Research Of Changes In Microstructure And Instability Of Polymer Films Under The Action Of The External Field

As special classes of functional polymer, conjugated polymers exhibit not only the excellent optical and electrical properties of metal and semiconductor materials but also processing and mechanical properties of the polymers. The external field can induce microstructure changes of the conjugated polymer films,Then form ordered structures. thiophene derivative monomer were synthesized by using 3-methylthiophene then polythiophene derivative were synthesized by using Ni(dppp)Cl2 as metal catalyst.The results showed that temperature and solvent annealing process can affect the orientation of polythiophene derivatives.The evolution of the wavelike surface undulations in polymethyl methacrylate(PMMA) film with silica nanoparticles(NPS) under thermal stress is investigated. With the increase of temperature, the elastic stresses in the plane of the polymer thin films is induced by fixed lateral constraints within the film(immobilized NPs) that resist in-plane film thermal expansion. The wavelike surface undulations arising from the stress relaxation have been observed as the thin film systems are heated above the glass transition temperature, Tg. The thermal stress affects both characteristic wavelengths and amplitudes of wavelike surface undulations. The evolutions of the wavelengths and amplitudes in undulation films include three stages, the intermediate stage and late stage shows characteristic time dependence.(1) The orientation of polythiophene derivatives can be controlled by temperature and solvent annealing process. After temperature and solvent annealing, the polymer thin films appears ordered structures, the number of ordered structures increase with annealing time.(2) The evolutions of the wavelengths and amplitudes in undulation films include three stages. In the early stage(t < t1), wavelength and amplitude grow slowly. In the intermediate stage(t1 < t < t2), wavelength and amplitude started to grow rapidly growth. In the late stage(t > t2), wavelength and amplitude tends to equilibrium.(3) The wavelength and amplitude of wavelike surface undulations increase significantly after the samples undergo the solvent annealing. The evolutions of the wavelengths and amplitudes in undulation films also include three stages. The time between intermediate stage and late stage is reduced comparing with before undergo the solvent annealing.