김대식 교수

Guanidinium-functionalized poly(arylene ether sulfone) anion exchange polymer electrolytes were synthesized via activated fluorophnyl-amine reaction, followed by the methylation with dimethyl sulfate. The activated fluorine-amine reaction gives precise control of cation functionality without the deleterious side reactions and allows the direct connection of guanidinium into stable phenyl rings.

A new sulfonated side-chain grafting unit containing two or four sulfonic acid groups was synthesized using sulfonated 4-fluorobenzophenone (FBP) and 1,1-bis(4-hydroxyphenyl)-1,4-((4-fluorophenyl)thio)phenyl-2,2,2-trifluoroethane (3FBPT). A conventional aromatic nucleophilic substitution (S N Ar) was used for copolymerization of poly(arylene ether sulfone) containing a methoxy group. After converting the methoxy group to the reactive hydroxyl group, this functionalized copolymer was reacted to g

A poly(arylene ether) (PAE) with high fluorine content and a poly(arylene ether nitrile) (PAEN) with high nitrile content, each containing pendant phenyl sulfonic acids were synthesized. The PAE and PAEN were prepared from decafluorobiphenyl (DFBP) and difluorobenzonitrile (DFBN) respectively, by polycondensation with 2-phenylhydroquinone (PHQ) by conventional aromatic nucleophilic substitution reactions. The sulfonic acid groups were introduced by mild postsulfonation exclusively on the para -p

Perfluorosulfonic acids such as Nafion are industrial standard cation exchange ionomers for polymer electrolyte membrane fuel cells because of their high gas permeability, hydrophobicity, and inertness to electro-chemical reaction. In this research, pentamethylguanidinium functionalized, perfluorinated hydroxide conducting ionomers for alkaline membrane fuel cells were prepared and characterized. The alkaline stability of the ionomers largely depended on the adjacent group that connected the cat

Abstract Organic–inorganic hybrid membranes of poly(vinylidene fluoride)‐cohexafluoropropylene (PVDF‐HFP) and silica composites containing sulfonic acid groups were prepared via in situ polymerization of tetraethoxysilane (TEOS) and sulfosuccinic acid (SSA) using the sol‐gel process. The membranes containing more sulfonic acid groups showed a higher vapor sorption and greater swelling behavior. The bound and free water content of the membrane is proportional to the SSA concentration. However, th

The effect of the premixed ratio and supply condition of premixed fuel on the combustion and emission characteristics of a partial homogeneous charge compression ignition (HCCI) engine has been investigated experimentally and numerically. The fuel, which is supplied by an additional port fuel injector in the intake manifold, is premixed with air. The homogeneous charge is compressed and ignited by directly injected diesel fuel in the combustion chamber. In this work, the experimental investigati

Abstract Flat sheet submerged membranes coupled with a membrane bioreactor (MBR) have been run for 200 days to evaluate membrane performance during wastewater treatment. The chlorinated poly(vinylchloride) (CPVC) membranes prepared in this study have different characteristics such as the degree of hydrophobicity or hydrophilicity and different pore sizes. Poly(vinylpyrrolidinone) (PVP) was used as the pore‐forming agent and to increase the wettability of the surface. A relatively hydrophilic mem