In-situ GIXD Studies of the Conjugated Polymer-Phospholipid Composite Films: Temperature and Gas Adsorption Effect

Abstract

Conjugated polymers, which have a band gap between their valence and conduction bands, can absorb energy upon light irradiation with electron excitation from the valence to conduction band. The absorbed energy can be emitted as light or heat, or charge carriers (electrons and holes) can be transferred to surroundings to participate in photocatalytic reactions [1]. When they are in forms of nanomaterials, significantly enhanced luminescence intensity and photostability were expected, in which the conjugated polymer chains can be separated from surrounding continuous, free-flow media as a discontinuous phase, thereby considerably reducing the radiationless decay and photodegradation. The fluorescence quantum yield of conjugated polymer nanoparticles could be 39% in an aqueous medium, which was comparable to that of conjugated polymers dissolved in non-polar solvents (40~50%) but much higher than that of conjugated polymer electrolytes (<5%) [2]. Therefore, the conjugated polymers of nanomaterials forms have attracted significant attention in aqueousbase applications (fluorescence imaging, photoaccoustic imaging, photothermal therapy, and etc.) and photocatalytic reactions (water splitting for hydrogen generation and organic pollutant degradation) [3-7]. In this study, the conjugated polymer nanoparticles made of the conjugated polymer and phospholipids were used to prolong the photostabiliby of the conjugated backbones. The structural studies by the in-situ grazingincidence X-ray diffraction (GIXD) techniques under various temperature and gas conditions will be discussed in detail.