2)连续下降。透光率测试结果表明聚硅氧烷表面能与环氧树脂表面能差越大,透光率越小,当表面能差达到8.2 mJ·m^(-2)时,可见光透过率(700 nm)大幅下降了56.6%,此时树脂间不相容性显著提高。扫描电子显微镜-能谱分析仪测试表明硅树脂在固化混合物中的质量分数是从底面到表面逐渐增加,发生了明显的分层。超支化聚硅氧烷的热氧稳定性也随苯基硅氧烷的摩尔分数提升而增强。

A series of hyperbranched polymers with continuously adjustable surface energy and high solid content were synthesized by hydrolytic condensation at various feed ratio of siloxane monomers containing epoxy group and phenyl group for meeting the polysiloxanes performance requirements in different application scenarios.The reaction process was traced through the conductivity test.Based on results of hydrogen nuclear magnetic resonance spectroscopy and triple detector gel permeation chromatography,a typical spherical hyperbranched polymer with hydrolysis degree of 96.1%,branching degree of 51.2%and Mark-Houwink parameterαof 0.3 could be obtained after reaction for 4 hours under pH=1.The surface energy of prepared polymer could be calculated from the contact angle and decreased gradually in the range of 36.5-46.7 mJ×m^(-2) with the increase of phenylsiloxane mole fraction,indicating the increase of hydrophobicity.Light transmittance tests revealed that the light transmittance of mixed thermosets decreased with the increasing of surface energy difference between polysiloxane and epoxy resin.When the surface energy difference reached 8.2 mJ×m^(-2),the visible light transmittance(700 nm)sharply dropped by 56.6%,indicating the presence of remarkable incompatibility.Scanning electron microscopy and energy dispersive spectroscopy results showed that the mass fraction of polysiloxane increased from the top surface to the bottom,indicating the occurrence of stratification.The thermal oxygen stability of prepared polysiloxanes increased with the increase of the mole fraction of phenylsiloxane as well.