본 실험에서는 폴리올레핀을 이용하여 중공사 형태의 분리막을 제조하였다. 권취속도를 달리하여 중공사막을 제조하였으며, 보어로는 질소를 사용하였다. 제조된 중공사는 만능재료시험기를 이용하여 응력과 변현율을 측정하였다. 그리고 시차주사열량계(DSC)를 이용하여 각각의 샘플의 결정화도를 측정하였고, 권취속도와 어닐링 효과에 따른 결정화도의 거동을 조사하였다. 냉연신과 열연신을 거친 중공사 분리막은 전계방출형주사현미경(FE-SEM)을 이용하여 단면, 표면의 모폴로지를 관찰하였다.

The straight nanopores in cellulose acetate (CA) polymers for battery gel separators were generated by utilizing both hydrated metal salts and water pressure. When polymer film was exposed to water pressure, the continuous nanopores were generated after complexing with hydrated metal salts. These results could be explained by that polymer chains were weakened because of the plasticization effect of the hydrated regions incorporated into the CA. Pore size could also be easily controlled by adjusting the water pressure. The generated pores in CA polymers were confirmed by scanning electron microscopy (SEM) images. The coordinate interactions between CA polymer and metal salts, and ionic states of metal salts were investigated by FT-IR and Raman spectroscopy, respectively.

Porous graphites were synthesized by removing the template in HF after cabothermal conversion for 3 h at 900 ℃, accompanied by intercalations of pyrolyzed fuel oil (PFO) in the interlayer of Co or Ni loaded magadiite. The X-ray powder diffraction pattern of the porous graphites exhibited 00l reflections corresponding to a basal spacing of 0.7 nm. The particle morphology of the porous graphites was composed of carbon plates intergrown to form spherical nodules resembling rosettes like a magadiite template. TEM shows that the cross section of the porous graphites is composed of layers with very regular spaces. In particular, crystallization of the porous graphite was dependent on the content of Co or Ni loaded in the interlayer. The porous graphite had a surface area of 328-477 m2/g. This indicates that metals such as Co and Ni act as catalysts that accelerate graphite formation.

In this study, we synthesize tungsten oxide thin films by electrodeposition and characterize their electrochromic properties. Depending on the deposition modes, compact and porous tungsten oxide films are fabricated on a transparent indium tin oxide (ITO) substrate. The morphology and crystal structure of the electrodeposited tungsten oxide thin films are investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). X-ray photoelectron spectroscopy is employed to verify the chemical composition and the oxidation state of the films. Compared to the compact tungsten oxides, the porous films show superior electrochemical activities with higher reversibility during electrochemical reactions. Furthermore, they exhibit very high color contrast (97.0%) and switching speed (3.1 and 3.2 s). The outstanding electrochromic performances of the porous tungsten oxide thin films are mainly attributed to the porous structure, which facilitates ion intercalation/deintercalation during electrochemical reactions.

In this study, the appearance change and the heat․moisture transfer properties of knitted fabric by yarn shrinkage were examined to obtain useful data on the development of thermo-sensitive functional materials. Eleven types of knitted fabric were knitted using highly bulky acrylic-blended yarn. After shrinking the specimens using dry heat treatment, the appearance change and thickness were measured. An HEC simulator was adopted for measuring the heat․moisture transfer properties of specimens by yarn shrinkage. When holes were arranged vertically in the mesh structure, the specimens with 2,500 and 5,000 holes showed high percent change of hole area, appearance, and thickness. When holes were diagonally arranged in the mesh structure, the percent change of hole area in the specimen with 1,250 holes was larger than the one with 2,500 holes. However, the dimensional stability of the specimen with 2,500 holes was better because of its smaller appearance and thickness change. In the tuck structure, the percent change of hole area in the specimen with 625 and 416 holes was relatively large compared with the appearance and thickness change. Furthermore, the hole size in the tuck structure was smaller than that in the mesh structure but the percent change of hole area was larger. Therefore, it was proved that the tuck structure is more suitable than the mesh structure for developing thermo-sensitive functional materials. Heat․moisture transfer property test verified that the change of hole area by yarn shrinkage enabled obtaining the thermal effect due to the distinct temperature difference in the inner layer.

Porous materials such as polymeric foam are widely adopted in engineering and biomedical fields. Porous materials often exhibit complex nonlinear behaviors and are sensitive to material and environmental factors including cell size and shape, amount of porosity, and temperature, which are influenced by the type of base materials, reinforcements, method of fabrication, etc. Hence, the material characteristics of porous materials such as compressive stress-strain behavior and void volume fraction according to aforementioned factors should be precisely identified. In this study, unconfined uniaxial compressive test for two types of closed-cell structure polyurethane foam, namely, 0.16 and 0.32 g/cm3 of densities were carried out. In addition, the void volume fraction of three different domains, namely, center, surface and buckling regions under various compressive strains (10%, 30 %, 50 % and 70 %) were quantitatively observed using Micro 3D Computed Tomography(micro-CT) scanning system. Based on the experimental results, the relationship between compressive strain and void volume fraction with respect to cell size, density and boundary condition were investigated.

KAERI의 PRIDE 시설에서 공학규모의 전해환원용 원료물질인 UO2 다공성펠렛 제조를 위해 공정과 장치를 최적화시킨 내 용을 다루었다. UO2 분말과 별도로 attrition 밀링된 대용산화물 분말을 출발분말로, 정밀 칭량을 통해 사용후핵연료 조성을 모사하였다(Simfuel). Simfuel 분말은 각각 tumbling mixer로 혼합하여 균질화 하고, rotary press로 성형하여 furnace를 이 용해 소결하였다. 4% H2-Ar 분위기에서 1450℃ 24시간 고온 열처리하여 제조된 소결펠렛은 6.89 g·cm-3의 벌크밀도를 가 지며 이는 후속 전해환원 공정의 요구에 부합한다. 소결된 다공성펠렛의 미세구조 관찰을 통해 다공성 기지상과 함께 산화/ 금속 석출물이 관찰되어 사용후핵연료의 상이 모사됨을 확인하였다. 본 결과는 향후 공학규모 이상의 파이로 연구를 위한 UO2 다공성펠렛 제조에 중요한 기초자료로 활용 될 것이다.

Mesoporous carbon nanofibers as electrode material for electrical double-layer capacitors(EDLCs) are fabricated using the electrospinning method and carbonization. Their morphologies, structures, chemical bonding states, porous structure, and electrochemical performance are investigated. The optimized mesoporous carbon nanofiber has a high sepecific surface area of 667 m2 g−1, high average pore size of 6.3 nm, and high mesopore volume fraction of 80 %, as well as a unifom network structure consiting of a 1-D nanofiber stucture. The optimized mesoporous carbon nanofiber shows outstanding electrochemical performance with high specific capacitance of 87 F g−1 at a current density of 0.1 A g−1, high-rate performance (72 F g−1 at a current density of 20.0 A g−1), and good cycling stability (92 F g−1 after 100 cycles). The improvement of the electrochemical performance via the combined effects of high specific surface area are due to the high mesopore volume fraction of the carbon nanofibers.

The highly performing polyamide (PA) thin film composite (TFC) reverse osmosis (RO) membrane was prepared using the commercialized porous polyolefin (PO) membrane as a support. The PO-supported TFC (PO-TFC) membrane was fabricated via a conventional interfacial polymerization process. The highly permselective PA layer was formed by optimizing membrane fabrication parameters such as monomer/additive composition and post-treatment. The uniform pore structure and high surface porosity of the PO support are beneficial for improving the membrane permselectivity. As a result, the prepared PO-TFC membrane showed ~30% higher water flux and ~0.4% higher NaCl rejection compared to a commercial RO membrane. In addition, the PO-TFC membrane exhibited excellent mechanical properties and organic solvent resistance.

본 연구에서는 Polyvinylidene Fluoride(PVDF)와 Polyacrylonitrile(PAN)의 중공 사막 표면에 계면중합하여 복합막을 제조하였다. 지지체 중공사 막은 기존에 상 용화된 제품을 사용하였고, Poly(4-styrene sulfonic acid)(PSSA)와 Polyetherimide 의 농도변화, 이온세기의 변화, 코팅시간의 변화에 따라 막을 제조하였다. 제조한 막의 특성평가를 위해 NaCl, MgCl2, CaSO4 100ppm의 공급액을 이용하여 일정 가동압력과 공급유량에서 막의 투과도와 배제율을 측정하였다.

The gas separation through membrane is considered as a promising solution for the stabilization of greenhouse gas level of atmosphere attributed from CO2. The separation process of membrane allows low energy requirement, low cost, and ease of operation. However, conventional polymeric membranes generally suffer from the trade-off between permeability and selectivity, which remains as one of the most important challenges for commercialization. Mixed matrix membranes (MMMs), consisting of a polymer matrix and porous nano-filler, are considered to be a promising solution to overcome the trade-offs in polymeric membranes. Herein the porous nano-structures were fabricated to enhance the permselectity of CO2 separation membranes. The MMM which were fabricated with prepared porous nano-filler showed permeability improvement without significant selectivity loss.

본 연구는 열유도 상분리법(thermally induced phase separation, TIPS)을 사용하여, 수처리 분리막에 적용하기 위 해, 응고조의 열용량의 변화를 위해 서로 다른 두 용액의 함량을 조절하였다. 또한, 온도의 변화를 통해 분리막의 구조 변화 에 대하여 관찰하였다. 분리막을 제조하기 위한 소재로는 수처리 분리막에 주로 이용되는 기계적 물성과 내화학성이 우수한 poly (vinylidene fluoride)(PVDF)를 사용하였고, 첨가제로 실리카를 이용하였다. 희석제는 PVDF와 호환성이 좋은 dioctyl phthalate (DOP), dibutyl phthalate (DBP)를 사용하였다. 응고액의 함량 변화에 따른 열용량 변화에 따라 제조된 분리막의 구 조를 관찰하기 위해 SEM 이미지를 촬영하였다. 열용량이 증가할수록 PVDF의 결정화 속도가 느려져 큰 기공을 나타내며 열 용량이 작을수록 결정화 속도가 증가하여 작은 기공이 생기는 것을 확인하였다.

본 논문에서는 변형에 의해 유발된 패턴변화(pattern transformation)에 기반하여 압축(compression)과 인장(tension) 하중 모두에서 음의 포아송 비(negative poisson’s ratio)를 나타내는 다공성(porous) 구조를 제안한다. 기존에 개발된 원형 구멍을 이용한 구조는 연결선(ligament)의 회전 모멘트 부족으로 인해 인장 시 양의 포아송 비를 나타내는 한계점이 있었으며, 타원 형 구멍을 이용한 구조는 응력집중 현상으로 인하여 내구성(durability)이 약한 문제점이 있었다. 이에 본 연구에서는 휘어진 연결선의 배열을 통하여 인장하중 하에서의 회전 모멘트를 증가시키는 동시에 응력집중 현상을 완화하고 변형에너지(strain energy)를 구조물 전반에서 고르게 흡수하도록 설계하였다. 이를 통해 10%의 공칭 변형률(nominal strain) 범위 내의 압축 과 인장 모두에서 음의 포아송 비를 가지며, 기존 모델에 비하여 강성(stiffness)과 내구성이 개선된 구조를 개발하였다. 비선 형 유한요소해석을 통하여 기존 타원형 구멍 모델과의 비교를 수행하였으며 제안된 모델이 구조의 강성과 내구성 측면에서 현저히 개선됨을 확인하였다.

Porous polytetrafluoroethylene (PTFE) thin films are fabricated by spin-coating using a dispersion solution containing PTFE powders, and their crystalline properties are investigated after thermal annealing at various temperatures ranging from 300 to 500°C. Before thermal annealing, the film is densely packed and consists of many granular particles 200-300 nm in diameter. However, after thermal annealing, the film contains many voids and fibrous grains on the surface. In addition, the film thickness decreases after thermal annealing owing to evaporation of the surfactant, binder, and solvent composing the PTFE dispersion solution. The film thickness is systematically controlled from 2 to 6.5 μm by decreasing the spin speed from 1,500 to 500 rpm. A triboelectric nanogenerator is fabricated by spin-coating PTFE thin films onto polished Cu foils, where they act as an active layer to convert mechanical energy to electrical energy. A triboelectric nanogenerator consisting of a PTFE layer and Al metal foil pair shows typical output characteristics, exhibiting positive and negative peaks during applied strain and relief cycles due to charging and discharging of electrical charge carriers. Further, the voltage and current outputs increase with increasing strain cycle owing to accumulation of electrical charge carriers during charge-discharge.

For possibility of specific gas sieve and adsorption, metal organic framework has attracted expectation in the gas separation field. But, this enhances gas transport performance only at high loading. So we designed effective composite growing MOF on porous 2D template to improve membrane at low concentration. The mixed matrix membranes showed improved CO2 permeability drastically by improved CO2/N2 diffusion selectivity and showed anti-plasticization effect.

본 연구에서는 다공성 PAN(Polyacrylonitrile) 중공사 분리막을 지지체로 이용하여 계면중합반응을 통해 나노여과막을 제조하였다. 지지체로는 PAN을 사용하였으며 수용상으로는 피페라진으로 중공사 분리막 내부에 코팅한 후 유기상인 TMC와 반응하여 계면중합이 일어나도록 진행하였다. 지지체로 사용된 UF 중공사 분리막은 분획분자량 10,000, 30,000, 100,000Da를 각각 사용하였으며 피페라진(Piperazine) 농도를 0.1%, 02%, 0.3%, TMC(Trimesoyl Chloride)의 농도를 0.05%, 0.1%, 0.2%로 변화시켜 제조 하여 5bar에서의 수투과도(LMH)와 MgSO4 2000ppm, Na2SO4 2000ppm, NaCl 500ppm 수용액으로부터 염배제율(Rejection, %)을 확인하였다.

A porous polyolefin (e.g. polypropylene and polyethylene) membrane has been commercialized as a lithium ion battery separator. The highly performing thin film composite (TFC) forward osmosis (FO) membrane was fabricated using the porous polyolefin membrane as a support via typical interfacial polymerization process. A very thin thickness (~8 μm) and highly interconnected pore structure of the polyolefin support can greatly reduce the internal concentration polarization, leading to high water flux, as evidenced by its low structural parameter (~168 μm). The prepared polyolefin-supported TFC membrane showed ~3.7 times higher water flux and ~33% lower specific salt flux compared to HTI-CTA commercial FO membrane with 1.0 M NaCl draw solution and DI water feed solution in FO mode. In addition, its excellent mechanical strength enables stable membrane operation.

The straight nanopores in cellulose acetate (CA) polymers for battery gel separators were generated by utilizing both Ni(NO3)2·6H2O and water pressure. When polymer film was exposed to water pressure, the continuous nanopores were generated after complexing with Ni(NO3)2·6H2O. These results could be explained by that polymer chains were weakened because of the plasticization effect of the Ni(NO3)2·6H2O incorporated into the CA. The well controlled CA membrane after water pressure treatment enabled fabrication of highly reliable cell by utilizing 2032-type coin cell structure. The resulting cell performance exhibited both the effect of the physical morphology of CA separator and the chemical interaction of electrolyte with CA polymer which facilitates the Li-ion in the cell.

Carbonaceous materials have widely been used as sorbents. For advanced applications, fine-tuning porosity and polarity of carbonaceous materials is highly desired. Various control methods for porosity and polarity of carbonaceous materials are introduced and the designed carbonaceous materials are implemented for their intrinsic adsorption applications for various gas molecules (e.g., CO2, N2, H2), organic molecules, and metal ions.

본 연구는 수처리 분리막에 제조하기 위하여 열유도 상분리법(thermally induced phase separation, TIPS)을 이용 하였고, 기계적 물성과 내화학성이 우수한 폴리플루오르화비닐리덴(poly(vinylidene fluoride)(PVDF)) 고분자와 실리카를 이용 하여 특성평가를 진행하였다. 특성평가에 사용된 희석제는 dioctyl phthalate (DOP), dibutyl phthalate (DBP)를 사용하였으며, PVDF와 실리카의 비율에 따른 분리막 제조 조건을 알아보기 위하여 결정화 온도, 흐림점, SEM 이미지 등을 관찰하였다. 실 리카의 함량이 증가할수록 결정화 온도와 흐림점이 증가하였음을 확인하였고, 상평형도 작도를 통하여 분리막 제조 조건을 확인하였다.