Role of carbon quantum dots and film thickness on enhanced UV shielding capability of flexible polymer film containing carbon quantum dots/N-doped ZnO nanoparticles

Uthirakumar, Periyayya,Devendiran, M.,Yun, Jin-Hyeon,Kim, Gyu Cheol,Kalaiarasan, S.,Lee, In-Hwan Elsevier 2018 Optical materials Vol.84 No.-

<P><B>Abstract</B></P> <P>We report a simple method for preparing flexible polymer film containing carbon quantum dots/N-doped ZnO (CQD/N-ZnO) nanoparticles, as UV shielding material. The polymer film showed an enhanced UV shielding capability with increasing of CQD/N-ZnO nanoparticles. The maximum of 47% of UV shielding capability was achieved with 1 wt.% of CQD/N-ZnO nanoparticles and two-order enhancement was achieved by controlling film thickness to 250 μm. It was found that CQDs plays important role to promote compatibility of hydrophilic ZnO into hydrophobic polymer matrix without disturbing the transparency of the film. An excellent UV shielding capability of 85% and 92% was witnessed in 250 μm thick polymer film under a UV lamp and direct daylight, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Free-standing and flexible polymer films were prepared with CQD/N-ZnO nanoparticles. </LI> <LI> Owing to the surface modification by the CQDs, CQD/N-ZnO nanoparticles were able to disperse readily in the polymer matrix. </LI> <LI> High transparency polymer films were obtained due to better dispersion of CQD/N-ZnO nanoparticles. </LI> <LI> The CQDs assist to improve the dispersion N-ZnO in polymer matrix. </LI> <LI> An excellent UV-shielding property, irrespective to different light sources. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A free-standing and flexible polymer film containing CQD/N-ZnO nanoparticles can be explored as potential candidate as UV light filter. The maximum of ∼92% of UV light was shielded by the 250 μm thick polymer film containing just 1.0% of CQD/N-ZnO nanocomposites, under the direct daylight and the results are consistent with UV lamp source.</P> <P>[DISPLAY OMISSION]</P>

열 나노임프린트 리소그래피 공정 소재용 스탬프와 폴리머 필름 사이의 점착력 측정

김광섭(Kwang-Seop Kim),강지훈(Ji-Hoon Kang),김경웅(Kyung-Woong Kim) 한국트라이볼로지학회 2006 한국트라이볼로지학회 학술대회 Vol.2006 No.6

Nanoimprint lithography (NIL) is one of the most promising nanofabrication technologies to fabricate integrated nano-size patterns due to its high-throughput and large processing latitude at low cost. However, adhesion between a stamp and a polymer film occurs inevitably in NIL because a stamp physically contacts with a polymer film. In order to reduce the adhesion, an anti-sticking film is usually used. In this paper, the adhesion characteristics between stamp coated with an anti-sticking film and a thermoplastic polymer film used in thermal NIL are investigated experimentally. The anti-sticking films are derived from fluoroalkylsilanes ((1H, 1H, 2H, 2H perfluorooctyl)trichlorosilane(F₁₃OTS), (3,3,3-trifluoropropyl)trichlorosilane(FPTS)) and coated on a fused silica stamp in vapor phase. The adhesion force between the stamp and the polymer film is measured and the surfaces of stamp and polymer film after separation are observed. The anti-sticking films remarkably reduce adhesion force by one fifth and damages of polymer film surface. It is also found that the anti-sticking film derived from FPTS which has shorter chain length than F₁₃OTS is less effective to reduce adhesion force than that derived from F₁₃OTS, but both of them do not make any damages on the surface of polymer films.

폴리머-탄소나노튜브 복합체 에어로졸 입자의 생성 및 이를 이용한 하이브리드 복합체 박막 제조

김휘동,안지영,김수형 한국입자에어로졸학회 2010 Particle and Aerosol Research Vol.6 No.2

In this paper, we describe a new method to form polymer thin films, in which carbon nanotubes (CNTs) are homogeneously distributed so that they can strengthen the mechanical property of resulting polymer film. To do so, we first homogeneously mixed CNTs with polymer in a DMF solvent. With the assistance of ultrasonic nebulizer, the polymer/CNT solution was then aerosolized into micro-sized droplets and finally turned into solidified polymer/CNT composite particles by gas-phase drying process. As the results of SEM and TEM analysis, CNTs were found to be homogeneously immobilized in the polymer matrix particles due to rapid drying process in the gas phase. For comparison purpose,(i) the polymer/CNTs composite particles prepared by aerosol processing method and (ii) polymer/CNTs sheets prepared by simple solution-evaporation method were employed to form polymer/CNTs composite thin films using a hot press. As the result, the aerosol processing of composite particles was found to be a much more effective method to form homogeneously distributed-CNTs in the polymer matrix thin film.

시멘트의 초기수화에서 폴리머의 영향

박필환,송명신,이경희,Park, Phil-Hwan,Song, Myong-Sin,Lee, Kyoung-Hee 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.11

The properties of the polymer-modified mortars are influenced by the polymer film, cement hydrates and the combined structure between the organic and inorganic phases. Also, this quality of polymer modified cement strongly depend on weather condition and polymer cement ratio. To overcome this problem, polymer-modified cement were prepared by varying polymer/cement mass ratio (P/C) with $0{\sim}20%$ and constant water/cement mass ratio of 0.5. The effect of polymer on the hydration of this polymer cement is studied on different polymer cement ratio. The results showed that the polymer cement paste have increased the viscosity in addition the amount of polymer dosage and the polymers is completed resulting in a reduced degree of hydration caused by different ion elution amount. Also we know that the reactants is calcium acetate as a results of chemical reaction between acetate group in EVA which is hydrolysis in water and $Ca^{2+}$ ion during hydration of cement.

Translated structural morphology of conductive polymer nanofilms synthesized by vapor phase polymerization

Ali, Mohammad Amdad,Wu, Kuang-Hsu,McEwan, Jake,Lee, Jaegab Elsevier 2018 Synthetic metals Vol.244 No.-

<P><B>Abstract</B></P> <P>Vapor phase polymerization (VPP) is at the forefront for synthesizing highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT). However, little attention has been directed towards the factors affecting chain growth in solid-state polymerization. In this study, we revealed the VPP growth mechanism of a PEDOT film and thus provided a link to the structure-property relationship. Our results show that the monomers are activated on the oxidant layer and the chain growth is guided by the substrate morphology <I>via</I> diffusion into the oxidant layer, producing a thin PEDOT-stuffed layer. Further film growth proceeds through diffusion of the monomer into the oxidant layer following the structural texture of the oxidant film. This reaction-diffusion process generates a propagating PEDOT-stuffed/oxidant interface (with a constant velocity), thus leading to the film growth. As a result, the film grows linearly with EDOT evaporation time and the structural texture of the oxidant film was translated to the PEDOT film, thus determining the critical properties, such as the morphology, conductivity, and transparency of the film.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Evidence-based growth mechanism of a PEDOT nanofilm in vapor phase polymerization (VPP) was demonstrated. </LI> <LI> EDOT monomer diffuses into the spin-coated oxidant film, which serves as a scaffold guiding the polymerization. </LI> <LI> The structural texture of the oxidant film was translated to the PEDOT film. </LI> <LI> These findings will help us to control the film quality and process efficiency, especially for conductive polymer coating onto a nanostructure. </LI> </UL> </P>

Film-trigger applicator (FTA) for improved skin penetration of microneedle using punching force of carboxymethyl cellulose film acting as a microneedle applicator

김유성,Hye Su Min,Jiwoo Shin,남지혜,Geonwoo Kang,Jeeho Sim,양휘석,정형일 한국생체재료학회 2022 생체재료학회지 Vol.26 No.4

Background: Dissolving microneedle (DMN) is a transdermal drug delivery system that creates pore in the skin and directly deliver drug through the pore channel. DMN is considered as one of the promising system alternatives to injection because it is minimally invasive and free from needle-related issues. However, traditional DMN patch system has limitations of incomplete insertion and need of complex external devices. Here, we designed film-trigger applicator (FTA) system that successfully delivered DMN inside the skin layers using fracture energy of carboxymethyl cellulose (CMC) film via micropillars. We highlighted advantages of FTA system in DMN delivery compared with DMN patch, including that the film itself can act as DMN applicator. Methods: FTA system consists of DMNs fabricated on the CMC film, DMN array holder having holes aligned to DMN array, and micropillars prepared using general purpose polystyrene. We analyzed punching force on the film by micropillars until the film puncture point at different CMC film concentrations and micropillar diameters. We also compared drug delivery efficiency using rhodamine B fluorescence diffusion and skin penetration using optical coherence tomography (OCT) of FTA with those of conventional DMN patch. In vivo experiments were conducted to evaluate DMN delivery efficiency using C57BL/6 mice and insulin as a model drug. Results: FTA system showed enhanced delivery efficiency compared with that of the existing DMN patch system. We concluded CMC film as a successful DMN applicator as it showed enhanced DMN penetration in OCT and rhodamine B diffusion studies. Further, we applied FTA on shaved mouse dorsal skin and observed successful skin penetration. The FTA group showed higher level of plasma insulin in vivo than that of the DMN patch group. Conclusions: FTA system consisting of simple polymer film and micropillars showed enhanced DMN delivery than that of the existing DMN patch system. Because FTA works with simple finger force without sticky patch and external devices, FTA is a novel and promising platform to overcome the limitations of conventional microneedle patch delivery system; we suggest FTA as a next generation applicator for microneedle application in the future.

고분자압출필름의 연신에 관한 연구

최만성(Choi, Man-Sung) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.2

다량의 무기물이 첨가된 고분자제품을 초박막의 두께로 고속생산 할 경우 가장 중요한 요소는 적절한 원재 료의 선정도 중요하지만 대개의 경우 한정된 범위의 수지를 사용할 수밖에 없기 때문에, 가장 중요한 요소는 압출기 내에서 흘러나온 용융수지의 흐름을 균일하게 유지할 수 있도록 고분자의 용융 유동에 적합한 최적의 다이스 설계와 압출기의 공정 파라미터의 제어를 통해 균일한 두께 유지와 연신이 필요하다. 이와 관련하여 고분자 압출필름의 적절 한 연신을 위하여 압출조건이 연신에 미치는 영향에 대한 연구가 필요하지만 관련된 연구는 아직 충분히 이루어지지 않고 있다. 따라서 본 연구는 통기성 필름의 압출필름에 주로 사용되는 LLDPE(Linear Low Density Polyethylene)에 대하여 압출기의 실린더 온도, 압출속도, 압출기의 다이스온도, 냉각롤의 온도, 연신비, 그리고 연신롤 온도 등의 압출 조건의 변화가 압출필름의 연신에 미치는 영향에 대하여 압출실험을 통하여 연구하였다. 연구결과에서 연신비가 2.0:1 일 때 고분자압출필름의 연신에 가장 큰 영향을 미침을 알 수 있었다. Optimization of process parameters in polymer extrusion is an important task to reduce manufacturing cost. To determine the optimum values of the process parameters, it is essential to find their influence on the elongation of polymer breathable thin film. The significance of six important process parameters namely, extruder cylinder temperature, extruder speed, extruder dies temperature, cooling roll temperature, stretching ratio, stretching roll temperature on breathable film elongation of polymer extrusion was determined. Moreover, this paper presents the application of Taguchi method and analysis of variance(ANOVA) for maximization of the breathable film elongation influenced by extrusion parameters. The optimum parameter combination of extrusion process was obtained by using the analysis of signal-to-noise ratio. The conclusion revealed that stretching ratio were the most influential factor on the film elongation. The best results of film elongation were obtained at lower stretching ratio.

Liquid Crystal Alignment Behavior and OTFT Performance of Poly(3-hexylthiophene) Blends with Comb-Like Poly(oxyethylene)

배진우,송기국,손은호,강효,이종찬 한국고분자학회 2015 Macromolecular Research Vol.23 No.5

Alignment characteristics of nematic liquid crystal (LC) on the surface of conjugated semi-conducting polymer blends with a comb-like polymer were studied. Conoscopic polarized optical microscope images show vertical alignment of LC on the blend films regardless of blend ratio. The LC alignment behavior on the blended film surface can be explained by a preponderance of comb-like polymers at the film surface. The mobility values of organic thin film transistors (OTFT) prepared with the blend film as an active layer are found to be similar to those with a pure conjugated semi-conducting polymer film. This result suggests a novel route for effectively reducing the amount of active semi-conducting polymer without significant deterioration of charge carrier mobility in an OTFT device. Since the LC alignment can be controlled on the surface of channel layer of OTFT by employing the polymer blend as the semi-conducting layer, the LC alignment and OTFT performance with the blend composition can be investigated simultaneously.

Measurement of Viscosity of Confined Polymer Melt Using Capillary Kinetics

Suh, Kahp Y.,Kim, Pilnam,Jeong, Hoon Eui,Kim, Jae Kwan Taylor Francis 2006 Nanoscale and microscale thermophysical engineerin Vol.10 No.3

<P> We present a simple method to measure viscosity of thin polymer melt that is confined between a substrate and a permeable plate using a modified Poiseuille equation. When a patterned polydimethylsiloxane (PDMS) mold is placed on a styrene-butadiene-styrene (SBS) block copolymer film spin-coated onto a substrate and heated above the polymer's glass transition temperature, capillarity forces the polymer melt into the void of the channel. To calculate the viscosity of the confined polymer melt, the height of capillary rise was measured as a function of time for a number of film thicknesses (220, 350, 540, 1000, and 1300 nm) and at two different temperatures (70 and 100°C). It was found that the viscosity increases with decreasing film thickness at 70°C, whereas it decreases with decreasing film thickness at 100°C. This discrepancy might be related to the confinement-induced solid-like behavior of the polymer melt and wall slip at the polymer/solid interface. Furthermore, the viscosity turned out to be nearly equal to the bulk value for relatively large film thickness (> ∼ 500 nm) regardless of the temperature, which corresponds to earlier findings.</P>

2,1,3-Benzothiadiazole-5,6-dicarboxylicimide-Based Polymer Semiconductors for Organic Thin-Film Transistors and Polymer Solar Cells

Yu, Jianwei,Ornelas, Joshua Loroñ,a,Tang, Yumin,Uddin, Mohammad Afsar,Guo, Han,Yu, Simiao,Wang, Yulun,Woo, Han Young,Zhang, Shiming,Xing, Guichuan,Guo, Xugang,Huang, Wei American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.48

<P>A series of polymer semiconductors incorporating 2,1,3-benzothiadiazole-5,6-dicarboxylicimide (BTZI) as strong electron-withdrawing unit and an alkoxy-functionalized head-to-head linkage containing bithiophene or bithiazole as highly electron-rich co-unit are designed and synthesized. Because of the strong intramolecular charge transfer characteristics, all three polymers BTZI-TRTOR (P1), BTZI-BTOR (P2), and BTZI-BTzOR (P3) exhibit narrow bandgaps of 1.13, 1.05, and 0.92 eV, respectively, resulting in a very broad absorption ranging from 350 to 1400 nm. The highly electron-deficient 2,1,3-benzothiadiazole-5,6-dicarboxylicimide and alkoxy-functionalized bithiophene (or thiazole) lead to polymers with low-lying lowest unoccupied molecular orbitals (-3.96 to -4.28 eV) and high-lying highest occupied molecular orbitals (-5.01 to -5.20 eV). Hence, P1 and P3 show substantial and balanced ambipolar transport with electron mobilities/hole mobilities of up to 0.86/0.51 and 0.95/0.50 cm(2) V-1 s(-1), respectively, and polymer P2 containing the strongest donor unit exhibited unipolar p-type performance with an average hole mobility of 0.40 cm(2) V-1 s(-1) in top-gate/bottom-contact thin-film transistors with gold as the source and drain electrodes. When incorporated into bulk heterojunction polymer solar cells, the narrow bandgap (1.13 eV) polymer P1 shows an encouraging power conversion efficiency of 4.15% with a relatively large open-circuit voltage of 0.69 V, which corresponds to a remarkably small energy loss of 0.44 eV. The power conversion efficiency of P1 is among the highest reported to date with such a small energy loss in polymer:fullerene solar cells.</P>