Antithrombogenic poly(2-methoxyethyl acrylate) elastomer via triblock copolymerization with poly(methyl methacrylate)

For the development of blood-contacting biomedical devices, preventing platelet adhesion and avoiding subsequent thrombosis through antithrombogenic surface are vitally important. Poly (2-methoxyethyl acrylate) (PMEA) is a synthetic viscous polymer with an excellent antithrombogenic property, which has already been used as an antithrombogenic coating for biomedical purposes. The PMEA coating, however, can be easily broken due to its liquid-like feature, since the glass transition temperature (T_g) of PMEA is at −25^οC. Solidifying PMEA has, therefore, been desperately desired for the improvement of the stability of PMEA coating. Also, once solidified, PMEA could be utilized not only for coating but also for structural materials for medical devices, expanding the application range of PMEA. In this study, PMEA was first solidified by triblock copolymerization with poly (methyl methacrylate) (PMMA) to obtain thermoplastic elastomers with excellent antithrombogenicity. We synthesized PMMA-PMEA-PMMA triblock copolymers with different volume fractions of PMMA (f_MMA) by atom transfer radical polymerization (ATRP). The synthesis and the chemical structures of the new triblock copolymers were characterized and confirmed by proton nuclear magnetic resonance (¹H NMR) analyses and gel permeation chromatography (GPC). The synthesized elastomeric triblocks were then compression-molded at 180^οC to obtain solid transparent films. The tensile property was measured and the drastic change from the soft-elastomer phase to the hard-plastic phase was clearly observed by varying f_MMA. It was found that the new triblocks possessed significantly higher tensile strengths than the other solidified PMEA by the previous studies. The platelet adhesion test revealed that the number of adherent platelets on the triblocks with f_MMA of 0.12 and 0.40 was almost the same as that on pure PMEA, indicating that the synthesized triblocks possessed excellent antithrombogenicity similar to liquid PMEA. Further investigation on hydrated water and microphase-separated structures eventually revealed that the new triblock copolymers with a sufficient amount of intermediate water or with microphase separation on the surface resulted in excellent antithrombogenicity.