Poly(Vinyl Alcohol)/Poly(Acrylic Acid) Hydrogel in a dc Electric Field: Swelling, Shape Change, and Actuation Characteristics

Abstract

Poly(vinyl alcohol) (PVA)/Poly(acrylic acid) (PAA) hydrogel can be utilized as a biomimetic actuator and coating material for tissue-implant interface, when employing an electrical stimulus. The swelling, shape change, and actuation characteristics of PVA/PAA hydrogel in a range of dc electrical fields were determined to find the optimal electric field for the hydrogel application as biomimetic actuator and coating materials. The hydrogel samples were prepared by dissolving PVA and PAA in deionized water at 4 wt% and mixed together at 1:1 ratio. Two custom made experimental setups were fabricated; one used for the measurement of swelling ratio of the hydrogels; and the other used for the shape changes or actuation characteristics of the hydrogels. Swelling experiments show increased swelling ratios of the hydrogel due to 10 V, 20 V, and 30 V electric fields. The rate of increment of the swelling ratio of hydrogel samples under 10V was higher compare to those samples under 20 V and 30 V. The width and height changes of rectangular shapes and maximum deflection along the length of hydrogel sample due to a range of electric fields (0-30V) were measured using an optical microscope. Incremental shape change up to a specific threshold value (around 10V) was observed due to electric stimulus. Electrostatic actuation pressure of hydrogel samples under 10V was higher compare to those samples under 20 V and 30 V. These results suggested that optimal performance of PVA/PAA hydrogel can be achieved around 10V.

Electroconductive Hydrogel Based on Functional Poly(Ethylenedioxy Thiophene)

“…Freeze-dried specimens were incubated in PBS (pH = 7.4 at 37 °C) and weighed at different times. Hydrogels were found to exhibit a remarkable water uptake after 48 h (∼5000%), which was comparable to the swelling ratio of other PAA copolymer hydrogels (Figure A) . The swelling of the hydrogels was due to the ionization at pH = 7.4 of the pendant carboxylic groups present on both polymers (PAA and f-PEDOT).…”

“…Hydrogels were found to exhibit a remarkable water uptake after 48 h (∼5000%), which was comparable to the swelling ratio of other PAA copolymer hydrogels ( Figure 2 A). 41 The swelling of the hydrogels was due to the ionization at pH = 7.4 of the pendant carboxylic groups present on both polymers (PAA and f-PEDOT). As the proton of the carboxylic groups dissociates in pH = 7.4, electrostatic repulsion between the polymer chains caused the network to uptake water.…”

An Overview of Polymeric Hydrogel Applications for Sustainable Agriculture

“…Natural polymer-based hydrogels are made of polymers derived from alginate [18], pectin [19], carrageenan [20], chitosan [21], polylysine [22], collagen [18], carboxymethyl chitin [23], carboxymethylcellulose [24], dextran [25], agarose [26], and pullulan [27], among other matrices [28][29][30]. Synthetic polymer-based hydrogels include polyvinyl alcohol [31], polyethylene glycol [32], and polyacrylic acid [33], among others.…”

Effect of pH on the Poly(acrylic acid)/Poly(vinyl alcohol)/Lysozyme Complexes Formation

“…Poly(acrylic acid) (PAA) and poly(vinyl alcohol) (PVA) have gained much attention due to the possibility of developing, through their combination, materials with well-controllable properties for a wide variety of applications. A significant number of studies refer to materials based on PAA–PVA mixtures, which, due to their great versatility, can have a multitude of applications: solid polymer electrolytes [ 1 , 2 ], materials for the removal of pollutants from wastewater [ 3 , 4 , 5 , 6 , 7 ], hydrogels for soilless cultivation [ 8 ], food packaging applications [ 9 ], drug delivery systems [ 10 , 11 ], materials for various biomedical applications [ 12 , 13 ], etc. PAA is a weak polyelectrolyte with carboxyl groups along the main chain that dissociate as the pH increases.…”