Shear induced smectic- A-smectic- C transition in side-chain liquid-crystalline polymers

We show that the smectic layer orientation in side-chain liquid-crystalline polymers depends on the molecular weight and the shear rate. Parallel orientation is obtained with the low molecular weight polymer and reveals a shear induced decrease of the smectic layer thickness. In contrast with usual liquid crystals, the shear torque acts at the mesogen scale through an efficient coupling between the polymer main chain and the mesogens resulting in a smectic- A-smectic- C transition.