서강대학교

초록/요약

PartⅠ. Design and Synthesis of Electrochemically Cleavable PS-b-PEO Block Copolymer Combination of two different fields in chemistry can often make novel results in a synergy way. Our group envisioned to bring a conception of electrochemistry into polymer chemistry. We have designed and synthesized poly(styrene-block-ethylene oxide) which can be cleaved by electrolysis. Due to the simple solvent annealing process to make long-range order of cylinderical nanostructures normal to the surface, poly(styrene-block-ethylene oxide) has drawn a lot of attention to be used as a template for many purposes such as electronic devices, separation membranes, and sensors. If the linkage of the block copolymer can be electrochemically cleaved and one domain can be removed by a selective solvent, this polymer should be useful for fabrication of porous film on an electrode. To synthesize the desired block copolymer with well-defined molecular weight and functionalities, we have employed the atom transfer radical polymerization (ATRP) technique. As for the electrolytically active linker between the two blocks, quinone type or alkoxylbenzene type fragments were introduced. These block copolymers were successfully cleaved by electrolysis in acetonitrile/water (9:1) under 2.0 V applied voltage. The removal of PEO domains was verified by various analytical tools such as 1H-NMR, GPC, AFM, and SEM PartⅡ. Remote Substituent Effect on Thermolysis of Meldrum’s Acid Moieties in Polymer Matrix Thermolysis of 5, 5’-dialkyl Meldrum’s acid (MA) is known to generate ketene functionality with concomitant release of carbon dioxide and acetone. Ketene has proven to be a versatile functional group in organic synthesis and it has found useful applications in materials science. Although the thermolysis of MA has been well studied in pyrolysis chemistry, not much detailed study has been accomplished in respect to thermolysis mechanism and structure-activation energy relationship. In an effort to find structural variations of MA derivatives for lower thermolysis temperature, we have found an interesting remote substituent effect on the thermolysis temperature. Several test compounds, 9-hydroxy-3, 3-dimethyl-7,11-diaryl-2,4-dioxaspiro[5.5]undecane-1,5-diones, were prepared by following the modified procedure in the literature and they were integrated in polymer matrices by radical polymerization of their 9-methacrylate congeners. So far, seven different polymers in which have the substituents at para-positions of 7, 11-diaryl rings are varied. The three-dimensional arrangement of the monomer adopts a conformation where the MA moiety is wrapped by the adjacent two aryl groups. The thermolysis reaction rate constants of the polymers seem to follow the Hammett relationship with the substituents at para-position of the aryl groups as demonstrated by the substituent constant (σ) - thermolysis reaction rate constant. Generation of ketene was verified by various analytical tools such as 1H-NMR, IR spectrometry and TGA. PartⅢ. Design and Synthesis of Macrocycle Containing Meldrum’s acid Moieties Through a continuous research about 5,5’-dialkyl Meldrum’s acid (MA), We realized that it has an unique structural property. In case of 5,5’-dibenzyl Meldrum’s acid, the three-dimensional arrangement of the compound adopts a conformation where the MA is wrapped by the adjacent two aryl groups. We investigated using this free organized conformational property and synthesize a macrocycle. We supposed that there was angle formed naturally between para-position of aryl group and 5-carbon in MA which is almost 153o by computer simulation. So we could design and synthesize macrocycle by using Sonogashira coupling and Cu-promoted Glaser-Eglinton alkyne-alkyne homocoupling. Synthesis of each compound was verified by analytical tools such as 1H-NMR, and 13C-NMR.