The effect of the solvent on the optical behaviour of macromolecules in laminar flow

IT HAS been shown in a number of communications tha t the magnitude and sign of the inherent optical anisotropy of macromoleeules is dependent on the properties of the solvent used [1-5]. In our first investigations we explained this solvent effect in terms of the degree of hindrance to rotation of the side groups of the polymer molecules [1-3]. Subsequent studies showed however tha t even when there are no side groups in the macromolecules the measured segmental anisotropy, (~1--~), is considerably dependent on the solvent, and this effect is greater the greater the anisotropy of the molecules [4]. We therefore suggested [4] tha t this phenomenon may be due to mutual orientation of the monomer units in the chain and the solvent molecules, i.e. to the existence of short-range orientational order in the solution. The measured (~1--~) will then be a combination of the segmental auisotropy of the macromolecules, (~l--~s)k, and the anisotropy, (~1--~2),, due to orientated solvent molecules: