Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 40504
Title Autophobicity and layering behavior of thin liquid-crystalline polymer films.
Author(s) Wielen, M.W.J. van der; Cohen Stuart, M.A.; Fleer, G.J.
Source Langmuir 14 (1998). - ISSN 0743-7463 - p. 7065 - 7071.
Department(s) Physical Chemistry and Colloid Science
Publication type Refereed Article in a scientific journal
Publication year 1998
Abstract The stability against breaking-up of thin spin-coated films of liquid-crystalline polymers depends on the film thickness and annealing temperature. This study concerns side-chain liquid-crystalline polymers, based on alternating copolymers of maleic anhydride and mesogenic alkenes. The mesogenic group is a methoxybiphenyl. The as-prepared films are homogeneous and remain stable below the glass transition temperature. Upon annealing above this temperature, the films start to dewet. At the final stage of dewetting only droplets remain on top of a rather stable bilayer, which itself does not participate in the dewetting. This indicates autophobic behavior. The bilayer is even present above the isotropization temperature. In the mesophase we have a layered film, and dewetting may occur over several ordered layers. In all cases the dewetting is not linear in time and polymer slippage seems to take place on top of the stable bilayer. In the case of polymer slippage, a t2/3 dependence is expected for the growth rate. That is indeed found above the isotropization temperature. In the mesophase the dewetting differs from the "normal" slippage behavior and a weaker time dependence is observed. Around the isotropization temperature there is a strong increase in the (initial) dewetting velocity of over more than 2 orders of magnitude, due to the sudden drop in viscosity.
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