Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597952
Title: Nanoporous materials from block copolymers
Author: Cooney, D. T. P.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2007
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Abstract:
This project assesses the potential for block copolymers (BCPs) to be used in making nanoporous membranes. BCPs self assemble to produce structured phase morphologies based on their molecular composition. One such structure is composed of cylinders of one polymer phase in a matrix of another. It is proposed that nanoporous products could be produced by selectivity removing the material forming the cylindrical phase in an aligned BCP sample. Methods of inducing good phase alignment in BCP samples are reviewed. The effects of high shear rates on the orientation of a cylindrical phase formed by a triblock copolymer are investigated using the Cambridge Multipass Rheometer and a customised X-ray diffraction system. A new X-ray collection technique is developed and used to show that high shear rates can destroy phase orientation in a BCP melt. BCP etching is investigated. The removal of a cylindrical poly(lactide) phase in a P(S-b-LA) BCP by hydrolysis is examined. The method is shown to produce complete removal of the PLA phase, with the etch considered to be reaction limited. Diffusion of acid and alkali through such etched samples is observed in a specially designed cell. Transport in aqueous conditions is established through samples up to 7 mm long, proving pore continuity in the material and establishing the practical validity of the proposed idea. Thin films of BCP aligned using electric fields are obtained and etched. Acid transport through the films indicates porosity has been introduced. Size exclusion experiments using gold colloids prove that small particles are transmitted by these films, whilst large particles are retained. These experiments establish that size separation could be conducted using BCP products, as proposed, and form the basis for future work in developing such products.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.597952  DOI: Not available
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