Ismail Cakmak

Polymerization of acrylamide by the redox system cerium(IV) with poly (ethylene glycol) with azo groups

Abstract Polymerization of acrylamide using Ce(IV) with poly(ethylene glycol) having azo and hydroxyl functions, was carried out to yield acrylamide-(ethylene glycol) block copolymers with labile azo linkages in the main chains. These prepolymers were used to induce the radical polymerization of acrylonitrile and acrylamide through the thermal decomposition of the azo group, resulting in the formation of multiblock copolymers.

Recovery of boric acid from boronic wastes by leaching with water, carbon dioxide- or sulfur dioxide-saturated water and leaching kinetics

Abstract B 2 O 3 was recovered from waste samples such as borogypsum, reactor waste, boronic sludges, waste mud and concentrator waste by leaching processes using distilled water, sulfur dioxide- and carbon dioxide-saturated water. In the leaching processes, temperature, stirring time and solid-to-liquid ratio were taken as parameters. The amount of B 2 O 3 leached increased with increasing temperature and stirring time and it also increased with decreasing solid-to-liquid ratio, but the increase was less than that recorded for the leaching temperature and the stirring time. SO 2 saturated water is a more effective leaching solvent than CO 2 saturated water for boronic wastes. By the end of the experiments, more than 90% of B 2 O 3 recovery was found as boric acid. In the leaching of boric acid from boronic wastes in water saturated with sulfur dioxide, it was observed that the leaching rate increases with increasing temperature and leaching time. The overall average values of the kinetic parameters were: apparent activation energy ( E ) 33.2 kJ mol −1 , pre-exponential factor ( A ) 8.2×10 9 min −1 , reaction order ( n ) 0.97 and rate constant ( k ) 3.37×10 3 min −1 for the leaching processes of the boronic wastes.

Synthesis of block copolymers by redox macro initiators

Redox systems in block copolymer synthesis are reviewed, especially those methods that lead to well-defined structures: poly (ethylene oxide), azo, macroazo, peroxy or hydroperoxy redox macro initiators from vinyl monomers.

Synthesis of block copolymers via anion-to-radical transformation

Abstract Synthesis of (methyl methacrylate)-styrene block copolymers was carried out using anion-to-radical transformation. For this purpose, living polystyryl anion, prepared by using a new anionic difunctional initiator, 1,5-di(2-(3,3-dimethyl butyl-1-lithio)naphthalene, was terminated by the addition of 4,4′-bromomethyl dibenzoyl peroxide. Polystyrene samples having peroxide terminal groups were then used as initiators in the polymerization of methyl methacrylate. Block copolymers were characterized by spectroscopic and fractional precipitation methods.

Synthesis of multiblock copolymers via macroiniferter

Abstract A macroiniferter having photolabile thiuram disulfide groups an poly(ethylene glycol) segments was prepared by the solution polycondensation of bis(2-hydroxyethyl) thiuram disulfide with adipoyl chloride and poly(ethylene glycol) in the presence of triethyl amine. The macroiniferter obtained was used in the photoinduced polymerization of methyl methacrylate to yield active poly(methyl methacrylate-b-ethylene glycol) block copolymers. The active block copolymers were also used for photopolymerization of styrene to obtain multiblock copolymers. Block copolymers were characterized by spectroscopic examination, fractional precipitation and gel permeation chromatography.

Polymerization of methyl methacrylate initiated by the redox system H2O2-poly(ethylene oxide) with xanthate groups

Abstract Polymerization of methyl methacrylate using H 2 O 2 with poly(ethylene oxide) having xanthate groups, was carried out to yield methyl methacrylate-ethylene oxide block copolymers. Principal parameters affecting the synthesis were examined. Block copolymers were characterized by spectroscopic methods.

Synthesis of Epichlorhydrin-Styrene Block Copolymers via Cation-to-Radical Transformation Process

Abstract Poly(epichlorhydrin-b-styrene-b-epichlorhydrin) block copolymers were prepared by a two step process via cationic-to-radical transformation in two steps. For this purpose, epichlorhydrin(ECH) was polymerized using HBF4 as catalyst and reacted with the sodium salt of 4,4′-azo-bis(4-cyanopentanoic acid)(ACPA) to yield PECH possessing thermally labile azo group. PECH-macroazoinitiator was then used to initiate the thermal radical block copolymerization of styrene.