X-RAY ANALYSIS OF THE SELF ASSEMBLING TUBULAR STRUCTURES FORMED BY POLYMETHYACRYLATES WITH HIGHLY TAPERED SIDE GROUPS J. Blackwell, S.N Chvalun, Y.K. Kwon and V. Percec, Department of Macromolecular Science, Case Western Reserve University, Cleveland OH 44106-7202, USA

A poly(methacrylate) with highly tapered side chains: poly{2-{2-[2-(2-methacryloyloxyethoxy)ethoxy]ethoxy} ethyl-3,4,5-tris(p-dodecyloxy-benzyloxy)-benzoate} , has been shown to form an ordered hexagonal structure at room temperature, and to undergo transitions to a columnar hexagonal liquid crystalline phase above ~40deg.C and to an isotropic phase above ~100deg.C. In the columnar hexagonal phase, the structure consists of cylinders of diameter 60.4Å at 40deg.C, decreasing to 53.0Å at 95deg.C, in which there is little internal order other than limited stacking correlations for the side chains. In the ordered hexagonal state at room temperature, the cylinders have an ordered internal structure with an axial repeat of 5.03Å. Based on the observed density, this repeat would contain 8 monomer units within a cylinder of diameter 59.8Å (at 21.6deg.C). Strong off-meridional intensity on the first layer line suggests that the "planes" of the aromatic units are tilted by 40-50deg. to the chain axis. Possible 8-fold helical models have been refined to obtain qualitative agreement with the observed X-ray intensity data. Parallel investigations of the structure of the unpolymerized monomer precursor also show the existence of supramolecular assemblies forming ordered hexagonal and columnar hexagonal phases. Of particular interest are the dimensional changes that occur with temperature, and the effect of annealing on these data.