The Crystal Properties Of Poly(Ethylene Oxide) In Polymer Thin Film

In recent years, with the development of computer, electronic, data storage technology, the polymer thin and ultra-thin film blend studies are received more and more attention. As crystalline and amorphous polymer blend is the most common type, particular attention has been paid. In this paper, Polyethylene oxide (PEO) is used as a crystalline polymer. For use of the strong hydrogen bond interaction between PVPh and PEO, we use Layer-by-layer self-assembly technique to prepare polymer multilayers, and thin films with different thickness of this system through the Spin-coating was prepared at the same time. This paper studies the crystallization kinetics and crystalline morphology.PEO in this polymer multilayer shows an amorphous state both before and after the heat treatment because of the strong hydrogen bond between the PEO/PVPh and the layer interpenetration. The wafer substrate is more efficient for chain rearrangement compare with the glass substrate, so as the increase of the layer number and the adsorption timeFor the samples of PEO/PVPh blend prepared with Spin-coating method, when the film thickness is greater than200nm, the impact of the base to the system is negligible, and with the crystallization temperature increasing, the rate of crystallization reduces significantly. Crystals show significant dendritic morphology and branches start sparse. Samples with film thickness of100nm-200nm still have dendritic morphology, but the interval between the branches is very large and no similar spherulitic morphology is observed. With the crystallization temperature increasing, the branches become sparse, while the width increases which in line with the growth of the diffusion model. Also the edge of the branches becomes smooth to jagged. When the crystalline temperature is40C, the crystal in the sample is mainly oriented edge-on, with the crystallization temperature increasing, the orientation of the crystal occurs edge-on to flat-on transition. For the ultra-thin film of PEO/PVPh which thickness is10-20nm, the crystal orientation is flat-on arrangement, the surface is smooth. With increasing the crystallization temperature, the thickness of lamellae increases, and also the surface is even smoother.For the samples of PEO prepared with Spin-coating method on different substrates which thickness is about10nm, single-layer lamellas are distributed. When using the hydroxylated wafer and wafer with the absorption with a PEO layer, a lower surface roughness of the lamellae is observed. Also screw dislocations appear when the substrate adsorbed a layer of PEO.