title: A microfluidic platform for integrated synthesis and dynamic light scattering measurement of block copolymer micelles.
abstract: Microfluidic devices were developed that integrate the synthesis of well defined block copolymers and dynamic light scattering (DLS) measurement of their micelle formation. These metal devices were designed to operate in contact with organic solvents and elevated temperatures for long periods, and thus were capable of continuous in-channel atom transfer radical polymerization (ATRP) of styrene and (meth)acrylate homopolymers and block copolymers. These devices were equipped with a miniaturized fiber optic DLS probe that included several technology improvements, including a measurement volume of only 4 microlitres, simple alignment, and reduced multiple scattering. To demonstrate the integrated measurement, poly(methyl methacrylate-b-lauryl methacrylate) and poly(methyl methacrylate-b-octadecyl methacrylate) block copolymers were processed on the device with a selective solvent, dodecane, to induce micelle formation. The in situ DLS measurements yielded the size and aggregation behavior of the micelles. For example, the block copolymer solutions formed discrete micelles (D(H) approximately = 25 nm) when the corona block was sufficiently long (f(MMA) < 0.51), but the micelles aggregated when this block was short. This study demonstrates the utility of these new devices for screening the solution behavior of custom synthesized polymeric surfactants and additives.
authors.affiliation: Polymers Division, National Institute of Standards and Technology, 100 Bureau Drive MS8542, Gaithersburg, Maryland 20899, USA. thomas.chastek@nist.gov
authors.forename: Thomas Q
authors.initials: TQ
authors.lastname: Chastek
authors.forename: Kazunori
authors.initials: K
authors.lastname: Iida
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Amis
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Fasolka
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Beers
mesh_terms: D000473:Alkanes / Q000737:chemistry; D007850:Lauric Acids / Q000032:analysis / Q000138:chemical synthesis; D008689:Methacrylates / Q000032:analysis / Q000138:chemical synthesis; D008823:Micelles; D044085:Microfluidics / Q000295:instrumentation / Q000379:methods*; D053758:Nanoparticles / Q000032:analysis / Q000737:chemistry; D010316:Particle Size; D011108:Polymers / Q000032:analysis / Q000138:chemical synthesis; D012542:Scattering, Radiation; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D020058:Styrene / Q000032:analysis / Q000138:chemical synthesis; D013501:Surface-Active Agents / Q000032:analysis / Q000138:chemical synthesis; D013696:Temperature
chemical_list: D000473:Alkanes; D007850:Lauric Acids; D008689:Methacrylates; D008823:Micelles; D011108:Polymers; D012997:Solvents; D013501:Surface-Active Agents; C421257:poly(lauryl methacrylate); C007548:n-dodecane; D020058:Styrene