Polymer crystallization in quasi-two dimensions. I. Experimental results

We have used atomic force microscopy to investigate the patterns obtained b y isothermal crystallization of quasi-2-D monolayers of poly(ethylene oxide ) adsorbed onto bare silicon wafers. These monolayers were prepared by a ps eudo-dewetting process. Fingerlike branched structures were observed with a characteristic width which increased rapidly with crystallization temperat ure. The patterns are explained by a simple model considering the interplay of transport on the surface and the probability of attachment to the cryst al. The influence of molecular weight was also studied. The average stem le ngth increases with increasing temperature for the longer polymer. The shor ter one crystallized in the (almost) fully extended form for all temperatur es investigated. Temperature jumps during crystallization resulted in patte rns with two different length scales. (C) 2000 American Institute of Physic s. [S0021- 9606(00)50309-2].