Generation of Monodispersed Spherical Thermosensitive Gels and Their Swelling and Shrinking Behaviors in Aqueous Polymeric Solutions

Raden Rinova Sisworo,Kousuke Nakashima,Yu Norimatsu,Masato Hasegawa,Yukio Tada

doi:10.3390/app10062016

Raden Rinova Sisworo, Kousuke Nakashima + Show 3 more

Open Access

https://doi.org/10.3390/app10062016

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Abstract

This study investigates the factors affecting the formation of monodispersed thermosensitive gels and the parameters influencing the movement of gel particles containing N-isopropyl acrylamide in an aqueous polymeric solution in an upper heating system. Monodispersed thermosensitive gels were generated, and their swelling and shrinking behaviors were observed. The results revealed that continuous-phase flow rate and kinematic viscosity were most influential on the size of the monodispersed thermosensitive gels, which exhibited swelling and shrinking at both low and high temperatures of the polymeric aqueous solution, respectively, and demonstrated negative thermal expansion. In a low-temperature solution, the buoyancy force acting on the gel particles exceeded the gravitational force, because of which the size of the gels increased and the gels to ascended. At higher temperatures, the gels shrank because the gravitational force outweighed the buoyancy force, causing the gels to descend. The gels with a larger diameter tended to have longer durations of vertical movements within the aqueous polymeric solution than the smaller-sized gels; moreover, equilibrium conditions were quickly achieved by the smaller gels.

Highlights

Every material demonstrates a thermal response to temperature changes in its surroundings; a material’s behavior could vary under different conditions
Thermosensitive gels are one such material; they shrink when submerged in high-temperature liquids such as aqueous polymeric solutions and swell when submerged in cooler fluids
The thermosensitive gels used in this study were generated in a laboratory for application in the upper heating system of a rectangular enclosure

Summary

Introduction

Every material demonstrates a thermal response to temperature changes in its surroundings; a material’s behavior could vary under different conditions. The diameter difference between the capillaries was quite small; decreases in droplet size were primarily affected by the drag force triggered by the continuous-phase flow [35]. Droplet size is affected by the junction geometry of the microfluidic devices, the flow rates of the continuous phase, and the physical characteristics of the fluid i.e., its interfacial tension and viscosity [37]. The episodic motions continuously occur provided a relevant condition supporting the movements that can be maintained, i.e., the satisfactory concentration of the solution, the appropriate gel diameter, and a preserved temperature difference between the upper and lower walls of the enclosure. The effects of viscosity and flow-rate variations of the continuous-phase flow on gel size formation, and the volume change of the gels together with their vertically repetitive motions within the aqueous solutions were investigated

Materials and Methods

Method for Generating Mono-dispersed Thermosensitive Gels

Method to Observe andtoShrinking

Results and Discussion

13. Vertical

Conclusions