Viscosity – Molecular Weight Relationships and Unperturbed Dimensions of Linear Chain Molecules

A range of water-soluble hydrophilic−hydrophobic diblock copolymers of 2-(dimethylamino)ethyl methacrylate and methyl methacrylate were shown to form micelles if first dissolved in a nonselective solvent (THF or methanol) and subsequently diluted with water. Critical micelle concentrations were found to increase with the length of the hydrophobic block if the the hydrophilic block length is fixed. Increasing the overall molar mass of the copolymer also increased the cmc for a given composition. The hydrodynamic diameters and approximate association numbers of these micelles were obtained by dynamic light scattering and analytical ultracentrifugation. Micellar diameters and association numbers were in the range 10−18 nm and 10−33 chains per micelle, respectively, depending on copolymer composition. Increasing the overall molar mass of the copolymer for a given composition produces larger micelles with lower association number. Both micelle size and association number decrease with the length of the hydroph...

Micellization of poly(2-(dimethylamino)ethyl methacrylate-block-methyl methacrylate) copolymers in aqueous solution

Living radical polymerization through the use of iniferters: Controlled synthesis of polymers

Near-monodisperse micrometer-sized polystyrene particles were produced by dispersion polymerization in alcoholic media using poly(2-(dimethylamino)ethyl methacrylate-b-alkyl methacrylate) copolymer stabilizers. The effect of varying stabilizer concentration, copolymer composition, solvent, and reaction temperature on latex particle size was investigated. A maximum particle size of 2.8 μm was found for 1-butanol in a series of alcoholic solvents ranging from methanol to 1-octanol. As expected, the particle size decreased slightly with increasing stabilizer concentration; however, varying the copolymer composition had, surprisingly, little or no effect on particle size. As the polymerization temperature was increased, the size and polydispersity of the latexes increased.

Use of Block Copolymer Stabilizers for the Dispersion Polymerization of Styrene in Alcoholic Media

PVA nanofibers have been successfully prepared via an electrospinning process by optimizing the electrospinning operational parameters including applied voltage, polymer concentration, feed rate, and working distance. Inexpensive NaCI and Fe(NO 3 ) 3 are found to reduce the fiber size drastically (minimum of 157 and 169 nm, respectively) even at a low loading. The thermal stability is investigated by both thermogravimetric analysis and differential scanning calorimetry. Fourier transform infrared spectroscopy is utilized to characterize the functionality of the fibers and to investigate the interaction between PVA and inorganic additions. Glass transition and melting temperatures of the PVA fibers have slight change with the increase of the salt loading.

E.M. Schuele

Papers

Properties of dilute polymer solutions I—Osmotic and viscometric properties of solutions of conventional polymethyl methacrylate