Polymerization Kinetics and Nanostructure Evolution of Reactive Lyotropic Liquid Crystals with Different Reactive Group Position

• Published in: Macromolecules 2009-12, Vol.42 (23), p.9243-9250
• Main Authors: Sievens-Figueroa, Lucas, Guymon, C. Allan
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Physicochemistry of polymers; Polymerization; Polymers and radiations
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma901318f

The synthesis of polymers with inherent nanostructure has recently received much attention because of the wide range of potential application in which these materials could be used. To understand the factors that affect the nanoscopic order preservation upon polymerization, this work examines the influence of reactive group position in polymerizable surfactants that form reactive lyotropic liquid crystals (LLCs) on polymerization kinetics and order before and after polymerization. Less ordered LLC phases are formed with reactive surfactants bearing reactive groups in the nonpolar tail compared to reactive surfactants with reactive groups near the polar head. The polymerization kinetics are influenced by both the LLC order and the position of the reactive group. Higher polymerization rates are observed for reactive surfactants with the reactive group near the polar head with increasing surfactant concentration and LLC order. On the other hand, lower polymerization rates are observed for the reactive surfactant with the reactive group in the aliphatic tail at higher surfactant concentrations and LLC order. This behavior is mainly due to segregation of the reactive groups in different regions of the LLC phases as indicated by an apparent increase in both the propagation and termination kinetic constants. When using initiators that induce higher polymerization rates, greater LLC order preservation is observed after polymerization. Also, by using higher light intensities, the resulting polymer exhibits higher degrees of LLC order retention than that observed when polymerization is initiated with lower light intensities and corresponding lower polymerization rate.