Fabrication of Cationic Poly(vinyl alcohol) Films Cross-Linked Using Copolymers Containing Quaternary Ammonium Cations, Benzoxaborole, and Carboxy Groups

Abstract

Water-insoluble cationic poly(vinyl alcohol) (PVA) films were fabricated using a mixed aqueous solution of PVA and poly ([2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC)-co-methacrylic acid (MAAc)-co-5-methacrylamido-1,2benzoxaborole (MAAmBO)) copolymer (3D). The surface of the PVA film is typically negatively charged, and simple fabrication methods for water-insoluble PVA films with cationic surface charges are required to expand their application fields. METAC, which has a permanent positive charge owing to the presence of a quaternary ammonium cation, was selected as the cationic unit. The MAAc and MAAmBO units were used as two types of cross-linking structures for the thermal cross-linking of the hydroxy and carboxy groups of the MAAc unit (covalent bonding) as well as the diol and benzoxaborole groups of the MAAmBO unit (dynamic covalent bonding). The films were thermally cross-linked at 135 °C for 4 h without the addition of materials. After immersion in surplus water at 80 °C for 3 h, the cross-linked PVA/3D films retained almost 100% of their weights. The ζ-potential of the water-insoluble PVA/3D film was 9.4 ± 0.8 mV. The PVA/3D film was strongly dyed using anionic acid red 1 (AR1) because of its positively charged surface. Interestingly, it could also be slightly dyed using cationic methylene blue (MB) and became transparent (original state) after immersion in water for 2 days. These results suggested that positive and negative charges coexisted in the PVA/3D film, and the surface properties were positively inclined. Moreover, the degree of hemolysis of the PVA/3D films was similar to that of the negative control, which showed high blood compatibility. To our knowledge, this is the first report on the fabrication of water-insoluble cationic PVA films using two types of cross-linking structures containing carboxy and benzoxaborole groups. The cross-linked PVA films were analyzed using Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), and contact angle (CA) and ζ-potential measurement, as well as by determining the mechanical properties, adsorption of charged molecules, and biocompatibility. These readily fabricated waterinsoluble PVA films with positive charges can show potential applications in sensors, adsorption systems, and antimicrobial materials.

Cicada-Wing-Inspired Nanopillar Hydrogels Consisting of Poly(vinyl alcohol) and Poly(methacrylic acid) for Capturing Bacteria through Their Flexibility and Wide Range of Motion

“…In fact, the ζ-potential of the PVA/poly­(MAAc) (25 wt % of poly­(MAAc)) film was −7.7 ± 1.9 mV. Additionally, the negative surface charges of the mixed PVA films were turned to a positive charge of 9.4 ± 0.8 mV by copolymerizing MAAc with a cationic monomer . The negatively charged surface was selected to prevent the adsorption of bacteria onto polymeric materials by electrostatic repulsion.…”

“…Poly­(vinyl alcohol) (PVA) and poly­(methacrylic acid) (poly­(MAAc)) were used to fabricate the nanopillars. PVA is a highly biocompatible polymer that has been applied in a wide range of fields such as medical devices, food packages, glues, and displays. − The hydroxy groups of PVA have been used as points for thermal cross-linking with low-toxic and inexpensive compounds with carboxy groups including poly­(acrylic acid) (poly­(AAc)) and poly­(MAAc). − The polymeric aqueous solution consisting PVA and poly­(MAAc) was poured into the porous template, and the resulting dry films were treated at 135 °C for thermal cross-linking between the hydroxy and carboxy groups. The cross-linked nanopillars were highly flexible with no structural disruption being observed on tilting them.…”

“…Hydrogels having electrostatic repulsion, such as negatively charged poly­(MAAc), are generally capable of containing water resulting in a considerable expansion. The swelling ratios of PVA/poly­(MAAc) films decreased from 2.09 ± 0.08 to 1.46 ± 0.18 when the poly­(MAAc) content was increased from 10 to 50 wt % . These findings suggest that by carefully regulating the cross-linked structures, negatively charged hydrogels with a low expansion rate can be created.…”

“…There was no significant difference in the parameters of nanopillars with a change in poly­(MAAc) content ( p > 0.05). In our previous study, we discovered that PVA/poly­(MAAc) flat films with varying amounts of poly­(MAAc) had varying thermodynamic properties, including glass transition temperature ( T g ), melting point ( T m ), enthalpy change (Δ H m ), and degree of crystallization (χ cr ) . The T g , T m , Δ H m , and χ cr of the PVA/poly­(MAAc) flat film containing 10 wt % of poly­(MAAc) were 80.2 ± 2.6 °C, 191.2 ± 2.1 °C, −12.8 ± 1.0 J/g, and 10.3 ± 0.8%, respectively.…”

“…The nanopillar films were We have previously prepared water-insoluble flat films of thermally cross-linked PVA and poly(MAAc). 19,20 After 3 h of immersion in surplus water at 80 °C, the thermally cross-linked films retained almost 100% of their weight. Under the same conditions, the nonthermal cross-linked film of PVA/poly-(MAAc) dissolved completely in water.…”