Morphology Transformation by Annealing Electrospun Polymer Fibers

• Main Authors: Fan, Ping-Wen, 范秉文
• Other Authors: Chen, Jiun-Tai
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/91344224015207071355

碩士 === 國立交通大學 === 應用化學系碩博士班 === 100 === Electrospinning is a simple and convenient technique to prepare polymer fibers, and various electrospun polymer fibers have been generated for different applications. But the annealing effect of the polymer fibers, which is critical for controlling the properties and morphologies of the polymer fibers, has been rarely studied. Here we study the annealing effect of electrospun poly(methyl methacrylate) (PMMA) and polystyrene (PS) fibers and their transformation into microspheres or microparticles under thermal annealing. The polymer fibers are first prepared by electrospinning and the diameters of the electrospun fibers are controlled by the electrospinning condition. In part 1, polymer fibers are annealed in ethylene glycol. The fibers undulate and transform into microspheres, driven by Rayleigh instability. The morphology can be controlled by using different annealing times and annealing temperatures. The sizes of the microspheres are found to be fitted well with the theoretical calculations. Polymers with different molecular weights are also used to investigate the effect of molecular weights. In part 2, we study the annealing effect of the electrospun fibers on different substrates. Various morphology transformations are obtained by annealing the fibers on different substrates, and the relationship between the polymer interfacial energy and the Rayleigh instability is studied. The polymer fibers transform into microparticles caused by the reduction of the interface energy, and the sizes of particles also fit well with the theoretical values. The shapes of the polymer particles are confirmed by removing the polymer film using selective solvent. Both AFM and SEM show that hemispherical polymer particles can be formed by annealing PS fibers on PMMA film coated substrates.