Hydrophilic Modification And Antibacterial Properties Of Silicone Elastomers

Silicone(PDMS)elastomers have a wide range of applications in the biomedical field,but the strong hydrophobicity of PDMS surface can cause many problems,such as non-specific protein adsorption and bacterial adhesion,so the surface needs to be functionalized.There are no active reactive functional groups on the surface of PDMS,which need to be pretreated by plasma treatment、chemical etching and so on,and then functional groups on the surface of PDMS are grafted with functional molecules.The processing steps are cumbersome,so the modification method still needs further exploration.In this paper,different surface functionalization modification methods of PDMS are studied.The work contents are as follows:(1)Surface chemical graft of hydrophilic molecules on the surface reduces the hydrophobicity of the PDMS.Firstly,surface hydrosily functionalized PDMS was prepared by one-step method that controls the mass ratio of vinyl polysiloxane(DMS)and poly(methylhydrosiloxane)(HMS).The results of Fourier transform attenuated total reflection infrared spectrometer(FTIR)showed that the mass ratio of the main reactants in order to maximize the surface hydrosilation was 1:1.Secondly,the PEG derivative with double bond was grafted by hydrosilylation reaction to improve the hydrophilicity of PDMS.And by testing its mechanical properties、optical properties、water contact angle、lipid adsorption rate and protein adsorption rate to analyze the effects of molecular weight and molecular structure of PEG derivatives on the properties of modified samples.(2)Surface physical adsorption and in situ reduction of metal ions improves the antimicrobial properties of the PDMS surface.Firstly,the surface of PDMS was modified by dopamine.Due to the large amount of hydroxyl and amino groups in polydopamine(PDA),the hydrophilicity of PDMS can be improved.The optimum modification time of PDA was 12 h by testing the water contact angle of the modified material which decreased from 85° to 55°.Secondly,the PDMS-PDA material was immersed in silver ammonia solution to adsorp and reduce silver ions.The silver onthe modified surface was characterized by X-ray photoelectron spectroscopy(XPS)in the form of ion and single substance,respectively.The results of Scanning electron microscopy(SEM)showed that when the concentration of dopamine was 2 mg/mL,the distribution and size of silver nanoparticles(AgNPs)was the most uniform(40nm-50 nm).By characterizing protein adsorption of silver-loaded PDMS,it was found that when PDMS-PDA immersed in silver ammonia solution for 2 h,the relative protein adsorption amount was 40% of that of pre-modified PDMS.In the study of antibacterial properties,the adhesion of modified PDMS to E.coli was found to be reduced by 50%,and the sustained-release solution of modified material can inhibit the growth of E.coli.