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Frequency-Dependent Ultrasonic Stimulation of Poly(N-isopropylacrylamide) Microgels in Water

Razavi, Atieh ; Rutsch, Matthias ; Wismath, Sonja ; Kupnik, Mario ; Klitzing, Regine von ; Rahimzadeh, Amin (2022)
Frequency-Dependent Ultrasonic Stimulation of Poly(N-isopropylacrylamide) Microgels in Water.
In: Gels, 2022, 8 (10)
doi: 10.26083/tuprints-00022833
Article, Secondary publication, Publisher's Version

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Item Type: Article
Type of entry: Secondary publication
Title: Frequency-Dependent Ultrasonic Stimulation of Poly(N-isopropylacrylamide) Microgels in Water
Language: English
Date: 7 November 2022
Place of Publication: Darmstadt
Year of primary publication: 2022
Publisher: MDPI
Journal or Publication Title: Gels
Volume of the journal: 8
Issue Number: 10
Collation: 8 Seiten
DOI: 10.26083/tuprints-00022833
Corresponding Links:
Origin: Secondary publication DeepGreen

As a novel stimulus, we use high-frequency ultrasonic waves to provide the required energy for breaking hydrogen bonds between Poly(N-isopropylacrylamide) (PNIPAM) and water molecules while the solution temperature is maintained below the volume phase transition temperature (VPTT = 32 °C). Ultrasonic waves propagate through the solution and their energy will be absorbed due to the liquid viscosity. The absorbed energy partially leads to the generation of a streaming flow and the rest will be spent to break the hydrogen bonds. Therefore, the microgels collapse and become insoluble in water and agglomerate, resulting in solution turbidity. We use turbidity to quantify the ultrasound energy absorption and show that the acousto-response of PNIPAM microgels is a temporal phenomenon that depends on the duration of the actuation. Increasing the solution concentration leads to a faster turbidity evolution. Furthermore, an increase in ultrasound frequency leads to an increase in the breakage of more hydrogen bonds within a certain time and thus faster turbidity evolution. This is due to the increase in ultrasound energy absorption by liquids at higher frequencies.

Uncontrolled Keywords: poly(N-isopropylacrylamide), microgels, ultrasound, turbidity, hydrogen bond, acousto-responsive
Status: Publisher's Version
URN: urn:nbn:de:tuda-tuprints-228332
Additional Information:

This article belongs to the Special Issue Thermoresponsive Microgels

Classification DDC: 500 Science and mathematics > 530 Physics
600 Technology, medicine, applied sciences > 600 Technology
600 Technology, medicine, applied sciences > 620 Engineering and machine engineering
Divisions: 18 Department of Electrical Engineering and Information Technology > Measurement and Sensor Technology
05 Department of Physics > Institute for Condensed Matter Physics > Soft Matter at Interfaces (SMI)
Date Deposited: 07 Nov 2022 12:03
Last Modified: 14 Nov 2023 19:05
SWORD Depositor: Deep Green
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/22833
PPN: 501610391
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