Effect of Poly(vinyl alcohol) Macromer Chemistry and Chain Interactions on Hydrogel Mechanical Properties

Abstract

Poly (vinyl alcohol) (PVA) is a versatile polymer that when modified with functional groups can be polymerized to produce hydrogels with a range of mechanical properties. In this study, PVA was modified with pendent acrylamide groups and crosslinked via photopolymerisation. The swelling behavior and tensile properties of the resulting hydrogels were studied as a function of percent macromer at the time of polymerization, functional group density, backbone molecular weight, and percent hydrolysis of the PVA. Percent macromer had the strongest influence, with tensile modulus increasing in direct proportion to increasing percent macromer. Changing the functional group density of the macromers as well as changing the molecular weight of the PVA backbone significantly impacted the swelling and mechanical behavior. Although percent hydrolysis of the PVA backbone resulted only in slight variations in the network, it did prove to be a significant variable. However, it was also found that the tensile modulus was directly related to the amount of polymer in the hydrogel. Rheological studies demonstrated that by increasing the number of chain interactions in solution (i.e., increasing the percent macromer, etc.) the resulting network produced was more interconnected and thus stronger. Overall, it was found that hydrogels produced from PVA macromers that had larger molecular weights and more functional groups per PVA chain and were less hydrophilic and formulated into higher percent macromer solutions were stronger, stiffer materials.