【作者】 张勇；

【导师】 崔树勋； 鲍雨；

【作者基本信息】 西南交通大学 ， 机械， 2023， 硕士

【摘要】 聚甲基三氟丙基硅氧烷（PMTFPS）是在甲基乙烯基硅氧烷主链上引入三氟丙基侧链的聚合物,三氟丙基的引入使其既具备了聚硅氧烷的优异热稳定性又具有含氟材料的良好耐油耐溶剂性,从而在航空航天、汽车等领域得到了广泛的应用。含氟高分子常被用来设计离子偶极作用。但目前对于离子偶极作用的研究大多都是选用聚偏氟乙烯共六氟丙烯（PVDF-co-HFP）作为偶极子,来和阳离子进行反应。而PMTFPS同样作为含氟高分子的一种,它是否会和带电离子发生离子偶极作用目前尚不清楚。对于PMTFPS与带电离子之间相互作用的研究有望让PMTFPS作为一种新的高分子来进行自修复聚合物以及离子导体的设计,并对PMTFPS力学性能的改善提供指导信息。因此,本论文选用一种自下而上的方法,使用基于原子力显微镜的单分子力谱（AFM-SMFS）技术从单分子层面上对PMTFPS的单链弹性以及PMTFPS与各种阳离子的相互作用进行了研究。基于以上的研究,本论文主要得出以下结论:（1）利用AFM-SMFS技术得到了PMTFPS在壬烷中的单链弹性,并结合量子力学（QM）计算,发现该单链弹性代表PMTFPS的本征弹性。随后研究了PMTFPS在去离子水的单链力学行为,结果表明水环境不会对PMTFPS的单链弹性产生影响。然后研究了聚二甲基硅氧烷（PDMS）在壬烷中的单链力学行为,并与PMTFPS的本征弹性对比后发现,CF₃基团的极性会影响PMTFPS的单链弹性。（2）利用AFM-SMFS技术研究了PMTFPS-AMIMCl（烯丙基离子液体）复合物在壬烷和水中的单链力学行为,证明了PMTFPS与AMIMCl之间存在离子偶极作用,且该作用的强度会随着接触时间的增加而增强,直至增大到最大值保持不变。此外,水会加速离子偶极作用的形成,但也会使离子偶极作用消失。最后,增大PMTFPS与AMIMCl之间的摩尔比例会加速离子偶极作用的形成,但当PMTFPS与AMIMCl之间的摩尔比例过小时（<1:2.5）,不会产生离子偶极作用。（3）利用AFM-SMFS技术研究了PMTFPS-Mg Cl₂（氯化镁）复合物和PMTFPS-Na Cl（氯化钠）复合物在壬烷中的单链力学行为,结果表明Mg²⁺也会和PMTFPS产生离子偶极作用,但Na⁺与PMTFPS之间并没有离子偶极作用的发生。最后将三种阳离子与PMTFPS发生相互作用的强度进行比较后发现,AMIMCl的结合强度最强,其次是Mg²⁺,Na⁺没有与PMTFPS发生离子偶极作用。更多还原

【Abstract】 Poly[methyl（trifluoropropyl）siloxane]（PMTFPS）is a polymer that introduces trifluoropropyl side chain on the methyl vinyl siloxane backbone,and the introduction of trifluoropropyl makes it have both excellent thermal stability of polysiloxane and good oil resistance and solvent resistance of fluorine-containing materials,so that it has been widely used in aerospace,automotive and other fields.Fluorinated polymers are often used to design ion-dipole interactions.At present,most of the research on ion-dipole interactions are to use the CF₃ group in poly（vinylidene fluoride-co-hexafluoropropylene）（PVDF-co-HFP）as a dipole to react with cations.PMTFPS is also a fluorinated polymer.It is not known whether it will have ion-dipole interaction with charged ions.The study of the interaction between PMTFPS and charged ions is expected to provide PMTFPS as a new polymer for the design of self-healing polymers and ionic conductors,and provide guidance for the improvement of the mechanical properties of PMTFPS.Therefore,in this paper,the single-chain elasticity of PMTFPS and the interaction between PMTFPS and various cations were studied by using atomic force microscopy-based single-molecule force spectroscopy（AFM-SMFS）techniques.Based on the above studies,the main conclusions can be summarized as follows:（1）The single-chain elasticity of PMTFPS in nonpolar organic solvent was obtained by using AFM-SMFS technique.Combined with quantum mechanics（QM）calculation,it is found that the single-chain elasticity can represent the inherent elasticity of PMTFPS.Subsequently,the single-chain mechanical behavior of PMTFPS in water was studied,and the results showed that water had no effect on the single-chain elasticity of PMTFPS.Then,the single-chain mechanical behavior of polydimethylsiloxane in nonane was studied,and compared with the inherent elasticity of PMTFPS,it is found that the polarity of CF₃ group can affect the single-chain elasticity of PMTFPS.（2）The single-chain mechanical behavior of PMTFPS-AMIMCl（1-allyl-3-methyl imidazolium chloride）complex in nonane and water was studied by AFM-SMFS technique,and the ion-dipole interaction between PMTFPS and AMIMCl was proved,with the increase of contact time,the strength of the interaction will also increase and remain stable after increasing to the maximum value.In addition,water accelerates the formation of ion-dipole interactions,but also makes ion-dipole interactions disappear.Finally,increasing the molar ratio between PMTFPS and AMIMCl will accelerate the formation of ion-dipole interaction,but when the molar ratio between PMTFPS and AMIMCl is too small（<1:2.5）,the ion-dipole interaction will not occur.（3）The single-chain mechanical behavior of PMTFPS-Mg Cl₂（magnesium chloride）complex and PMTFPS-Na Cl（sodium chloride）complex in nonane were studied by AFM-SMFS technique.The results show that Mg²⁺also has ion-dipole interaction with PMTFPS,but there is no ion-dipole interaction between Na⁺and PMTFPS.Finally,the strength of the interaction between the three cations and PMTFPS was compared.It was found that the binding strength of AMIMCl was the strongest,followed by Mg²⁺.There is no ion-dipole interaction between Na⁺and PMTFPS.更多还原