Co-reporter:Junheng Xing;Jiangqiong Chen;Yanhong Zhang;Hui Li;Li Zhong
Industrial & Engineering Chemistry Research July 2, 2014 Volume 53(Issue 26) pp:10667-10672
Publication Date(Web):Publication Date (Web): June 3, 2014
DOI:10.1021/ie5014585
The present work introduces a new HBF4-based electrolyte for the preparation of anodic TiO2 nanotubes (NTs). It is shown that, by optimizing the preparation parameters, highly ordered and extremely smooth TiO2 NTs can be successfully fabricated in the HBF4-containing electrolyte via a two-step anodization approach (so-called the BF4–TiO2 NTs). The obtained BF4–TiO2 NTs have unique hierarchical upper-nanopore/lower-nanotube structure and show both enhanced photoelectrochemical and photocatalytic performances than the referenced TiO2 NTs formed in the F–-containing electrolyte (i.e., the F–TiO2 NTs). We consider that the decomposition of BF4– into F– under high electric field is the key for the formation of anodic BF4–TiO2 NTs, and this allows the growth of BF4–TiO2 NTs going through a quite different way as compared to that of the F–TiO2 NTs. These findings may pave an alternative way for the preparation of TiO2 NTs with enhanced geometrical features and application properties.
Co-reporter:Liang Lei, Zhengbin Xia, Li Zhang, Yanhong Zhang, Li Zhong
Progress in Organic Coatings 2016 Volume 97() pp:19-27
Publication Date(Web):August 2016
DOI:10.1016/j.porgcoat.2016.03.011
•Amine functional reduced graphene oxide (A-rGO) is prepared.•A-rGO is covalently incorporated into polyurethane.•A-rGO/WPU hybrid emulsions are obtained by in situ polymerization.•A-rGO improves the mechanical property and thermostability of WPUs.In this study, we provided a novel method to prepare amino-functional reduced graphene oxide/waterborne polyurethane (rGO/WPU) hybrid emulsions. Firstly, the silane-functionalized reduced graphene oxide (A-rGO) with free amine groups on its surface was prepared via the modification of GO with 3-aminopropyltriethoxysilane (APTES) and the reduction by diethanol amine (DEA). Then, the obtained A-rGO sheets were incorporated into polyurethane by in situ polymerization to prepare A-rGO/WPU hybrid emulsions. The results from Fourier transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD), thermal gravity analysis (TGA), and Raman spectra clearly indicated that APTES was grafted on the surface of GO, and GO was reduced by DEA. With the increase of A-rGO content, the glass transition temperature, mechanical property, storage modulus, and thermal stability of A-rGO/WPU films increased gradually due to the homogeneous dispersion of A-rGO sheets in the WPU matrix and the strong covalent interaction between A-rGO sheets and WPU matrix. When the content of A-rGO sheets was 0.5 wt%, the A-rGO sheets could homogeneously dispersed in the WPU matrix, and the A-rGO/WPU films exhibited excellent overall performance.
Co-reporter:Hui Li, Jiangqiong Chen, Zhengbin Xia and Junheng Xing
Journal of Materials Chemistry A 2015 vol. 3(Issue 2) pp:699-705
Publication Date(Web):05 Nov 2014
DOI:10.1039/C4TA05021E
We report a microwave-assisted chemical reduction method with NaBH4 to prepare bulk abundant Ti3+ self-doped TiO2 nanotube arrays (MR-TNTs). UV-vis diffuse reflection spectra show that the light absorption spectrum range of MR-TNTs extends from the UV to visible light region and the electrochemical impedance spectra indicate that the induced oxygen vacancies of MR-TNTs enhance their electrical conductivity as well as charge transfer. The MR-TNTs show an 8-fold increase in visible light photocurrent density compared to the pristine TNTs, and the optimized saturation photocurrent density and photoconversion efficiency under AM1.5 irradiation are identified to be 3.05 mA cm−2 at 1.23 V vs. RHE and 1.66% respectively, which are the highest values ever reported for doped TNT photoelectrodes. The incident photon to current conversion efficiency (IPCE) spectrum increases both in UV and visible light regions. Moreover, the MR-TNTs exhibit much more stable PEC performance than the NaBH4 treated TNTs without microwave assistance, which is attributed to the self-doped Ti3+ mainly existing in the bulk rather than on the surface.
Co-reporter:Hui Li, Junheng Xing, Zhengbin Xia, Jiangqiong Chen
Carbon 2015 Volume 81() pp:474-487
Publication Date(Web):January 2015
DOI:10.1016/j.carbon.2014.09.080
Coaxial heterogeneous graphene quantum dot-sensitized TiO2 nanotube arrays (GQDs/TNTs) are prepared by a coupling technique of linker molecule binding and electrophoretic deposition (EPD). The silane linker molecules act as a superb medium for integrating GQDs and TNTs by covalent amide linkage, thus preventing GQDs from clogging the tube entrances and forming a uniform GQD layer tightly attached to the inside tube walls during the following EPD process. By adjusting the time of EPD, appropriate thickness of the deposited GQDs in the internal tube walls of TNTs can be controlled. Compared to the pristine TNTs and GQDs/TNTs prepared by the conventional impregnation–precipitation method, the hybrids fabricated by EPD exhibit significantly enhanced photoelectrochemical water-splitting activity and photocatalytic organic dye decomposition performance for their broad photo-absorption range, fast separation of photogenerated charge, and stability.
Co-reporter:Jiangqiong Chen, Zhengbin Xia, Hui Li, Qiao Li, Yajun Zhang
Electrochimica Acta 2015 Volume 166() pp:174-182
Publication Date(Web):1 June 2015
DOI:10.1016/j.electacta.2015.03.058
•PANI/H-TiO2 NTs is prepared by hydrogenation and electrochemical deposition.•PANI/H-TiO2 NTs exhibits higher capacitance than PANI/TiO2 NTs.•PANI/H-TiO2 NTs achieves the highest capacitance value of 999 F g−1 based on TiO2 NTs.•PANI/H-TiO2 NTs has remarkable cycling stability and great rate capability.A combination method of hydrogenated reduction and electrochemical deposition is employed to prepare highly capacitive polyaniline/black TiO2 nanotubes (PANI/H-TiO2 NTs) for supercapacitor. PANI/H-TiO2 NTs shows capacitance of 999 F g−1 at the current density of 0.6 A g−1. To the best of our knowledge, this result is the highest value based on TiO2 nanotubes (TiO2 NTs) or its composites (PANI/TiO2 NTs) for supercapacitor electrode. Moreover, PANI/H-TiO2 NTs also shows remarkable long-term cycling stability with only 29.8% reduction of the initial capacitance at a current density of 24.0 A g−1 after 2000 charge-discharge cycles, as well as great rate capability. The electrochemical impedance spectroscopy of PANI/H-TiO2 NTs shows that this electrode has low resistance. The solution resistance and charge-transfer resistance is as low as 0.1554 and 2.723 Ω cm−2, respectively, which indicate the better electronic transport ability and high charge-transfer rate of PANI/H-TiO2 NTs.
Co-reporter:Liang Lei, Zhengbin Xia, Canbin Ou, Li Zhang, Li Zhong
Progress in Organic Coatings 2015 Volume 88() pp:155-163
Publication Date(Web):November 2015
DOI:10.1016/j.porgcoat.2015.07.002
•The crosslinking density of WPUs is determined by the TMP content.•The relation equation of peel strength and TMP content is obtained.•The relation equation of peel strength and crosslinking density is obtained.•The relation equation of crosslinking density and TMP content is obtained.•An optimal crosslinking density is a key for WPUs with excellent adhesion property.A series of waterborne polyurethanes (WPUs) with different crosslinking densities were synthesized by varying the amount of trifunctional crosslinker trimethylolpropane (TMP). The effects of the TMP content on the adhesion behavior of WPUs were investigated in terms of the cohesive strength of WPUs, and the interface adhesion strength between WPUs and the substrate–polyethylene glycol terephthalate (PET) film. It was found that with the increase of TMP content, the interface adhesion strength decreased due to the decreased mobility of PU molecular chains, the cohesive strength of WPUs films increased because of the increase in the crosslinking density (υe), and the T-peel strength (T) initially increased and then decreased with the change of debonding failure from a cohesive failure to an interface failure. An empirical equation, revealing the relation between peel strength and TMP content (x), was found to be T = 1.94 + 0.81x − 0.22x2, and another empirical equation, T=1.59+750.44υe−128313.62υe2, showing the relation between peel strength and crosslinking density was obtained. Moreover, crosslinking density was mainly determined by TMP content, and it was found that the relationship between υe and x could be showed by the equation υe = 0.00045 + 0.0013x or υe = 0.00050 + 0.0013x. On the whole, crosslinking played an important role in the adhesion behavior of WPUs, and an optimal crosslinking density was a key for preparing the WPUs with outstanding adhesion property. In this study, the optimal υe was 0.00292 mol/cm3.
Co-reporter:Liang Lei;Xiaoqiong Lin;Tao Yang ;Li Zhong
Journal of Applied Polymer Science 2015 Volume 132( Issue 12) pp:
Publication Date(Web):
DOI:10.1002/app.41688
ABSTRACT
In this study, a series of waterborne polyurethanes (WPUs) with different contents of long-branched aliphatic chains were synthesized through variation of the amount of diol chain extender trimethylol propane monooleate (TMPM). The effects of the TMPM content on the adhesion properties of the WPUs were investigated in terms of their surface tension, interfacial tension, contact angle, and adhesion strength. Fourier transform infrared and 1H-NMR spectra demonstrated the successful incorporation of TMPM into the polyurethanes. An increase in the TMPM content produced decreases in the surface tension of the WPUs and the interfacial tension and contact angle between the WPUs and plastic films. This indicated that the wetting properties of the WPUs on the plastic films was improved. The improved wettability enhanced the adhesion strength of the WPUs, and this showed that the long-branched aliphatic chains could effectively improve the adhesion performance of the WPUs on the plastic films. Moreover, TMPM, with its hydrophobic aliphatic chains, increased the hydrophobicity and thermal stability of the WPU films. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41688.
Co-reporter:Hui Li, Junheng Xing, Zhengbin Xia and Jiangqiong Chen
RSC Advances 2014 vol. 4(Issue 44) pp:23214-23217
Publication Date(Web):13 May 2014
DOI:10.1039/C4RA01857E
Highly ordered anodic single-walled TiO2 nanotubes (SW-TiO2 NTs) and double-walled TiO2 nanotubes (DW-TiO2 NTs) are prepared in the unique NH4BF4 based electrolyte. The formation of SW-TiO2 NTs and DW-TiO2 NTs can be simply tuned by the voltages. The DW-TiO2 NTs show higher photoelectrochemical performance than the SW-TiO2 NTs.
Co-reporter:Gaohua Cao;Liang Lei;Yanhong Zhang ;Junheng Xing
Journal of Applied Polymer Science 2014 Volume 131( Issue 10) pp:
Publication Date(Web):
DOI:10.1002/app.40270
ABSTRACT
Polyester-based waterborne polyurethane (WPU) dispersions having poly(ethylene glycol) adipate diol, isophorone diisocyanate, and hexamethylene diisocyanate as the main raw materials were synthesized by an acetone process. In each step of the synthesis process, the intermediate products were collected, and the crystallization morphologies and relative crystallinity (X) of the soft segments (SSs) in their films were investigated by means of polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction. The fracture surfaces and thermostability of the intermediate films were also investigated by scanning electron microscopy (SEM) and TGA, respectively. The results show that the crystalline dimensions of the SSs decreased substantially during the synthesis process of WPU. X of the SSs decreased after the prepolymerization reaction and increased after the hydrophilic chain-extending reaction, then decreased after emulsification, and finally increased after the secondary chain-extending reaction. Moreover, The SEM photos indicate that with decreasing crystalline dimensions, the fracture mechanisms of the intermediate films varied gradually from brittle failure to ductile fracture. The thermostability of the intermediates obtained in each step of the synthesis process was in accordance with the variation tendency of the X of the SSs. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40270.
Co-reporter:Xin Fan;Lin Niu
Colloid and Polymer Science 2014 Volume 292( Issue 12) pp:3251-3259
Publication Date(Web):2014 December
DOI:10.1007/s00396-014-3377-7
Raspberry-like composite particles and microcapsules were prepared with anionic sulfonated polystyrene (PSS) particles as templates and cationic aniline monomer as assembly medium. With the help of the sulfonated microgel shells, aniline and silica particles could not only adsorbed onto template surfaces but also go inward shells and finally form microcapsules with varied silica shell thickness. The sulfonation extent of PSS particles first climbed up and then decreased with sulfonation time due to the competition of sulfonation reaction and PSS chain detachment. The silica content in composite particles and shell thickness of microcapsules followed similar trend with sulfonation extent. The choice of aniline as assembly medium was checked by comparing with methyl methacrylate and [2-(methacryloyloxy) ethyl] trimethylammonium chloride, and it was found that the cationic and water-insoluble properties of aniline are both important for the composite efficiency.
Co-reporter:Fang-qiang Fan, Zheng-bin Xia, Qing-ying Li, Zhong Li
Progress in Organic Coatings 2013 Volume 76(Issue 5) pp:844-851
Publication Date(Web):May 2013
DOI:10.1016/j.porgcoat.2013.02.002
In the present work, the effects of inorganic fillers on the fire retardant performance of waterborne intumescent coatings are investigated by thermogravimetry (TG), capillary rheometer, X-ray diffraction spectroscopy (XRD) and fire retardant test, etc. The TG results indicate that the thermal stability of vinyl acetate-vinyl ester of versatic acid copolymer (hereafter VAc-VeoVa) in VAc-VeoVa/Si–Al powder composite or in VAc-VeoVa/Halloysite nanometer-tube (HNTs) composite is improved mainly due to the release of the crystal water in Si–Al powder or HNTs. Capillary rheometer analysis results demonstrate that the VAc-VeoVa/HNTs composite melt possesses the highest shear viscosity, because of the large specific surface area of HNTs and the strong interaction force between HNTs and VAc-VeoVa. Weight loss difference (ΔT) of filler/ammonium polyphosphate (APP) composites show antagonism effects at 300 °C < T < 650 °C and synergistic effects at T > 650 °C. The fire retardant test results show the coatings using TiO2/Si–Al powder/HNTs (8/1/1) as multiple fillers obtains an intumescent char layer with intumescent ratio of 28.14 and presents excellent fire retardant performance (3327 s). It is found that the high melt viscosity, resulted from the effect of inorganic filler, immobilizes the relaxation and rotation of polymer chain, restricts the intumescent behavior of the coatings, which leads to the formation of an intumescent char layer with lower intumescent ratio and the shortening of the fire retardant time. Moreover, the antagonism effect between filler and APP reduces the catalytic dehydration efficiency of pentaerythritol (PER) and VAc-VeoVa, which, as a result, also affects the final fire retardant performance of coatings.Highlights► The effects of clay on the thermal stability of polymer are by physical method. ► The viscosity of VAc-VeoVa/filler melt influences the intumescent ratio of coatings. ► VAc-VeoVa/filler melt with highly viscosity leads to form lower intumescent char. ► APP/filler(ΔT) shows a negative effect at 300–650 °C and a positive effect at T > 650 °C. ► For intumescent coatings, multi-fillers are better than single filler.
Co-reporter:Lin Niu;Liang Lei;Yanhong Zhang ;Li Zhong
Journal of Applied Polymer Science 2013 Volume 128( Issue 6) pp:4237-4244
Publication Date(Web):
DOI:10.1002/app.38660
Abstract
In this work, a one-pot route to prepare emulsions of silica/polymer core-shell composite particles was developed through the direct sol–gel processing of alkoxysilane on the surface of newly synthesized template polymer particles in emulsifier-involved aqueous emulsions. It included two continuous steps: first, the polymer emulsions were synthesized through emulsion polymerization, and second, the template particles in the emulsions were directly coated with silica via sol–gel reaction of precursors without adding ethanol or removing emulsifiers. The size and morphology of the composite particles were characterized, and the results showed that the silica/polymer composite particles with core-shell structure could be prepared only on the basis of cationic template emulsions, and the in situ-coating reaction of sol–gel precursors carried on easier with the increasing of the positive charge density on the surface of template particles. The films formed from the composite emulsions were found to have superior optical and flame-retardant properties compared to polymer films, owing to the core-shell composite microstructure of the particles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Fangqiang Fan;Qingying Li
Journal of Thermal Analysis and Calorimetry 2013 Volume 114( Issue 3) pp:937-946
Publication Date(Web):2013 December
DOI:10.1007/s10973-013-3099-y
Phosphorus-containing styrene–acrylic copolymers are synthesized by free radical seeded emulsion polymerization with the monomers of MMA/St/BA/MAA and phosphorus-containing vinyl monomer (SIPOMER PAM100). The properties of copolymer films are characterized by water adsorption test, thermogravimetry, Fourier transform infrared spectroscopy (FTIR), and energy dispersive spectroscopy (EDS), etc. The copolymer emulsions are used as the binder in an intumescent coatings formulation, and the fire-retardant performances of the coatings are determined by an instrument which the furnace temperature is analoging the cellulose fire temperature. The water adsorption of copolymer film increases remarkably owing to the increasing of phosphoric acid group in the polymer chain. The thermal decomposition stability and thermal-oxidative decomposition stability of the copolymer are improved when PAM100 is introduced into its chain, which is strongly supported by the FTIR and EDS results of copolymer residual treated at different temperature. The EDS results also illustrate that the fire retardancy enhanced by PAM100 during combustion owing to the condensed-phase mechanism. The fire-retardant test results show that the intumescent coatings using StA-P1.5 copolymer emulsion as the binder obtains the best fire retardant performance. We suggested that StA-P1.5 presents the lower reactivity with the acid source (APP) in 275–400 °C, and the higher reactivity with APP when the temperature is greater than 500 °C would be benefit for the swelling–charring process and the final fire retardant performance. The exorbitant crosslinking in StA-P7 brings a negative effect on the fire-retardant performance of intumescent coatings, even if it introduces a densy swollen char layer.
Co-reporter:Lin Niu
Colloid and Polymer Science 2012 Volume 290( Issue 8) pp:699-707
Publication Date(Web):2012 June
DOI:10.1007/s00396-011-2579-5
The emulsion polymerization of acrylic and vinyl acetate monomers using poly(vinyl alcohol) (PVA) as protective colloid has been studied for a long time, whereas rare reports ranged over the lateral comparison of the two systems and the reason for the unstability of the PVA/MMA polymerization system was still indistinct. Here in this paper, a collection of experiments of methyl methacrylate (MMA) and vinyl acetate (VAc) were performed respectively with varied amount of PVA as the sole stabilizer. The grafting extent of the polymerisate was characterized through the fraction and FTIR and it was found that the grafted amount of PVA was even larger in the PVA/MMA copolymers than PVA/VAc copolymers, so the grafted mode of PVA was considered. Based on the kinetics, the slower initiation rate of sulfate radical towards MMA was found to be responsible for the unstability of corresponding colloids accompanied with the relatively quicker hydrogen abstraction of radical to PVA, which resulted in “layer-by-layer” grafting structure inside and the particle surface-grafting density was lowered thereof. This was proved with TEM and static contact angle measurements and a pseudo-homopolymer model was employed to describe the relationship of colloidal stability and the PVA density on surfaces.
Co-reporter:Liang Lei, Zhengbin Xia, Canbin Ou, Li Zhang, Li Zhong
Progress in Organic Coatings (November 2015) Volume 88() pp:155-163
Publication Date(Web):1 November 2015
DOI:10.1016/j.porgcoat.2015.07.002
•The crosslinking density of WPUs is determined by the TMP content.•The relation equation of peel strength and TMP content is obtained.•The relation equation of peel strength and crosslinking density is obtained.•The relation equation of crosslinking density and TMP content is obtained.•An optimal crosslinking density is a key for WPUs with excellent adhesion property.A series of waterborne polyurethanes (WPUs) with different crosslinking densities were synthesized by varying the amount of trifunctional crosslinker trimethylolpropane (TMP). The effects of the TMP content on the adhesion behavior of WPUs were investigated in terms of the cohesive strength of WPUs, and the interface adhesion strength between WPUs and the substrate–polyethylene glycol terephthalate (PET) film. It was found that with the increase of TMP content, the interface adhesion strength decreased due to the decreased mobility of PU molecular chains, the cohesive strength of WPUs films increased because of the increase in the crosslinking density (υe), and the T-peel strength (T) initially increased and then decreased with the change of debonding failure from a cohesive failure to an interface failure. An empirical equation, revealing the relation between peel strength and TMP content (x), was found to be T = 1.94 + 0.81x − 0.22x2, and another empirical equation, T=1.59+750.44υe−128313.62υe2, showing the relation between peel strength and crosslinking density was obtained. Moreover, crosslinking density was mainly determined by TMP content, and it was found that the relationship between υe and x could be showed by the equation υe = 0.00045 + 0.0013x or υe = 0.00050 + 0.0013x. On the whole, crosslinking played an important role in the adhesion behavior of WPUs, and an optimal crosslinking density was a key for preparing the WPUs with outstanding adhesion property. In this study, the optimal υe was 0.00292 mol/cm3.Download full-size image
Co-reporter:Fangqiang FAN, Zhengbin XIA, Qingying LI, Zhong LI, Huanqin CHEN
Chinese Journal of Chemical Engineering (February 2013) Volume 21(Issue 2) pp:113-120
Publication Date(Web):1 February 2013
DOI:10.1016/S1004-9541(13)60448-6
ZrO2/PMMA nanocomposite particles are synthesized through an in-situ free radical emulsion polymerization based on the silane coupling agent (Z-6030) modified ZrO2 nanoparticles, and the morphology, size and its distribution of nanocomposite particles are investigated. Scanning electron microscopy (SEM) images demonstrate that the methyl methacrylate (MMA) feeding rate has a significant effect on the particle size and morphology. When the MMA feeding rate decreases from 0.42 mlmin−1 to 0.08 mlmin−1, large particles (about 200-550 nm) will not form, and the size distribution become narrow (36-54 nm). The average nanocomposite particles size increases from 34 nm to 55 nm, as the MMA/ZrO2 nanoparticles mass ratio increased from 4 : 1 to 16 : 1. Regular spherical ZrO2/PMMA nanocomposite particles are synthesized when the emulsifier OP-10 concentration is 2 mgml−1. The nanocomposite particles could be mixed with VAc-VeoVa10 polymer matrix just by magnetic stirring to prepare the ZrO2/PMMA/VAc-VeoVa10 hybrid coatings. SEM and atomic force microscopy (AFM) photos reveal that the distribution of the ZrO2/PMMA nanocomposite particles in the VAc-VeoVa10 polymer matrix is homogenous and stable. Here, the grafted-PMMA polymer on ZrO2 nanoparticles plays as a bridge which effectively connects the ZrO2 nanoparticles and the VAc-VeoVa10 polymer matrix with improved comparability. In consequence, the hybrid coating with good dispersion stability is obtained.
Co-reporter:Hui Li, Jiangqiong Chen, Zhengbin Xia and Junheng Xing
Journal of Materials Chemistry A 2015 - vol. 3(Issue 2) pp:NaN705-705
Publication Date(Web):2014/11/05
DOI:10.1039/C4TA05021E
We report a microwave-assisted chemical reduction method with NaBH4 to prepare bulk abundant Ti3+ self-doped TiO2 nanotube arrays (MR-TNTs). UV-vis diffuse reflection spectra show that the light absorption spectrum range of MR-TNTs extends from the UV to visible light region and the electrochemical impedance spectra indicate that the induced oxygen vacancies of MR-TNTs enhance their electrical conductivity as well as charge transfer. The MR-TNTs show an 8-fold increase in visible light photocurrent density compared to the pristine TNTs, and the optimized saturation photocurrent density and photoconversion efficiency under AM1.5 irradiation are identified to be 3.05 mA cm−2 at 1.23 V vs. RHE and 1.66% respectively, which are the highest values ever reported for doped TNT photoelectrodes. The incident photon to current conversion efficiency (IPCE) spectrum increases both in UV and visible light regions. Moreover, the MR-TNTs exhibit much more stable PEC performance than the NaBH4 treated TNTs without microwave assistance, which is attributed to the self-doped Ti3+ mainly existing in the bulk rather than on the surface.
![Poly[oxy-1,4-butanediyloxy(1,6-dioxo-1,6-hexanediyl)]](http://img.cochemist.com/ccimg/25000/24936-97-8.png)
![Poly[oxy-1,4-butanediyloxy(1,6-dioxo-1,6-hexanediyl)]](http://img.cochemist.com/ccimg/25000/24936-97-8_b.png)