Study on water properties and spatial structure of water in poly(2-methoxy ethylacrylate)s with different molecular weights by nuclear magnetic resonance spectroscopy

Poly(2-methoxyethyl acrylate) (PMEA) is known for its favorable blood compatibility, attributed to its unique intermediate water content, as identified by differential scanning calorimetry. Previously, we reported that PMEA contains two types of water—upfield and downfield waters—characterized by ²H-nuclear magnetic resonance (²H-NMR) and proposed that upfield water is a key factor in expressing good blood compatibility. In the present study, further investigations of the role of upfield water and clarification of the spatial water structure were performed using PMEAs with different molecular weights. ²H-NMR analysis revealed that the upfield water content was almost constant, regardless of the molecular weight, whereas the downfield water content increased with an increase in the molecular weight of PMEA. Based on these findings, the role of upfield water is discussed. Homonuclear and heteronuclear Overhauser effect spectroscopies revealed that upfield water existed near the methoxy group of PMEA, within a 0.5 nm range.