Zwitterionic sulfobetaine-containing polyelectrolyte for controlling humidity-sensitivity

• Published in: Sensors and actuators. B, Chemical Vol. 145; no. 1; pp. 254 - 258
• Main Authors: Han, Dae-Sang, Gong, Myoung-Seon
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 04.03.2010
• Subjects: Actuators; Chains (polymeric); Copolymer; Copolymers; Humidity; Humidity sensor; Hysteresis; Ingredients; Membranes; Polyelectrolyte; Polyelectrolytes; Sensors; Styrenes; Sulfobetaine-type salt; Zwitterionic; Humidity sensor; Polyelectrolyte; Copolymer; Sulfobetaine-type salt; Zwitterionic
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2009.12.008

Three components copolymers poly(MEPAB-co-DMMSA-co-ST) were synthesized to utilize as humidity-sensitive membranes. The major ingredient of a humidity-sensitive membrane is polyelectrolytes obtained from the copolymers [2-[(methacryloyloxy)ethyl]dimethyl]propylammonium bromide (MEPAB)/ N, N-dimethyl- N-methacryloxyethyl- N-(3-sulfopropyl) ammonium (DMMSA)/styrene (ST) = 6/1/2, 6/2/1, 7/1/2 and 7/2/1. The humidity sensor prepared from the 20% solution of MEPAB/DMMSA/ST = 6/1/2 and 7/1/2 showed average impedances of 754.4–0.92 and 1137.6–0.65 kΩ, respectively, in a 30–90%RH range. The impedance of the sensor so prepared changes linearly for 3.5 orders of magnitude over the range of 30–90%RH, showing a high sensitivity and good linearity in a semi-logarithmic scale. In addition, it exhibits the advantages of quick response and recovery and very small hysteresis (<1%RH). It is proposed that the good humidity-sensitive properties are related to the introduction of the sulfobetaine-type zwitterion to polymer chain in the humidity-sensing film.