Study On Preparation And Properties Of Antibacterial Silicone Rubber Based On Methacrylate With Pyridyl Quaternary Ammonium Salts And Its Polymers

Due to the excellent flexibility,low toxicity,biocompatibility and physiological inertia,silicone rubber has become a widely used polymer materials.Once bacterial contamination occurred during the application of silicone rubber materials,it will not only cause harm to the users'health,but also cause potential pain and burden on the users.Therefore,the research of silicone rubber with antibacterial effect has not only scientific value,but also practical application value.Adding antibacterial agent is the main approach to produce antibacterial silicone rubber,while this approach has the drawback of easy migration,resulting in unsustainable antibacterial efficacy of silicone rubber.Methyl vinyl silicone rubber?MVQ?,that have double bonds on its own molecular chain,provides reactive sites for antibacterial agent that also have double bond,so they can be grafted onto the molecular chain of the silicone rubber during the vulcanization process,endowing the silicone rubber with long-term antibacterial efficacy.Antibacterial polymers which have high molecular weight can hardly migrate,thus they can also be used to prepare antibacterial rubber with long-term antibacterial efficacy.Therefore,in this study,a series of quaternary pyridine ammonium polymerizable monomers containing methacrylate structure and its polymers were synthesized and they were added into MVQ to prepare silicone rubber with long-term antibacterial efficacy.All the results were listed as below:?1?Five kinds of quaternary pyridine ammonium intermediates?QPD-m?were synthesized through the reaction of 2-hydroxymethyl pyridine and 1-bromodecane,1-bromododecane,1-bromotetradecane,1-bromohexadecane and 1-bromooctadecane,respectively.And then QPD-m were react with 2-isocyanatoethyl methacrylate to synthesize a series of novel quaternary pyridine ammonium polymerizable monomers which containing methacrylate structure?QIPD-m?,and their structures were confirmed by FT-IR and ¹H-NMR spectra.The initial decomposition temperature of QIPD-m were over 200°C,which implied that the QIPD-m showed excellent thermal stability and they were stable at the vulcanization temperature of MVQ compound.The critical micelle concentration?CMC?of QIPD-m decreased gradually with the increase of the alkyl chain length of QIPD-m.The minimum inhibitory concentration?MIC?and the minimum bactericidal concentration?MBC?of QIPD-m was initially decreased and then increased with the increase of the length of alkyl chain in QIPD-m.QIPD-m showed excellent antibacterial efficacy,among which QIPD-14showed the strongest antibacterial efficacy?2?Five kinds of polymer antibacterial agents with different alkyl chain lengths?PQIPD-m?were synthesized by polymerization of QIPD-m using 2,2'-azobis?2-methylpropionitrile?as initiator and their structures were confirmed by FT-IR and ¹H-NMR spectra.The weight-average molecular weight of PQIPD-m were between 23000²6100g/mol,the polydispersity index were between 1.49¹.73 and the initial decomposition temperature of PQIPD-m were higher than QIPD-m.?3?The addition of QIPD-m endowed MVQ antibacterial materials with hydrophilicity,which was gradually increased as the amount of QIPD-m were improved.QIPD-m decelerated the vulcanization of QIPD-m/MVQ compounds and worsened the dispersion of SiO₂.It also had influence on the crosslinking density and mechanical properties of QIPD-m/MVQ antibacterial materials.When 5 phr or less QIPD-m were added,the prepared QIPD-m/MVQ antibacterial material can meet the general requirements.?4?The addition of QIPD-m gave MVQ excellent antibacterial effect and resistance to ethanol-extracting.When there were same amount of QIPD-m,the antibacterial efficacy of the prepared QIPD-m/MVQ antibacterial material initially increased and then decreased with the increase of the length of alkyl chain in QIPD-m,and when the alkyl chain length was 14,the silicone rubber had the most excellent antibacterial efficacy.When the alkyl chain length of the QIPD-m was same,the antibacterial efficacy of the prepared QIPD-m/MVQ antibacterial material enhanced with the increase of the amount of QIPD-m.The QIPD-m/MVQ antibacterial material did not show cytotoxicity.?5?PQIPD-m decelerated the vulcanization of PQIPD-m/MVQ compounds and worsened the dispersion of SiO₂.It also made the crosslinking density,mechanical properties,and hydrophilicity of prepared PQIPD-m/MVQ antibacterial materials show downward trend.When 3 phr or less PQIPD-m were added,the prepared PQIPD-m/MVQ antibacterial material can meet the general requirement.?6?The addition of PQIPD-m endowed MVQ with excellent antibacterial efficacy.When the alkyl chain length of the PQIPD-m was same,the antibacterial efficacy of prepared PQIPD-m/MVQ antibacterial material gradually improved as the increased of the amount of PQIPD-m.When there were same amount of PQIPD-m,the antibacterial efficacy of prepared PQIPD-m/MVQ antibacterial material was initially increased and then decreased with the increase of the length of alkyl chain in PQIPD-m.The PQIPD-m/MVQ antibacterial material did not show cytotoxicity.The antibacterial efficacy of PQIPD-m/MVQ antibacterial material prepared by adding 5 phr PQIPD-m did not reduce obviously after ethanol extraction for 48 h,and its antibacterial efficacy to E.coli and S.aureus was still above 95%,which showed excellent long-term antibacterial properties.