Current Position: Infrastructure Asset Engineer, Strathclyde Partnership for Transport
Undergraduate Institution: Oxford University

M. Eng. (Oxford) Thesis Research:

The nanofabrication industry is continually seeking methods of producing devices with nanoscale precision. Thin films of sphere-forming diblock copolymers have a potential application as cost-effective, accurate nanolithographic templates. However, the high level of order that is required from the arrays of spherical microdomains within these copolymers cannot be produced by self-assembly. Thus, another processing route is required.

Previous work has suggested that the application of shear stress may induce alignment of these microdomains. In this thesis, the application of rheometer-induced shear stresses to thin bilayer films of sphere-forming diblock copolymers was investigated. A combination of optical microscopy and tapping mode atomic force microscopy (TMAFM) was used to study the microdomain order induced by shearing, in an attempt to establish the mechanism by which ordering occurred. Polystyrene-polyisoprene, poly(vinylcyclohexane)-poly(ethylene-propylene) and a series of polystyrene-poly(ethylene-propylene) diblock copolymers were investigated in order to provide a range of different chemistries and molecular weights.

Shear stress was not found to produce perfect global ordering in any of the polymers. The microdomain order did however improve as shear stress was increased and also as the molecular weight of the polymers was decreased. Based on these results it is suggested that investigation of further copolymers in the polystyrene-poly(ethylene-propylene) series may provide more definitive conclusions regarding the ordering mechanism.