Journal ArticleDOI
Comb-type grafted hydrogels with rapid deswelling response to temperature changes
Ryo Yoshida,Katsumi Uchida,Yuzo Kaneko,Kiyotaka Sakai,Akihiko Kikuchi,Yasuhisa Sakurai,Teruo Okano +6 more
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TLDR
In this paper, a crosslinked polymeric hydrogel with grafted side chains was used to induce rapid de-swelling by tailoring the polymeric gel architecture at the molecular level.Abstract:
MANY polymeric hydrogels undergo abrupt changes in volume in response to external stimuli such as changes in solvent composition1, pH2, electric field3 and temperature4–6. For several of the potential applications of these materials, such as 'smart' actuators, a fast response is needed. The kinetics of swelling and de-swelling in these gels are typically governed by diffusion-limited transport of the polymeric components of the network in water, the rate of which is inversely proportional to the square of the smallest dimension of the gel7–9. Several strategies have been explored for increasing the response dynamics10–14, such as introducing porosity14. Here we show that we can induce rapid de-swelling of a polymer hydrogel by tailoring the gel architecture at the molecular level. We prepare a crosslinked hydrogel in which the polymer chains bear grafted side chains; the latter create hydrophobic regions, aiding the expulsion of water from the network during collapse. Whereas similar gels lacking the grafted side chains can take more than a month to undergo full de-swelling, our materials collapse in about 20 minutes.read more
Citations
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Hydrogels in pharmaceutical formulations.
TL;DR: The aim of this article is to present a concise review on the applications of hydrogels in the pharmaceutical field, hydrogel characterization and analysis of drug release from such devices.
Journal ArticleDOI
Stimuli-reponsive polymers and their bioconjugates
Eun Seok Gil,Samuel M. Hudson +1 more
TL;DR: In this article, the authors focused on temperature and pH responsive polymer systems and additionally the other stimuli-based responsive polymers will be assessed, which is more helpful to design new approaches because the basic concepts and mechanisms are systematically connected.
Journal ArticleDOI
Thermosensitive sol-gel reversible hydrogels.
TL;DR: It is timely to summarize the polymeric systems that undergo sol-gel transitions, particularly due to temperature, with emphasis on the underlying transition mechanisms and potential delivery aspects.
Journal ArticleDOI
A review of stimuli-responsive nanocarriers for drug and gene delivery
TL;DR: There is a highly promising role of stimuli-responsive nanocarrier systems for drug and gene delivery in the future with greater understanding of the difference between normal and pathological tissues and cells.
Journal ArticleDOI
Hydrogel Nanoparticles in Drug Delivery
TL;DR: Hydrogel nanoparticles have gained considerable attention in recent years as one of the most promising nanoparticulate drug delivery systems owing to their unique potentials via combining the characteristics of a hydrogel system with a nanoparticle, each with its own advantages and drawbacks.
References
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Journal ArticleDOI
Solution Properties of Poly(N-isopropylacrylamide)
M. Heskins,J. E. Guillet +1 more
TL;DR: In this paper, a lower critical solution temperature of poly(N-isopropyl acrylamide was found to be due to an entropy effect, which was attributed to the formation of nonpolar and intermolecular hydrogen bonds.
Journal ArticleDOI
Volume phase transition in a nonionic gel
TL;DR: In this article, a nonionic Nisopropylacrylamide gel was found to undergo a discontinuous phase transition by changing a solvent composition or temperature, which is an evidence for the universality of the phase transition of polymer gels.
Journal ArticleDOI
Kinetics of swelling of gels
TL;DR: In this article, a theory of the kinetics of the swelling of polyacrylamide gels is presented, which is based on the assumption that the swelling time is determined by the diffusion coefficient of the fluid molecules.
Journal ArticleDOI
Collapse of Gels in an Electric Field
TL;DR: An infinitesimal change in electric potential across a polyelectrolyte gel produces a discrete, reversible volume change, which can be several hundred times smaller than that of the swollen gel.
Journal ArticleDOI
Phase Transitions in Ionic Gels
TL;DR: In this article, the polymer network of a gel undergoes a discrete transition in equilibrium volume with changes in solvent composition or temperature, and the volume collapse is also observed when the p\mathrm{H}$ within the gel is varied.
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