Reversible Poly Lactic Acid (PLA) Film for Volatile Organic Compounds (VOCs) Gas Sensor

Abstract

The detection of volatile organic compounds (VOCs) including hydrochloric acid (HCl), acetic acid (CH3COOH), and ammonia (NH3) in indoor air is crucial due to human health safety. In this study, halochromic poly lactic acid (PLA) film sensor were prepared. PLA film were fabricated by addition of polyethylene glycol (PEG) and bromocresol purple (BCP) into PLA using solution casting method. Visual observation and mechanical properties of the film were determined as well as its spectral properties to assess the potential of halochromic film as gas sensor. The response of the PLA film to acidic and alkaline gas and its reversibility were tested. It was found that PEG increased the free volume of PLA and made it possible for the PEG and the dye to diffuse and entrap between PLA chains. However, increasing BCP did not have significant impact on the PLA film flexibility or reduced its halochromic sensitivity. The results revealed that the film showed significant effect on NH3 which the film change from yellow to purple within a second and could also change its color back to yellow in the absence of the VOC. This properties enables wide potential in various applications that requires high sensitivity, rapid response and continuous monitoring.