High water‐absorbent and fast‐expanding PMMA bone cement with double‐bridged structure

The volume shrinkage of polymethyl methacrylate (PMMA) bone cement has been solved by the expandable additives. However, the water absorption and swelling capacity of composite were not maximized as the rapid solidification of the cement and the poor connectivity of the additives in the matrix. In this study, the double‐bridged structure was constructed in PMMA‐based bone cement. Poly(methyl methacrylate‐acrylic acid)‐graphene oxide [P(MMA‐AA)‐GO] was synthesized by the dispersion polymerization, graphene oxide (GO) with sheet layer formed a bridging effect between the poly(methyl methacrylate‐acrylic acid) [P(MMA‐AA)], accelerating water absorption; hydroxyethyl methacrylate in the liquid formed capillary networks, which bridged all the expansion units, increasing the pathways of water transfer in the matrix. The double‐bridged structure in the composite synergistically accelerated water absorption and swelling, causing complete water absorption and swelling performance before solidification, with maximum water absorption and swelling ratios of 125.2 ± 3.2% and 115.2 ± 4.7%, respectively. Surprisingly, the compressive strength of the composite had also been improved, and the maximum value was 78.3 ± 3.2 MPa, which satisfied the minimum compressive strength of acrylic implants in ISO 5833‐2002 and ASTM F451‐2016. This biomaterial exhibited a promising application prospect as its excellent expansion capacity and mechanical properties. The double‐bridged structure consisting of P(MMA‐AA)‐GO and P(MMA‐HEMA) in the composite bone cement synergistically accelerated water absorption and swelling, causing complete water absorption and swelling behavior before solidification of the matrix, with maximum water absorption and swelling ratios of 125.2 ± 3.2 % and 115.2 ± 4.7 %, respectively.