PVA/PAA thermo‐induced hydrogel fiber: Preparation and pH‐sensitive behavior in electrolyte solution

Abstract

ABSTRACT:The preparation of thermo-induced hydrogel fibers composed of poly(vinyl alcohol) and poly(acrylic acid) is presented. The hydrogel fiber was prepared by extruding the spinning dope from in situ polymerization of acrylic acid in the presence of PVA into a coagulating bath of saturated ammonium sulfate aqueous solution. The network was formed by thermally heating the dried fibers under vacuum. The final hydrogel fibers exhibit pH-sensitive behavior and show a hysteresis loop in the pH range from 3.0 to 12.0. The pH value, at which the swelling elongation ratio of the fiber had a jump, shifted to a lower value with increasing PAA content within the network. Increasing the heating temperature and time for the fibers, decreased the swelling elongation ratio, and the jump point pH shifted to higher pH value. The oscillatory swelling/contracting behavior of the hydrogel fiber exhibited a good reversible pH-responsive property. Transmission Electron Microscopy (TEM) showed that PVA and PAA have good compatibility and give a relative independent interpenetrating network. Scanning Electron Microscopy (SEM) showed that in the surface of the fibers there were microholes and ditches due to some diffusion of PAA into the coagulating solution.

Porous poly(vinyl alcohol)/sepiolite bone scaffolds: Preparation, structure and mechanical properties

“…Similar to PVA, PAA also displays excellent biocompatibility and has been used in applications such as sitespecific drug delivery systems [26,27], wound dressing materials [28] and partially degradable bone cements [29]. It has also been used in conjunction with PVA to form hydrogel fibres where the degree of swelling can be easily controlled by the degree of crosslinking [30]. [30][31][32].…”

“…It has also been used in conjunction with PVA to form hydrogel fibres where the degree of swelling can be easily controlled by the degree of crosslinking [30]. [30][31][32]. It is composed of blocks, which are characterized by a sandwich structure of a central magnesium octahedral sheet between two silica tetrahedral sheets, forming a capillary network of parallel channels [31][32][33].…”

“…For crosslinking, all the film and foam samples with varying concentrations of sepiolite were operated under vacuum at 150 o C for 30 minutes to improve their stability and mechanical properties according to the methods described in the literature [26,27,30]. PAA with a low molecular weight of 2,000 g/mol was chosen as the crosslinking agent due to its chain mobility in PVA, as previously mentioned.…”

Preparation and Characterization of Novel Temperature Sensitive Poly(N‐isopropylacrylamide‐co‐acryloyl beta‐cyclodextrin) Hydrogels with Fast Shrinking Kinetics

“…[1][2][3][4][5] Hydrogels can be mainly classified into two categories: conventional hydrogels and environmentalsensitive hydrogels. [6] Environmental-sensitive hydrogels exhibit marked property changes when the external conditions fluctuate slightly, and the influential factors include temperature, [7][8][9][10][11] pH, [12,13] solvent, [14,15] additives [16] and ionic strength, [17,18] etc.…”

Preparation and characterization of pH‐sensitive hydrogel fibers based on hydrolyzed‐polyacrylonitrile/soy protein

“…[17][18][19][20][21] Fei et al prepared the thermoinduced pH-sensitive hydrogel fibers composed of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) and found that the higher the PAA content of the hydrogel the lower the jump point pH value in the static behavior and more microholes were formed, which greatly improved the response property. 20 Sun et al prepared the pH-sensitive hydrogel fibers from chitosan/poly(propylene glycol) composite via solution spinning, which were then crosslinked by epichlorohydrin (ECH) and glutaraldehyde (GA). They studied the mechano-electro-chemical behavior of the hydrogel fibers and found that CS/PEG crosslinked by ECH is more sensitive than that by GA. 21 Umemoto et al produced the pH-sensitive hydrogel fibers from commercially available poly(acrylonitrile) (PAN) fibers, which can be changed by the preoxidation step from a linear chain structure to a planar network structure constructed with cyano groups and pyridine rings as a crosslinker.…”