Dynamic shear oscillation measurements at small strain were used to characterize the viscoelastic properties and related differences in the molecular structure of hydrogels based on gelatin methacrylamide. Gelatin was derivatized with methacrylamide side groups and was subsequently cross-linked by radical polymerization via photoinitiation. The light treatment of methacrylamide gelatin solutions resulted in the production of hydrogel films with high storage modulus (G'). Mechanical spectra and thermal scanning rheology of the obtained hydrogels are described. The temperature scan of the network below and above melting point of gelatin allowed us to identify the respective contributions of chemical and physical cross-linkage to the hydrogel elastic modulus. The results indicate that the rheological properties of the gelatin-based hydrogels can be controlled by the degree of substitution, polymer concentration, initiator concentration, and UV irradiation conditions.
The isothermal crystallization of three different types of poly[ε-caprolactone-co-ethylene
glycol] (PCL−PEG) incompatible block copolymers [A−B, (A)2−B, and A−B−A] was investigated using
DSC. The PEG weight fraction in the copolymers was slightly varied from 18 to 22 wt %. It was established
that the kinetic parameters from the Avrami equation (the half time of crystallization, τ0.5, and the rate
constant of overall crystallization, z) for the PCL constituent, which crystallizes first, are similar to the
kinetic parameters of the corresponding homopolymer (PCL). The growth retardation of the constituent
which crystallizes second (PEG block) is attributed to the mutual influence between the PEG constituent
and the PCL crystal phase which fixes (hardened) the total copolymer structure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.