The effect of pH on the LCST of poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide-co-acrylic acid).
Poly(N-isopropylacrylamide) (PNIPAAm) and poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAAm-co-AAc)) hydrogels are synthesized by irradiating the aqueous solutions of NIPAAm and NIPAAm/AAc with 60Co gamma-ray. The effects of pH on the swelling ratio and on the lower critical solution temperature (LCST) are studied by determining the dependence of swelling ratio on temperature in different pH butter solutions. Differential scanning calorimetry (DSC) is applied in determination of the LCST of the hydrogels. Fourier transform infrared (FT-IR) spectrometry is used in the comparison of hydrogels swelled in various pH conditions. As a result, PNIPAAm was found to be a pH-sensitive hydrogel and the LCST of the PNIPAAm and P(NIPAAm-co-AAc) hydrogels are influenced by pH.
Pei
Yong
Y
Department of Chemical Engineering and Technology, School of Environmental and Chemical Engineering, Shanghai University (Jiading Campus), Shanghai 201800, China.
Chen
Jei
J
Yang
Liming
L
Shi
Lili
L
Tao
Qiong
Q
Hui
Baojun
B
Li
Jian
J
D000178:Acrylamides / Q000737:chemistry*; D000179:Acrylates / Q000737:chemistry*; D000180:Acrylic Resins / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D020100:Hydrogels / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D011108:Polymers / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
D000178:Acrylamides; D000179:Acrylates; D000180:Acrylic Resins; D020100:Hydrogels; C090629:N-isopropylacrylamide-acrylic acid copolymer; D011108:Polymers; C052970:poly-N-isopropylacrylamide