自黏附硅橡胶表面水凝胶润滑层的原位生长及其性能研究

In-Situ Growth of Hydrogel Lubrication Film on Self-Adhesive Silicon Elastomer Surface and Its Performance

在水体环境中,水凝胶润滑薄膜与基底之间可逆以及便捷的结合是润滑材料领域的挑战之一.本研究中将自黏附硅橡胶与具有润滑功能的水凝胶相结合,获得了一种具有可逆湿黏附功能的水凝胶润滑材料.在低交联度聚二甲基硅氧烷(PDMS)表面/亚表面填埋引发剂二苯甲酮,通过表面光引发聚合的方式使其表面生长具有润滑功能的水凝胶-聚(丙烯酸-co-丙烯酰胺)[P(AA-co-AAm)].研究结果表明:水凝胶与硅橡胶基材在交界处形成连接致密的一体结构.当丙烯酸与丙烯酰胺摩尔比为1:1时,水凝胶表现出优异的摩擦学性能,并且力学强度较高.PDMS的模量随着固化剂含量增加而升高,而摩擦系数则呈现相反的趋势;当PDMS硅烷预聚体与固化剂质量比例为30:1时具有较好的机械性能、黏附性能以及较低的摩擦系数.所制备的可黏附水凝胶使得水润滑材料具有水下可黏附特性,该体系与金属、陶瓷以及聚合物等多种基底表面均具有良好的黏附性能,多次重复黏附测试后,黏附强度基本保持不变.该方法解决了水凝胶润滑材料与基底的结合问题,有望为医疗器械表面的润滑改性提供一种新思路.

Reversible and convenient bonding underwater between hydrogel lubrication film and substrate is one of the challenges in the field of tribology.In this study,the lubrication film was combined with the silicone rubber to prepare hydrogel-lubricated silicone rubber with reversible wet adhesion.Polydimethylsiloxane(PDMS)with low degree of crosslink was used as an underwater adhesion material,and the initiator benzophenone was buried on its surface/subsurface,then the hydrogel lubricating film Poly(acrylic acid-co-acrylamide)[P(AA-co-AAm)]was grown on the surface through surface photopolymerization.The interface structure of obtained hydrogel-lubricated silicone rubber was explored by field emission scanning electron microscope(FESEM).The effects of ratio of hydrogel monomers,concentration of crosslinking agent,and polymerization time on performance of films were explored.The ratio of curing agent in PDMS was adjusted to explore its effects on adhesion and tribological properties of films.The results showed that a densely connected structure formed between the interface of hydrogel and PDMS.As the content of acrylic acid increased,the friction coefficient showed a trend of first decrease and then increase.When the content of acrylamide was further reduced,the acrylic acid segment absorbed water easily and swelled,leading to the reduction of mechanical strength and increase of friction coefficient.When the molar ratio of acrylic acid to acrylamide was 1:1,the hydrogel exhibited excellent tribological properties and mechanical strength.When the content of the crosslinking agent increased,the mechanical properties of hydrogel was optimized,and it exhibited better lubrication property.In addition,the modulus of PDMS increased as the content of curing agent,while the friction coefficient showed the opposite trend.;when the mass ratio of PDMS silane prepolymer to curing agent was 30:1,PDMS had favorable mechanical properties,adhesion performance and low friction coefficient.The prepared hydrogel-lubricated silicone rubber made the hydrogel adhesive underwater and endowed the silicone rubber with excellent lubrication and anti-wear properties.PDMS substrate was worn severely in the sliding direction after the friction test,its surface was damaged and there were obvious pits.In contrast,the hydrogel film only produced very slight scratches.The wear scar of the hydrogel was investigated,and the results showed that after nearly 3000 cycles,the surface layer of the hydrogel film did not change much,which proved that the hydrogel film had excellent resistance to abrasiveness compared to PDMS.After repeated adhesion tests,the hydrogel film still had excellent adhesion properties.In addition,the hydrogel-lubricated silicone rubber had different adhesion on two sides.PDMS side showed good adhesion to titanium alloy,PTFE,and ceramics underwater while the hydrophilic hydrogel layer had no adhesion to titanium alloys,ceramics,etc.underwater,and directly falls off the surface of the materials.