• 대한화학회지
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• 제55권1호
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• pp.14-18
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• 2011

methacrylic acid과 ethylene glycol과의 에스테르화 반응을 ZSM-5에 지지된 heteropolyacids [HPA: $H_4SiW_{12}O_{40}$(STA)와 $H_3PW_{12}O_{40}$(PTA)] 하에서 수행하였다. 비교를 위하여, 지지하지 않은HPA, $H_2SO_4$, $BF_3$와 PTSA 하에서 같은 반응을 수행하였다. 연구한 촉매 중에서, HPA는 $H_2SO_4$, $BF_3$와 PTSA와 비교하여 더 좋은 활성을 보여주었다. 촉매 활성을 HPA지지 ZSM-5 촉매와 비교하였는데, 그 결과 ZSM-5위에 지지된 30 wt% PTA는 bulk PTA와 거의 같은 활성을 나타내었다. 이 반응은 methacrylic acid에 관하여 1차 속도 법칙을 따랐으며, 반응 생성물은 $^1H$-NMR과 FT-IR을 이용하여 확인하였다.

• Korean Membrane Journal
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• 제10권1호
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• pp.20-25
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• 2008

Proton conducting composite membranes were prepared by solution blending of poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-poly(sulfopropyl methacrylate) (P(VDF-CTFE)-g-PSPMA) graft copolymer and heteropolyacid (HPA). The P(VDF-CTFE)-g-PSPMA graft copolymer was synthesized by atom transfer radical polymerization (ATRP) using direct initiation of the secondary chlorines of P(VDF-CTFE). FT-IR spectroscopy revealed that HPA nanoparticles were incorporated into the graft copolymer via hydrogen bonding interactions. The water uptake of membranes continuously decreased with increasing HP A concentration up to 45wt%, after which it slightly increased. It is presumably due to the decrease in number of water absorption sites due to hydrogen bonding interaction between the HP A particles and the polymer matrix. The proton conductivity of membranes increased with increasing HPA concentration up to 45wt%, resulting from both the intrinsic conductivity of HP A particles and the enhanced acidity of the sulfonic acid of the graft copolymer.

• 멤브레인
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• 제19권2호
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• pp.96-103
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• 2009

본 연구에서는 poly(vinyl chloride) (PVC)가지형 공중합체 전해질과 헤테로폴리산(HPA)을 이용하여 유무기 합성 전해질막을 제조하였다. poly(vinyl chloride)-g-poly(styrene sulfonic acid) (PVC-g-PSSA)는 PVC의 이차 염소의 직접적인 개시를 이용한 atom transfer radical polymerization (ATRP)로 합성하였다. 이때, HPA 나노입자는 수소 결합을 통해 PVC-g-PSSA 가지형 공중합체와 결합하는 것을 FT-IR spectroscopy를 통하여 확인하였다. 전해질막의 수소이온 전도도는 HPA의 질량 분율이 0.3이 될 때까지 상온에서 0.049에서 0.068 S/cm로 증가하였다. 이것은 HPA 나노입자 고유의 전도도와 가지형 공중합체가 가지고 있는 술폰산의 강화된 산도 때문이라고 추정된다. 합습률은 HPA의 질량 분율이 0.45까지 증가할수록 130에서 84%로 감소하였다. 이것은 HPA나노입자와 고분자 메트릭스 사이의 수소 결합의 상호작용 때문에 물을 흡수하는 site의 수가 감소한 결과라고 볼 수 있다. 열중량 분석결과 HPA의 농도가 증가할수록 전해질막의 열적 안정성이 강화된다는 것을 알 수 있었다.

• 한국막학회:학술대회논문집
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• 한국막학회 2008년도 춘계 총회 및 학술발표회
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• pp.51-57
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• 2008

Mixed matrix membranes of poly(vinyl alcohol) (PVA), loaded with phosphomolybdic heteropolyacid (HPA) and crosslinked with glutaraldehyde have been prepared by the solution casting technique. Pervaporation (PV) experiments have been performed at $30^{\circ}C$ to separate water-isopropanol feed mixtures containing 10 to 40 wt.% of water. The membranes were characterized by DSC and DMTA to understand their thermal behavior and mechanical strength properties. At high content (i.e. 7 wt.% with respect to weight of PVA) of HPA, the mixed matrix membranes could extract water efficiently on the permeate side with a selectivity of 90,000 and a flux of 0.032 $kg/m^2h$ for 10 wt.% of water containing feed mixture (the lowest feed composition of water studied). Flux of the mixed matrix membranes decreased with increasing concentrations of HPA.

• 한국수소및신에너지학회논문집
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• 제16권1호
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• pp.40-48
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• 2005

Until recently, only perfluorinated ionomer membrane such as Nation and Aciflex practically could be successfully used in water splitting. However, these membrane are limited by high cost and loss of membrane performance such as proton conductivity at elevated temperature above 80$^{\circ}C$. The sulfonated aromatic polymers such as PEEK and PSf, polyimides, and polybenzimidazoles are expected to have lower production cost as well as satisfactory chemical and electrochemical properties. HPAs and sulfonated polymers could have a significant influence on water electrolysis performance at elevated temperatures above 80$^{\circ}C$, but these phenomena have received relatively little attention until now. Therefore, it would be desirable to investigate the interrelation between the HPA and sulfonated polymer, such as SPEEK. The SPEEK membrane were prepared by the sulfonation of PEEK, and HPA was blended with SPEEK to increase the mechanical strength and electrochemical characteristics. As a results, electrochemical characteristics such as proton conductivity and ion exchange capacity were improved with the addion of 0.5 g HPA. And the properties of polymer electrolyte, SPEEK/HPA were better than Nation membrane at elevated temperature above 80$^{\circ}C$.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2002년도 봄 학술발표회 논문집
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• pp.459-461
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• 2002

A new class of materials based on organic and inorganic species combined at a molecule level has obtained more attention recently[1]. HPA(heteropolyacid) shows unmatched applied perspective in terms of synthesis chemistry, analysis chemistry, biology, medicine and materials science[2]. As a potential photochemical material, the hybrid system of HPA and polymer has been investigated. However, the design and synthesis of heteropolyacid-based hybrids, which are at the forefront of the materials chemistry research, is still in its infancy. (omitted)

• 멤브레인
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• 제16권1호
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• pp.9-15
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• 2006

Polyvinylalcohol (PVA)을 전해질 막으로 이용하여 위하여 가교제로서 sulfosuccinic acid (SSA)와 무기물 첨가제로 phosphotungstic acid (PWA), silicotungstic acid (SiWA) 등의 HPA (heteropolyacid)를 사용하여 PVA/SSA/HPA 복합막을 제조하였다. PVA/SSA/HPA 복합막은 HPA의 농도가 증가함에 따라 함수율은 감소하였으나 IEC값은 증가하는 경향을 나타내었다. PVA/SSA/HPA 복합막의 XRD 분석 결과 HPA의 농도가 증가함에 따라 HPA가 복합막 속으로 잘 분산되는 것을 확인할 수 있었으며 HPA로서 PWA보다 SiWA의 분산성이 우수하였다. TGA 분석결과 PVA/SSA 복합막은 가교 결합으로 인하여 PVA 보다 열안정성이 우수하였으며 복합막의 HPA의 농도가 증가할수록 열안정성이 더욱 증대되는 것을 알 수 있었다. PVA/SSA/HPA 복합막의 메탄올 투과저항은 Nafion보다 현저히 우수하였으며 HPA의 농도가 증가할수록 메탄올의 투과도는 감소하였다.

• Journal of Photoscience
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• 제10권3호
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• pp.231-236
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• 2003

TiO$_2$ has been used as photocatalyst since two and half decades ago. The efficiency in its photocatalytic reactions has been improved by increasing the surface area of the photocatalyst by supporting fine TiO$_2$ particles on some porous materials. In this work, heteropolytungstic acid (HPA) - encapsulated into the titanium exchanged SBA-15 mesoporous materials (TiSBA-15) were prepared and characterized. Also their photocatalytic effects on decomposition of phenol were investigated and the photodecomposition rates of the phenol were observed to be increased by 2.5 8 fold, as compared to those observed in the presence of HPA-encapsulated SBA-15 or TiSBA-15 without HPA.

• 한국막학회:학술대회논문집
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• 한국막학회 2008년도 춘계 총회 및 학술발표회
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• pp.147-150
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• 2008

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.569-578
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• 2011

The $SiO_2$ membranes for polymer electrolyte membrane fuel cell (PEMFC) are preapared by electrospinning method. It leads to high porosity and surface area of membrane to accommodate the proton conducting materials. The composite membrane was prepared by impregnating of Nafion ionomer into the pores of electrospun $SiO_2$ membranes. The $SiO_2$:heteropolyacid (HPA) nano-particles as a inorganic proton conductor were prepared by microemulsion process and the particles are added to the Nafion ionomer. The characterization of the membranes was confirmed by field emission scanning electron microscope (FE-SEM), thermogravimetry analysis (TGA), and single cell performance test for PEMFC. The Nafion impregnated electrospun $SiO_2$ membrane showed good thermal stability, satisfactory mechanical properties and high proton conductivity. The addition of the $SiO_2$:HPA nano-particle improved proton conductivity of the composite membrane, which allow further extension for operation temperature in low humidity environments. The composite membrane exhibited a promising properties for the application in high temperature PEMFC.