• Macromolecular Research
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• 제13권2호
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• pp.147-151
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• 2005

The main objective of this study was to modulate pH-sensitive polymers (poly($\beta-amino esters$)) by controlling their molecular weight during their synthesis. These pH-sensitive and biodegradable polymers were synthesized by Michael-type step polymerization. 1,4-Butane diol diacrylate was used as the unsaturated carbonyl compound and piperazine as the nucleophilic compound. Various molecular weight polymers were obtained by varying the mol ratio of piperazine/1,4-butane diol diacrylate. The synthesized polymers were characterized by $^{1}H-NMR$ and their molecular weights were measured by gel permeation chromatography(GPC). The dependence of the molecular weight on the mol ratio was evaluated by the titration method. Also, the pH dependent turbidity of the polymers was determined by UV-Vis spectrophotometry. This pH dependent property of the polymers could be very useful for preparing drug carriers that are sensitive to pH.

• Bulletin of the Korean Chemical Society
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• 제21권10호
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• pp.1031-1034
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• 2000

• 한국염색가공학회지
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• 제20권6호
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• pp.82-86
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• 2008

Cooling function is definitely one of the most desirable attribute of clothing. In spite of the recent progress on phase changing material(PCM) research, the final products with sufficient amount of cooling capability have not yet to be developed in market. A new concept of cooling fabrics has been proposed by applying "Peltier effect" to textile materials. It occurs whenever electrical current flows through two dissimilar conductors; depending on the direction of current flow, the junction of the two conductors is absorbed or released heat. This effect has been tested on P-type and N-type conducting polymers. A P-type conductive polypyrrole coated fabric was synthesized by in-situ polymerization on plain weave PET to make conductive fabrics. And an N-type electrically conductive material was synthesized by treatment of MWNT and polyethyleneimine(PEI). A noticeable amount of temperature difference has been found on the fabrics.

• 한국전기전자재료학회논문지
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• 제30권3호
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• pp.180-184
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• 2017

In this study, we examine the electrical properties of diketopyrrolopyrrole (DPP) containing polymer semiconductors that have been reported to show high performance with ambipolar characteristics. We prepared three different DPP based polymer semiconductors (PDPPTPT, PDPP3T, and PDPP2T-TT) and fabricated organic thin film transistors (OTFTs) with ambipolar polymer semiconductors as an active layer. All three DPP polymers showed only p-type properties at initial measurements. However, after annealing in vacuum oven for 24 hours, it was found that the DPP based polymers have both p-type and n-type properties. It is speculated that the residual impurities supposedly regarded as a strong electron trap source were eliminated during the vacuum process.

• 한국전기전자재료학회논문지
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• 제22권2호
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• pp.163-168
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• 2009

Hyperbranched conjugated polymers (p-HPPV and m-HPPV) with para and meta linkages were synthesized from $A_2$ and $B_4$ type monomers through Wittig polycondensation. The synthesized p-HPPV and m-HPPV were completely soluble in common organic solvents such as chloroform, tetrahydrofuran, 1,2-dichloroethane, etc. and thermal gravimetric analyses showed that p-HPPV and m-HPPV are stable up to $350^{\circ}C$. The molecular weights (from GPC), UV-visible, and photoluminescence maximum peaks of p-HPPV and m-HPPV are characterized in detail. The fabricated EL devices using the synthesized hyperbranched polymers, (ITO/(p-HPPV or m-HPPV)/Al), showed EL emission at about 507 nm and 481 nm (681 nm), respectively. Especially, EL device from m-HPPV were found to exhibit nearly white emission with approximate CIE coordinates of (0.31, 0.34) compared with (0.310, 0.316) of NTSC white color at $100\;cd/m^2$. The good photophysical properties combine with good film-form ability could make these hyperbranched polymers to be a potential candidate for the EL materials.

• 한국군사과학기술학회지
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• 제3권1호
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• pp.164-175
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• 2000

Three compounds of Cu(II)-loaded N,N,N'-trimethylethylenediaminated Merrifield-type polymers were synthesized with yields higher than 80%, and the hydrolysis reaction rates of O-isopropylmethyl-phosphonofluoridate(GB) and O-pinacolylmethylphosphonofluoridate (GD) catalyzed by them have been surveyed. GB and GD hydrolysis by Cu(II)-loaded polymers occurs via intermediate complex mechanism where rapid equilibrium to form intermediate complex between substrate and Cu(II)-loaded polymers($K_f$) is followed by rate determining hydrolysis step($k_1$). The measured activation parameters for $k_1$ are ${\Delta}H^{\ddag}$ : $17.75{\pm}0.98kJ/mol$ ${\Delta}S^{\ddag}$ / : $-218.42{\pm}3.35J/mol$ K, $E^{\circ}_a$ : $20.22{\pm}0.98kJ/mo1$ for GB and ${\Delta}H^{\ddag}$ / : $11.16{\pm}1.15kJ/mol,$${\Delta}S^{\ddag}$ /: $-258.57{\pm}3.93J/mol$ K, $E^{\circ}_a$ : $13.64{\pm}1.15 kJ/mol$ for GD. Standard enthalpy/entropy changes corresponding to the intermediate complex formation constant $K_f$ are ${\Delta}H^{\circ}$ : $37.05{\pm}2.19 kJ/mo1,$$ {\Delta}S^{\circ}$ : $163.12{\pm}7.49 J/mol$ K and ${\Delta}H^{\circ}$ : 418.59{\pm}2.04 kJ/mol,$ ${\Delta}S^{\circ}$ : 4111.92{\pm}6.98 J/mol$ K for GB and GD, respectively, The electron push-pull mechanism by Cu(II)-loaded polymers lowers the P-F bond breaking energy(~400 kJ/mol) to less than 1/20 compared to the case in which no Cu(II)-loaded resin presents. Analysis of $K_f$ and 4k_1$ over pH=6.5~8.0 range suggest that the GB and GD hydrolysis occurs intramolecularily with $pK_a$ =7.29 for ligated $H_2O$ and $t_{1/2}$=36.9 sec, $pK_a$ = 7.06 and $t_{1/2}$=177.7 sec for GB and GD, respectively.

• 한국전기전자재료학회논문지
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• 제30권10호
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• pp.665-671
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• 2017

Herein, we report the fabrication of low-voltage N-type organic field-effect transistors by using high capacitance fluorinated polymer gate dielectrics such as P(VDF-TrFE), P(VDF-TrFE-CTFE), and P(VDF-TrFE-CFE). Electron-withdrawing functional groups in PVDF-based polymers typically cause the depletion of negative charge carriers and a high contact resistance in N-channel organic semiconductors. Therefore, we incorporated intermediate layers of a low-k polymerto prevent the formation of a direct interface between PVDF-based gate insulators and the semiconducting active layer. Consequently, electron depletion is inhibited, and the high charge resistance between the semiconductor and source/drain electrodes is remarkably improved by the in corporation of solution-processed charge injection layers.

• 대한화학회지
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• 제43권4호
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• pp.393-400
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• 1999

Hyperbranched polymer를 이용한 나뭇가지꼴 카보실란 거대분자를 합성하였다 Hyperbranched polymer의 영세대 화합물의 합성은 $HSiMe_{3-n}$$(CH_2CH=CH_2)_n$(n=2; $AB_2$,3;$AB_3$형)의 수소화규소첨가반응 방법을 이용하여 합성하였다. Hyperbranched polymer $AB_2$와 $AB_3$형 고분자 화합물은 수소화규소첨가반응과 알켄첨가반응에 의해 Gn+1형 나뭇가지꼴 거대분자로 성장하였다. Gn+2P세대 화합물은 $HSiMeCl_2$와의 수소화규소첨가반응 방법에 의해 모든 가지가 동일형 화합물을 형성하지 못했다. Gn과 Gn+1형 고분자 화합물은 9-BBN과의 반응과 반응생성물의 산화반응에 의해서 polysilol을 형성하였다. 반응의 정도는 NMR에 의해서 확인할 수 있었다.

• 대한화장품학회지
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• 제33권1호
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• pp.7-10
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• 2007

수용성 폴리머와 계면활성제의 상호작용을 레올로지와 표면 장력을 측정하여 연구하였다. 본 연구에 사용된 폴리머는 acrylates/$C_{10-30}$ alkyl acrylate crosspolymer (AC), ammonium acryloyldimethyltaurate/VP copolymer (AV)이다. 계면활성제는 PEG-40 hydrogenated castor oil (HC), polysorbate 60 (P60)이다. HC와 P60은 AC 폴리머 주위에서 마이셀을 형성하여 점도를 증가하였다. 그러나, HC는 P60보다 보다 높은 농도 범위에서 점도 증가 거동을 보였다. 같은 농도 범위에서 계면활성제들의 표면장력을 비교해보면, 표면장력이 AC/HC의 농도 증가에 따라 증가한 반면, AC/P60의 농도증가에 대해서는 거의 증가하지 않았다. 이런 결과는 AC/HC 사이의 마이셀이 강하게 조직화된 구조를 형성하기 때문으로 추정된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.145.1-145.1
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• 2013

A prerequisite for the development of graphene-based field effect transistors (FETs) is reliable control of the type and concentration of carriers in graphene. These parameters can be manipulated via the deposition of atoms, molecules, and polymers onto graphene as a result of charge transfer that takes place between the graphene and adsorbates. In this work, we demonstrate a unique and facile methodology for the homogenous and stable p-type doping of graphene by hybridization with ZnO thin films fabricated by MeV electron beam irradiation (MEBI) under ambient conditions. The formation of the ZnO/graphene hybrid nanostructure was attributed to MEBI-stimulated dissociation of zinc acetate dihydrate and a subsequent oxidation process. A ZnO thin film with an ultra-flat surface and uniform thickness was formed on graphene. We found that homogeneous and stable p-type doping was achieved by charge transfer from the graphene to the ZnO film.