Effects of the hydration states of water molecules on the mechanical properties of dual movable cross-linked polymeric gels

水の水和状態が二重可動架橋ポリマー材料の機械的性質に及ぼす影響

河合 優作*; Park, J.*; 元川 竜平   ; 以倉 崚平*; 村山 駿介*; 山岡 賢司*; 藤井 義久*; 池本 夕佳*; 田中 賢*; 松葉 豪*; 加藤 隆史*; 高島 義徳*

Kawai, Yusaku*; Park, J.*; Motokawa, Ryuhei; Ikura, Ryohei*; Murayama, Shunsuke*; Yamaoka, Kenji*; Fujii, Yoshihisa*; Ikemoto, Yuka*; Tanaka, Masaru*; Matsuba, Go*; Kato, Takashi*; Takashima, Yoshinori*

The material properties of polymeric materials in aqueous environments are significantly influenced by water content. It is widely recognized that polymeric materials become more brittle with increased water content. However, the specific relationship between hydration levels and polymer chains has not been fully elucidated, leaving many uncertainties. Conversely, intermediate water (IMW), which refers to adsorbed water, plays an active role in influencing the biocompatibility and antifouling properties of these materials. In this study, we examined the correlation between IMW and toughness (Gf) / Youngs modulus (E). We synthesized dual cross-network (DC) elastomers through the bulk copolymerization of cyclodextrin (CD) monomers and vinyl monomers in the presence of movable cross-linked elastomers. The resulting DC elastomers exhibited both high Gf and high E. We used poly(2-methoxyethyl acrylate) (PMEA) as the primary polymer and poly(N,N-dimethyl acrylamide) (PDMAA) as the secondary polymer. The DC materials were formulated as DC(MEA-DMAA)(100-w:w)(Wc), where w and Wc represent the weight percentage of the secondary polymer (PDMAA) and the water content, respectively. The mechanical properties of the DC materials mostly decreased with increasing amounts of the secondary polymer. However, DC(MEA-DMAA)(90:10)(22), which contained 10 wt percent of PDMAA, exhibited the highest Gf and E among all samples. Differential scanning calorimetry (DSC) measurements indicated the presence of IMW in DC(MEA-DMAA)(90:10)(22). We propose that the IMW in this sample facilitates the formation of crosslinks between polymer chains and water molecules, contributing to the observed enhancements in E and Gf.