Stimulus responsive behavior of elastin-based side chain polymers

Linear poly(VPGVG) has been extensively studied over the years as a model for the structural protein elastin. Elastin is characterized by a lower critical solution temperature (LCST). This LCST can be influenced by several factors, mainly molecular weight, concentration, and pH. An ABA type block copolymer was synthesized using atom transfer radical polymerization (ATRP), in which the VPGVG sequence is in the side chain of the A block and the B block is poly(ethylene glycol) (PEG). The LCST behavior of this series of elastin based side chain block copolymers was investigated by changing the degree of polymerization, polymer concentration, and pH. The effects of these parameters on the LCST of the side chain block copolymers were similar when compared with linear poly(VPGVG). The aggregates which were formed above the transition temperature were investigated using light scattering and cryo-SEM techniques.