Thesis (M.Sc.)--Chulalongkorn University, 2012

In this work, polyaniline/poly(methyl methacrylate) (PANI/PMMA) composite fibrous mats were fabricated by electrospinning technique and used as ammonia sensing. Various factors which affect the morphology of fiber were investigated by scanning electron microscopy (SEM). The diameters of obtained fibers were in the range of 170-450 nm. The solvent system used for dissolution the polymer signigicantly influenced both the fiber formation and diameter of fibers. The main properties of solvents that caused this result are volatility and dielectric constant. The voltage, the distance between a needle and a collector and flow rate of polymer solution only influenced the diameter of the electrospun fibers. The optimum condition for preparation of PANI/PMMA composite fibrous mats was the electric potential of 15 kV, polymer solution flow rate of 10 µL/min and distance between a needle and a collector of 10 cm. In ammonia gas sensing study, the reflectance of PANI/PMMA composite fibrous mats was measured at 800 nm. The sensing performance of PANI/PMMA composite fibrous mats was depended on prepared solvent and %PANI. The initial percent reflection (%Ri) as well as the change of percent reflection (Δ%R) were increased as a series; DMF < DMF:ethyl acetate (1:1) < ethyl acetate:acetone (1:1). For effect of %PANI, %Ri and Δ%R was decreased when %PANI increased. Moreover, PANI/PMMA composite fibrous mats using DMF:ethyl acetate (1:1) solvent system gave the best sensing profile and the fastest sensing in which the response time was 7.5 min and recovery time was 7.5 min.