SELF-LUBRICATING PROPERTIES OF POLYSTYRENE-POLYDIMETHYLSILOXANE 2-PHASE MATERIALS

Polymeric two-phase systems containing polystyrene (PS) and poly(dimet hylsiloxane) (PDMS) can be prepared as block copolymers (Cop) and as b inary (PS-Cop) or ternary systems (PS-Cop-PDMS); the latter contain fr ee PDMS oil inclusions of controlled size in a continuous PS phase. Th e ternary systems are prepared by polymerization of styrene in the pre sence of silicone oil and of a PS-PDMS block copolymer acting as an em ulsifier. The presence of PDMS either as silicone oil or PDMS chain fr om the Cop contributes self-lubricating properties to these systems, w hen rubbing on a selected solid substrate such as steel or polyvinyl c hloride. With the ternary systems, a layer of silicone oil is then pre sent between the two rubbing materials and a kinetic friction coeffici ent of around 0.1 can be observed with an oil content above 10% in wei ght. Such polymer materials are interesting because of their permanent lubricating properties. The PS-PDMS block copolymer by itself also ha s a lubricating effect.