View Journal Article: Combinatorial Measurements of Crystallization Growth Rate and Morphology in Thin Films of Isotactic Polystyrene
Beers, Kathryn, Douglas, Jack, Amis, Eric and Karim, Alamgir (2003). Combinatorial Measurements of Crystallization Growth Rate and Morphology in Thin Films of Isotactic Polystyrene. Langmuir19 (9). 3935-3940.
Combinatorial methods are utilized to study the influence of film thickness (13 nm < h < 120 nm) and crystallization temperature (131 °C < Tx < 193 °C) on the
crystallization of isotactic polystyrene. Films with continuous gradients in film thickness were prepared by flow coating, crystallized on an orthogonal temperature gradient stage, and observed
under an optical microscope. Spherulite growth rates were measured as a function of film thickness and temperature, as determined from an optical micrograph library of numerous subregions within
the gradient films.Weobserved that the growth rate had amaximum near 180 °C and varied inversely to film thickness, consistent with the results of Sawamura et al. A transition from hexagonal plate
to circular growth was observed with increasing undercooling in the thickness range between 23 and 80 nm. Both hexagonal and disordered branched crystalline morphologies formed in ultrathin regions
where the film thickness is less than the radius of gyration