The Study of Ultrasonic Degradation of Superabsorbent Hydrogels

Abstract

Viscometry is a valid and practical approach for monitoring the degradation of polymers in solution. In this work, at constant power and pulse, the effects of different operating parameters such as time of irradiation, temperature, solution concentration, volume, solvent, and immersion depth of horn on the rate of degradation have been investigated in aqueous solution using laboratory scale operation. A method of viscometry was used to study the degradation behavior of aqueous dispersions of microgels. The experimental results show that the viscosity of polymer solution decreased with an increase in the ultrasonic irradiation time and approached a limiting value. The present work has enabled us to understand the role of the different operating parameters in deciding the extent of viscosity reduction in aqueous dispersions of microgels and also the controlling effects of them.

Color-Changing Reflection Hologram for Quality Assurance of Therapeutic Ultrasound Systems

“…Therefore, it is postulated that the color change/opaque region in the holograms was achieved due to the temperature-assisted (>40 °C) modification of the polymer film combined with the delivery of acoustic pressure. Ultrasonic degradation of polymers such as polyacrylamide (PAA) is reported in the literature; , “degradation” in this context is defined as a change in the chemical and/or physical structure of the polymer chain, which causes a decrease in the molecular weight of the polymer. The opaque region is therefore likely visible due to the modification of the diacetone acrylamide and bisacrylamide polymer chains within the photopolymer film; the accompanying visible green color is likely due to the distortion of the reflection grating and its planes by the generated bubbles.…”

Recent advances in various stimuli-responsive hydrogels: from synthetic designs to emerging healthcare applications

“…These involved the use of pH, 22 light, 23 temperature, 24 electrical 25 and magnetic fields, 26 chemical agents, 27 and ultrasound irradiation. 28 Stimuli-responsive hydrogels have extensive uses in the healthcare sector: for example, for biosensing; 29 as controlled/sustained drug carrier matrices; [30][31][32] in tissue and bone regeneration; [33][34][35] in bio-adhesives, 36 hemostats, 37 and shape-memory matrices; 38 in actuation 39 or in robotics. 40 The challenge for the development of stimuliresponsive hydrogels or nanogels is mainly to quantify the…”

Stimuli-Responsive DNA-Based Hydrogels on Surfaces for Switchable Bioelectrocatalysis and Controlled Release of Loads

“…Stimuli-responsive hydrogel materials − have attracted growing interest as “smart” materials for diverse applications, such as sensing, − controlled drug release, − tissue engineering, − self-healing, − shape-memory, − robotics, and actuation. − Different physical and chemical stimuli to trigger hydrogel materials and control their stiffness properties were introduced, including light, − electrical fields, − temperatures, ,− magnetic fields, ,− ultrasound irradiation, , pH, − and chemical agents. − An important subclass of stimuli-responsive hydrogels includes biomaterial-based hydrogels − and particularly, nucleic acid-based hydrogel matrices. …”