Please use this identifier to cite or link to this item: https://doi.org/10.1006/jcis.2001.8063
Title: The influence of cold treatment on properties of temperature-sensitive poly(N-isopropylacrylamide) hydrogels
Authors: Zhang, X.-Z.
Yang, Y.-Y.
Chung, T.-S. 
Keywords: Cold treatment
Fast response
Hydrogel
Poly(N-isopropylacrylamide)
Temperature-sensitive
Issue Date: 2002
Source: Zhang, X.-Z., Yang, Y.-Y., Chung, T.-S. (2002). The influence of cold treatment on properties of temperature-sensitive poly(N-isopropylacrylamide) hydrogels. Journal of Colloid and Interface Science 246 (1) : 105-111. ScholarBank@NUS Repository. https://doi.org/10.1006/jcis.2001.8063
Abstract: Poly(N-isopropylacrylamide) (PNIPAAm) hydrogel exhibits a response to external temperature variation and shrinks in volume abruptly as the temperature is increased above its lower critical solution temperature. It has great potential applications in biomedical fields. A rapid response rate is essential, especially when this material is designed as an on-off switch for targeted drug delivery. However, due to the appearance of a thick, dense skin layer on the hydrogel surface during the shrinking process, the deswelling rate of conventional PNIPAAm gels is low. In this article, a novel method is proposed to modify the surface morphology of PNIPAAm gel, in which the swollen gels are frozen at low temperature (-20°C). The scanning electron micrographs revealed that a fishnet-like skin layer appeared on the surfaces of the cold-treated gels. Dramatically rapid deswelling was achieved with the cold-treated gels since the fishnet-like structure with numerous small pores prevented the formation of a dense, thick skin layer during the deswelling process, which commonly occurs in normal PNIPAAm hydrogels. Prolonging the cold treatment from 1 day to 10 days resulted in a slightly higher deswelling rate. Rearrangement of the hydrogel matrix structure during the freezing process might contribute to the formation of the fishnet-like skin layer. The water uptake of the hydrogels increased nearly in proportion to the square root of time, indicating that the reswelling rate of hydrogels was controlled predominantly by water diffusion into the network. However, there were no significant differences in the equilibrated swelling ratio and reswelling kinetics at room temperature (22°C) between normal gels and cold-treated gels, which implied that cold treatment did not change bulk porosity and gel tortuosity much. © 2002 Elsevier Science.
Source Title: Journal of Colloid and Interface Science
URI: http://scholarbank.nus.edu.sg/handle/10635/66869
ISSN: 00219797
DOI: 10.1006/jcis.2001.8063
Appears in Collections:Staff Publications

Show full item record
Files in This Item:
There are no files associated with this item.

SCOPUSTM   
Citations

46
checked on Dec 5, 2017

WEB OF SCIENCETM
Citations

48
checked on Dec 5, 2017

Page view(s)

21
checked on Dec 11, 2017

Google ScholarTM

Check

Altmetric


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.