Yesim Hepuzer

Block copolymers of thiophene-capped Poly(methyl methacrylate) with pyrrole

Poly(methyl methacrylate) with a thiophene end group having narrow polydispersity was prepared by the Atom Transfer Radical Polymerization (ATRP) technique. Subsequently, electrically conducting block copolymers of thiophene-capped poly(methyl methacrylate) with pyrrole were synthesized by using p-toluene sulfonic acid and sodium dodecyl sulfate as the supporting electrolytes via constant potential electrolysis. Characterization of the block copolymers were performed by CV, FTIR, SEM, TGA, and DSC analyses. Electrical conductivities were evaluated by the four-probe technique.

Immobilization of invertase in conducting copolymers of 3-methylthienyl methacrylate

Immobilization of invertase in conducting copolymer matrices of 3-methylthienyl methacrylate with pyrrole and thiophene was achieved by constant potential electrolysis using sodium dodecyl sulfate (SDS) as the supporting electrolyte. Polythiophene (PTh) was also used in entrapment process for comparison. Kinetic parameters, Michaelis-Menten constant, K(m), and the maximum reaction rate, V(max), were investigated. Operational stability and temperature optimization of the enzyme electrodes were also examined.

Poly(p-phenylene) graft copolymers with polytetrahydrofuran/polystyrene side chains

Abstract 1,4-Dibromo-2,5-bis(bromomethyl)benzene was used as a bifunctional initiator in cationic ring opening polymerization (CROP) of tetrahydrofuran. The resulting macromonomer, with a central 2,5-dibromobenzene ring, was reacted in combination with 2,5-dihexylbenzene-1,4-diboronic acid by a Suzuki coupling, in the presence of Pd(PPh3)4 as catalyst, leading to a poly(p-phenylene) (PPP) with alternating polytetrahydrofuran (PTHF) and hexyl side chains. A polystyrene (PSt) based macromonomer with a central benzene ring bearing cyclic boronic acid propanediol diester groups, synthesized by atom transfer radical polymerization (ATRP), was also used as partner for PTHF in the cross-coupling reaction. A PPP with alternating PSt and PTHF side chains was obtained. PTHF macromonomer was also homopolymerized by a Yamamoto reaction. The resulting PPPs have high solubility in common organic solvents at room temperature. The new polymers were characterized by GPC, 1H NMR, 13C NMR, IR and UV analysis. Thermal behavior of the precursor PTHF macromonomer and the final polyphenylenes were investigated by TGA and DSC analyses and compared.

Immobilization of invertase in conducting thiophene-capped poly(methylmethacrylate)/polypyrrole matrices.

Immobilization of invertase in thiophene-capped poly(methylmethacrylate)/polypyrrole matrices was achieved by constant potential electrolysis using different supporting electrolytes. Optimum reaction conditions such as substrate concentration, temperature, and pH for the enzyme electrodes were determined. The temperature and pH were found to be 60 degrees C and 4.8, respectively. The effect of supporting electrolyte on the enzyme activity revealed that SDS was the best in the immobilization procedure. Michaelis-Menten constant and the maximum reaction rate in PMMA/PPy matrices were of the order of that of pristine polypyrrole. However, in terms of repeated use, the copolymer matrices were superior to polypyrrole.

Controlled Synthesis of Block Copolymers Containing Side Chain Thiophene Units and Their Use in Electrocopolymerization with Thiophene and Pyrrole

Abstract This paper reports on the synthesis of conducting polypyrrole and polythiophene grafted block copolymers of methylmethacrylate (MMA) and 3‐methylthienylmethacrylate (MTM) by a multi‐step process. For this purpose, block copolymers of MMA and MTM were prepared by controlled radical polymerization using 1,1‐diphenylethene (DPE). Subsequently, polypyrrole and polythiophene sequences were grafted onto these block copolymers by constant potential electrolysis.

Synthesis and characterisation of thermomesogenic polysiloxanes with 2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione units in the main chain

The synthesis of the first two liquid crystalline polysiloxanes bearing 3,6-diaryl-2,5-dihydropyrrolo-[3,4-c]pyrrole-1,4-dione units in their main chain are described. Investigations on their thermotropic phase behaviour by polarising microscopy reveal nematic or smectic enantiotropic phases, respectively.

Synthesis and mesophase properties of block and random co-polymers of electroactive and liquid crystalline monomers

Homo-polymers and random co-polymers of electroactive and liquid crystalline monomers, namely 3-thienylmethyl methacrylate (MTM) and 6-(4-cyanobiphenyl-4′-oxy)hexyl acrylate (LC6), were prepared by conventional free radical polymerization. Block co-polymers of MTM and LC6 were also synthesized by using the 1,1-diphenylethene (DPE) method. The obtained random and block co-polymers exhibited liquid crystal behavior depending on the content of the LC6 units. It was found that microphase separation of the polymer blocks is an effective means to stabilize the mesophase in the block co-polymers relative to compositionally similar random co-polymers

Block Copolymer Synthesis and Chain Extension from TEMPO-Terminated Chains Formed by Ultrasonic Chain Scission

Long poly(ethyl methacrylate) (Mn 5 2,300,000) and polystyrene (Mn 5 1,200,000) chains were subjected to ultrasonic scission in the presence of a radical scavenger, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO). This procedure yielded poly- mers with lower molecular weights and TEMPO terminal units. Application of these polymers in stable radical mediated polymerization of styrene resulted in chain exten- sion and block copolymers, depending on the precursor polymer. Block copolymer formation was evidenced by NMR measurement, and chain extension was shown by GPC analysis.

Bisacylphosphine oxides as bifunctional photoinitiators for block copolymer synthesis

Block copolymers of styrene (St) and methyl methacrylate (MMA) were prepared via a two-step procedure by using bisacylphosphine oxide (BAPO) as photoinitiator. Photolysis of BAPO at λ = 420 nm in the presence of St yielded polymers with monoacylphosphine oxide terminal groups. Subsequent irradiation of the polymers in the presence of MMA at λ = 380 nm produced block copolymers. Block copolymer formation was evidenced by spectral measurements and GPC analysis.

The Synthesis of Liquid Crystalline Copolymers with Block Copolymer Grafts

The synthesis of novel copolymers consisting of a side-group liquid crystalline backbone and poly(tetrahydrofuran)-poly(methyl methacrylate) block copolymer grafts was realized by using cationic-to-free-radical transformation reactions. Firstly, photoactive poly(tetrahydrofuran) macroinimers were prepared by cationic polymerization of tetrahydrofuran and subsequent termination with 2-picoline N-oxide. Secondly, the macroinimers and acrylate monomers containing different spaced cyanobiphenyl mesogenic groups were copolymerized to yiel the respective graft copolymers. Eventually, these were used for indirect photochmical polymerization of methyl methacrylate by UV irradiation in the presence of anthracene as a photosensitizer leading ti the final copolymers with block copolymer grafts. The liquid crystalline, semi-crystalline, and amorphous blocks were micro-phase separated in the graft copolymers.