• Macromolecular Research
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• 제12권4호
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• pp.325-335
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• 2004

Molecular weight distributions of poly(vinyl neo-decanoate) produced by the bulk polymerization of the monomer to low conversions were investigated to obtain values of the rate constants for the chain transfer to monomer ( $C_{M}$). The value of $C_{M}$ of 7.5($\pm$0.6)${\times}$10$^{-4}$ was obtained from a logarithmic plot of the number distribution at 5,25, and 5$0^{\circ}C$, which suggests that the activation energy for chain transfer is on the order of 20-25 kJ ㏖$^{-1}$ . These plots were linear between the number and weight-average degrees of polymerization, but not over the whole molecular weight range for which a significant signal was observed in the gel permeation chromatography (GPC) trace. Modeling suggests that the deviations observed at high molecular weights can be explained by branching of the chains through chain transfer to the polymer, with a branching density as low as 10$^{-5}$ , without affecting the slope at low values of the number of monomer unit, N. This deviation from the expected distribution of linear chains was used to estimate the branching densities at low conversion.ion.

• Journal of the Korean Physical Society
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• 제73권12호
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• pp.1808-1813
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• 2018

I develop a transfer matrix algorithm for computing the geometric quantities of a square lattice polymer with nearest-neighbor interactions. The radius of gyration, the end-to-end distance, and the monomer-to-end distance were computed as functions of the temperature. The computation time scales as ${\lesssim}1.8^N$ with a chain length N, in contrast to the explicit enumeration where the scaling is ${\sim}2.7^N$. Various techniques for reducing memory requirements are implemented.

• 폴리머
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• 제36권3호
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• pp.351-356
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• 2012

디스플레이 전자 장치의 제작에 사용되는 대표적인 유기물첨가제는 아크릴 바인더이다. 이 아크릴 바인더는 라디칼 중합으로 제조되는데 본 연구에서는 glycidyl methacrylate(GMA), methyl methacrylate(MMA), methacrylic acid(MAA)를 이용하여 공중합을 시도하였다. 그리고 이 공중합체의 접착력 향상을 위해서 실란계 mercaptane 화합물을 사슬 이동제(CTA)로 사용하였다. 본 연구에서 사용된 CTA는 (3-mercaptopropyl) trimethoxysilane(MPTMS)이며, 제조된 공중합체들의 분자량, 코팅의 두께, 투과도, 접착력 등의 물성 등을 살펴보았다. 사용된 MPTMS 함량에 따라 분자량이 조절되었고, MPTMS의 함량이 증가할수록 접착력이 향상되었다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.322-322
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• 2006

Well-defined poly(N-vinylcarbazole), poly(NVC), was synthesized by macromolecular design via interchange of the xanthate (MADIX)/reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of a suitable xanthate-type chain transfer agent (CTA). Good control of the polymerization was confirmed by the linear first-order kinetic plot, the molecular weight controlled by the monomer/CTA molar ratio, linear increase in the molecular weight with the conversion, and the ability to extend the chains by the second addition of the monomer. Star polymers having various architectures were also synthesized using this technique.

• 폴리머
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• 제36권3호
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• pp.262-267
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• 2012

할로겐화알킬($PhCH_2Br$, $PhCH_2Cl$, MeI)과 설폰산에스테르(MeOTf)를 개시제로 사용하여 $100^{\circ}C$, 24시간의 반응조건으로 2-(1,3,3-trimethyl-6-azabicyclo[3,2,1]-oct-6-yl)-4,5-dihydro-1,3-oxazoline(TAO)의 중합을 실시, 개시제에 의한 폴리머구조의 영향을 관찰한 결과, 양쪽 개시제 모두 거의 동일한 연쇄이동에서 나타나는 경향과 비슷한 결과를 얻었다. 그러나 개시제에 의한 폴리머의 구조는 설폰산에스테르계 개시제에서는 거의 100% pendant type 폴리머가 생성되는 반면, 할로겐화알킬계 개시제를 사용한 TAO중합은 pendant type 단위와 main chain type의 단위가 소량 생성됨이 확인되어 이것은 구핵성이 높은 할로겐 음이온에 의한 이중이성화중합이 부분적으로 진행되었음을 확인하였으며, 개시제로 Merrifield수지를 사용한 TAO와의 공중합에서는 다량의 단일중합체가 부생되는 그래프트 공중합체가 생성되었다.

• Bulletin of the Korean Chemical Society
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• 제16권10호
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• pp.972-976
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• 1995

A trace amount of 4-biphenylcarboxylate having a pre-twisted biphenyl moiety was attached to a poly(methyl methacrylate) side chain and the fluorescence properties of the chromophore were investigated in various solvents such as ethyl acetate and butyl chloride. At room temperature, the polymer exhibited a distinct red shift of the short wavelength emission (325 nm) and an enhanced emission intensity around 430 nm upon excitation at the absorption red edge. The temperature dependence of the intensity ratio (R) of the 325 nm emission to the 430 nm emission was observed when exciting at the red edge over the temperature range between -20 and 60 ℃. However, the temperature dependence was not observed when exciting at the shorter wavelength. The Arrhenius plot of the R value shows the activation energy of 6.0 kJ/mol which is in good agreement with the energy required for the twist of the biphenyl moiety. Together with the results of red edge excitation effects it was concluded that the pre-twisted geometry of the biphenyl moiety is preserved by the restriction of the polymer chain to facilitate the formation of the twisted intramolecular charge transfer (TICT) state upon excitation.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.319-319
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• 2006

RAFT polymerization can produce under controlled conditions polymer chains incorporating well-defined chain ends. By designing a simple way of producing functional RAFT agents, a variety of ${\Box}-end$ groups was successfully introduced onto hydrophilic polymer chains. The ${\Box}-end$ group being a thiocarbonyl thio function was used as efficient chain transfer agent in dispersion or emulsion polymerization to produce original functional latex particles.

• 폴리머
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• 제32권4호
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• pp.385-389
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• 2008

반응온도의 안정화, 용매 hexafluoropropylene(HFP) 투입량, 그리고 단량체 hexafluoropropylene oxide(HFPO)의 투입속도와 같은 반응조건이 HFPO 음이온 중합의 사슬확장과 사슬이동에 미치는 영향에 대해 연구하였다. Cesium fluoride(CsF)와 tetraethyleneglycol dimethylether(TG)를 사용하여 합성된 음이온 개시제를 이용한 HFPO의 음이온 중합반응에서, 안정적인 반응온도 $-35{\sim}-36^{\circ}C$, 개시제 투입량에 대한 HFP 투입 몰비 31.5, 그리고 HFPO 투입속도 11.57 g/hr의 반응조건으로부터 평균분자량 14800의 고분자량 poly(HFPO)를 얻을 수 있었다. 반면, 불안정한 반응온도, 최적화되지 않은 용매의 투입량과 HFPO 투입속도는 중합물의 사슬이동을 증가시켜 중합체가 원활하게 성장하지 못하였다. 결론적으로, HFPO 음이온 중합반응에서의 사슬확장과 사슬이동은 반응온도의 안정화, 용매의 투입량과 단량체의 투입속도에 매우 민감하게 영향을 받고 있음을 알 수 있었다.

• Macromolecular Research
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• 제17권5호
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• pp.319-324
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• 2009

A new $\pi$-conjugated polymer, poly[(2-methoxy-(5-(2-(4-oxyphenyl)-5-phenyl-1,3,4-oxadiazole)-hexyloxy))-1,4-pheny1ene-1,2-etheny1ene-alt-(10-hexyl-3,7-phenothiazine )-1,2-ethenylene] (PTOXDPPV), was synthesized by the Heck coupling reaction. The electron transporting unit, conjugated 1,3,4-oxadiazo1e (OXD), is attached on the main chain via linear 1,6-hexamethylenedioxy chain. The band gap and photoluminescence (PL) maximum of PTOXDPPV are 2.35 eV and 565 nm, respectively. These values are very close to those of po1y[(2,5-didecyloxy-1,4-phenylene-1,2-etheny1ene )-alt-(l0-hexyl-3,7-phenothiazine)-1,2-ethenylene] (PTPPV), which does not have OXD pendant. The estimated HOMO energy level of PTOXDPPV was -4.98 eV, which is very close to that of PTPPV (-4.91 eV). The maximum wavelength of EL device based on PTOXDPPV and PTPPV appeared at 587 and 577 nm, respectively. In the PL and EL spectrum, the emission from OXD pendant was not observed. This indicates that the energy transfer from OXD pendants to main chain is occurred completely. The EL device based on PTOXD-PPV (ITO/PEDOT/PTOXDPPV/AI) has an efficiency of 0.033 cd/A, which is significantly higher than the device based on PTPPV (ITO/PEDOT/PTPPV/AI) ($4.28{\times}10^{-3}\;cd/A$). From the results, we confirm that the OXD pendants in PTOXDPPV facilitate hole-electron recombination processes in the emissive layer effectively.

• Macromolecular Research
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• 제11권5호
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• pp.393-397
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• 2003

By applying a configurational-bias Gibbs ensemble Monte Carlo algorithm, priority simulation results regarding the conformation of non-dilute polyelectrolytes in solvents are obtained. Solutions of freely-jointed chains are considered, and a new method termed strandwise configurational-bias sampling is developed so as to effectively overcome a difficulty on the transfer of polymer chains. The structure factors of polyelectrolytes in the bulk as well as in the confined space are estimated with variations of the polymer charge density.