Study On The Morphology Of LB Film Of Block Copolymer PS-b-PEO And Its Blends

Due to the excellent self-assembling property of amphiphilic block copolymer, many scholars at home and abroad have applied it to the research of LB films. The mechanical and chemical properties of the LB ultrathin films can be improved a lot by regulating the micro-structures. But it is difficult to explain the processes of solution and surface behavior as well as the abundant aggregation morphologies and their reasons, which have been the research focuses.The effect of the selective solvent on the Langmuir monolayer and LB film of block copolymer PS-b-PEO(SEO) was studied by using of Langmuir technology and atomic force microscopy(AFM). The effects of subphase's temperature, dropping volumn and deposited pressure were also considered. According to the analyses of theÏ€-A isotherms, hysteresis curves of the monolayers and the images of LB films, we found that there were certain effects of selective solvent on the spreading impact of the samples, the position of the isotherm's plateau region rised gradually with the increase of temperature, the dropping volume didn't play a function on the trends of isotherms. The micelle grains became densers and grew as the deposited pressures increased. The samples spread with CHCl3 could disperse evenly, but the surface planeness wasn't as good as the ones spread with C7H8. In order to get a better pattern of LB films for SEO, the molecular weight of hydrophobic chain PS must be at least 10000 or the content of PS is more than 50%.The blend system of SEO and PS, spread with CHCl₃, has also been investigated to improve the film forming effect of PS with SEO, which has not a good film forming effect as SEO, and to find the necklace-network structure. It was shown that, with the increase of homopolymer, the island micelles turned into regular circular micelles gradually as the density became more bigger. The film forming effect of PS could be improved by SEO, but for the sake of the hindering effect of PEO, the necklace-network structures haven't been found in the system of PS/SEO9500. For the system of PS/SEO5000, when the content of PS is up to 80%, the dropping volumn is 20μl, finally the novel necklace-network structrues were discovered at the deposited pressures 1, 2 and 7 mN/m, especially good for the one at 7mN/m.