Preparation And Properties Of Multiple Hydrogen Bonds-crosslinked Polysiloxane-polyurethane Elastomers

Silicon-containing polymers and materials are extremely important for daily life and industrial production,and are widely used in various fields.There are a wide variety of products,including silicone oil,silicone resin,silicone rubber,silane coupling agent and their derivatives.Organosilicon materials were praised for its excellent biocompatibility,high gas permeability,low glass transition temperature,low surface energy,good thermal and oxidative stability,and water repellency.Over the past decade,supramolecular silicone materials have attracted much attention due to their outstanding properties,such as high stiffness,high stretchability,self-healing ability,thermoplastic capacity,etc.These unprecedented properties are attributed to the dynamic nature of supramolecular bonds,whose energies are low enough to allow bond exchanging under mild conditions.Typical examples are thermoplastic elastomers of poly(siloxane-urethane)and poly(siloxane-urea),where the hydrogen-bonding of urethane/urea units and the phase separation between soft polysiloxane segments and hard polyurethane/polyurea responsible for their excellent mechanical properties and thermoplastic abilities.For hydrogen-bonded silicone materials,manipulating the hydrogen-bonding force is an effective way to optimize their properties and also expand their library.In this thesis,a series of novel polysiloxane-polyurethane were designed and synthesized by introducing urea-pyrimidone and imidazolidyl urea into the main chain of polysiloxane,and a variety of organosilicon elastomers with excellent mechanical properties and dynamic plasticity were prepared.Specific work was summarized as follows:1.A series of novel polysiloxane-polyurethanes were designed and synthesized by introducing urea-pyrimidone units(UPy)into the main chain of polysiloxanes.A series of new polysiloxane-polyurethane elastomers were developed by adjusting the ratio of soft and hard segments and the molecular weight of polysiloxane chain segments.Through 1H NMR,FT-IR,TGA,DSC and tensile tests,the molecular structures,thermal properties of the polymer and the mechanical properties,microstructure,wettability and plasticity of the elastomers were systematically investigated.It was found that the design of urea-pyrimidone in the main chain could provide polysiloxane-polyurethane elastomers with good mechanical properties and dynamic plasticity,thus providing a new idea and inspiration for the development of high performance supramolecular organosilicon elastomers2.In order to further improve the mechanical properties of the elastomers,imidazolidyl urea with six hydrogen bonds was introduced into the polysiloxane-polyurethane system,and the influence of hydrogen bond changes on the properties of the elastomer was investigated.A series of polysiloxane-polyurethane elastomers with six hydrogen bonds were developed by adjusting the hydrogen bond content and molecular weight of polysiloxane chain segment.Through IH NMR,FT-IR,TGA,DSC and tensile tests,the molecular structures,thermal properties and mechanical properties,microstructure,wettability and plasticity of the hydrogen bond elastomer were characterized in detail.It is found that the introduction of six-fold hydrogen bond can significantly improve the mechanical properties of the materials.The reversibility of hydrogen bonds further gives the obtained materials the ability to dissolve and reform.This work can provide a new idea for regulating the mechanical properties of organosilicon hydrogen bond elastomers.3.By virtue of the metal coordination ability of the carbonyl groups in the polymer,rare earth europium ions were introduced into the polysiloxane-polyurethane elastomers containing UPy,and a moisture responsive luminescent elastomer was developed.The thermal properties,mechanical properties,microstructure and wettability of the elastomer were systematically characterized.The experimental results show that the europium ion coordination polysiloxane-polyurethane elastomer retains its original mechanical properties and possesses photoluminescent properties.The elastomer also exhibits unique fluorescence moisture responsiveness through competing coordination.The luminescent elastomer further enriches the types of organosilicon materials and provides a new idea for the application of polysiloxane-polyurethane elastomer.