• Bulletin of the Korean Chemical Society
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• 제18권1호
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• pp.38-43
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• 1997

Poly(ethylene 2, 6-naphthalate-co-tetramethylene 2, 6-naphthalate) (PEN/PBN) copolymers were synthesized and studied by 13C NMR spectroscopy, DSC analysis and X-ray diffraction. A minimum in the melting point vs. composition curve was found at approximately 60 mol% tetramethylene 2, 6-naphthalate. The PEN/PBN copolymers were shown to be statistically random throughout the range of 1, 4-butanediol compositions. The melting point depression behavior of annealed PEN/PBN copolymers depended upon the sequence propagation probability, PS, which is suggested by indivisual crystal formation of two pure comonomers; that is, ethylene-naphthalate-ethylene, EE, and tetramethylene-naphthalate-tetramethylene, BB. However, it can be seen from the X-ray curve that the peaks of PEN/PBN copolymers appear from a crystal lattice which is governed only by the rich component between two different aliphatic units in the copolymer composition.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.42-47
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• 2018

This work reports a facile and effective antibacterial coating for oxide substrates. As a coating material, a random copolymer, abbreviated as poly(TMSMA-r-PEGMA), was synthesized by radical polymerization of 3-(trimethoxysilyl)propyl methacrylate (TMSMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA). Polymeric self-assembled monolayers of poly(TMSMA-r-PEGMA) were formed on various inorganic oxide substrates, including silicon oxide, titanium dioxide, aluminum oxide, and glass, via the simple dip-coating process. The polymer-coated substrates were characterized by ellipsometry, contact angle measurements, and X-ray photoelectron spectroscopy. The bacterial adhesion on the polymer-coated substrates was completely suppressed compared to that on the uncoated substrates.

• 폴리머
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• 제24권5호
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• pp.638-645
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• 2000

디올 또는 다가 알콜의 존재 하에서 DL-락트산 및 L-락티드를 연속 중합하여 선형 (ABA 형)과 스타형 ((AB)$_{n}$ 형)의 폴리락트산 입체블록 공중합체를 합성하고 분석하였다. 알콜의 함량에 따라 블록 공중합체의 분자량을 어느 정도 범위에서 조절할 수 있었으며, 합성된 중합체는 비교적 좁은 분자량 분포를 나타내었다. 폴리락트산 입체블록 공중합체의 유리전이온도는 5$0^{\circ}C$ 부근이었으며, 융점은 구조와 분자량에 따라 100~14$0^{\circ}C$ 범위에서 관찰되었다. 용융 엔탈피로부터 얻은 결정화도의 측정 결과로부터 블록구조를 갖는 공중합체는 D-입체이성질체 단량체의 높은 조성(~35%)에서도 결정화가 충분히 일어남을 확인하였는데 이는 유사한 조성의 랜덤 공중합체의 성질과 대비된다. 선형과 스타형 블록 공중합체의 경우 모두 열처리 온도와 시간에 따른 결정화도의 변화를 관찰하였다.다.

• Fibers and Polymers
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• 제3권1호
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• pp.18-23
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• 2002

The structure development and dynamic properties of fibers produced by high-speed spinning of P(EN-ET) random copolymers were investigated. The as-spun fibers were found to remain amorphous up to the spinning speed of 1500 m/min, and subsequent increases in speed resulted in the crystalline domains containing primarily $\alpha$ crystalline modification of PEN. The f modification was not found up to spinning speeds of 4500 m/min. On the other hand, annealing of constrained fibers spun at the 2100 m/min at 180,200, and 240^{\circ}C$ exhibited $\beta$-form crystalline structure, while the annealed fibers spun in 600-1500 m/min range exhibited dominantly $\alpha$-form. However $\beta$-form crystals disappeared above the spinning speed of 3000 m/min. With increasing spinning speeds from 600 to 4500 m/min, the storage modulus of as-spun fibers increased continuously and reached a value of about 10.4 spa at room temperature. The tan $\delta$curves showed the $\alpha$-relaxation peak at about 155-165^{\circ}C$, which is considered to correspond to the glass transition. The $\alpha$-relaxation peaks became smaller and broader, and shift to higher temperatures as the spinning speed increases, meaning that molecular mobility in the amorphous region is restricted by increased crystalline domain.

• 한국응용과학기술학회지
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• 제21권2호
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• pp.132-139
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• 2004

Film forming behavior of monodispersed model composite latexes with particle size of 190 nm, which consist of n-butyl acrylate as a soft phase monomer and methyl methacrylate as a hard phase monomer with different morphology was examined. Five different types of model latexes were used in this study such as random copolymer particle, soft-core/hard-shell particle, hard-core/soft-shell particle, gradient type particle, and mixed type particle. The film forming behavior was evaluated using pseudo on-line measurements of the cumulative weight loss, the UV transmittance, and the tensile fracture energy. Each stages of film formation I, II were not sensitive to the morphology of model latexes, but stage-ill was largely dependent on the morphology of model latexes. The chain mobility of polymer which composed the shell component was found to dominantly determine the behavior of film forming stage-III.

• Macromolecular Research
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• 제11권2호
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• pp.80-86
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• 2003

The polymerization of a cyclopolymerizable disubstituted dipropargyl ether, his(3-trimethylsilyl-2-propynyl)ether (BTPE), was attempted by various transition metal catalysts. The yield for the polymerization of BTPE was generally low, which is possibly due to the steric hindrance of bulky substituents. In general, the catalytic activities of Mo-based catalysts were found to be greater than those of W-based catalysts. The highest yield was obtained when the MoCl$_{5}$,-EtAlCl$_2$(1:2) catalyst system was used. The copolymerization of BTPE and diethyl dipropargylmalonate yielded a random copolymer with conjugated polymer backbone. However the polymers were partially desilylated, depending on the reaction conditions. The thermal and morphological properties of the resulting polymers were also discussed.d.

• Composites Research
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• 제35권3호
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• pp.127-133
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• 2022

폴리프로필렌은 가교폴리에틸렌을 대체할 수 있는 차세대 고전압 전력케이블 절연체로써 큰 주목을 받고 있다. 하지만, 폴리프로필렌은 탄성률이 크고 충격에 취약하여 단독으로 절연체로 사용될 수 없고, 중합 단계에서 고무상이 혼재된 공중합체 형태로 주로 활용된다. 본 논문에서는 내충격성 폴리프로필렌, 폴리올레핀 탄성체, 그리고 프로필렌-에틸렌 랜덤공중합체의 용융 혼합을 통해 연성의 폴리프로필렌계 블렌드를 제조하였다. 폴리프로필렌 기재를 유지하면서도 다량의 탄성체 상들을 지니는 적정 비율의 3성분계 블렌드를 개발하였고, 탄성체 상들의 도입에 의해 폴리프로필렌의 탄성률을 감소시킬 수 있을 뿐만 아니라, 25도 및 -40도에서의 충격강도 및 연신율을 크게 증가시킬 수 있었다. 또한, 동적기계분석을 통해 가교폴리에틸렌이 기계적 물성을 손실하는 100도 이상의 온도에서도 3성분계 블렌드는 고체 형태를 유지할 수 있는 범위의 저장탄성률을 나타내었다. 뿐만 아니라, 3성분계 블렌드는 30 kV/mm의 직류 전압 인가 하에서 공간전하를 효과적으로 억제시키는데 유리한 것으로 나타났다.

• 대한화학회지
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• 제40권1호
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• pp.11-19
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• 1996

에너지기인 azido기($-CH_2N_3$), nitrato기($-CH_2ONO_2$)로 치환된 옥세탄의 단량체를 $BF_3$촉매하의 공중합에 관해서 반경험적인 MINDO/3, MNDO, AM1 그리고 HF/3-21G 방법 등을 사용하여 이론적으로 고찰하였다. 옥세탄 치환제와 $BF_3$ 이분자 착물의 입체적, 정전기적 구조를 이론적으로 설명할 수 있다. 옥세탄의 공중합 성장단계에서 반응성은 옥세탄의 반응중심 탄소의 양전하 크기와 옥세탄 성장단계의 친전자체의 낮은 LUMO에너지에 좌우됨이 예측된다. 옥세탄의 공중합 반응성비는 계산치와 실험값이 일치하는 랜덤 공중합 반응이다. 평형상태의 고리형 oxonium 이온과 열린 carbenium 이온의 농도 크기가 반응 메카니즘의 결정단계이며, 형태와 계산을 기초로하여 빠른 평형을 예상하여 볼 때 선폴리머 성장단계에서 $S_N1$ 메카니즘이 $S_N2$ 메카니즘보다 빠르게 반응할 것으로 예측된다.

• Korea-Australia Rheology Journal
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• 제21권4호
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• pp.203-211
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• 2009

In flows with deformation rates larger than the inverse Rouse time of the polymer chain, chains are stretched and their confining tubes become increasingly anisotropic. The pressures exerted by a polymer chain on the walls of an anisotropic confinement are anisotropic and limit chain stretch. In the Molecular Stress Function (MSF) model, chain stretch is balanced by an interchain pressure term, which is inverse proportional to the $3^{rd}$ power of the tube diameter and is characterized by a tube diameter relaxation time. We show that the tube diameter relaxation time is equal to 3 times the Rouse time in the limit of small chain stretch. At larger deformations, we argue that chain stretch is balanced by two restoring tensions with weights of 1/3 in the longitudinal direction of the tube (due to a linear spring force) and 2/3 in the lateral direction (due to the nonlinear interchain pressure), both of which are characterized by the Rouse time. This approach is shown to be in quantitative agreement with transient and steady-state elongational viscosity data of two monodisperse polystyrene melts without using any nonlinear parameter, i.e. solely based on the linear-viscoelastic characterization of the melts. The same approach is extended to model experimental data of four styrene-butadiene random copolymer melts in shear flow. Thus for monodisperse linear polymer melts, for the first time a constitutive equation is presented which allows quantitative modeling of nonlinear extension and shear rheology on the basis of linear-viscoelastic data alone.

• 폴리머
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• 제24권1호
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• pp.58-64
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• 2000

폴리부틸렌테레프탈레이트 (poly(butylene terephthalate), PBT)와 파라아세톡시벤조산 (p-acetoxybenzoic acid, ABA)의 조성비를 4/6, 5/5, 6/4로 하고, 온도를 각각 250, 260, 27$0^{\circ}C$로 하여 용융 에스테르 교환반응시킴으로써 poly(butylene terephthalate-co-oxybenzoate) (PBOT)를 합성하였다. 이에 대한 양성자 핵자기 공명 분광($^1$H FT-NMR) 분석을 통해서 분자내 서열 분석을 해본 결과 연속된 oxybenzoate 단위의 수는 1.2에서 1.5사이의 값을 가졌다. 이 값은 같은 조성비 및 같은 반응온도에서 합성된 폴리에틸렌테레프탈레이트(poly(ethylene terephthalate), PET)/ABA (PEOT)쌍에 비해 상대적으로 큰 값임을 알 수 있었다. 이와 같은 블록길 이상의 차이는 열분해 거동에 영향을 미치며 그 결과 폴리옥시벤조에이트(POB), PBT 및 PEOT가 1단계의 열분해를 하는 반면 PBOT는 2단계의 열분해 거동을 나타내었다. 또한 PBOT는 PBT-rich 상, PBT와 ABA의 랜덤분포 상 및 ABA-rich 상의 3상 구조를 가지는 것으로 추측되었다.