Stimuli Responsive Poly(1-[11-acryloylundecyl]-3-methyl-imidazolium bromide): Dewetting and Nanoparticle Condensation Phenomena

• Published in: Langmuir Vol. 27; no. 11; pp. 7148 - 7157
• Main Authors: Ma, Xiumin, Ashaduzzaman, Md, Kunitake, Masashi, Crombez, Rene, Texter, John, Slater, Lisa, Mourey, Thomas
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 07.06.2011
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Hydrodynamics; Imidazoles - chemical synthesis; Imidazoles - chemistry; Materials: Nano-and Mesostructured Materials, Polymers, Gels, Liquid Crystals, Composites; Molecular Weight; Nanoparticles - chemistry; Phase Transition; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Polymerization; Polymers - chemical synthesis; Polymers - chemistry; Surface Tension; Temperature; Separation; Film; Nanoparticle; Polymerization; Quartz; Ionic surfactant; Condensation; Chromatography; Dewetting; Ionic liquid; Relaxation; Distribution; Homopolymer; Ion exchange; Molecular mass; Diameter; Methyl bromide
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la200184c

A stimuli-responsive homopolymer poly(ILBr) is fabricated via a “two-phase” atom transfer radical polymerization (ATRP) process, where ILBr stands for the reactive ionic liquid surfactant, 1-[11-acryloylundecyl]-3-methyl-imidazolium bromide. An extraordinarily wide molecular weight distribution (PDI = 6.0) was obtained by introducing the initiator (4-bromomethyl methyl benzoate) in a heterogeneous two-phase process. The molecular weight distribution of poly(ILBr) was characterized by size-exclusion chromatography (SEC). The resulting homopolymer was found to be surface active and stimuli responsive. Poly(ILBr) films coated on quartz exhibit stimuli-responsive dewetting after ion exchange of Br− by PF6 −. This dewetting phenomenon can be understood in chain segmental terms as a stimuli-induced structural relaxation and appears to be the first such reported stimuli-responsive polymeric dewetting. Titrating aqueous poly(ILBr) with aqueous bis(2-ethylhexyl)sulfosuccinate induces nanophase separation and results in the condensation of nanoparticles 30−60 nm in diameter.