Synthesis and Characterization of Modified Poly(vinyl alcohol) Membrane and Study of Its Enhanced Water-Induced Shape-Memory Behavior

Nowadays, shape-memory polymers (SMPs) are regarded as smart materials. To get new functions, SMPs should be modified or fabricated in the composite form. Herein, poly (vinyl alcohol) (PVA) membranes were prepared by a solution casting method and subsequently modified using a solution of borax and glutaraldehyde. The physicochemical properties, including the mechanism of water-induced shape-memory behavior of all prepared membranes, were systematically studied. From the results obtained, it is observed that the modification agents into the PVA polymer matrix, enhanced the properties of the prepared modified membranes. The modified membranes have more hydrophilicity than pure PVA membrane. The gel fraction value of modified membranes was more than 90%. The crystallinity of modified samples was lower than pure PVA membrane due to the destruction of original inter and intra-molecular hydrogen bonding. In addition, mechanical properties (tensile strength and elongation at break) were evaluated for both modified and unmodified PVA membranes. The shape recovery time of modified membranes were much lower than that of pure PVA membrane. The shape recovery values of all samples were almost 100%. Increase in the water immersion time (0 to 14 s) of the PVAG (modified with borax) sample, the storage modulus and glass transition temperature was drastically decreases from 9711 to 4226 MPa, and 35.03 to 12.35 °C, respectively. Further, in vitro biodegradation studies were conducted for all the prepared samples. Therefore, the above fabricated membranes can be applied in the biomedical field where water is the primary stimulus.