Co-reporter:
Polymer Engineering & Science 2017 Volume 57(Issue 1) pp:78-88
Publication Date(Web):2017/01/01
DOI:10.1002/pen.24387
The present investigation deals with the problems of unsatisfactory high-temperature resistance, inferior salt tolerance and poor comprehensive performance for the domestic fluid loss additives. In this study, a zwitterionic polymer, 2-acrylamido-2-methylpropanesulfonic acid/diallyldimethylammonium chloride/N,N-dimethylacryl amide/acrylic acid used as fluid loss agent for oil well cementing, was synthesized by free radical polymerization in aqueous solution with ammonium persulfate and N,N,N′,N′-tetramethylethylenediamine as initiator. The optimal synthesis conditions were obtained via single-factor variable analysis. The compositions, micro-structural morphologies, and thermal-stability of polymer were characterized by FT-IR, 1H NMR, SEM, DTG, and DSC techniques. The results manifested that the synthetic polymer cement slurry exhibited prominent advantages such as excellent fluid loss control capacity, thermal stability (up to 200°C), salt-tolerance (saturated brine) and rheological behavior. Even more strikingly, the zwitterionic polymer showed less impact on hardening cement and accelerated the post compressive strength of set cement, verified through the ultrasonic method. Additionally, the mechanism of fluid loss control was found to rely mainly on improving the filter cake quality and the polymer chemisorptions on the surface of hydrated cement through SEM, permeability and TOC analysis. In consequence, the zwitterionic polymer enhanced the comprehensive properties of cement slurry and had great potential to apply in high temperature and high salinity oil-well cementing. POLYM. ENG. SCI., 57:78–88, 2017. © 2016 Society of Plastics Engineers
Co-reporter:Di Chen, Jintang Guo, Xiujian Xia, Yongjin Yu, Jianzhou Jin, Ming Xu, Shuoqiong Liu, Yakai Feng
Construction and Building Materials 2017 Volume 149(Volume 149) pp:
Publication Date(Web):15 September 2017
DOI:10.1016/j.conbuildmat.2017.05.062
•Flash-setting or flocculation for carboxylic polymer modified cement happens around 120 °C.•Cross-linking for polycarboxylic cement hydrates is the main reason of the abnormal gelation.•Viscosity uprush of polymer solution occurred around 120 °C accelerates the abnormal gelation of slurry.•Optimization of polycarboxylic structure and addition of special salts could eliminate the abnormal gelation phenomenon.Cementing security is endangered by the abnormal gelation phenomenon of cement slurry incorporating polycarboxylic additives occurred around 120 °C. The differences between gelatinous and non-gelatinous sections were investigated through various techniques. The polymer structural change around 120 °C could explain the abnormal gelation phenomenon by viscosity-temperature characterization. The other reasons are the polycarboxylic additives combine with Ca2+, SiO42− and aluminate hydrate by cross-linking reaction. The cross-linking structure developed flocs which was embedded in calcium silicate hydrate (C–S–H) gel and intertwined around stirring shaft. The practicable methods were proposed to relieve or solve the abnormal phenomenon of cement slurry.
Co-reporter:Haixia Wang, Yakai Feng, Jing Yang, Jintang Guo and Wencheng Zhang
Journal of Materials Chemistry A 2015 vol. 3(Issue 16) pp:3379-3391
Publication Date(Web):13 Mar 2015
DOI:10.1039/C4TB02019G
Targeting gene engineering should be considered as an effective method for promoting endothelialization of vascular grafts. Herein, we developed a targeting REDV peptide functionalized polycationic gene carrier for carrying the pEGFP-ZNF580 plasmid with the aim of enhancing the transfection and migration capability of human endothelial cells. This polycationic gene carrier with the REDV peptide (mPEG-P(LA-co-CL)-PEI-REDV) was prepared by the conjugation of the Cys-Arg-Glu-Asp-Val-Trp (CREDVW) peptide with the amphiphilic block copolymer methoxy poly(ethylene glycol) ether-poly(L-lactide-co-ε-caprolactone)-poly(ethyleneimine) (mPEG-P(LA-co-CL)-PEI). mPEG-P(LA-co-CL)-PEI nanoparticles (NP) and mPEG-P(LA-co-CL)-PEI-REDV nanoparticles (REDV-NP) were formed by the self-assembly of the corresponding polycationic polymers, and then their pEGFP-ZNF580 complexes were prepared via the electrostatic interaction with pEGFP-ZNF580 plasmids, respectively. Gel electrophoresis results show that the targeted REDV-NPs could compress pEGFP-ZNF580 plasmids into stable complexes and protect the plasmids against desoxyribonuclease degradation. MTT assay indicates that these targeted REDV-NP/pEGFP-ZNF580 complexes exhibit better cyto-compatibility than the non-targeted NP/pEGFP-ZNF580 complexes and the control PEI 1800 Da/pEGFP-ZNF580 complexes. In vitro transfection experiments and western blot analysis of EA.hy926 endothelial cells show that the pEGFP-ZNF580 plasmid expression and the relative protein level transfected by targeted REDV-NP/pEGFP-ZNF580 complexes are roughly consistent with that transfected by PEI 25 kDa/pEGFP-ZNF580 complexes. More importantly, the scratch wound assay results demonstrate that the migration capability of EA.hy926 cells has been improved significantly by the expression of the pEGFP-ZNF580 plasmid. Our results indicate that the polycationic polymer with functional REDV peptides can be a potential candidate as a pEGFP-ZNF580 plasmid delivery carrier and may be used in the endothelialization of vascular grafts.
Co-reporter:Jintang Guo 郭锦棠;Peiyun Yu 郁培云;Haixia Wang 王海霞
Transactions of Tianjin University 2015 Volume 21( Issue 5) pp:406-411
Publication Date(Web):2015 October
DOI:10.1007/s12209-015-2492-y
A series of 4,4’-disubstituted-[2,2’]-bipyridines, featuring electron withdrawing/donating functional groups such as amino, chloro, nitro, ethoxycarbonyl, carboxy, methyl, methoxy and hydroxymethyl, have been synthesized and employed in the copolymerization of carbon monoxide(CO)and styrene. The available bipyridine and its derivatives were coordinated with palladium(II)acetate for catalyzing the copolymerization of CO and styrene, and the concomitant polyketone was characterized by means of 13C NMR, FTIR, differential scanning calorimetry( DSC)and element analysis techniques concerning its structure and thermal performance. The effect of different electron-donating and electron-withdrawing groups on catalyst performance and molecular weight of copolymer was studied under certain experimental condition. It has been proved that the enhancement of electron donating and conjugative effects on bipyridine ligand will not only improve the catalytic activity of the composition, but also increase the molecular weight of the as-prepared polyketone. The catalytic activity is the highest in hydroxymethyl substituted 2,2’-bipyridine ligand(1 356 gSTCO/(gPd · h)), when the molecular weight and polydispersity index of the polyketone are Mn=8 502,Mw=1 3440 and Mw/Mn=1.581, respectively.
Co-reporter:Jintang Guo 郭锦棠;Miao Xiao 肖 淼;Haixia Wang 王海霞
Transactions of Tianjin University 2014 Volume 20( Issue 2) pp:86-90
Publication Date(Web):2014 April
DOI:10.1007/s12209-014-2237-3
The dipping method was devised to deposit Pd onto carbon nanotube as supported catalyst (Pd/CNT) for the copolymerization of carbon monoxide (CO) and styrene(ST) towards the formation of polyketone (PK). The Pd/CNT was characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The construction and crystallization property of PK were evaluated by Fourier transform infrared spectroscopy (FTIR), 13C-nuclear magnetic resonance(NMR) and XRD, respectively. The catalyst showed excellent activity and reusability in promoting the fabrication of PK. It can be recycled 14 times with the highest total catalytic activity of 4 239.64 gPK/ (gPd·h) at Pd content of 8.63wt%. The results indicate that the prepared catalyst is effective to catalyze the copolymerization of CO and styrene.
Co-reporter:Haixia Wang 王海霞 郭锦棠;Guang Hu 胡 光
Transactions of Tianjin University 2014 Volume 20( Issue 1) pp:48-53
Publication Date(Web):2014 February
DOI:10.1007/s12209-014-2161-6
The copolymerization of CO and styrene catalyzed by Pd/C toward the formation of polyketones (PK)was studied in the N-valeronitrile-N′-methylimidazolium hexafluorophosphate ([C4CNmim]+PF6-) medium. The synthesized PK was characterized by Fourier transform infrared(FTIR), elemental analysis, 13C-nuclear magnetic resonance (13C-NMR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and gel permeation chromatography (GPC). The supported ionic liquid film on the surface of Pd/C catalyst can prevent the products from covering the hole of active carbon due to its chemical stability and weak coordination ability with metal ions, and thus efficiently improve the catalytic activity. The effects of different amounts of ionic liquid on the catalytic activity and reusability of the catalyst and the molecular weight of PK were discussed. When the usage of ionic liquid is 10wt% (0.1 g ionic liquid / 1 g active carbon carrier) and the theoretical content of Pd2+ is 5wt% (0.05 g Pd2+/ 1 g active carbon carrier), the highest catalytic activity 2 963.64 gSTCO/(gPd · h) is achieved with the molecular weight and polydispersity index of PK as Mn = 9 684, Mw = 13 452 and Mw/Mn = 1.389.
Co-reporter:Jintang Guo;Shan Gao;Zhenhui Lv ;Yaqin Ye
Journal of Applied Polymer Science 2012 Volume 123( Issue 6) pp:3292-3297
Publication Date(Web):
DOI:10.1002/app.34834
Abstract
In this article, novel 2,2′-bipyridyl derivatives were synthesized and the excellent bipyridyl ligands were chosen as catalyst to apply in the copolymerization of carbon monoxide (CO) and styrene (ST) to prepare polyketone. 4,4′-Dicarboxyl-2,2′-bipyridine(4,4′-dcpy) was synthesized by use of synthesized 4,4′-dimethyl-2,2′-bipyridine(4,4′-dmpy). The products (4,4′-dmpy and 4,4′-dcpy) were characterized by melting point, NMR, IR, GC-MS, and elemental analysis. The effects of different ligands and various reaction conditions incuding the usage of ligand, p-toluenesulfonic acid, solvent, p-benzoquinone, the CO pressure, and reaction temperature on catalytic activity of the copolymerization were investigated. The catalytic activity of 4,4′-dmpy, 4,4′-dcpy and 2,2′-bipyridine were compared. The results showed that the addition of the electron-donating substituent can enhance catalytic activity, with the sequence as follows: 4,4′- dimethyl-2,2′-bipyridine > 2,2′-bipyridine > 4, 4′-carboxy 2,2′- bipyridine. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 000: 000–000, 2012
Co-reporter:Jintang Guo;Guang Hu;Shan Gao ;Peng Li
Journal of Applied Polymer Science 2012 Volume 126( Issue 5) pp:
Publication Date(Web):
DOI:10.1002/app.34819
Abstract
The following article from the Journal of Applied Polymer Science, “Palladium (II)—Rare Earth Metal Catalyzed Copolymerization of CO and Styrene in [bmim]+PF6− Ionic Liquid” by Jintang Guo, Guang Hu, Shan Gao, and Peng Li, published online on 14 November 2011 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors; the journal's Managing Editor, Stefano Tonzani; and Wiley Periodicals, Inc. The retraction has been agreed due to the inappropriate use of previously published work, in particular Figures 6 and 7.
Co-reporter:Jintang Guo 郭锦棠;Guang Hu 胡 光;Zhikun Chen 陈志坤
Transactions of Tianjin University 2012 Volume 18( Issue 1) pp:8-14
Publication Date(Web):2012 February
DOI:10.1007/s12209-012-1805-7
A series of electron donors, including 1,1-cyclopentanecarboxylic acid diethyl ester (CPCADEE), 1,1-cyclopentanedimethanol acetic diester (CPDMAD), 1,1-biethoxymethyl pentane (BEMP), 2,2-diethyl diethylmalonate (DEDEM)and 2,2-diethyl-1,3-propanediol acetic diester (DEPDADE), were synthesized by diethyl malonate (DEM). The purities and structures of the above products were characterized by gas chromatography (GC) and gas chromatography-mass spectrometer (GC-MS), respectively. Furthermore, the possible optimal three-dimensional structures of these donors were simulated by means of Gaussian 03 and Chem 3D. Then these electron donors were coordinated with tetrachloro titanium (TiCl4) and chloride magnesium (MgCl2) to obtain the catalysts for the polymerization of propylene. The catalytic activities and properties of polypropylene are greatly improved by adding external donor(ED) when CPCADEE or DEPDADE is used as internal donor(ID). However, when BEMP was used as ID, the highest catalytic activity is obtained without adding ED, which can reduce production costs and simplify catalytic synthesis. The experiments indicate that BEMP has the shortest distance of oxygen atoms and the highest electronegativity.
Co-reporter:Jintang Guo 郭锦棠;Guang Hu 胡 光;Shan Gao 高 珊
Transactions of Tianjin University 2011 Volume 17( Issue 2) pp:107-110
Publication Date(Web):2011 April
DOI:10.1007/s12209-011-1564-x
N-valeronitrile-N′-methylimidazolium hexafluorophosphate ([C4CNmim]+PF6−), as a novel ionic liquid with polar nitrile functional group, was prepared. The structure of the ionic liquid was characterized by using IR and 1H NMR. As a medium, the ionic liquid plays an important role in copolymerization of carbon monoxide (CO) with styrene (St). Some synthetic conditions were determined, including the usage of ionic liquid, palladium composite catalyst and methanol, CO pressure, reaction time and reaction temperature. The influence of these factors on catalytic activity was analyzed. The results show that the catalytic activity has reached 1 724.1 gStCO/(gPd·h) and the catalyst could be reused 5 times under the optimal condition: composite catalyst 0.015 mmol, ionic liquid 3 mL, methanol 0.75 mL, CO pressure 2 MPa, reaction time 2 h and reaction temperature 70 °C. This CO/St copolymerization within [C4CNmim]+PF6− system could facilitate ionic liquids with efficient and economical applications to polymeric materials.
Co-reporter:Jin Tang Guo;Ya Qin Ye;Ya Kai Feng ;Hai Yang Zhao
Polymers for Advanced Technologies 2010 Volume 21( Issue 11) pp:759-766
Publication Date(Web):
DOI:10.1002/pat.1479
Abstract
Films of PCUs grafted with L-nitrosocysteine (L-CySNO) were successfully prepared in the presence of 3-aminopropyltriethoxysilane (APTES). The final products (L-CySNO-grafted PCU) were characterized with ATR-FTIR, SEM, XPS, and tensile strength measurement. Tensile strength of the L-CySNO-grafted PCU was decreased compared to that of non-grafted PCU. In vitro NO release from the produced films was obtained by using ascorbic acid (Vc) as reducing agent, and the velocity of the released NO was measured by the Griess assay. The effects of temperature, molecular weight of polycarbonate diols (PCN), and thickness of the films on in vitro NO release were investigated in detail. It was found that with the increase of temperature, the velocity of NO release increased, whereas with the increase of molecular weight of polycarbonate diols, the velocity decreased. However, thickness of PCU films has no effect on NO release. The results of cytotoxicity test and hemolytic test indicate that blood compatibility and biocompatibility of the grafted PCU are better than those of the synthesized PCU. Copyright © 2009 John Wiley & Sons, Ltd.
Co-reporter:JinTang Guo, YaQin Ye, Shan Gao, YaKai Feng
Journal of Molecular Catalysis A: Chemical 2009 Volume 307(1–2) pp:121-127
Publication Date(Web):15 July 2009
DOI:10.1016/j.molcata.2009.03.017
In the present work, polyketone (STCO) was successfully synthesized by use of carbon monoxide (CO) and styrene (ST) in the presence of Pd/C (5.4 wt%), bipyridine and p-toluenesulfonic acid. The final products were characterized by infrared Spectroscopy (IR), 13C nuclear magnetic resonance (13C NMR), elemental analysis, thermogravimetry (TG), differential scanning calorimetry (DSC), gel permeation chromatography (GPC) and transmission electron microscopy (TEM). The effects of various reaction conditions, including Pd/C catalyst usage, ligands, p-toluenesulfonic acid, reaction temperature and reaction time were investigated in detail, and the reusability of Pd/C catalyst in the copolymerization of CO and ST was also probed. It is found that the Pd/C catalyst shows higher catalytic activity and reusability in the copolymerization of CO and ST. It can be reused for 12 times with the highest catalytic activity of 1255.17 STCO/(g Pd h). The molecular weights and polydispersity index of the polyketone were as follows: Mn = 10,700, Mw = 19,079 and Mw/Mn = 1.78, respectively.In the present work, polyketone (STCO) was successfully synthesized by use of carbon monoxide (CO) and styrene (ST) in the presence of Pd/C (5.4 wt%), bipyridine and p-toluenesulfonic acid. The final products were characterized by many methods. The effects of various reaction conditions were investigated in detail, and the reusability of Pd/C catalyst in the copolymerization of CO and ST was also probed.
Co-reporter:Jintang Guo;Hongxin Zhang;Bo Wang;Yaqin Ye
Frontiers of Chemical Science and Engineering 2008 Volume 2( Issue 2) pp:165-170
Publication Date(Web):2008 June
DOI:10.1007/s11705-008-0010-7
The crosslinked polyacrylonitrile (PAN) was synthesized by suspension polymerization using acrylonitrile (ANT) and divinylbenzene (DVB). Effects of a variety of conditions on the polymerization of PAN particle size and stiffness were investigated. Polyketone was prepared by the copolymerization of carbon monoxide (CO) and styrene (ST) catalyzed by PAN resin-supported palladium acetate. The resin-supported catalyst and the copolymerization product were characterized by infrared spectroscopy (IR) and Scanning Electron Microscopy (SEM). Effects of the components of a catalytic system and reaction time on the catalytic activity were studied. The reusability of the resin-supported catalyst was also investigated.Results indicated that the resin-supported catalyst has excellent catalytic property. The yield of polyketone was 6.2348 g when using 1 g of resin and 22.4 mg of palladium acetate.
Co-reporter:Jing Tian 田 晶 郭锦棠;Xuemei Zhang 张雪梅
Transactions of Tianjin University 2008 Volume 14( Issue 3) pp:193-197
Publication Date(Web):2008 June
DOI:10.1007/s12209-008-0035-5
Room temperature ionic liquids as solvents for palladium-catalyzed copolymerization of carbon monoxide and styrene were prepared by reaction of aqueous lead tetrafluoroborate with correspond-ing chloride or bromide salts. The recyclability of palladium composite catalyst in various ionic liquids was investigated. [Pd(bipy)2][BF4]2 showed a lower catalytic activity than [Pd(bipy)2][PF6]2 in similar conditions, although the catalytic activity of each composite catalyst in ionic liquids still existed after 4 successive recycles. It was shown the catalytic activity of palladium composite catalyst was higher than that of the catalyst formed in situ from palladium acetate, 2,2′-bipyridyl, and HA (A=PF6−, BF4−) in ionic liquids. The effects of volume of ionic liquids, reaction time, and the dosage of benzoquinone on the copolymerizati on were also studied.
Co-reporter:Jintang GUO, Xiujian XIA, Shuoqiong LIU, Jianzhou JIN, ... Qianfeng YU
Petroleum Exploration and Development (October 2013) Volume 40(Issue 5) pp:656-660
Publication Date(Web):1 October 2013
DOI:10.1016/S1876-3804(13)60087-7
With regard to slow development or super retarding happening at the top of cement slurry in deep and ultra-deep wells with long cementing intervals, a new type of retarder HTR-300L was developed and its properties were evaluated. Thickening property tests at different temperatures for slurries with HTR-300L and IR, DSC and TG analysis show that: HTR-300L has good temperature-resistance performance and stable molecular structure. It can be used at the bottom hole circulating temperature of 70 to 200 °C. The thickening time of the slurry can be regulated effectively by adjusting the additive amount of HTR-300L. Thickening property tests for slurries with different salt contents show that HTR-300L has good salt-resistance performance and can be used in salty cement slurry. Strength development, thickening time, fluidity and API filtration of slurries with HTR-300L were studied at different top-bottom temperature differences. The results show that: The slurry with HTR-300L develops well in strength at large temperature difference and can overcome super retarding of the top of the slurry in long cementing interval. HTR-300L is applicable for large temperature range and can be used for slurries with both high and low densities. The slurry with HTR-300L has good overall performance, easy to regulate and control, and can satisfy cementing requirements for long cementing interval.
Co-reporter:Jintang GUO, Haichuan LU, Shuoqiong LIU, Jianzhou JIN, Yongjin YU
Petroleum Exploration and Development (June 2012) Volume 39(Issue 3) pp:385-390
Publication Date(Web):1 June 2012
DOI:10.1016/S1876-3804(12)60055-X
The domestic fluid loss additives often have lower thermal stability and poor salt-tolerance and their comprehensive properties are not good enough. To solve the problems, a novel cement fluid loss additive HTF-200C, which can resist high temperature and high salt content, was synthesized using the monomers of 2-acrylamido-2-methyl-propane sulphonic acid (AMPS), N, N-dimethyl acrylamide (DMAA) and a new compound with double carboxyl by the method of aqueous solution polymerization. The microstructural characterization and application performance of HTF-200C show that the polymer with the structure of all the monomers has an excellent thermal stability and strong salt tolerance, and can be used in 200 °C or in saturated brine. And the problem of the normal fluid loss additive being easy to hydrolyze due to high temperature can be solved with HTF-200C. What's more, it can also deal with the bulge of thickening curve in consistency test. The cement slurry prepared mainly by HTF-200C presents good comprehensive properties such as low filtration, high thermal stability, strong salt tolerance, rapid development of strength in low temperature, without far delayed solidification, short transit time during thickening process, and so on. The cementing job quality of Well Chengu 1-3 in the Liaohe Oilfield is excellent after it is used.
Co-reporter:Haixia Wang, Yakai Feng, Jing Yang, Jintang Guo and Wencheng Zhang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 16) pp:NaN3391-3391
Publication Date(Web):2015/03/13
DOI:10.1039/C4TB02019G
Targeting gene engineering should be considered as an effective method for promoting endothelialization of vascular grafts. Herein, we developed a targeting REDV peptide functionalized polycationic gene carrier for carrying the pEGFP-ZNF580 plasmid with the aim of enhancing the transfection and migration capability of human endothelial cells. This polycationic gene carrier with the REDV peptide (mPEG-P(LA-co-CL)-PEI-REDV) was prepared by the conjugation of the Cys-Arg-Glu-Asp-Val-Trp (CREDVW) peptide with the amphiphilic block copolymer methoxy poly(ethylene glycol) ether-poly(L-lactide-co-ε-caprolactone)-poly(ethyleneimine) (mPEG-P(LA-co-CL)-PEI). mPEG-P(LA-co-CL)-PEI nanoparticles (NP) and mPEG-P(LA-co-CL)-PEI-REDV nanoparticles (REDV-NP) were formed by the self-assembly of the corresponding polycationic polymers, and then their pEGFP-ZNF580 complexes were prepared via the electrostatic interaction with pEGFP-ZNF580 plasmids, respectively. Gel electrophoresis results show that the targeted REDV-NPs could compress pEGFP-ZNF580 plasmids into stable complexes and protect the plasmids against desoxyribonuclease degradation. MTT assay indicates that these targeted REDV-NP/pEGFP-ZNF580 complexes exhibit better cyto-compatibility than the non-targeted NP/pEGFP-ZNF580 complexes and the control PEI 1800 Da/pEGFP-ZNF580 complexes. In vitro transfection experiments and western blot analysis of EA.hy926 endothelial cells show that the pEGFP-ZNF580 plasmid expression and the relative protein level transfected by targeted REDV-NP/pEGFP-ZNF580 complexes are roughly consistent with that transfected by PEI 25 kDa/pEGFP-ZNF580 complexes. More importantly, the scratch wound assay results demonstrate that the migration capability of EA.hy926 cells has been improved significantly by the expression of the pEGFP-ZNF580 plasmid. Our results indicate that the polycationic polymer with functional REDV peptides can be a potential candidate as a pEGFP-ZNF580 plasmid delivery carrier and may be used in the endothelialization of vascular grafts.
![[2,2'-Bipyridine]-4,4'-diamine](http://img.cochemist.com/ccimg/18600/18511-69-8.png)
![[2,2'-Bipyridine]-4,4'-diamine](http://img.cochemist.com/ccimg/18600/18511-69-8_b.png)
![Poly[oxy(1-oxo-1,6-hexanediyl)]](http://img.cochemist.com/ccimg/25300/25248-42-4.png)
![Poly[oxy(1-oxo-1,6-hexanediyl)]](http://img.cochemist.com/ccimg/25300/25248-42-4_b.png)
