Directed molecular recognition: furfurylamine appended ditopic receptor for succinic acid

A furfurylamine appended ditopic receptor (R1) for dicarboxylic acids has been designed and synthesised. The association constants (K_a) between receptors and dicarboxylic acids have been determined using UV–vis and NMR titration techniques. The binding constant (K_a) of succinic acid with R1 was observed maximum, which implies the optimum chain length selectivity for succinic acid. Theoretical calculation and molecular modelling using Gaussian 03 program also support the optimised receptor's cavity for succinic acid.     

Preparation of Polyester Polyol from Epoxidized Palm Olein

In this work, polyester polyols with high weight average molecular weight (M_w) (M_w?10000–15000) were prepared from epoxidized palm olein (EPO_o) and a series of dicarboxylic acids (C₆–C₁₂) at elevated temperature under non‐catalyzed condition. The optimal reaction conditions were determined as 180°C for 4 h. Longer carbon chain length of dicarboxylic acids was more reactive when reacted with EPO_o. The physical appearance of the product was observed as liquid at room temperature. This palm oil‐based polyester polyol is proposed as starting material for flexible polyurethane. For reaction monitoring purposes, FTIR was used while ¹H NMR analysis was carried out to characterize the important functional groups of the products. The effects of reaction time and temperature on the M_w of the reaction mixture were also studied by GPC.     

生物基化工与材料产业技术的开发与探索

本文阐述了中国石油化工集团公司(中国石化)在生物基化工与材料领域的探索路径和发展战略,介绍了中国石化近年来在生物基单体、生物基材料与可降解材料等领域开展的创新实践及取得的阶段性成果,主要包括乳酸—聚乳酸、丁二酸/二元醇—生物可降解材料、长链二元酸—生物基尼龙以及生物质芳烃—聚对苯二甲酸乙二酯(PET)等技术领域.提出了建立生物基化工与材料科学技术平台、突破关键技术、发展新兴产业等建议.     

The chemical effect of furfuryl amide on the enhanced performance of the diphenolic acid derived bio-polybenzoxazine resin

As a renewable chemical, diphenolic acid (DPA) has attracted immense interest in bio-based polymer science. However, its application for polybenzoxazines is limited due to decarboxylation, that is, the release of CO₂ during the curing reaction of benzoxazine. In this study, the amidation strategy of converting DPA to diphenolic amides (DPAM) was demonstrated to solve this problem while simultaneously improving the thermal properties of polybenzoxazine. DPA was amidated by separately using four amines (hexamine, cyclohexylamine, furfurylamine, and aniline), then reacted with furfurylamine and paraformaldehyde to synthesize their benzoxazine monomers. By using TGA and DMA, all amide-containing polybenzoxazines were found to exhibit excellent thermal stabilities. Among all of the benzoxazine resins, poly(DFA-fa), which was obtained from amidation with furfurylamine, exhibited the highest glass transition temperature (T_g) of 310°C and a decomposition temperature (T_d10) of 406°C. Furthermore, a possible post-curing reaction mechanism was proposed to explain the outstanding thermal performance of poly(DFA-fa) resin. This study proposes an innovative strategy to solve the decarboxylation of DPA-based polymers, which is of significance for high-performance bio-based polymers.     

Synthesis and hydrolytic degradation of poly (glycerol succinate) based polyesters

The limited availability of petroleum resources motivates the research towards value-added products production from bio-resources. This study reports the synthesis of glycerol and succinic acid-based polyesters and their detailed characterization. The modification of poly (glycerol succinate) was done by using other diacids like glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid. The sysnthesized polyesters were characterized using various techniques such as thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The addition of different dicarboxylic acids to poly (glycerol succinate) based co-polyesters increased the thermal stability of poly (Glycerol succinate). Glass transition temperatures were obtained in the range of ?17.2 to ?22.5 °C and it increased with chain length. The progress of reaction was monitored by determining acid number, ester number, and degree of esterification. The hydrolytic degradation of polyesters was carried out in acidic and basic medium. The polyesters was found to degrade under basic conditions whereas no weight loss of poly (glycerol succinate) was found under acidic conditions. Particularly, about 40% of poly (glycerol succinate) was degraded within 24 h under basic conditions (pH = 12). The analysis of morphology of polyesters during degradation showed that the increase in hydrolysis time increased the heterogeneity in polyester matrix.     

基于松香酸酐的环氧树脂体系固化动力学及TTT图绘制

研制了基于松香酸酐固化剂的生物质环氧树脂体系,采用全动态DSC法研究了树脂体系的固化反应动力学,通过半经验的唯象模型拟合得到了固化反应参数,活化能Ea为59.68 kJ/g,指前因子A0为1.28×1015s-1,反应级数n为2.483,由此建立了体系固化温度/时间/固化度间的关系;采用恒温DSC及DMA方法测试玻璃化转变温度,应用DiBenedetto经验方程拟合得到了玻璃化转变温度与固化度间的关系.应用锥板旋转黏度计测试了树脂体系不同温度下的凝胶时间,通过线性回归分析得到了凝胶时间与温度之间的关系.由唯象模型和DiBenedetto方程分别计算得到凝胶时的固化度为0.386,玻璃化转变温度为26.22°C.由上述工作绘制了基于松香酸酐生物质树脂体系的TTT(time-temperature-transition diagram)固化图,可确定树脂体系在不同温度任意时间下的状态.     

Thermal curing behavior of MWCNT modified vinyl ester‐polyester resin suspensions prepared with 3‐roll milling technique

This study aims to investigate the curing behavior of a vinyl ester‐polyester resin suspensions containing 0.3 wt % of multiwalled carbon nanotubes with and without amine functional groups (MWCNTs and MWCNT‐NH₂). For this purpose, various analytical techniques, including Differential Scanning Calorimetry (DSC), Fourier infrared spectroscopy (FTIR), Raman Spectroscopy, and Thermo Gravimetric Analyzer (TGA) were conducted. The resin suspensions with carbon nanotubes (CNTs) were prepared via 3‐roll milling technique. DSC measurements showed that resin suspensions containing CNTs exhibited higher heat of cure (Q), besides lower activation energy (E_a) when compared with neat resin. For the sake of simplicity of interpretation, FTIR investigations were performed on neat vinyl ester resin suspensions containing the same amount of CNTs as resin. As a result, the individual fractional conversion rates of styrene and vinyl ester were interestingly found to be altered dependent on MWCNTs and MWCNT‐NH₂. The findings obtained from RS measurements of the cured samples are highly proportional to those obtained from FTIR measurements. TGA measurements revealed that CNT modified nanocomposites have higher activation energy of degradation (E_d) compared with the cured polymer. The findings obtained revealed that CNTs with and without amine functional groups alter overall thermal curing response of the surrounding matrix resin, which may probably impart distinctive characteristics to mechanical behavior of the corresponding nanocomposites achieved. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1511–1522, 2009     

The chemical synthesis of conductive polyaniline doped with dicarboxylic acids

The chemical polymerization of aniline was carried out in media containing different linear dicarboxylic acids with the use of oxidants such as K₂Cr₂O₇, KMnO₄, K₂S₂O₈, KIO₃ and FeCl₃. The highest yield and the conductivity were observed with K₂Cr₂O₇. The yield and the conductivity of the polyaniline (PAn) synthesized were observed to decrease in the order of oxalic acid > malonic acid > succinic acid > glutaric acid > adipic acid > phthalic acid. The solubility tests carried out in solvents such as DMF, DMSO and NMP showed that the larger the dopant molecule, the higher is the solubility of polyaniline. The PAn synthesized was characterized by measurements of conductivity, intrinsic viscosity, density and FTIR, UV-VIS and TGA techniques.     

Modifying an amorphous polymer to a fast crystallizing semi‐crystalline material by copolymerization with monodisperse amide segments

Segmented block copolymers of polysulphone with monodisperse amide segments were synthesized by a melt and a solution polymerization method. Both triblock and multiblock copolymers were prepared. The length of the difunctional polysulphone was varied from 2000 to 20,000 g/mol. The monodisperse amide segment was the tetra‐amide T6T6T based on terephthalic acid (T) and hexamethylene diamine (6) units. The main goal of this work was to study if the high T_g amorphous polysulphone could be modified to a high T_g semi‐crystalline PSU‐T6T6T copolymer. The copolymers were characterized by viscosity measurements, NMR, FTIR, MALDI‐TOF, DSC, and DMA. Depending on the amide concentration in the copolymers the T6T6T melting temperatures ranged between 220 and 270 °C and thus the crystallization window was small 50–100 °C. From the FTIR results, it was revealed that the crystallinity of the T6T6T segments in the copolymer could be very high, up to 92–97%. The T6T6T has crystallized out into nanoribbons with a high aspect ratio. These high T_g semi‐crystalline copolymers had a high dimensional and solvent resistance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 63–73, 2010     

Curing reaction of unsaturated (epoxy) polyesters based on different aliphatic glycols

The influence of the structure of succinic or glutaric anhydride modified linear unsaturated (epoxy) polyesters on the course of the cure reaction with styrene initiated by benzoyl peroxide (BPO) or the mixture of benzoyl peroxide/tetrahydrophthalic anhydride (BPO/THPA) or benzoyl peroxide/maleic anhydride, as well as viscoelastic properties and thermal behavior of their styrene copolymers have been studied by DSC, DMA, and TGA analyses. Additionally, mechanical properties: flexural properties using three-point bending test and Brinell’s hardness for studied copolymers were evaluated. It was confirmed that the structure of used polyesters had a considerable influence on the course of the cure reaction with styrene, viscoelastic, thermal, and mechanical properties of prepared styrene copolymers. Generally, one or two asymmetrical peaks for the cure reaction of succinic or glutaric anhydride modified linear unsaturated epoxy polyesters with styrene were observed. They were connected with various cure reaction, e.g., copolymerization of carbon–carbon double bonds of polyester with styrene, thermal curing of epoxy groups, polyaddition reaction of epoxy to anhydride groups in dependence of used curing system. In addition, only one asymmetrical, exothermic peak attributed to the copolymerization process of succinic or glutaric anhydride modified linear unsaturated polyesters with styrene was visible. Moreover, the obtained styrene copolymers based on succinic or glutaric anhydride modified linear unsaturated epoxy polyesters were characterized by higher values of E_{20 ^°\textC}^￠ E_{{20\,^{\circ}{\text{C}}}}^{\prime} , T _g, E″, ν _e, E _mod, F _max, hardness, IDT, FDT but lower ε − F _max compared to those values observed for styrene copolymers prepared in the presence of succinic or glutaric anhydride modified linear unsaturated polyesters. This supported to the production of stiffer and more thermally stable polymeric structure of copolymers based on unsaturated epoxy polyesters. Moreover, the copolymers prepared in the use of glutaric anhydride modified linear unsaturated (epoxy) polyesters were described by lower values of E_{20 ^°\textC}^￠ E_{{20\,^{\circ}{\text{C}}}}^{\prime} , T _g, E″, ν _e, E _mod, F _max, hardness, IDT, FDT but higher ε − F _max than those based on succinic anhydride modified linear unsaturated (epoxy) polyesters. The presence of longer aliphatic chain length in polyester’s structure leads to produce more flexible network structure of styrene copolymers based on glutaric anhydride modified linear unsaturated (epoxy) polyesters than those based on succinic anhydride modified linear unsaturated (epoxy) polyesters.     

Preparation and Characterization of Biobased Lignin-Co-Polyester/Amide Thermoplastics

More than 23 million tonnes of lignin are produced annually in the US from wood pulping and 98% of this lignin is burnt. Therefore, creating products from lignin, such as plastics, offers an approach for obtaining sustainable materials in a circular economy. Lignin-based copolymers were synthesized using a single pot, solvent free, melt condensation reaction. The synthesis occurred in two stages. In the first stage, a biobased prepolymer consisting of butanediol (BD, 0.8–1 molar content) and a diacid (succinic (SA), adipic (AA) and suberic acids (SuA), with varying amounts of diaminobutane (DAB, 0–0.2 molar content) was heated under vacuum and monitored by Fourier transform infra-red (FTIR) spectroscopy and electrospray ionization-mass spectrometry (ESI-MS). In the second stage, prepolymer was mixed with a softwood kraft lignin (0–50 wt.%) and further reacted under vacuum at elevated temperature. Progression of the polymerization reaction was monitored using FTIR spectroscopy. The lignin-copolyester/amide properties were characterized using tensile testing, X-ray diffraction (XRD), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. Lignin co-polymer tensile (strength 0.1–2.1 MPa and modulus 2 to 338 MPa) properties were found to be influenced by the diacid chain length, lignin, and DAB contents. The lignin-copolymers were shown to be semi-crystalline polymer and have thermoplastic behavior. The SA based copolyesters/amides were relatively stiff and brittle materials while the AA based copolyesters/amides were flexible and the SuA based copolyesters/amides fell in-between. Additionally, > 30 wt.% lignin the lignin- copolyesters/amides did not exhibit melt behavior. Lignin-co-polyester/amides can be generated using green synthesis methods from biobased building blocks. The lignin- copolyesters/amides properties could be tuned based on the lignin content, DAB content and diacid chain length. This approach shows that undervalued lignin can be used in as a macromonomer in producing thermoplastic materials.     

Curing and Glass Transition of Epoxy Resins from Ester-Carboxylic Acid Derivatives of Mono- and Disaccharides,and Alcoholysis Lignin

Mono- and disaccharides (SAC) such as glucose (Glc), fructose (Frc) and sucrose (Suc), and also alcoholysis lignin (AL) were dissolved in ethylene glycol and each of the obtained mixtures was reacted with succinic anhydride to form a mixture of ester-carboxylic acid derivatives such as SAC-polyacid, SACPA, and AL-polyacid, ALPA. Ethylene glycol-polyacid (EGPA) was also prepared from ethylene glycol. Each of the obtained mixtures of ester carboxylic acid derivatives was reacted with ethylene glycol diglycidyl ether in the presence of a catalytic amount of dimethylbenzylamine to form ester-epoxy resins. The molar ratios of epoxy groups to carboxylic acid groups ([EPOXY]/[ACID] ratios, mol mol⁻¹) was maintained at 1.0. The contents of SACPA and ALPA in the mixtures of SACPA/EGPA, and ALPA/EGPA, respectively, were also varied from 0 to 100 %. The curing reaction of SucPA and ALPA was studied by differential scanning calorimetry (DSC). Activation energy of the curing reaction for the SucPA system was 80.5 kJ/mol. Thermal properties of epoxy resins were studied by DSC. Glass transition temperatures (T_g) decreased with increasing numbers of repeating units in ester chains between cross-linking points, suggesting that ester chain lengths between cross-linking points mainly affect the mobility of ester chains in epoxy resin networks.     

High-Solids,Solvent-Free Modification of Engineered Polysaccharides

The nature-identical engineered polysaccharide α-(1,3) glucan, produced by the enzymatic polymerization of sucrose, was chemically modified by acylation with succinic anhydride. This modification reaction was initially performed at the micro scale in a TGA reactor to access a range of reaction conditions and to study the mechanism of the reaction. Subsequently, the best performing conditions were reproduced at the larger laboratory scale. The reaction products were characterized via coupled TGA/DSC analysis, FT-IR spectroscopy, solution viscosity and pH determination. The acylation path resulted in partially modifying the polysaccharide by altering its behavior in terms of thermal properties and solubility. The acylation in a solvent-free approach was found promising for the development of novel, potentially melt-processable and fully bio-based and biodegradable ester compounds.     

Controlled shrinkage polymers: Characterization of epoxy resins cured with spirobislactones

The diglycidyl ether of bisphenol A (DGEBA) was cured with either an aliphatic or an aromatic spirobislactone using a tertiary amine catalyst. The products were characterized by FTIR, TGA, DSC, dilatometry, and single-fiber adhesion measurements, and their performance was compared to that of DGEBA cured with acid anhydrides. Both aliphatic and aromatic bislactones are effective curing agents for DGEBA. FTIR and dilatometry confirm that both lactone rings open early in the curing reaction and initially offset shrinkage caused by polymerization. After the bislactone has been consumed, oxirane reactions proceed in a normal fashion. The final shrinkage of cured DGEBA polymers, with or without addition of bislactones, is 3.0–3.5%. Bislactone-modified materials possess superior thermal properties, when compared to those of anhydride-cured materials.     

Immobilization of pyrene on quartz plate surface via a flexible long spacer and its sensing properties to dicarboxylic acids

It is known that polycyclic aromatic hydrocar-bons (PAHs) form excimer easily, and show both monomer and excimer emission in polar medium[1]. This character comes from their hydrophobic nature and plane structures. The ratio of the intensity of ex-cimer emission to that of monomer emission is a func-tion of distance between neighbouring PAHs in a sys-tem. It is not difficult to understand that many factors, such as the concentration of PAHs, temperature, pres-ence and concentration of othe…     

Capillary GC Determination of Short-Chain Dicarboxylic Acids in Rain,Fog, and Mist

Abstract

A capillary GC and GC-MS method, employing dibutyl esters is described for determining short-chain dicarboxylic acids in rain, fog and mist samples collected in the Los Angeles area. Approximately twenty dicarboxylic acids (C₂-C₁₀) were identified in the water samples, including cis (maleic) and trans (fumaric) unsaturated, saturated, normal, branched and aromatic. Oxalic acid is the dominant acid, followed by succinic and malonic acids. The total concentrations measured are 2.9–51μM, 64–66 μM and 12 μM for rain, fog and mist samples, respectively. These diacids are probably produced by photooxidation of anthropogenic and possibly biogenic organic compounds in the atmosphere.     

Kinetics of Condensation Reactions between Ethanolamine (Amino‐Alcohol) and Dicarboxylic Acids at 413 K

The kinetics of condensation polymerization reactions between amino‐alcohol and various dibasic acids ranging from oxalic acid (n = 0 number of –CH₂ groups) to sebacic acid (n = 8) is studied at 413 K in an inert atmosphere, with a catalyst and ensuring removal of product water. All of the studied reactions are chemically identical, and their rates may differ only in so far as reactivity affected by molecular weight. Our analysis of the kinetic data reveals that all reactions obey third‐order kinetics, and the degree of polymerization increases even upto 20 h, if same stoichiometry for both the reactants is maintained. The velocity constants for the reactions were found to be in the order for the acids as succinic > oxalic > sebacic > adipic. The rates are also comparable to similar reactions of diols and diacids. The analysis further reveals that the chain length as well the structural characteristics of the reactant molecules govern the speed of the reaction. It seems that the proper conformations and structural geometry do play an important role in the collisional process of formation of products in a desired time. The probable implications of the results and analysis of these observations are discussed.     

Adsorption of dicarboxylic acids by clay minerals as examined by in situ ATR-FTIR and ex situ DRIFT

The adsorption of dicarboxylic acids by kaolinite and montmorillonite at different pH conditions was investigated using in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) and ex situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The sorption capacity of montmorillonite was greater than that of kaolinite. Adsorption of dicarboxylic acids (succinic acid, glutaric acid, adipic acid, and azelaic acid) was the highest at pH 4 as compared with those at pH 7 and 9. These results indicate that sorption is highly pH-dependent and related to the surface characteristics of minerals. The aliphatic chain length of the dicarboxylic acids highly influenced the sorption amount at acidic pH, regardless of the clay mineral species: succinic acid [HOOC(CH2)2COOH] < glutaric acid [HOOC(CH2)3COOH] < adipic acid [HOOC(CH2)4COOH] < azelaic acid [HOOC(CH2)7COOH]. With in situ ATR-FTIR analysis, most samples tend to have outer-sphere adsorption with the mineral surfaces at all tested pHs. However, inner-sphere coordination between the carboxyl groups and mineral surfaces at pH 4 was dominant from DRIFT analysis with freeze-dried complex samples. The complexation types, inner- or outer-sphere, depended on dicarboxylic acid species, pH, mineral surfaces, and solvent conditions. From the experimental data, we suggest that organic acids in an aqueous environment prefer to adsorb onto the test minerals by outer-sphere complexation, but inner-sphere complexation is favored under dry conditions. Thus, organic acid binding onto clay minerals under dry conditions is stronger than that under wet conditions, and we expect different conformations and aggregations of sorbed organic acids as influenced by complexation types. In the environment, natural organic material (NOM) may adsorb predominantly on positively charged mineral surfaces at the aqueous interface, which can convert into inner-sphere coordination during dehydration. The stable NOM/mineral complexes formed by frequent wetting-drying cycles in nature may resist chemical/microbial degradation of the NOM, which will affect carbon storage in the environment and influence the sorption of organic contaminants.     

Cure mechanism of novel bismaleimide resins based on fluorene cardo moiety and their thermal properties

In this paper, two novel bismaleimide resins based on 9, 9-bis[4-(4-maleimidophenoxy) phenyl] fluorene (PFBMI), 9, 9-bis[4-(4-maleimidophenoxy)-3-methylphenyl]fluorene (MFBMI), and 2, 2’-diallyl bisphenol A (DABPA) were prepared. Their curing mechanism and curing kinetic were carefully investigated by Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The thermal mechanical properties of the composites based on these BMI resins and the glass cloth were obtained by Dynamic mechanical analysis (DMA), displaying that the novel resins whose T_g were 296°C and 289°C had excellent thermal performance. In addition, Thermogravimetric analysis (TGA) results showed that both the cured PD and MD resins possessed good thermal stability, and their T_5% were all higher than 410°C.     

A fully biobased epoxy resin from vegetable oils: From the synthesis of the precursors by thiol‐ene reaction to the study of the final material

A novel vegetable oil‐based polyamine issued from grapeseed oil (GSO) was prepared using cysteamine chloride (CAHC) by thiol‐ene coupling (TEC). The structure of the polyamine oil (AGSO) was carefully examined using a large range of chemical analyses (FTIR, ¹H NMR and ¹³C NMR, LC‐MS…). The effects of the amination of GSO on the vegetable oil properties were also studied using viscosimetry. Then, AGSO was employed as a novel curing agent for bio‐based epoxy resin. The thermal crosslinking reaction between AGSO and epoxidized linseed oil (ELO) was studied by DSC and rheology. This study also dealt with the definition of the thermomechanical properties of the final material obtained by the mixing and curing of AGSO with ELO in stoichiometric proportions. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011