Okan Sirkecioglu

Synthesis of asymmetric difunctional initiators and their use in the preparation of block copolymers via ATRP and SFRP

Abstract Novel asymmetric difunctional initiators 2-phenyl-2-[(2,2,6,6-tetramethylpiperidino)oxy]ethyl 2-bromo-2-methyl propanoate and of 2-phenyl-2-[(2,2,6,6-tetramethylpiperidino)oxy]ethyl 2-bromo propanoate were synthesized in a three-step reaction sequence and used in atom transfer radical polymerization (ATRP) of methyl methacrylate or tert-butyl acrylate leading to corresponding polymer with tempo moiety as chain end. These polymers were found to be efficient initiators for stable free radical polymerization (SFRP) of styrene. 1H NMR and g.p.c. studies of the obtained polymers show that block copolymers are readily formed as a result of combination of ATRP and SFRP mechanisms.

Synthesis of new functional dioxepin polymers

Abstract Poly(dioxepin–maleic anhydride) copolymers containing some new functional groups were prepared on the reaction of free radical polymerisation of dioxepines with maleic anhydride in toluene at 80°C. The copolymers obtained were characterised with FT-IR and 1 H NMR spectra. Inherent viscosities of copolymers were measured.

Ladder type polymers from dihydroxyaromatic compounds and dialdehydes

Ladder polymers were synthesized by reaction of dihydroxynaphthalene and bisphenols with malondialdehyde and glutardialdehyde. Differential scanning calorimetry and thermogravimetric analysis were used to determine the thermal behaviour of the polymers, and conductivities of two representative polymers were measured. Ladder polymers with higher molecular weights showed better thermal resistance.

ALIPHATIC THIOETHERS BY S-ALKYLATION OF THIOLS VIA TRIALKYL BORATES

A simple and convenient one-pot procedure is described for the synthesis of thioethers via boron esters. This procedure involves in-situ generation of alkyl sulfates by reaction of trialkyl borates with concentrated sulfuric acid and subsequent reaction with thiols in the presence of pyridine. The reactions with boron esters of primary or secondary alcohols proceed cleanly at 100°C and afford aliphatic thioethers in reasonable yields (59–93%) within 24 h. Interestingly, the 1H NMR spectra of the products showed no sign of positional isomerisms. The method fails however with thiophenol and does not yield aromatic thioethers, due to electrophilic substitution at the phenyl ring.