Preparation And Properties Of Aminopropyl Polysiloxane Carboxylate Ionogel

Ionogels are hybrid materials that combine the high conductivity of ionic liquids with the flexibility,stretchability,and safety of gels.In recent years,it has received extensive attention in the fields of flexible electronic devices,sensors,and functional film materials.The current common ionogels are basically carbon-based,and their performance is poor in unconventional environments,and there is an urgent need for improvement.Aminopropyl polysiloxane has excellent thermal stability and low glass transition temperature,as well as good biocompatibility and dielectric properties.After improving its low mechanical properties,it will be a kind of ideal silicon-based ionogel composition.In the previous work,aminopropyl polysiloxane was modified by carboxylic acid,and the produced ammonium salt showed greatly improved modulus and viscosity,because of the existence of electrostatic interaction.Therefore,in this thesis,different types of aminopropyl polysiloxane carboxylate ammonium salts were prepared by reacting aminopropyl polysiloxane with different polymerization activity carboxylic acids and used to compound with ionic liquids to construct different cross-linking types ionogels,and their morphology,mechanical properties and electrical properties were systematically studied.The study found that in the polysiloxane non-polymerizable ammonium carboxylate ion gel system,the electrostatic gel formed by the mixed ammonium carboxylate salt of succinic acid and adipic acid has better performance.Especially when the molar ratio of amino/carboxyl group is 1/1,the molar ratio of succinic acid to adipic acid was 7/3,and the content of ionic liquid was 60 wt%,the ionogel without leakage of ionic liquid could be obtained,but the problem of insufficient mechanical properties still existed.When the polymerizable carboxylic acid used is maleic acid,whether using a single or a mixed aminopropyl polysiloxane system with different molecular weights,the obtained ionogels could show some elastic,but it is still impossible to effectively entrapped with the ionic liquid to prepare a qualified ionogel.When the acrylic acid is used as polymerizable carboxylic acid,a new type of electrostatic-chemical double-crosslinked silicon-based ionogels with good mechanical properties and no leakage of ionic liquid was successfully prepared after photo-initiated chain polymerization.When the crosslinking agent is polyethylene glycol(200)diacrylate in an amount of 0.6 mol%,and the ionic liquid is 1-butyl-3-methylimidazole trifluoromethanesulfonimide salt,the elongation at break of this silicon-based ionogel can reach 300%,the conductivity at room temperature can reach 1.4 m S/cm,the temperature for weight loss of 5%can reach 230°C,and there is no phase transition in the range of-60°C-100°C.Compared with the three carbon-based systems with similar structural composition,the optical transmission ability of silicon-based ion gel is slightly poorer,and the hydrophobic performance is not significantly ahead.However,this kind of ionogels have the better exhibitions in terms of the most important properties.They showed better mechanical and electrical,better gel forming ability,better structural stability,higher resilience,higher temperature stability,and higher electrical conductivity.The results of the sensing properties show that the new electrostatic-chemical double-crosslinked network polysiloxane ammonium acrylate-based ionogels have good human body sensing ability,and its sensitivity,response speed is basically the same as that of carbon-based ionogels in similar systems,which enable them to have good application prospects.