Separation of branched polystyrene by comprehensive two-dimensional liquid chromatography

Im, Kyuhyun,Kim, Youngtak,Chang, Taihyun,Lee, Kwanyoung,Choi, Namsun Elsevier 2006 Journal of chromatography A Vol.1103 No.2

<P><B>Abstract</B></P><P>Branched polystyrenes (PS) featuring a bivariate distribution in the molecular weight and in the number of branches were characterized by comprehensive two-dimensional liquid chromatography (2D-LC). The branched PS were prepared by anionic polymerization using <I>n</I>-butyl Li as an initiator and a subsequent linking reaction with <I>p</I>-(chlorodimethylsilyl)styrene (CDMSS). The <I>n</I>-butyl Li initiator yields polystyryl anions with broad molecular weight distribution (MWD) and the linking reaction with CDMSS yields branched PS with different number of branches. For the first dimension (1st-D) separation, reversed-phase temperature gradient interaction chromatography (RP-TGIC) was employed to separate the branched polymer according to mainly the molecular weight. In the second dimension (2nd-D) separation, the effluents from the RP-TGIC separation are subjected to liquid chromatography at chromatographic critical conditions (LCCC), in which the separation was carried out at the critical condition of linear homo-PS to separate the branched PS in terms of the number of branches. The 2D-LC resolution of RP-TGIC×LCCC combination worked better than the common LCCC×size-exclusion chromatography (SEC) configuration due to the higher resolution of RP-TGIC in molecular weight than SEC. Furthermore, by virtue of using the same eluent in RP-TGIC and LCCC (only the column temperature is different), RP-TGIC×LCCC separation is free from possible ‘break through’ and large system peak problems. This type of 2D-LC separation could be utilized efficiently for the analysis of branched polymers with branching units distinguishable by LC separation.</P>

Preparation of well-defined acid-cleavable branched polymers composed of methacrylates and acrylates

손해성,김동균,이예리,차상호,이종찬 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1

Acid-cleavable branched polymers composed of a methacrylate and two acrylates were preparedthrough reversible addition-fragmentation chain transfer (RAFT) polymerization. The molecular weightof primary chains and the degree of branching of the polymers were controlled by the feed ratio ofmonomer/chain transfer agent (CTA) and brancher/CTA, respectively. Glass transition temperatures ofthe polymers increased as the degree of branching grew due to an increase in molecular weight. Whenthe branched polymers were hydrolyzed, molecular weight and polydispersity index value were similarto those of linear polymer prepared by RAFT polymerization with the samemolar feed ratio of monomer/CTA.

Preparation of well-defined acid-cleavable branched polymers composed of methacrylates and acrylates

Sohn, Hae-Sung,Kim, Dong-Gyun,Lee, Aeri,Cha, Sang-Ho,Lee, Jong-Chan Elsevier 2015 Journal of industrial and engineering chemistry Vol.21 No.-

<P><B>Abstract</B></P> <P>Acid-cleavable branched polymers composed of a methacrylate and two acrylates were prepared through reversible addition-fragmentation chain transfer (RAFT) polymerization. The molecular weight of primary chains and the degree of branching of the polymers were controlled by the feed ratio of monomer/chain transfer agent (CTA) and brancher/CTA, respectively. Glass transition temperatures of the polymers increased as the degree of branching grew due to an increase in molecular weight. When the branched polymers were hydrolyzed, molecular weight and polydispersity index value were similar to those of linear polymer prepared by RAFT polymerization with the same molar feed ratio of monomer/CTA.</P>

Scalable synthesis of an architectural library of well‐defined poly(acrylic acid) derivatives: Role of structure on dispersant performance

Lunn, David J.,Seo, Sungbaek,Lee, Sang‐,Ho,Zerdan, Raghida Bou,Mattson, Kaila M.,Treat, Nicolas J.,McGrath, Alaina J.,Gutekunst, Will R.,Lawrence, Jimmy,Abdilla, Allison,Anastasaki, Athina,Knigh John WileySons, Inc. 2019 Journal of polymer science Part A, Polymer chemist Vol.57 No.6

<P><B>ABSTRACT</B></P><P>The synthesis and systematic comparison of a comprehensive library of well‐defined polymer architectures based on poly(acrylic acid) is reported. Through the development of new synthetic methodologies, linear, single branched, precision‐branched comb, and star polymers were prepared and their performance as dispersants was evaluated. The ability to accurately control chain lengths and branch points allows the subtle interplay between structure and dispersant performance to be defined and affords critical insights into the design of improved polymeric additives for coating formulations. The general industrial relevance of ionic polymers and branched macromolecular architectures supports these design rules for a wide range of other applications and materials, including as additives for personal care products and in water treatment. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. <B>2019</B>, <I>57</I>, 716–725</P>

용융중합에 의한 분지형 폴리카보네이트의 유변학적 특성 연구

최수정(Su Jung Choi),윤경화(Kyung Hwa Yoon),김희승(Hee Seung Kim),유승윤(Seung Yoon Yoo),김연철(Youn Cheol Kim) 한국고분자학회 2011 폴리머 Vol.35 No.4

폴리카보네이트(polycarbonate, PC)에 화학적 구조가 다른 두 가지의 분지제를 첨가하여 용융중합으로 분지형 폴리카보네이트(branched PC, B-PC)를 합성하였다. 분지제의 함량은 0.001∼0.005 mol% 내에서 조절하였다. 합성된 PC의 화학구조는 FTIR, 1H NMR과 13C NMR 스펙트럼을 이용하여 확인하였으며, 분자량, 유리전이온도 및 분해온도는 GPC, DSC와 TGA를 이용하여 측정하였다. Phloro type의 분지제를 가지는 B-PC의 분자량이 낮은 값을 보여주었으며, 유리전이온도는 분자량에 따라 증가하였다. 두 형태의 B-PC 모두 선형 PC와 비교하였을 때 낮은 주파수(frequency) 영역에서 복합점도(complex viscosity)가 높게 나타났고, shear thinning 현상이 크게 나타났다. Shear thinning의 정도를 표시하는 power law index(n)는 선형회귀분석에 의해 계산되었고 0.483∼0.996 범위의 값을 보여주었다. Phloro 타입의 B-PC가 높은 shear thinning 경향을 보였으며 이들 B-PC의 유변학적 특성은 동적유변측정기를 이용하여 측정하였다. The branched polycarbonates (B-PCs) with two different branching agents were synthesized from melt polymerization. The contents of branching agent were in the range of 0.001∼0.005 mol%. The chemical structure of the synthesized PC was determined by FTIR, 1H NMR, and 13C NMR, spectroscopy. The molecular weight, glass transition and degradation temperatures were determined by GPC, DSC, and TGA. The molecular weight of the phloro type B-PC had a lower value than the other one, and the glass transition temperature increased with molecular weight. Compared with linear PC, the rheological properties of the B-PC indicated an increase of complex viscosity in the low frequency region and shear thinning tendency. Power law index(n) representing shear thinning was calculated by linear regression and the values were in the range of 0.483~0.996. The rheological properties of the B-PCs were measured by a dynamic rheometer.

Dynamic crack branching and curving in brittle polymers

Lee, J.,Hong, J.W. Pergamon Press 2016 International journal of solids and structures Vol.100 No.-

<P>This paper presents peridynamics simulation on crack branching and curving in a pre-existing center notched brittle polymer. Fracturing patterns in brittle polymer under a biaxial tensile loading condition are compared with experimental observations for validation. Then, several numerical examples are conducted in order to investigate crack initiation and propagation of the pre-existing center notch under the effect of different loading ratios. Further to this, the crack development sequences of branching and curving are in detail discussed, and their underlying causes are identified through various perspectives including crack curving and branching angles, elastic strain energy, and branching damage patterns. The numerical results reasonably reflect the physical observations. This paper both complements the test results and provides insightful information for the prediction of crack branching and curving in brittle polymers. (C) 2016 Elsevier Ltd. All rights reserved.</P>

플러렌 변성 폴리스티렌의 물성에 관한 연구

이석,김환기,김건형,김정안,강호종 한국섬유공학회 2004 한국섬유공학회지 Vol.41 No.5

Star-shaped polystyrenes with the [60]fullerene core were synthesised via anionic polymerization. The solution, thermal, and UV absorbance properties were investigated as a function of number of branched polystyrene chains on the [60]fullerene core. The solution viscosity (intrinsic viscosity) of the [60]fullerene-modified polystyrene decreased with the number of branching due to molecular entanglement. The better coating property of the [60]fullerene-modified polystyrene compared with those of the polystyrene/[60]fullerene mixtures seems to arise from a lower aggregation state of the [60]fullerene core induced by the branched polystyrene chain. An increase in the glass transition temperature of the modified polystyrene with the number of branched chains was observed as well.

Bis(thienothiophenyl) Diketopyrrolopyrrole-Based Conjugated Polymers with Various Branched Alkyl Side Chains and Their Applications in Thin-Film Transistors and Polymer Solar Cells

Shin, Jicheol,Park, Gi Eun,Lee, Dae Hee,Um, Hyun Ah,Lee, Tae Wan,Cho, Min Ju,Choi, Dong Hoon American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.5

<P>New thienothiophene-flanked diketopyrrolopyrrole and thiophene-containing π-extended conjugated polymers with various branched alkyl side-chains were successfully synthesized. 2-Octyldodecyl, 2-decyltetradecyl, 2-tetradecylhexadecyl, 2-hexadecyloctadecyl, and 2-octadecyldocosyl groups were selected as the side-chain moieties and were anchored to the N-positions of the thienothiophene-flanked diketopyrrolopyrrole unit. All five polymers were found to be soluble owing to the bulkiness of the side chains. The thin-film transistor based on the 2-tetradecylhexadecyl-substituted polymer showed the highest hole mobility of 1.92 cm<SUP>2</SUP> V<SUP>–1</SUP> s<SUP>–1</SUP> due to it having the smallest π–π stacking distance between the polymer chains, which was determined by grazing incidence X-ray diffraction. Bulk heterojunction polymer solar cells incorporating [6,6]-phenyl-C71-butyric acid methyl ester as the n-type molecule and the additive 1,8-diiodooctane (1 vol %) were also constructed from the synthesized polymers without thermal annealing; the device containing the 2-octyldodecyl-substituted polymer exhibited the highest power conversion efficiency of 5.8%. Although all the polymers showed similar physical properties, their device performance was clearly influenced by the sizes of the branched alkyl side-chain groups.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-5/am508026s/production/images/medium/am-2014-08026s_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am508026s'>ACS Electronic Supporting Info</A></P>

Modeling of the polymerization of linear monomers in the presence of multifunctional units

Son, Sang Hwan,Han, Joong Jin,Lee, Jong Min Elsevier 2017 Polymer Vol.126 No.-

<P><B>Abstract</B></P> <P>A rigorous model is developed to predict the configurations of the branched polymers formed by the copolymerization of linear monomers in the presence of multifunctional branching units. Conventional studies on the configuration of branched polymers generally consider the statistical properties of the growth of only one element or polymerization from one component (e.g., dendrimers, hyperbranched, and hypergrafted polymers from AB<I>m</I> or ABC-type monomers). This study considers combinations of several types of linear and branched elements and the simultaneous aggregation of branched element-branched element and monomer-monomer elements. The proposed method is based on a new conceptual model that splits a multifunctional unit into a set of seeds with each functional group, assembling the branched elements after the independent propagation of each seed. Accordingly, the propagation steps of each element are described as dynamic balance equations in terms of the moments of the number chain length distribution. Analysis of the simulation of a batch sulfonated poly(aryl ether ketone) copolymerization process with trifunctional units is performed with the proposed model. The simulation results show that the proposed model reflects the characteristics of real copolymerization processes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A model of the polymerization of linear monomers in the presence of multifunctional units is proposed. </LI> <LI> A new conceptual model, that splits a multifunctional unit into seeds with each functional group, is introduced. </LI> <LI> The configurations of branched elements are derived from the configurations of stems and connectors. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Successive Synthesis of Well-Defined Star-Branched Polymers by an Iterative Approach Based on Living Anionic Polymerization

Higashihara Tomoya,Inoue Kyoichi,Nagura Masato,Hirao Akira The Polymer Society of Korea 2006 Macromolecular Research Vol.14 No.3

To successively synthesize star-branched polymers, we developed a new iterative methodology which involves only two sets of the reactions in each iterative process: (a) an addition reaction of DPE or DPE-functionalized polymer to a living anionic polymer, and (b) an in-situ reaction of 1-(4-(4-bromobutyl)phenyl)-1-phenylethylene with the generated 1,1-diphenylalkyl anion to introduce one DPE functionality. With this methodology, 3-, 4-, and 5-arm, regular star-branched polystyrenes, as well as 3-arm ABC, 4-arm ABCD, and a new 5-arm ABCDE, asymmetric star-branched polymers, were successively synthesized. The A, B, C, D, and E arm segments were poly(4-trimethylsilylstyrene), poly(4-methoxystyrene), poly(4-methylstyrene), polystyrene, and poly(4-tert-butyldimethylsilyloxystyrene), respectively. All of the resulting star-branched polymers were well-defined in architecture and precisely controlled in chain length, as confirmed by SEC, $^1H$ NMR, VPO, and SLS analyses. Furthermore, we extended the iterative methodology by the use of a new functionalized DPE derivative, 1-(3-chloromethylphenyl)-1-((3-(1-phonyletheny1)phenyl) ethylene, capable of introducing two DPE functionalities via one DPE anion reaction site in the reaction (b). The number of arm segments of the star-branched polymer synthesized by the methodology could be dramatically increased to 2, 6, and up to 14 by repeating the iterative process.