Low Temperature Suspension Polymerization of Methyl Methacrylate for the Preparation of High Molecular Weight Poly(methyl methacrylate)/Silver Nanocomposite Microspheres

Yeum, Jeong-Hyun,Ghim, Han-Do,Deng, Yulin The Korean Fiber Society 2005 Fibers and polymers Vol.6 No.4

In order to prepare high molecular weight poly(methyl methacrylate) (PMMA)/silver nanocomposite microspheres, methyl methacrylate was suspension-polymerized in the presence of silver nanoparticles at low temperature with 2,2'-azobis(2,4-dimethylvaleronitrile) as an initiator. The rate of conversion was increased by increasing the initiator concentration. When silver nanoparticles were added, the rate of polymerization decreased slightly. High monomer conversion (about $85\%$) was obtained in spite of low polymerization temperature of $30^{\circ}C$. Under controlled conditions, PMMA/silver microspheres with various number-average degrees of polymerization (6,000-37,000) were prepared. Morphology studies revealed that except for normal suspension microspheres with a smooth surface, a golf ball-like appearance of the microspheres was observed, due to the migration and aggregation of the hydrophilic silver nanoparticles at the sublayer beneath the microsphere's surface.

Electrospinning fabrication and characterization of poly(vinyl alcohol)/montmorillonite nanofiber mats

Lee, Hyun Woo,Karim, Mohammad Rezaul,Ji, Hyun Mi,Choi, Jin Hyun,Ghim, Han Do,Park, Sung Min,Oh, Weontae,Yeum, Jeong Hyun Wiley Subscription Services, Inc., A Wiley Company 2009 Journal of applied polymer science Vol.113 No.3

<P>Poly(vinyl alcohol) (PVA)/montmorillonite clay (MMT) nanofiber mats have been fabricated by the electrospinning technique. The PVA/MMT nanofiber mats were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and mechanical measurements. The study showed that the introduction of MMT results in improvement in tensile strength, and thermal stability of the PVA matrix. XRD patterns and SEM micrographs suggest the coexistence of exfoliated MMT layers over the studied MMT contents. FTIR revealed that there might be possible interaction occurred between the MMT clay and PVA matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009</P>

현탁중합에 의한 폴리(비닐 아세테이트)/은 중공 미세입자의 제조

염정현(Jeong Hyun Yeum) 한국고분자학회 2011 폴리머 Vol.35 No.5

현탁중합에 의한 폴리(비닐 아세테이트)((poly(vinyl acetate)(PVAc))/은 미세입자 제조시 사용된 은 나노입자가 중합속도 및 PVAc 미세입자의 형태에 미치는 영향을 고찰하였다. 주사전자현미경, 투과전자현미경, X선 회절, 원자흡수분광분석법을 이용하여 제조된 미세입자의 형태와 특성을 분석한 결과, 사용된 은 나노입자 표면의 친수성 정도와 계면활성제의 농도에 따라 미세입자의 표면이 골프공 표면처럼 오목해지거나 다양한 형태의 중공 구조를 가지는 PVAc/은 미세입자가 제조됨이 관찰되었다. 계면활성제로 개질된 은 나노입자를 이용하여 중합한 경우에 중합속도가 약간 증가하였으며, 80% 이상의 전환율을 가지는 PVAc/은 미세입자를 제조할 수 있었다. Effects of silver nanoparticles on the polymerization rate and morphology of poly(vinyl acetate) (PVAc)/silver microspheres prepared by suspension polymerization of VAc were investigated. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction and atomic absorption spectrometry were used to characterize the morphology and properties of the PVAc/silver microspheres. Due to the change of hydrophilicity of silver nanoparticles, appearance of the microspheres having golf balllike convave surfaces was observed. Under controlled concentration of surfactant, PVAc/silver microspheres with various hollow structures were synthesized. In the case of silver nanoparticles modified by surfactant, the polymerization rate increased slightly. PVAc/silver microspheres with a conversion up to 80% were prepared via suspension polymerization.

전기방사법을 이용한 폴리(비닐 알코올)/ 수분산 폴리우레탄/몬모릴로나이트 나노복합섬유의 제조 및 특성분석

염정현(Jeong Hyun Yeum),김인교(In Kyo Kim) 한국고분자학회 2011 폴리머 Vol.35 No.6

전기방사법을 이용하여 폴리(비닐 알코올)(poly(vinyl alcohol), PVA)/수분산 폴리우레탄(waterborne polyurethane, WBPU)/montmorillonite clay(MMT) 나노복합섬유를 제조하고 특성을 분석하였다. Scanning electron microscopy(SEM), transmission electron microscopy(TEM), X선 회절, thermal gravimetric analyzer(TGA) 의 분석장비들을 이용하여 제조된 나노복합섬유의 형태와 구조적, 열적특성을 확인한 결과, 평균직경이 600∼900 nm인 나노복합섬유들이 성공적으로 제조되었으며, MMT가 나노섬유 내에 완전박리되어 기존의 고분자 나노섬유에 비해 열적성질이 향상되었음을 확인할 수 있었다. 본 연구를 통해 제조된 나노복합섬유는 친수성이고 생체친화적인 재료들을 이용하여 제조되었으며, 의료 분야를 비롯하여 의류 및 산업용 코팅제, 필터 등의 분야로 이용이 가능할 것 으로 보인다. Poly(vinyl alcohol) (PVA)/waterborne polyurethane (WBPU)/montmorillonite clay (MMT) nanocomposite nanofibers were prepared using electrospinning technique of aqueous solutions. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction and thermal gravimetric analyzer were used to characterize the morphology and properties of the nanocomposite nanofibers. Since PVA, WBPU and MMT are hydrophilic, non-toxic and biocompatible materials, these nanocomposite nanofibers can be used for filter and medical industries as wound dressing materials, antimicrobial filters, etc.

Alginate/iron Oxide Nanohydrogels as MRI Contrast Enhancing Agents

Ga Hyun Lee,Yongmin Chang,Han Do Ghim,Jeong Hyun Yeum,Jin Hyun Choi 한국고분자학회 2006 한국고분자학회 학술대회 연구논문 초록집 Vol.2006 No.10

Poly(vinyl alcohol)/chitosan oligosaccharide blend submicrometer fibers prepared from aqueous solutions by the electrospinning method

Lee, Hyun Woo,Karim, Mohammad Rezaul,Park, Jae Hyeung,Ghim, Han Do,Choi, Jin Hyun,Kim, Ketack,Deng, Yulin,Yeum, Jeong Hyun Wiley Subscription Services, Inc., A Wiley Company 2009 Journal of applied polymer science Vol.111 No.1

<P>Submicrometer fibers of poly(vinyl alcohol) (PVA) and chitosan oligosaccharide [COS; i.e., (1→4)-2-amino-2-deoxy-β-D-glucose] were prepared by an electrospinning method with aqueous solutions with polymer concentrations of 7.5–15 wt %. Scanning electron microscopy, Fourier transform infrared, X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis were used to characterize the morphology and properties of the PVA/COS fibers. The PVA/COS mass ratio, the total polymer concentration, and processing parameters such as the applied voltage and capillary-to-collector distance played important roles in controlling the fiber morphology. Fourier transform infrared and X-ray diffraction data demonstrated that there were possibly hydrogen bonds between COS and PVA molecules that weakened the interactions in COS and improved the electrospinnability of PVA/COS. Moreover, with a higher percentage of COS in the PVA/COS blend fibers, superior thermal stability could be obtained. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009</P>

Novel Poly(vinyl alcohol)/Carbon Nanotube Nanocomposite Microspheres Prepared via Suspension Polymerization and Saponification

Kwon, Il Jun,Park, Sung Min,Jeong, Min Gi,Yang, Seong Baek,Yoo, Sung Hun,Jeong, Dae Won,Sabina, Yeasmin,Oh, Weontae,Choi, Jin Hyun,Yeum, Jeong Hyun American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.11

<P>Poly(vinyl acetate) (PVAc)/poly(vinyl alcohol)/carbon nanotube (CNT) nanocomposite microspheres with a core/shell structure were prepared by heterogeneous saponification of a PVAc/CNT microsphere suspension polymerized for the first time. We investigated the effects of various polymerization conditions on the conversion of vinyl acetate (VAc) into PVAc, such as time, temperature, and CNT concentration. The results indicated that the rate of polymerization decreased with CNT addition. In addition, the time and temperature had significant effects on the polymerization rate, and it was difficult to obtain higher conversion of VAc into PVAc at lower temperature and time. However, 65% conversion could be achieved despite the presence of CNTs at low temperature for a polymerization time of 25 h. Field-emission scanning electron microscopy was performed to examine the CNT distribution in the PVAc microspheres, and the results revealed that CNT particles were completely inserted into the polymer matrix, indicating that PVAc/CNT microspheres could be prepared by in situ suspension polymerization. The detailed structure of the PVAc/CNT microspheres was determined using X-ray diffraction analysis, and the results suggested that CNTs were inserted into PVA microspheres, and PVAc/CNT nanocomposite microspheres were successfully prepared with 0.5 wt.% CNTs. The effects of various CNT concentrations on the degree of saponification of PVAc were examined using optical microscopy at various saponification times, and H-1-NMR results indicated that the saponification rate increased significantly with increasing CNT concentration and that almost fully saponified PVA microspheres were obtained in the presence of 0.5 wt.% CNTs for a saponification time of 120 h.</P>

높은 안정성을 갖는 초미립 폴리에틸렌이민-금 나노입자

김은정(Eun Jung Kim),염정현(Jeong Hyun Yeum),김한도(Han Do Ghim),이세근(Se Guen Lee),이가현(Ga Hyun Lee),이현주(Hyun Ju Lee),한상익(Sang Ik Han),최진현(Jin Hyun Choi) 한국고분자학회 2011 폴리머 Vol.35 No.2

본 연구는 수계에서 오랜 시간 동안 안정한 생체적합 금 나노입자의 제조에 관한 것으로, 환원제와 안정제의 역할을 동시에 수행하는 폴리에틸렌이민을 이용하여 응집성이 낮은 초미립 폴리에틸렌이민-금 나노입자를 상온의 수용액 상에서 합성하였다. 폴리에틸렌이민-금 나노입자의 평균 입자크기는 8∼12 nm이었고, 수계의 나노콜로이드 상에서 50 nm 내외의 클러스터를 형성하였으며, 매우 뛰어난 안정성을 보였다. 상대적으로 낮은 금속 전구체의 농도에서 나노입자를 제조하였을 때, 입자의 크기가 두드러지게 감소하는 경향을 나타내었다. 폴리에틸렌이민-금 나노입자의 X-선 회절분석 결과, 금에서 나타나는 전형적인 결정 피크가 발견되었다. 또한 세포배양실험 결과, 폴리에틸렌이민과는 달리 폴리에틸렌이민-금 나노입자는 98%의 세포 생존율을 보여 세포독성은 거의 없는 것으로 나타났다. 이상의 결과로부터 본 연구에서 합성된 폴리에틸렌이민-금 나노입자는 CT 조영제 등으로의 활용이 기대된다. This study is related to the preparation of biocompatible gold nanoparticles (AuNPs) which are stable in aqueous solutions for a long time. Ultrasmall polyethyleneimine (PEI)-capped AuNPs (PEIAuNPs) with limited agglomeration were prepared in aqueous solutions at room temperature, which were based on the roles of PEI as a reductant and a stabilizer. PEI-AuNPs with an average size of 8∼12 nm formed highly stable nanocolloids with an average hydrodynamic cluster size of around 50 nm in aqueous media. At a low concentration of metal precursor hydrogen tetrachloroaurate(III), the particle size was reduced noticeably. The typical peaks of gold were observed in the X-ray diffraction pattern of AuNPs. The cell viability of 98% was obtained in the case of PEI-AuNPs, while PEI was cytotoxic. The PEI-AuNP is considered to be a potential candidate as a contrast agent for computed tomography.

Effect of Ethanol/water Solvent Ratios on the Morphology of Zein Nanofiber Mats and their Wettability

Jin Hyun Choi,Young Hwa Kim,Jeong Hyun Yeum 한국염색가공학회 2011 韓國染色加工學會誌 Vol.23 No.4

주부와 조리사의 환경친화적 음식소비행동 비교

서정희(Jeong-Hee Seo),홍순명(Soon-Myung Hong),유경희(Kyeong-Hee Yu),황혜진(Hye-Jin Hwang),염수경(Su-Kyung Yeum),김현주(Hyun-Ju Kim),양정아(Jeong-Ah Yang),서영은(Young-Eun Seo) 한국식품영양과학회 2000 한국식품영양과학회지 Vol.29 No.6

본 연구는 환경친화적 음식문화를 개발하고 보급하기 위한 프로그램을 개발하는데 필요한 기초자료를 제공하고, 음식물 쓰레기 감소를 통한 환경정책과 프로그램을 개발하는데 필요한 기초자료를 제공하기 위하여 이루어 졌다. 울산광역시에 거주하고 있는 주부와 조리사를 대상으로 하여 식단작성부터 식품구매, 조리 음식먹기 및 남은 음식물 처분에 이르기까지 음식소비의 전 과정에서음식물쓰레기를 감소시키기 위한 구체적 실천 전략인 환경친화적 음식소비행동을 비교해 보았다. 이는 연구결과를 요약하면 다음과 같다. 환경친화적 식품소비행동을 총체적으로 보면 조리사는 주부에 비하여 더 환경친화적으로 식품을 소비하고 있었다. 조리사는 먹는 사람의 의견을 고려하고, 제철 식품위주로 식단을 작성하고, 계획적으로 식품을 구매하고, 사온 식품을 바로 손질하고, 저울과 계량컵을 사용하여 정확한 양의 음식을 만들고, 가족행사 음식을 뷔페식으로 준비하고, 남은 음식을 필요한 사람에게 즉시 준다는 면에서는 더 환경친화적이라고 할 수 있다. 그러나 세부문항별로 볼 때 주부는 식품 포장단위가 큰 경우 이웃과 공동구매하고, 남은 음식은 1회정도 먹을 분량씩 포장하여 냉동보관하고, 음식재료가 싸더라도 많이 사지 않는다는 면에서는 조리사에 비하여 더 환경친화적이라고 할 수 있다. 먹는 사람의 수보다 넉넉하게 식품 구입, 가능한 적은 포장단위로 구입, 채소를 다듬을 때 버리는 양이 많음, 가족행사 음식은 먹고 남을 정도로 넉넉하게 준비, 야채 자투리, 배추 우거지, 파뿌리, 멸치머리, 북어머리, 닭뼈 등은 국물을 만드는데 이용, 국이나 찌개를 함께 준비, 국이나 찌개의 국물의 양은 넉넉하게 주문, 여러 가지의 반찬 준비, 덜어 먹는 상차림 준비, 외식할 때 남을 정도로 넉넉하게 주문, 외식할 때 남은 음식 싸옴, 냉장고에 보관하다 버리는 음식 및 재료가 많음, 음식은 부족하지 않고 남을 정도로 준비 등은 조리사와 주부간에 의미 있는 차이를 보이지 않았다. 환경친화적 음식소비행동은 성별, 결혼여부 및 교육수준에 따라서는 의미 있는 차이를 보이지 않았다. 남자와 미혼은 모두 조리사이므로 주부를 제외한 조리사만을 선택하여 성별과 결혼여부에 따라 환경친화적 음식소비 행동에 차이를 알아보기 위한 결과 역시 차이를 보이지 않았다. 환경친화적 음식소비행동은 연령, 월평균소득 및 엥겔계수와 의미 있는 상관관계를 보이지 않았다. 조리사와 주부는 음식을 소비하는 전 과정에서 가장 많이 관여하고 있는 집단이다. 그런데 조리사와 주부 모두 전반적으로는 환경친화적 음식소비행동의 수준이 높지 않음으로 합리적인 식생활문화를 생활화할 수 있도록 교육과 홍보가 필요하다고 본다. 주부의 경우 유치원이나 어린이집, 초중고등학교에서 하는 부모교육과 반상회의 홍보자료에 반드시 환경친화적 음식소비행동에 관한 교육이 포함되어야 한다. 조리사의 경우 정기교육과정에 환경친화적 음식소비행동에 관한 교육과 홍보를 함께 함으로써 외식이나 단체급식에서 발생하는 음식물 쓰레기의 양을 줄일 수 있을 것이다. This research aims to examine the differences between the behaviors of the two representative groups, housekeepers and cooks in menu-planning, purchasing of ingredients, cooking and disposal of leftover. The sample groups consist of 217 housekeepers and 129 cooks, respectively, residing in the Ulsan Metropolitan City. The cook can be seen as more pro-environmentally in their reflection to the opinion of consumers; considering the seasonal period in menu-planning; immediate handling of them upon getting; using measuring cups and scale for accuracy; arranging in the buffet style in the familial feast; distributing promptly the leftover to the people who need it. On the other hand, the housekeepers act more pro-environmentally in their co-purchasing of materials with neighbors when the size of purchase is big; storing food in the freezer in small package for each meal; avoiding the unnecessary purchasing even when the price of foods is cheap. There were no significant divergences between the two groups' pro-environmental behavior in their preparing food more than enough; favoring the minimum size of ingredients; wasting large amount when they trim vegetables; preparing food more than enough. Gender, marital status, education does not produce any meaningful difference in the pro-environmental behavior. Nor there was significant relationship between that behavior pattern and age, monthly average income, and Engel co-efficient. In conclusion, we found that both the housekeeper and cook, although the most important actor in the whole process of food consumption, are not so conscious of pro-environmental food consumption behavior. This indicates that the education and campaign for establishing the pro- environmental food consumption behavior are needed.