Nanoscale Structures of Poly(oligo ethylene glycol methyl ether methacrylate) Hydrogels Revealed by Small-Angle Neutron Scattering

The nanostructures of temperature-responsive and biocompatible gels were investigated by small-angle neutron scattering (SANS). The gels were copolymerized using two types of monomers with different ethylene glycol side chain lengths: diethylene glycol methacrylate (MeO(2)MA) (short side chain) and oligo-ethylene glycol methyl ether methacrylate (OEGMA) (long side chain). The temperature-responsive behavior was ascribed to the nanoscale structures and depended on the copolymerization ratio. The SANS profiles of swollen OEGMA-rich gels exhibited a characteristic peak, indicating a strong correlation with the hydrophobic main chain domains in the hydrophilic matrix. The long hydrophilic side chains of OEGMA acted as a cushioning material between the domains. On the other hand, the domains were randomly distributed in the MeO(2)MA-rich gels. As the temperature increased, the domains grew in the gels due to hydrophobic interactions between the dehydrated polymers. As a result, the peaks, that is, the domain periodicity, disappeared in the SANS profiles. The results of this study should lead to a synthesis strategy to control the physical properties and structures of such hydrogels for advanced applications, for example, biofilms, coatings, and carriers.

Automated summary

The nanostructures of temperature-responsive and biocompatible gels were investigated using small-angle neutron scattering. The behavior of these gels was dependent on the copolymerization ratio, with the swollen gels exhibiting characteristic peaks in the SANS profiles. The long hydrophilic side chains acted as a cushioning material between the domains, while the domains were randomly distributed in the other gel type. The results of this study have implications for controlling the physical properties and structures of hydrogels for advanced applications.