title: Synthesis and Gelation Characteristics of Photo-Crosslinkable Star Poly(ethylene oxide-co-lactide-glycolide acrylate) Macromonomers.
abstract: Viability of encapsulated cells in situ crosslinkable macromonomers depends strongly on the minimum concentration of polymerization initiators and monomers required for gelation. Novel 4-arm poly(ethylene oxide-co-lactide-glycolide acrylate) (SPELGA) macromonomers were synthesized and characterized with respect to gelation, sol fraction, degradation, and swelling in aqueous solution. SPELGA macromonomers were crosslinked in the absence of N-vinyl-2-pyrrolidone (NVP) monomer to produce a hydrogel network with a shear modulus of 27±4 kPa. The shear modulus of the gels increased by 170-fold as the macromonomer concentration was increased from 10 to 25 wt%. Sol fraction ranged between 8-18%. Addition of only 0.4 mol% NVP to the polymerization mixture increased modulus by 2.2-fold from 27±4 (no NVP) to 60±10 kPa. The higher modulus was attributed to the dilution effect of polymer chains in the sol, by delaying the onset of diffusion-controlled reaction, and cross-propagation of the growing chains with network-bound SPELGA acrylates. Degradation of SPELGA gels depended on water content and density of hydrolytically degradable ester groups.
authors.affiliation: Biomimetic Materials and Tissue Engineering Laboratories, Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208.
authors.forename: Seyedsina
authors.initials: S
authors.lastname: Moeinzadeh
authors.forename: Saied Nouri
authors.initials: SN
authors.lastname: Khorasani
authors.forename: Junyu
authors.initials: J
authors.lastname: Ma
authors.forename: Xuezhong
authors.initials: X
authors.lastname: He
authors.forename: Esmaiel
authors.initials: E
authors.lastname: Jabbari