Binnur Aydogan

Long wavelength photoinitiated free radical polymerization using conjugated thiophene derivatives in the presence of onium salts

Long wavelength free radical photopolymerization of (meth)acrylic monomers using a conjugated thiophene derivative, namely 3,5-diphenyldithieno[3,2-b:2′,3′-d]-thiophene (DDT) and one of the following compounds, namely diphenyliodonium hexafluorophosphate (Ph2I+PF6−), triphenylsulfonium hexafluorophosphate (Ph3S+PF6−) and N-ethoxy-2-methylpyridinium hexafluorophosphate (EMP+PF6−), as photosensitizer and coinitiator, respectively, was described. Polymerization occurred only when DDT, in the presence of the onium salts, was irradiated at wavelengths where the salts have no absorption. A feasible initiation mechanism involves intermolecular electron transfer from photoexcited thiophene compound to the onium salt. The relative initiation efficiencies of the salts were investigated and evaluated in terms of their redox potentials.

Intramolecular Cross-linking of Polymers Using Difunctional Acetylenes via Click Chemistry

An efficient approach was described for the intramolecular cross-linking of azide-functionalized poly(styrene-co-chloromethyl styrene) co-polymers (PS-N3) via click chemistry at room temperature. Reaction of PS-N3 with the appropriate diacetylene functional compounds such as 1,4-diethynylbenzene (DEB) and 1,10-dipropargyloxy decane (DPD) in ultra-dilute solutions led to unimolecular particle-like structures. The resulting polymers were characterized in detail by 1H-NMR, FT-IR, GPC and DSC measurements.

Light Induced Processes for the Synthesis of Polymers With Complex Structures

Light induced reactions are based on the absorption of light that excites the electrons of a molecule and can, under favorable circumstances, lead to dissociation, isomerization, abstraction, electron or energy transfer, and bond formation. These reactions have been the subject of many studies in various fields including organic chemistry, molecular biology, electronics etc. Light induced reactions can advantageously be utilized in the field of polymer chemistry. Among them, light induced polymerization is of enormous commercial importance. Techniques such as curing of coatings on wood, metal and paper, adhesives, printing inks and photoresists are based on photopolymerization. There are some other interesting applications, including production of laser video discs and curing of acrylate dental fillings. In this chapter, general methods for the light induced polymerization processes involving radical and ionic reactions are described. Special emphasize is devoted to their application to more complex macromolecular structures such as block, graft and star copolymers, and polymer nanocomposites based on clay and metal.