Development Of Novel Functional Coatings And Its Application In Preparing Polymer Based Composite Films With Layer-by-Layer Structure

Polymer films have been widely used in various industries, for example agriculture, packaging, electronics and etc. However, in some cases, the polymer films are modified to meet unique requirement. So far, there are many technologies to fabricate polymer based composite films. Coating is still one of the most important methods in the standpoint of industrial application for its simple operation and minimized degradation on the physico-mechanic properties. In this thesis, two functional coatings have been formulated. One is the coating with BaTiO3 (BT) as filler and acrylates as binder resin for preparing high performace dielectric layer-by-layer structured polyethylene terephthalate(PET)/BT composite film. The other is based on silane coupling agents to form a cross-linked coating layer on the polyolefin films to introduce functional groups on the surface of the polymer films.In the first part, the first one isthe preparation and characterof flexiblecomposite film with layer-by-layer structure and high dielectric permittvity. The flexible layer-layer polyethylene terephthalate/bariumtitanate(PET/BT) composite films with enhanced dielectric permittivity were fabricated by spin coating method, consisting of PET substrate film layer and modified BaTiO3/acrylic resin hybrid coating layer. The thickness of coating layer was below 3μm and less than 2% of PET film, therefore the PET/BT composite films maintained flexibility even at high volume fraction of BaTiO3 particles. The volume contents of BaTiO3 were varied from 0% to 80%, and the solid contents of BaTiO3/acrylic resin were decreased from 73% to 52%. Scanning electron microscopy showed strong interaction of finely-dispersed BaTiO3 particles with acrylic resin. Morphological profile also displayed uniform coating of modified BaTiO3/acrylic resin and its strong adhesion with PET film. The dielectric constant of the PET/BaTiO3 composite films increased by about 26% at 60vol% BaTiO3 loading compared to pure PET film, while the dielectric loss decreased slightly. In addition, PET grafted poly(hydroxylethylene methacrylate) (PET-g-PHEMA) brushes were utilized as substrate to introduce covalent bonding with the coating layer. Further enhancement of dielectric constant and reduction of dielectric loss were realized compared to the composite films with bare PET substrate.The second partisthe preparation and application of functionalized polymer filmswith coating layer. Two kinds of silane coupling agent can form cross-linking network structure on the surface of lowdensity polyethylene(LDPE),producing coating layer with framework of (R1O)3-Si-R2-(OR1)3. The coating layer was compatible with LDPE film though functional group R2, and introduced functional groups on the surface, including amidogen and hydroxyl. In order to obtain the best silane-oxygeniccoating layer, the ratio of silane coupling agent and concentration have been optimizied. Furthermore,brominated LDPE film was used to initiate suface radical grafting polymerization, ethylene glycol dimethacrylate ester (EGDMA) as monomer. As result, LDPE-g-PEGDMA was successfullyobtained, which had intensely small contact angle, leading good hydrophily.