Premium
Swelling mechanism of porous P(VP‐ co ‐MAA)/PNIPAM semi‐IPN hydrogels with various pore sizes prepared by a freeze treatment
Author(s) -
Jin Shuping,
Bian Fengling,
Liu Mingzhu,
Chen Shilan,
Liu Hongliang
Publication year - 2009
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.2504
Subject(s) - swelling , microstructure , self healing hydrogels , diffusion , materials science , differential scanning calorimetry , scanning electron microscope , porosity , chemical engineering , kinetics , composite material , polymer chemistry , thermodynamics , physics , quantum mechanics , engineering
BACKGROUND: The objective of the work reported was to investigate the effect of gel microstructure on the swelling mechanism. A series of porous gels with various pore sizes were prepared by freeze‐treating a conventional hydrogel that contained various amounts of water at − 20 °C. Scanning electron microscopy and differential scanning calorimetry were used to characterize the microstructure of the porous gels. RESULTS: The experimental results showed that the water content during freezing was the key factor controlling the microstructure. Measurement of swelling kinetics showed that a greater amount of water during the freezing process would lead to a rapid swelling rate. The apparent diffusion coefficients ( D p ) at all times during the swelling process were obtained by fitting the experimental data to the diffusion equation. The values of D p suggested that the swelling mechanism of the gels depends on the pore size. The diffusion exponent ( n ) obtained by fitting the fractional mass change ( M t / M ∞ ) to equation of Fick's law further confirmed that the swelling mechanism of the gels is determined by the pore size. CONCLUSION: The swelling mechanism of the gels is determined by the microstructure related to the pore size and the thickness of struts. The microstructure can be controlled by adjusting the water content of the hydrogels by changing the pH of the swelling medium prior to freezing. Copyright © 2008 Society of Chemical Industry