Poly[4-pyridinyl-4´-(2-methacryloyloxyethoxy)styryl ketone-co-2-hydroxypropyl methacrylate]: Synthesis, Characterization, Thermal and Electrical properties, and Photocrosslinking behavior

Abstract

Synthesis of a chalcone bearing pyridine ring, 4-pyridinyl-4´-(2-hydroxyethoxy)styryl ketone, was carried out from the reaction of 4-acetyl pyridine and 4-(2-hydroxyetoxy)benzaldehyde in an aqueous solution of NaOH. 4-Pyridinyl-4´-(2-methacryloyloxyethoxy)styryl ketone which is the methacrylate monomer bearing chalcone structure in side chain, was obtained from acylation of 4-pyridinyl-4´-(2-hydroxyethoxy)styryl ketone with methacryloyl chloride in the cold. The copolymer of 4-pyridinyl-4´-(2-methacryloyloxyethoxy)styryl ketone and 2-hydroxypropyl methacrylate was prepared by free radical polymerization in presence of AIBN at 70 o C. FTIR, 1 H-NMR and 13 C-APT spectroscopic techniques were used for structural characterization of the Chalcone, the monomer and the copolymer. Thermal characterization of the copolymer was carried out using DSC and TGA techniques. DSC curve shows that this copolymer has a glass transition temperature of 78 o C. The TGA curve shows that decomposition given volatile product started at 230 °C and a residue of 21% left at 500 °C. Dielectric constant (ε´) of the copolymer decreased rapidly from 8.8 to 4.2 with increasing frequency in the range of 100-1000 Hz, and after this frequency ε´ quantity remained constant at a value such as 4.2. ε´ Value of the copolymer increased only from 4.2 to 4.9 with increasing from 290 K to 385 K. The AC conductivity of the copolymer increases from 5.01x10-10 S/cm to 126.0x10-10 S/cm as the frequency increase from 100 Hz to 5000 Hz. The AC conductivity increases slightly with increasing temperature, 2.52x10-9 S/cm at 300 K, and 2.89x10-9 S/cm at 385 K. After a solution of the copolymer was irradiated using UV light at 365 nm at room temperature, the absorption band at 356 nm disappeared and a new band was seen at 284 nm.

Solvatochromism, Acidochromism and Photochromism of the 2,6-Bis(4-hydroxybenzylidene) Cyclohexanone Derivative

“…After being irradiated with 254 nm UV light, the intensity of the absorption maxima decreases due to the disappearance of the double bond in the chalcone unit, and the intensity of the absorption around 278 nm slightly enhanced with increasing irradiation time from 0 to 185 min ( Figure 6 a,b). This increase in absorption intensity around 278 nm might be due to the formation of a new structure [ 28 ] through a cycloaddition reaction under UV irradiation. It is known that irradiation of molecular structures containing the reactive ketoethylene group (-CO-CH=CH-) with UV light can induce photoisomerization (cis-trans isomerization) and photocyclization between the polymer chains [ 23 ] and resulting new structures.…”