Preparation And Hydrophilic Modification Of Silicone Rubber Composites

Polydimethylsiloxane(PDMS)has a broad application prospect in the field of biomedical materials such as artificial intraocular lens,medical catheter,and artificial heart valve because of its excellent mechanical properties,non-toxicity and good biocompatibility.However,the hydrophobicity of PDMS itself causes its surface to adhere to bacteria easily in clinical applications,as well as its tendency to clot when it comes into contact with blood,limiting its further application in clinical applications.Therefore,it is necessary to modify PDMS using hydrophilic materials with good antifouling properties.The introduction of hydrophilic materials into polymers by physical or chemical strategies helps to improve the fouling resistance of the final material.However,the hydrophilic modification of PDMS materials is mainly limited to surface modification,which results in a rapid loss of hydrophilic materials in the process of exposure and contact in water environment,and subsequently leading to the failure of long-term maintenance of their hydrophilicity and antifouling ability.Therefore,it is particularly important to improve the stability and durability of PDMS with hydrophilic modification.In this thesis,by introducing different mass ratios of acrylic acid(AA)with ionizable carboxyl side groups and good hydrophilicity or N-vinylpyrrolidone(NVP)with excellent hydrophilic lactam group in the structure,free radical polymerization cross-linking reaction occurs with PDMS prepolymers under the action of photoinitiator.A series of PAA/PDMS and PVP/PDMS composites with different polyacrylic acid(PAA)or polyvinylpyrrolidone(PVP)contents and properties were obtained.Through Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),environmental scanning electron microscopy(ESEM),water contact Angle(WCA),thermogravimetric analysis(TGA)and other tests,The effects of monomer and dose on the composition,morphology,structure,physicochemical properties and wettability of two different composites were investigated.The main results of the study are as follows:1.FTIR,XPS and ESEM results confirm the successful preparation of PDMS composite with interpenetrating polymer network(IPN)structure by bulk modification through the photoinitiated free radical polymerization of AA or NVP monomer with PDMS prepolymer.2.The introduction of both PAA and PVP in PDMS matrix could effectively improve the hydrophilic properties of the material.When the content of PAA or PVP was up to 40 wt%,the static WCA of PAA/PDMS and PVP/PDMS could be reduced to 78.4° and 70.5°,respectively.Moreover,the results showed that 40 wt% PAA/PDMS still had very good hydrophilic stability after 8 months at room temperature.3.The results of TGA tests showed that the effect of the addition of hydrophilic monomer on the thermal stability of the two composites was significantly different.The thermal stability of PAA/PDMS composites decreased with the increase of AA content,but that of PVP/PDMS composites increased with the increase of NVP content.4.The light transmittance test results showed that the transparency of the composites decreased with the increase of hydrophilic monomer.This should be due to the existence of a certain phase separation which makes the decrease of transparency.5.The results of the mechanical property tests showed that the tensile strength of the composites with the addition of hydrophilic monomers was significantly improved compared with that of pure PDMS,which may be due to the double bond cross-linking reaction between PAA and PDMS or PVP and PDMS to form IPN.The generation of chemical bonds between different kinds of macromolecular chains and the enhancement of entanglement of molecular chains lead to the improvement of tensile strength of composites.In summary,this thesis innovatively replaces surface modification with bulk polymerization under the initiation of photoinitiator,and regulate the effect of different contents of hydrophilic monomers and their corresponding polymer content in final system on the wetting performance of the composites by regulating the degree of free radical polymerization cross-linking reaction among the components in the initiation system.Through the above research,the PDMS composites with stable hydrophilic modification effect was developed,which provides a reliable theoretical support for the future development of various silicone rubber-based hydrophilic modified composites by UV curing,and also provides an important reference value for the later antifouling application of PDMS-based composites.