• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.223.2-223.2
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• 2015

Polyurethane acrylate (PUA) has been introduced to utilize as a mold material for sub-100 nm lithography as it provides advantages of stiffness for nanostructure formation, short curing time, flexibility for large area replication and transparency for relevant biomedical applications. Due to the ability to fabricate nanostructures on PUA, there have been many efforts to mimic extracellular matrix (ECM) using PUA especially in a field of tissue engineering. It has been demonstrated that PUA is useful for investigating the nanoscale-topographical effects on cell behavior in vitro such as cell attachment, spreading on a substrate, proliferation, and stem cell fate with various types of nanostructures. In this study, we have conducted surface modification of PUA films with micro/nanostructures on their surfaces using plasma treatment. In general, it is widely known that the plasma treated surface increases cell attachment as well as adsorption of ECM materials such as fibronectin, collagen and gelatin. Effect of plasma treatment on PUA especially with surface of micro/nanostructures needs to be understood further for its biomedical applications. We have evaluated the modified PUA film as a culture platform using adipose derived stem cells. Then, the behavior of stem cells and the level of adsorbed protein have been analyzed.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1212-1215
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• 2004

Diffraction modes of holographic grating were fabricated with polyurethane acrylates(PUA). Two types of silica (AEROSIL 200 and AEROSIL R812) were added to reduce the shrinkage of polymer matrix. It was founded that shrinkage of PUA composite film was reduced with the addition of silica. HPDLC based PUA/silica composite also showed high diffraction efficiency. The morphology of the resultant gratings was analyzed by using scanning electron microscopy(SEM) and Tg of the polymer matrix by dynamic mechanical thermal analysis(DMTA).

• Korean Journal of Veterinary Research
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• v.63 no.2
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• pp.17.1-17.12
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• 2023

Antimicrobial (AM) resistance is a growing threat in human and veterinary medicine, spreading across species and perceived as One-Health issue. Prudent use of AM products is essential in mitigating this risk in both human and veterinary medicine. Farm veterinarians, responsible for prescribing appropriate AM and offering advice to farmers on their proper usage, are regarded as key players in the livestock industry. An online survey of farm veterinarians (n = 1,531) was conducted to assess their educational experience, beliefs, current status of prescription, practical behavior, and self-efficacy regarding the prudent use of antimicrobials (PUA). The data from 170 respondents were analyzed using descriptive statistics, regression and mediation analysis. Participants chose AM based on their experiences, academic resources, and peer veterinarians. Approximately 77% did not routinely conduct antibiotic-susceptibility-test. Most participants believed in the importance of PUA and the role of veterinarians to reduce AM resistance, but they reported a lack of awareness among farmers and insufficient national support interfere with their practical behavior with regard to PUA. Half of the participants had PUA-education, and 78.6% reported that education had a positive impact on their behavior with PUA. Self-efficacy partly mediates the relationship between belief and behavior for PUA, which accounted for 23.77% of the total effect that beliefs have on behavior for PUA. The findings of the study show that enhancing veterinarians' abilities to practice and their self-efficacy through education tailored to the current status of farms can contribute to the reduction of AMs in the livestock sector.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.1
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• pp.77-84
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• 2017

In this study, Poly-urethane acrylate (PUA) was synthesized by the reaction between Polycaprolactonetriol (PCLT) and Isophorone dissocyanate (IPDI) and hybridized with inorganic materials. Tetraethylortho silicate (TEOS) and nano clay (Closite 20A) were used as inorganic particles. For the hybridization of TEOS with PUA, sol-gel method is used, in which TEOS is made into spherical particle in the firsthand. In the case of Nano clay, hybridization is carried out through the dispersion as Nano clay has a layered structure. The solution of PUA hybrid was made into a film after UV curing and its thermo and electrical properties were measured. The experimental analysis and result demonstrate that the PUA hybrid shows an improved thermal properties and lower dielectric constant than that of the non-hybrid PUA. The trend of improved properties was different depending on structure of inorganic materials.

• Polymer(Korea)
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• v.38 no.6
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• pp.720-725
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• 2014

Aminopropyl terminated polydimethylsiloxane was synthesized by hydrosilylation reaction with hydride terminated polydimethlysiloxane and allyl amine. Polydimethylsiloxane modified urea with isocyanate group was prepared from cyclic trimer of hexamethyldiisocyanate with aminopropyl terminated polydimethylsiloxane. Polydimethylsiloxane modified urea/acrylate resin (PUA) was prepared from the urethane reaction of PU with isocyanate group and 2-hydroxyethylmethacrylate. PUA structure was analyzed by FTIR and NMR. Coating materials were prepared by mixing PUA, acrylic monomer, photo-initiator, and solvent and coated on PET film to obtain flexible hard coating film by UV irradiation.

• Elastomers and Composites
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• v.48 no.4
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• pp.249-255
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• 2013

Hydroxypropyl terminated PDMS was synthesized by the hydrosilylation reaction with allyl alcohol in the presence of Karstedt's catalyst. And them, an one-pot reaction with HDI isocyanurate trimer and hydroxyethyl methacrylate was conducted to give a silicone-modified urethane acrylate oligomer (PUA oligomer) having 9000 g/mol, weight average molecular weight. The synthesized PUA oligomer was characterized by using FT-IR and GPC. The UV-curable coatings were prepared by PUA oligomer blending with a reactive monomer (phenylthioethyl acrylate) under the different mole ratios. It was found that the refractive index of cured film increased when the reactive monomer was added but there was no relationship between the refractive index and amount of reactive monomer. Also, their transmittance for cured films was not change as increasing the content of reactive monomer.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.610-616
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• 2011

A series of polyurethane acrylate/ZnO (PUA/ZnO) nanocomposite films with different ZnO contents were successfully prepared via a UV-curing system. The synthesis and physical properties including morphological structure, thermal properties, barrier properties and optical properties, and antimicrobial properties were investigated as a function of ZnO concentration. FTIR and SEM results showed that these PUA/ZnO nanocomposite films did not have a strong interaction between PUA and ZnO, which may lead to no increase in thermal stability. By incorporating ZnO nanoparticles, the UV blocking and antibacterial properties increased as the content of ZnO increased. Specially, the oxygen permeability in composite films changed from $2005cc/m^2/day$ to $150cc/m^2/day$ by adding the ZnO nanoparticle, which indicates that the PUA/ZnO nanocomposite films can be applied as good barrier packaging materials. Physical properties of the UV-cured PUA/ZnO nanocomposite film are strongly dependent upon the dispersion state of ZnO nanoparticles and their morphology in the films.

• Polymer(Korea)
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• v.31 no.2
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• pp.111-116
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• 2007

Polyurethane modified acrylate $(PUA)/SiO_2$ hybrid films were prepared by ultraviolet curing and their surface properties were investigated by hardness and adhesion test. The films were examined by the manipulation of mole-ratio of organic to inorganic components. Under the silica content controlled, highly desirable films were achieved and scratch resistance and hardness property of film were also enhanced, which indicates that the crosslinked silica particles are homogeneously dispersed within PUA film.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.8-15
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• 2018

Films with special properties (e.g., water-repellent films, optical films, anti-reflection films, and flexible films) are referred to as functional films. Recently, there has been interest in fine patterning methods for film fabrication. In particular there have been many studies that use a UV nanoimprint process involving a UV curing method. In this paper, a polymer film was fabricated by the UV nanoimprint process with a micro-pattern, and its durability was evaluated by a wear test and a nano-indentation test. The film mechanical properties (such as coefficient of friction, hardness, and modulus of elasticity) were measured. Moreover, the choice of PUA type resin used in the UV nanoimprint process was confirmed to impact the durability of the thin film. Despite making the polymer film samples using the same method and PUA type resin, different coefficient of friction, hardness, and modulus of elasticity values were obtained. PUA 4 resin had the most favorable coefficient of friction, hardness, and modulus of elasticity. This material is predicted to produce a high durability functional film.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.24.2-24.2
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• 2010

고분자 몰드를 이용한 nanoimprint lithography (NIL)는 고분자소재의 유연성과 투명성으로 인하여, 유기전자소자나 유연한 디스플레이소자 등 다양한 응용이 가능하다. 하지만, 고분자소재는 일반적으로 열저항성과 내구성이 낮아서, 고분자 몰드를 이용한 패턴형성 시, 자외선 경화방식이 주로 사용된다. 만약 복제가 쉽고, 가격이 저렴하며, 열저항성과 내구성이 강한 고분자 몰드를 제작한다면, thermoplastic-NIL 기술에 적용할 수가 있기 때문에, 고온을 요구하는 소자의 패턴형성 공정에 사용 가능하다. 본 연구에서는 이러한 고분자 몰드 제작을 위하여, 열저항성과 내구성이 강한 polyimide 필름과 polyurethane acrylate (PUA)를 기반으로 제작된 resin을 이용하였다. 먼저 Polyimide 필름 위에 자외선 노광을 사용하여, PUA resin 을 경화시킴으로써 패턴을 형성하였다. 이렇게 만들어진 몰드를 thermoplastic-NIL기술에 적용함으로써, Si 기판 위에 sub-마이크로 급 패턴을 형성하였다. 또한, 제작된 고분자 몰드를 사용하여 반복적인 NIL 공정을 수행함으로써 몰드의 내구성을 확인하였으며, 곡면 기판 위에 NIL을 함으로써 몰드의 유연성을 확인 할 수 있었다.