PLA-PEO-PLA triblock copolymer hydrogels for soft tissue engineering: Properties, assembly, and structure
Biodegradable hydrogels show great promise in the area of biomaterials and specifically for tissue engineering applications. While much work in the past has studied the various biochemical signals associated with cell growth, more recent work has highlighted the importance of the mechanical environment as a stimulus for growth. This dissertation focuses on associative network hydrogels formed for poly(lactide)-b-poly(ethylene oxide)-b-poly(lactide) [PLA-PEO-PLA] triblock copolymers and the factors that influence their mechanical properties, assembly, and structure. By controlling the stereospecificity of the PLA endblocks hydrogels with either amorphous or crystalline hydrophobic domains were formed as characterized using both X-ray and neutron scattering techniques. This change in structure directly impacted the mechanical properties of the hydrogels. Furthermore, complications in synthetic techniques introduced contaminants (asymmetric triblock copolymers or "effective" diblock copolymers) that impacted the assembly of the network to again impact the mechanical properties. Ultimately, the PLA-PEO-PLA triblock copolymer was chemically modified so that the self-assembled physical network served as a template for the covalently crosslinked network formed by photocrosslinking. The photocrosslinked hydrogels maintained their mechanical integrity in an aqueous environment; however, the measured mechanical properties were dependent on the assumed constitutive relationship.
0541: Biomedical engineering