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Gels
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Thermoresponsive Microgels
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Thermoresponsive Microgels

A special issue of Gels (ISSN 2310-2861). This special issue belongs to the section "Gel Chemistry and Physics".

Deadline for manuscript submissions: closed (25 April 2023) | Viewed by 4055

Special Issue Editor

Dr. Paula Isabel Soares

E-Mail Website
Guest Editor
i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal
Interests: magnetic nanoparticles; cancer theranostics; thermoresponsive polymers; 3D printing; microgels
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue on “Thermoresponsive Microgels” is dedicated to recent advances in the development of thermoresponsive microgels, including their synthesis, characterization, and applications.

The quest for new and improved materials over the last several decades has produced new functional materials able to respond to external stimuli. This response can be translated into significant physical or chemical changes in the intrinsic structure of the material. Polymeric microgels take advantage of their intermediary state between branched polymers and macroscopic networks. These structures have molecular weights similar to those of linear polymers, but their intrinsically linked structure enables a special behavior upon contact with appropriate solvents: microgels can swell without dissolving, forming stable colloidal dispersions. Ever since the discovery by Pelton and Chibante in 1986 of poly(N-isopropylacrylamide) (PNIPAAm) thermoresponsive microgels, these structures have gained tremendous attention in different research areas, particularly in biomedical applications. These thermoresponsive microgels shrink upon temperature increase because of their intrinsic lower critical solution temperature, making them materials of choice for advanced drug delivery systems.

We welcome the submission of both theoretical and experimental studies in the design, engineering, and application of thermoresponsive microgels, with particular interest in the composition of innovative microgels. The most relevant fields of application will also be covered in this Special Issue to cover the most recent trends in the development of thermoresponsive microgels.

Dr. Paula Isabel Soares
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Gels is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • thermoresponsive
  • microgel
  • polymer
  • synthesis
  • branched structure
  • responsive material

Published Papers (2 papers)

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Research

8 pages, 1328 KiB  
Article
Frequency-Dependent Ultrasonic Stimulation of Poly(N-Isopropylacrylamide) Microgels in Water
by Atieh Razavi, Matthias Rutsch, Sonja Wismath, Mario Kupnik, Regine von Klitzing and Amin Rahimzadeh
Gels 2022, 8(10), 628; https://doi.org/10.3390/gels8100628 - 01 Oct 2022
Cited by 3 | Viewed by 1709
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Thermoresponsive Microgels)
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12 pages, 2002 KiB  
Article
Micron-Sized Silica-PNIPAM Core-Shell Microgels with Tunable Shell-To-Core Ratio
by Keumkyung Kuk, Lukas Gregel, Vahan Abgarjan, Caspar Croonenbrock, Sebastian Hänsch and Matthias Karg
Gels 2022, 8(8), 516; https://doi.org/10.3390/gels8080516 - 18 Aug 2022
Cited by 2 | Viewed by 1731
Abstract
Micron-sized hard core-soft shell hybrid microgels are promising model systems for studies of soft matter as they enable in-situ optical investigations and their structures/morphologies can be engineered with a great variety. Yet, protocols that yield micron-sized core-shell microgels with a tailorable shell-to-core size [...] Read more.
Micron-sized hard core-soft shell hybrid microgels are promising model systems for studies of soft matter as they enable in-situ optical investigations and their structures/morphologies can be engineered with a great variety. Yet, protocols that yield micron-sized core-shell microgels with a tailorable shell-to-core size ratio are rarely available. In this work, we report on the one-pot synthesis protocol for micron-sized silica-poly(N-isopropylacrylamide) core-shell microgels that has excellent control over the shell-to-core ratio. Small-angle light scattering and microscopy of 2- and 3-dimensional assemblies of the synthesized microgels confirm that the produced microgels are monodisperse and suitable for optical investigation even at high packing fractions. Full article
(This article belongs to the Special Issue Thermoresponsive Microgels)
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