Alignment of Red Poly[dodecadyin-1,12-diol-bis(4-butoxycarbonyl-methyl-urethane)] in Couette Flow

• Published in: The journal of physical chemistry. B Vol. 120; no. 34; pp. 9173 - 9179
• Main Authors: Xie, Donglin, Wei, Yalin, Qiao, Greg G, Dunstan, Dave E
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 01.09.2016
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/acs.jpcb.6b05566

The flow-induced alignment of red poly­[dodecadyin-1,12-diol-bis­(4-butoxycarbonyl-methyl-urethane)] (poly-4BCMU) in chloroform/toluene solution is reported. Absorption spectra have been measured over a range of shear rates in an optically transparent quartz Couette cell. The measured spectra show that the poly-4BCMU structure stays the same in flow, while the measured absorbance anisotropy is attributed to the flow-induced particle alignment in the red form poly-4BCMU solutions. A limiting orientation at shear rates >50 s–1 is observed. Numerical simulations show that the spectral changes are consistent with the rodlike poly-4BCMU particle having an aspect ratio of 2.9. The dichroic ratio of 1.9 interpreted from the data indicates that the individual poly-4BCMU chains do not aggregate amorphously in the rodlike conformation, rather they show a preferred orientation along the long axis of the prolate aggregates.