Polyisobutylene-toughened poly(methyl methacrylate): III. PMMA-l-PIB networks as bone cements

A series of novel polyisobutylene (PIB)-toughened poly(methyl methacrylate) (PMMA) networks consist of rubbery PIB domains covalently bonded to a glassy PMMA matrix. Materials containing 8.5-17 wt.% PIB (Mn = 18,000 g/mol) in a PMMA matrix (PIB/PMMA) were evaluated to assess their feasibility as the powder component along with methyl methacrylate (MMA) as the liquid component in a standard powder/liquid bone cement formulation. A standard ISO four-point bend test, commonly used for testing bone cements, was employed to investigate flexural properties. The mixing time and powder/liquid (P/L) ratio were studied to formulate novel PIB/PMMA cements for optimum toughness. Appropriate formulations led to improved toughness while adequate flexural strength and modulus were maintained. An experimental PIB/PMMA-system exhibited approximately 57 MPa flexural strength and approximately 2000 MPa flexural modulus.