通过掺杂不同质量分数的八缩水甘油醚基笼形低聚倍半硅氧烷(G-POSS),以溶胶凝胶法制备得到一种新型聚酰亚胺(PI)杂化薄膜.通过红外反射光谱(DRIFT-IR)、扫描电子显微镜(SEM)表征了其结构与薄膜断面形貌,以热重(TG)和机械性能分析研究了薄膜的耐热性与常温和低温(77 K)下的力学性能.结果表明,在掺杂量低于5%时,该杂化薄膜耐热性保持稳定,同时在常温和低温下都表现出优于纯PI膜的拉伸强度,其中在G-POSS掺杂量为3%时,杂化薄膜的拉伸强度为239.38 MPa(77 K),比纯 PI 膜提升了17%.这是由于在低温条件下,聚合物分子链被冻结,G-POSS 粒子与 PI 基底间的排列更加紧密,同时界面作用力更大.%A series of polyhedral oligomeric silsesquioxane (POSS)/polyimide (PI)hybrid films were prepared by the sol-gel technique.In these nanocomposite materials,different quality ra-tios of the γ-glycidyloxypropylsilsesquioxane (G-POSS)cage mixture was introduced to the poly(pyromellitic dianhydride-co-4,4'-oxydianiline),amic acid solution (PAA)and the pre-cursor of polyimide.Then,the intermediate products were cast to the glass templates and cir-cled to be nanocomposite films at a temperature program.Particular mechanical and thermal properties of the G-POSS/PI nanocomposite films were investigated,i.e.,the tensile strength of the hybrid films at cryogenic temperature (77 K)were obviously higher than that at room temperature.The highest tensile strength of the G-POSS/PI films was 239.38 MPa by incorpo-rating 3% G-POSS at 77 K,and 101.3 MPa with 5% G-POSS at room temperature,respec-tively.With the raise of G-POSS content,the tensile modulus of the films increased,while the elongation at break of these hybrid films decreased in tensile tests and it was also found that the thermal degradation temperatures of these materials had an obvious decrease which was attrib-uted to the weak thermal resistance of the organic groups of G-POSS molecule.As a conse-quence,the hybrid film with lower than 5% POSS content (e.g.,3%)would be more possibly used as a kind of novel material at cryogenic temperature compared with pure PI film in the cryogenic refrigeration technology and inertial confinement fusion (ICF)physics experiments.
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