Influence of Poly(acrylic acid) on the Mechanical Properties of Composite Hydrogels

Abstract

ABSTRACT Gelatin (Gel) and poly(acrylic acid) (PAA) have so many applications in wound dressing, drug release, and tissue engineering on the basis of their easy availability, biocompatibility, and biodegradability. A composition of Gel/PAA hydrogel is widely used as a biological glue of soft tissues. However, the influence of PAA on the mechanical properties of this composite hydrogel so far has not been determined. In this study, gel hydrogels were prepared at various PAA content, i.e., 10, 20, and 30 wt%, using a thermal‐initiated redox polymerization method. Afterward, as=prepared cylindrical hydrogel samples were subjected to a series of compressive loading to measure their linear elastic (elastic modulus, maximum stress and strain) and nonlinear hyperelastic (hyperelastic coefficients) mechanical properties. The potential ability of the Yeoh material model to closely address the nonlinear mechanical behavior of the hydrogel was verified using finite element (FE) modeling of the compression test. The results showed that the addition of PAA (>10 wt%) invokes a significant decrease in the Young's modulus and maximum stress of the hydrogels whereas a significant increase in the maximum strain. The highest Young's modulus (25 MPa) and maximum stress (12 MPa) were observed in the hydrogels with PAA (10 wt%), whereas the highest maximum strain (43%) was detected in the Gel/PAA (30 wt%) samples. The experimental results were well compared to those anticipated by the Yeoh and FE models. The results suggested that an optimum addition of PAA not only could enhance the mechanical strength of the hydrogels but also provide a nonlinear behavior of composite hydrogels, which is suitable for soft tissue engineering.