Synthesis And The Epitaxial Behavior On Oriented Polyethylene Substrate Of PEO-b-PCL

Poly(?-caprolactone) has been widely used in drug carrier material and surgery short -term implants. As we know, Poly(E-caprolactone) is hydrophobic, which restrains its applications. with poly(ethylene oxide) attached to poly(?-caprolactone) can improve the hydrophilic defection, which is hydrophilic. the synthesis and the crystalline behavior study of poly(ethylene oxide)-b-poly(?-caprolactone) copolymers were rapidly promoted by biocompatibility, amphiphilicity, self-assembly, permeability, and controllable biodegradability. Crystallization behavior has important implications for the final physical properties, mechanical properties, biodegradable properties and drug release mechanism of biological materials. Hetero-epitaxy of polymers has been extensively studied for it provides a useful way to control the crystalline structure of a wide variety of semi-crystalline polymeric materials. In hetero-epitaxy system, the effect of the substrate on the epitaxial substances results in the strict orientation relationship between the two, which can produce unusually morphological structure. Due to the strong physical binding of epitaxial interface has a great influence on the mechanical properties of the material, which causes widespread concerns.1. A series of different weight fraction ratio of PEO-b-PCL block copolymers were synthesized by living radical polymerization method?The crystallinity of fixed molecular weight PEO segment would change with different weight ratios.The PEO segment does not crystalline when the weight ratio of PEO is less than 16%. The spherulite growth rate of block copolymers increases with the PCL segment weight fraction larger.2. In experiment, we characterized isothermal crystallization process of different weight fraction of the block copolymers with analyzing the changes in crystallinity and crystallization process of two segments varying with the component. MPEG 1900-PCL2000 and MPEG20000-PCL20000, in which the segments have the close weight fraction, appear banded crystal structure. the band period increases with the crystallization temperature higher. The crystal morphology study of banded spherulite can explains the block copolymer banded crystal growth process.3. Oriented PE ultra-thin films were prepared by melt-drawn technique during the experiment of epitaxial orientation study, the rotated extinction phenomenon of samples shows the oriented crystalline has occurred. Sandwich structure can solve the problem of polymer agglomeration. The peeling film method was introduced to character the oriented crystalline on the substrate of highly oriented PE ultra-thin film. The effect of oriented PE substrate on the crystalline of PEO segment is very little, but with the PEO segment added, the epitaxial crystalline of PCL segment of the block copolymer on oriented PE film is affected.