聚对苯二甲酸-2,5-呋喃二甲酸乙二醇无规共聚酯的合成与表征

以对苯二甲酸、2,5-呋喃二甲酸(FDCA)和乙二醇为原料,钛酸四丁酯为催化剂,采用直接酯化法,通过改变对苯二甲酸与2,5-呋喃二甲酸摩尔比合成了一系列高分子量线性聚对苯二甲酸-2,5-呋喃二甲酸乙二醇无规共聚酯(PEFT).运用1H-NMR和13C-NMR表征并确立了共聚酯的结构,XRD结果显示该系列共聚酯在原生态状态下均为无定形聚集态结构,DSC结果表明该系列共聚酯只有一个玻璃化转变温度(73.3～84.2℃),介于PET和PEF之间,随着PEF含量的增加而增大.TGA结果显示该系列聚酯具有良好的热稳定性,起始热分解温度高于390℃,介于PET和PEF之间.拉伸测试结果表明共聚酯的组成对其力学性能有影响,其中PEFT-10,PEFT-70和PEFT-90的力学性能较好,优于PET.     

聚2,5-呋喃二甲酸乙二醇酯的合成与表征

以2,5-呋喃二甲酸和乙二醇为原料,草酸亚锡为催化剂,通过直接酯化法合成了线性高分子量聚2,5-呋喃二甲酸乙二醇酯(PEF).运用红外光谱(FTIR)和核磁共振氢谱(1H-NMR)表征了该聚酯的结构;由乌氏黏度计法和凝胶渗透色谱(GPC)建立了该聚酯在一种混合溶剂体系中特性黏数和重均分子量的关系:[η]=2.82×10-6Mw0.99dL/g,25℃,苯酚-四氯乙烷(1∶1,W/W);示差扫描量热法(DSC)和热失重分析(TGA)测定了该聚酯的热转变性能,结果表明该聚酯玻璃化转变温度为84℃,熔点为211℃,起始热分解温度高于370℃,具有良好的热稳定性;运用旋转流变仪研究了PEF的流变性能,结果表明,PEF熔体属于假塑性流体,随相对分子量的减小和温度升高,其非牛顿指数增大,在高于PEF熔点20～40℃,剪切速率为2.17×10-2～1.14×102s-1时,PEF的非牛顿指数为0.85左右.     

呋喃基聚酯的结构与性能关系研究进展

呋喃基聚酯是指以2,5-呋喃二甲酸(FDCA)为主要单体合成的生物基或部分生物基高分子,其主链含有刚性的呋喃环,因而在结构、性能上与大规模使用的传统石油基芳香族聚酯(如PET、PBT)相似,有望在瓶、片、薄膜、化纤等领域部分替代后者。本文综述了呋喃基聚酯的分子结构、聚集态结构以及力学、气体阻隔、降解等性能方面的最新研究进展,讨论了结构与性能之间的关系。重点关注呋喃基聚酯突出的阻隔性能及其对应的影响因素,主要从分子结构(呋喃环的非对称性和极性)和聚集态结构(结晶等)两方面加以阐明。简介了呋喃基聚酯的发展现状及其在包装、纺织等领域的潜在应用,并展望其主要研究趋势。     

运用1H-NMR和13C-NMR研究聚对苯二甲酸-2,5-呋喃二甲酸乙二醇共聚酯（PEFT）的序列结构

采用直接酯化法,通过改变对苯二甲酸(PTA)与2,5-呋喃二甲酸(FDCA)的摩尔比,制备了一系列聚对苯二甲酸-2,5-呋喃二甲酸乙二醇共聚酯(PEFT)。运用1H-NMR和13C-NMR测试手段研究PEFT共聚酯的链结构。通过观察PEFT共聚酯链上乙二醇单元中氢原子和碳原子的化学位移及相应的4种信号的强度变化,计算出共聚酯的数均序列长度(L),无规度值(B)和共聚物的组成。通过Yamadera和Murano公式计算所得共聚酯无规度值B均接近于1,说明PEFT共聚酯为无规共聚物;PEF-block-PET嵌段共聚物B为0.577,PEF-blend-PET共混物的B为0;差示扫描量热仪(DSC)测试结果表明,0PEFT共聚酯均有一个玻璃化温度,进一步说明了PEFT共聚酯为无规共聚物。其中PTA∶FDCA的摩尔比为1∶1时,即PEFT-50,B值最大,基于1H-NMR谱图计算得B=1.012,13C-NMR谱图计算得B=1.028。上述结果表明,2,5-呋喃二甲酸与对苯二甲酸在与乙二醇的亲核取代反应中活性相近。     

生物基聚酯单体2,5-呋喃二甲酸的制备及应用研究进展

化石资源的巨量使用所带来的环境污染、气候变暖和资源能源危机等问题已日益成为全球学术界和产业界关注的焦点,发展绿色可再生生物质资源是当今研究的重中之重.2,5-呋喃二甲酸(FDCA)作为最有价值的生物基平台化合物之一,逐渐受到广泛关注.综述了化学法和生物法制备FDCA的研究进展,介绍了FDCA在聚酯、聚酰胺、金属有机骨架材料、药化合成、增塑剂等方面的应用,并对应用前景和研究趋势进行了展望.     

含呋喃环生物基聚酰胺的合成

随着环境保护和化石资源问题的日益严峻,开发基于可再生生物质资源的生物基高分子材料,成为未来的发展趋势。作为最具有价值的生物基平台化合物之一,呋喃二甲酸及其衍生物可用于制造精细化学品和高分子材料。近年来,通过熔融聚合、溶液聚合、界面缩聚和固相缩聚等方法,将呋喃二甲酸及其衍生物与二元胺反应,制备出不同结构的生物基聚酰胺的均聚物和共聚物。本文从单体、聚合方法、聚合物结构和性能等方面,对含呋喃环生物基聚酰胺的合成作一总结,同时对这一领域的前景和挑战进行了探讨。     

FDCA基聚酯的合成、性能及应用研究进展

生物质资源是一种储量丰富的可再生资源。生物质资源的高效利用不仅具有非常巨大的经济和生态价值,而且对新能源与生物基合成材料的可持续发展战略具有重大意义。由植物纤维素等生物质材料经生物或者简单化学过程处理,可获得丰富的生物基单体2,5-呋喃二甲酸(FDCA)。FDCA可用于生物基聚酯材料的合成。FDCA系列聚酯材料性能优异,可作为由石油基单体对苯二甲酸(PTA)而合成的芳香族聚酯材料(例如PET)的一种潜在的高性能生物可降解替代材料。本文简要说明了生物基单体FDCA的物性及制备方法,并重点阐述了包括聚呋喃二甲酸乙二酯(PEF)与聚呋喃二甲酸丁二酯(PBF)等一系列FDCA基聚酯材料的合成及性质,同时对FDCA基聚酯材料的应用进展进行了简要介绍,最后对FDCA基聚酯生物基合成材料的发展前景作了初步展望。     

达格列净呋喃环杂质的合成

以5-溴-2-氯-4′-乙氧基二苯甲烷为原料，与2,3-二-O-叔丁基二甲基硅基-5,6-O-异亚丙基-D-葡糖醛酸-1,4-内酯缩合后，再经还原、脱保护、酯化及水解反应合成了达格列净呋喃环杂质--(1S)-1,4-脱水-1-(4-氯-3-(4-乙氧基苄基)苯基)-D-葡萄糖，总收率29.0%，纯度98.5%，其结构经¹H NMR，¹³C NMR， DEPT135，¹H-¹H COSY， HSQC， HMBC和MS(ESI)确证。     

HMF催化合成生物基聚酯单体FDCA

在石油资源日渐紧缺的背景下,充分利用自然界中可再生的生物质资源无疑是缓解当前和未来资源危机的有效手段,基于生物质平台分子的绿色化工正在逐渐替代传统石化产品的生产模式。来源于生物质的5-羟甲基糠醛(HMF)经过催化氧化可合成高附加值化学品2,5-呋喃二甲酸(FDCA)。FDCA是生产绿色聚合物聚2,5-呋喃二甲酸乙二酯(PEF)的重要单体。综合近年来利用热、电、光与生物催化模式进行的HMF氧化研究成果,热催化在产率与产品纯度方面显示出明显优势,但其对高能耗与高氧压的依赖限制了在工业中的应用。以电催化和光催化为基础的催化模式能够高效利用电能和太阳能,氧化活性物种丰富可调,有广阔应用前景。此外,生物催化模式虽目前产率较低,但具有反应条件温和、选择性高的突出特点,是未来有效利用生物质资源的重要发展方向。本文对氧化途径与相应反应机理进行讨论,并全面地总结了目前由HMF催化氧化生产FDCA的研究现状,包括已取得的进展与将面临的挑战,最后对未来发展方向与前景进行了展望。     

碳纳米管负载钯基催化剂催化氧化2,5-呋喃二甲醇合成2,5-呋喃二甲酸

为积极应对化石能源枯竭和生态环境日益严峻等问题,可再生生物质资源的深度开发并进一步替代传统能源或石化原料被广泛认可.利用高效催化技术将生物质资源转化为高附加值的平台化合物,有望衍生出大量具备新颖结构与功能的绿色化学品.2,5-呋喃二甲酸(FDCA)作为重要的生物质基平台化合物之一,具有巨大的市场应用价值,其中因其与化石基对苯二甲酸(PTA)有着极其相似的化学结构,以FDCA替代PTA作为合成单体制备大宗聚合物备受关注.以5-羟甲基糠醛(HMF)为原料,采用多相催化体系(主要是贵金属催化剂)选择氧化制备FDCA是目前广泛采用的方法.但“HMF路线”面临一些基础性的难题,如HMF熔点较低,需低温存储,增加了实际应用中的运输成本;HMF在碱性溶液中易降解,导致反应过程中碳平衡损失;HMF结构中含有的不对称的羟基和醛基官能团在氧化反应中会发生竞争反应,致使反应副产物较多;此外,碱性反应介质中通常会得到醛基优先氧化的中间体5-羟甲基-2-呋喃甲酸(HMFCA),但由于HMFCA结构中羧基官能团的存在使得羟基进一步氧化较为困难,通常需要增加碱浓度、提升温度或压力,使反应条件变得苛刻.因此,寻求新的原料替代HMF,实现温和条件下高效合成FDCA具有重要意义.本文采用改性后的碳纳米管负载Pd催化剂(Pd/o-CNT),从具有独特对称结构的2,5-二羟甲基呋喃(BHMF)出发,提出一种新颖、高效催化合成FDCA的“BHMF路线”.反应在60°C常压下进行,BHMF在20 min内即可完全转化,60 min后FDCA的产率最高可达93.0%,优于相同条件下HMF为原料时的性能(FDCA产率仅为35.7%).相比于未作处理的碳纳米管负载钯催化剂(Pd/CNT),Pd/o-CNT催化剂具有更高含量的氢化钯(PdH_x)物种,显著促进了FDCA产率的提升.Pd/o-CNT在循环使用10次后,BHMF仍能完全转化,FDCA产率维持在75%.稳定性下降可能与活性物种流失、团聚及价态变化有关.基于对照试验,本文提出了可能的反应路径,即BHMF主要是通过2,5-二甲酰基呋喃和5-甲酰基-2-呋喃甲酸作为过程中间体,有效转化为FDCA,从而规避并减少生成HMF和活性较低的HMFCA.本文通过以新原料BHMF作底物,实现了高效制备生物基平台化合物FDCA,为生物质的产业化应用提供了新的研究思路.     

Hyperbranched Polyesters Based on Adipic Acid and Glycerol

Summary: Hyperbranched polyesters with controlled molecular weights and properties have been prepared by an A₂ + B₃ approach by reacting glycerol and adipic acid without any solvents in the presence of tin catalysts. The hyperbranched polyesters have been evaluated by size exclusion chromatography (SEC) analysis and NMR spectroscopy in order to determine molecular weights and degrees of branching.

Idealized structure of the hyperbranched polyesters synthesized here from adipic acid and glycerol in the presence of tin catalysts.     

Preparation and Thermal Investigation of Renewable Resource Based Terpolymer Bearing Furan Rings as Pendant Groups

Condensation of renewable resources based monomer 2-formylfuran (FF), vanillin (V) and 4-hydroxyacetophenone (HA) at 80°C by polycondensation in the presence of alkaline conditions (potassium hydroxide) gives an amorphous polymer resin in 85% yield. The structure of terpolymer was elucidated by FT-IR, ¹H-NMR and Pyrolysis GC-MS technique. The number average and weight average molecular weight and polydispersity index of the terpolymer were found to be 5,595 and 8,504 g/mol and 1.52, respectively by gel permeation chromatography (GPC). The phase transition temperature was determined by differential scanning calorimetry (DSC). Apparent activation energies of the thermal decomposition of terpolymer were determined using isoconversional Flynn-Wall-Ozawa (FWO) method. The type of solid-state mechanism has been established by Craido method is proposed to be D₃ (three-dimensional diffusion). The terpolymer strongly inhibited the growth of a wide variety of microorganisms, including gram-positive bacteria, gram-negative and fungi. This newly developed terpolymer furan resin may be an exciting intermediates material for the construction of 3D-designed structural products.     

Click Polyester: Synthesis of Polyesters Containing Triazole Units in the Main Chain by Click Chemistry and Improved Thermal Property

A “click” polymerization of dialkynes that contain an ester linkages and diazides to has been performed to synthesize various polyesters, termed “click polyesters” with a high of 1.0 × 10⁴ to 7.0 × 10⁴ in an excellent yield. This polymerization accompanied a formation of 1,4‐disubstituted triazoles in the polyester main chain by a Cu^I catalyst. The triazole ring formation in the polyester main chain leads to improved thermal properties and enhancement of the even–odd effect of methylene chain length of the produced click polyesters. This report is the first report of the application of click chemistry to synthesize a series of polyesters under mild conditions.

     

Novel Aliphatic Polyesters Based on Functional Cyclic (Di)Esters

Recent progress in the chemical synthesis of novel aliphatic polyesters via ring‐opening polymerization of functional cyclic (di)esters are reviewed in this article. Syntheses of these functional aliphatic polyesters are being classified into three groups according to the structure of the cyclic monomers: (i) cyclic diesters, (ii) morpholine‐2,5‐dione derivatives, and (iii) cyclic esters. Progress in the synthesis and polymerization of monomers in each category is reported with an emphasis on controlled synthesis. The recent achievements have enabled the synthesis of a variety of novel aliphatic polyesters, including hydrophilic, halogenated, and unsaturated polyesters.

Structure of the most common R‐functionalized cyclic precursors of aliphatic polyesters.     

One‐Pot Synthesis of 2,5‐Furandicarboxylic Acid from 2‐Furoic Acid by a Pd‐catalyzed Bromination–Hydroxycarbonylation Tandem Reaction in Acetate Buffer

The one‐pot synthesis of 2,5‐furandicarboxylic acid from 2‐furoic acid with a yield of 57 % was achieved for the first time using a Pd‐catalyzed bromination‐hydroxycarbonylation tandem reaction in HOAc‐NaOAc buffer. This synthetic protocol shows major improvements compared to previously reported methods, such as using biomass‐based 2‐furoic acid as low‐cost raw material, one‐pot synthesis without isolation of intermediate products, and no need for an acidification procedure. Experiments indicate that the involved Xantphos‐modified Pd‐catalyst and the buffer solution play significant promoting roles for each individual reaction whereas Br₂ (as the brominating reagent) had a negative effect on the second hydroxycarbonylation step, while CO was deleterious for the first bromination step. Hence, in this practical one‐pot synthesis, Br₂ should be consumed in the first bromination step as fully as possible, and CO is introduced after the first bromination step has been completed.     

Preliminary Study on Lipase-catalyzed Synthesis of Polyesters Containing L-Malic Acid Units

Optically active L-malic acid has been known as an intermediate among the tricarboxylic acid cycle inside living organisms, and thus has been recognized as a kind of C-4 renewable natural resource. Poly(malic acid) and the polyesters containing L-malic ac…     

Luminescent Solar Concentrators Based on Renewable Polyester Matrices

This study reports for the first time the use of bio‐based alternatives for PMMA as host matrix for luminescent solar concentrators (LSCs). Notably, two types of renewable polyesters were synthesized in varying molar ratios via a two‐step melt‐polycondensation reaction with dibutyl tin oxide as catalyst. The first is a homopolymer of diethyl 2,3:4,5‐di‐O‐methylene galactarate (GxMe) and isosorbide (IGPn), and the second is a random copolymer of GxMe with 1,3‐propanediol and dimethyl terephthalate (GTPn). The two polyesters were found to be optically transparent, totally amorphous with a T_g higher than 45 °C and temperature resistance comparable to PMMA. Lumogen Red (LR) and an aggregation‐induced emission (AIE) fluorophore, TPETPAFN, were utilized as fluorophores and the derived thin polymer films (25 μm) were found highly homogeneous, especially for those prepared from GTPn, possibly due to the presence of compatibilizing terephthalate units in the matrix composition and the higher molecular weight. The spectroscopic characterization and the optical efficiency determination (η_opt) evidenced LSCs performances similar or superior to those collected from LR/PMMA thin films. Noteworthy, η_opt of 7.7 % and 7.1 % were recorded for the GTPn‐based matrix containing LR and TPETPAFN, respectively, thus definitely supporting the bio‐based polyesters as renewable and highly fluorophore‐compatible matrices for high‐performance LSCs.     

电催化氧化制备2,5-呋喃二甲酸

在第75届联合国大会上,我国承诺力争在2030年前实现碳达峰、2060年前实现碳中和。主要由光合作用产生的生物质将在双碳目标中扮演重要角色,通过高效转化可衍生出一系列替代化石产品的高值化学品。其中,2,5-呋喃二甲酸(FDCA)由于具有与石油基对苯二甲酸(TPA)相似的共轭碳环和二酸结构,可替代TPA用于合成热稳定性能、气体阻隔性能更优的生物基呋喃聚酯,大幅降低聚酯行业对化石资源的严重依赖。此外,FDCA在医药、香料、金属配位化学方面也有广泛应用,从而被认为是12种最具潜力的生物基平台化合物之一。FDCA通常可由5-羟甲基糠醛(HMF)通过催化氧化进行合成。相比于需要贵金属催化剂、高温和高压条件、以化学势作为驱动力的传统热催化方法,电催化氧化采用电极电势作为主要驱动力,是更为绿色和高效的新颖合成方法。本综述对电催化氧化制备FDCA反应所用的贵金属、过渡金属和非金属催化剂进行了总结与分析,梳理了催化剂设计和反应机理的研究脉络,并指出了该领域发展所面临的挑战与机遇。     

Novel Molecular Resist Based on a First Generation Dendrimer Possessing Furan Rings

Summary: A novel chemically amplified negative‐tone molecular resist for electron‐beam (EB) lithography was developed. The base matrix had six furan rings as a reactive functional group at its terminal. The resist containing the matrix, a crosslinker and a photoacid generator worked well as a negative‐tone resist with high sensitivity (3 µC · cm⁻²). Line and space patterns (1:2) of 200 nm could be fabricated.

SEM image of negative‐tone line and space patterns for the resist film formulated with G1‐dendrimer 5 .