Concurrent Order in a Semi-Crystalline Diblock Copolymer Involving Complexation with a Mesogen

A semicrystalline/liquid-crystalline diblock co-polymer formed by complexation of a wedge-shaped ligand, 2-(3',4',5'-tris(octyloxy)benzamido)propanoic acid, with P2VP-PEO copolymer was studied. The P2VP complex forms layers with a liquid-crystalline (LC) order causing phase segregation of the PEO block. The molar ratio ligand/pyridine (x) determines the strength of segregation between the blocks and the microphase morphology. For x >= 0.5, PEO forms cylinders within the LC matrix. The phase separation strongly shifts the crystallization temperature to lower values and forces PEO to crystallize within the block copolymer cylinders. In thin films, alignment of the smectic layers parallel to the substrate induces homeotropic orientation of the PEO cylinders. Inside these cylinders, the crystalline stems preferentially orient along the smectic normal. For x <= 0.33, PEO forms crystalline lamellae within the LC matrix and crystallization dominates the final structure.