Preparation And Adhesion Behaviors Of Honeycomb Porous Polyurethane Films

With the developing of technology and advancing of people living quality, adhesive materials have attracted much attention due to its wide potential application in environmental protection, bio-medical science,intelligent control, and etc. Inspired by the strong adherence of geckos and Boston iv, not only the bionic high adhesive materials but also their developments have attracted great attention by many scientific researchers. In this research field, the key is that how to choose the suitable raw materials and best preparation methods, optimize experimental parameters and scheme out ultra-strong adhesive materials, whose structures are similar to the chuck of Boston ivy. In this thesis, honeycomb porous polyurethane films were fabricated by micro phase separation according to the micro/nano-structures and strong adherence of Boston ivy. In order to improve surfac roughness of honeycomb porous polyurethane films, polydopamine(PDA) nano-particles were deposited on the surface. The surface wettabilities, surface adherence, surface morphologies and crystal structures were characterized by optical contact angle meter, field emission electron microscope(FE-SEM) and X-ray diffraction(XRD), respectively. Besides, the adhesion strength between water and ice on honeycomb porous polyurethane films was further tested. The main research contents in this thesis were as follows:(1) Through micro phase separation the preparation of the honeycomb porous polyurethane film. The results showed that the film morphologies and crystal structures were determined by the relative humidity of experimental conditions and concentration of polyurethane and dopamine hydrochloride. The regular honeycomb porous polyurethane films could be more easily obtained when the mass fraction of polyurethane and relative humidity of experimental conditions were above 2% and above 99%, respectively. After depositing PDA onto honeycomb porous polyurethane films and increasing the concentration of dopamine hydrochloride, more and more nano-scale particles appeared on the surface and internal face of the films.(2) Contact angle(CA) on the surface of honeycomb porous polyurethane films was determined by surface micro/nano-structures and surface energy. It was found that CA obviously increased after n-dodecanethil modification. Under the conditions of mass fraction with 2% and relative humidity with 100%, the CA of honeycomb porous polyurethane films without PDA modification was 84.43o. However, once modified by PDA, the CA increased above 160o and reversed superhydrophobicity. Honeycomb porous polyurethane film surface precipitation after the PDA to enhance the hydrophobic membrane, increase from 85oto 85oabove, film from hydrophilic to hydrophobic state.This is because the sample surface after precipitation PDA micro-nano structure reduced the sample surface and the contact area of water, the contact Angle is increased so that the film.(3) PDA enhanced water droplets on the honeycomb porous polyurethane film adhesion. Experiment found that polyurethane porous membrane surface precipitation after PDA, obviously increase the adhesion of water droplets, rolling Angle of 180o. On the one hand, because of hole wall in precipitation PDA nanoparticles with high adhesion to water, on the other hand because of polyurethane porous structure within the table face seal air increases with capillary effect, improve adhesion of the film surface of water droplets.(4) Ice in honeycomb porous polyurethane film surface has a strong adhesion strength. Stems from the existence of the polyurethane porous structure and surface precipitation PDA than surface after further increase, which kept the ice on the surface of the film, increased contact area, reduced the shear force of ice, ice in thin film on the surface of the bond strength increases greatly.