展望21世纪的高分子化学

回顾了高分子合成化学方法和高分子材料的发展历史,结合高分子化学的研究现状,展望了２１世纪的高分子化学的发展前景。     

抗氧剂在高分子领域的研究和应用

世界每年约生产高分子材料 2× 10 8t,它们中的大部份均要各种稳定剂来防止其老化。大量的有机物 (包括高分子、食用油脂、食品、石油制品和润滑油 )都存在氧化问题。防止这些有机材料氧化方法很多 ,但加入抗氧剂则是当今最有效和最有用的方法。本文介绍了抗氧剂的作用机理、最有效的组合、理想分子量、高分子抗氧剂、反应型抗氧剂、多功能抗氧剂和生物抗氧剂等方面的最近进展。近期抗氧剂发展倾向是无毒抗氧剂代替有毒抗氧剂 ,更注意合成理想分子量的、高分子化的、多功能化和反应型的抗氧剂 ,对生物抗氧剂也将更详细研究。除对抗氧剂在防护高分子热氧化外 ,在润滑油 ,食品工业和医疗保健中的应用也作了讨论。     

《离子交换与吸附》征稿简则

<正>《离子交换与吸附》是南开大学高分子化学研究所主办的反应性高分子学术期刊。本刊旨在反应国内外离子交换剂、吸附剂、高分子催化剂、高分子试剂、医用高分子材料以及其他功能高分子材料在科研、生产、应用和应用基础研究诸方面的进展和动向。     

绿色化学理念在高分子化学实验教学中的渗透

绿色化学是促进人类与自然和谐发展的化学,培养绿色化学意识是实现社会可持续发展的基本要求。高分子化学实验是高等院校高分子材料专业或材料化学高分子方向本科生开设的一门必修课,对学生进行绿色化学教育具有非常有利的条件。文章分析了在高分子化学实验课程中开展绿色化学教育的必要性与可行性;介绍了高分子化学实验教学中开展绿色化学教育的具体措施。通过绿色化学理念在高分子化学实验教学中渗透,在提高学生动手能力的同时,又增强了学生的绿色化学意识。     

导电高分子

介绍导电高分子的结构特征、基本物理性能和技术上应用前景;评价导电高分子领域突破性的研究进展和 ２１世纪导电高分子面临的挑战与机遇。     

《离子交换与吸附》征稿须知

《离子交换与吸附》是南开大学高分子研究所主办的反应性高分子学术期刊。本刊旨在反应国内外离子交换剂、吸附剂、高分子催化剂、高分子试剂、医用高分子材料以及其他功能高分子材料在科研、生产、应用和应用基础研究诸方面的进展和动向。     

CO2/生物基环氢化合物共聚制备绿色聚碳酸酯材料

以CO_2为原料合成脂肪族聚碳酸酯材料不仅利用了廉价、可再生的CO_2资源,而且可以实现全生物降解高分子材料的制备,是一条绿色可持续的高分子材料合成路线。但长期以来,该领域研究多集中在利用CO_2与一些石油来源的环氧烷烃(如环氧丙烷、环氧环己烷等)共聚方面,未能完全摆脱对石油资源的依赖。因此,发展基于生物基的环氧单体制备全生物基高分子材料逐渐成为CO_2基高分子材料研究的热点。生物基来源化合物的引入有助于丰富CO_2基高分子材料的结构和性能,拓展其应用领域。本文综述了近年来利用生物基环氧化合物与CO_2共聚合成全生物基高分子材料的研究进展,并对未来该领域发展的趋势进行了展望。     

•前言•生物医用高分子

“生物医用高分子”是生物材料的最重要组成部分, 是保障人类健康的必需品; 其应用不仅挽救了数以千万计人的生命, 提高了生命质量, 且对医疗技术和保健系统的革新、降低医疗费用也具有引导作用. 同时, 生物医用高分子又是高分子材料科学的重要分支, 是21世纪高分子材料科学, 特别是功能高分子或精细高分子领域内非常活跃而又重要的前沿发展方向. 作为一类生物材料, 在使用过程中必然与生理系统(血液、组织、细胞等)或其组成部分(蛋白、酶、DNA、多糖、无机盐和各类生物小分子)相接触, 因此其研究与发展与生命科学和医学也密切相关. 生物医用高分子的特征之一是生物功能性(biofunctionality), 即能够对生物体进行疾病诊断、组织替换或修复; 之二是生物相容性(biocompatibility), 即材料引起适当的机体反应的能力, 是区别于其他高技术材料的最重要的特征, 包括不引起生物体组织、血液等不良反应. 现代医学的进步与生物材料的发展密不可分, 如各种介入诊断和治疗导管、药物传递控释系统、创伤和烧伤敷料、血管内支架、人工关节与功能性假体等已得到广泛的应用. 但是, 生物医用高分子材料涉及化学、材料、生物、医学以及物理等诸多学科领域, 其使用又与生理系统相接触, 因此该材料的研究与开发具有相当的难度和挑战.     

聚丙烯酰胺分子量对其Hofmann反应的影响

协同效应;高分子效应;聚丙烯酰胺分子量对其Hofmann反应的影响     

金属主链高分子的量子化学计算

金属主链高分子是一类完全以金属原子作为主链的新材料,在光电、传感、电化学储能等领域都具有重要的应用前景.但是,如何获得具有较高分子量的金属主链高分子,仍然是一个挑战.本文通过密度泛函理论计算方法,对镍金属主链高分子进行了结构优化和稳定性分析,发现随着聚合物分子量的增加,镍金属主链高分子的单点能逐渐降低,说明高分子量的金属主链高分子具有稳定的分子构型.但是,随着分子量的进一步提高,计算量显著增加,密度泛函理论计算方法收敛困难.为此,本文进一步通过Hartree-Fock计算方法对该系列镍金属主链高分子进行了分子构型优化,得到了与密度泛函理论计算结果相似的规律,并且发现当分子量超过1×10⁴时,金属主链高分子仍然具有较高的结构稳定性.此外,这种电子离域在整个金属主链上的独特金属-金属的相互作用有利于实现电荷的高效传输;以金属原子为重复单元的分子结构,有望实现金属和高分子材料性能的有效结合,可以获得较高的热失重温度和熵弹性.     

聚苯硫醚及其碳纤维复合材料结晶动力学的研究

用膨胀计法研究了聚苯硫醚及其碳纤维复合材料的结晶动力学行为。发现其碳纤维复合材料对Avrami方程有较明显的偏离。聚苯硫醚具有中等的结晶速率,与PE、PMO等高聚物比较,它的σσ_c值、堆砌系数K_c以及结晶动力学方程中的前置指数G_0值较低。G_0是决定高聚物结晶速率的主要因素,ρ_a/ρ_c(值较小的高聚物有可能出现较高的结晶速率。     

Optical properties of low band gap alternating copolyfluorenes for photovoltaic devices

In a joint experimental and theoretical work the optical response and excited-state character of two novel conjugated polymers for photovoltaic applications are studied. The polymers, alternating polyfluorene (APFO) Green 1 and APFO Green 2, are both copolymers of fluorene, thiophene, and electron accepting groups. The band gaps are extended into the red and near infrared with onsets of 780 and 1000 nm, respectively, due to alternating donor and acceptor moieties along the polymer chain. Spectroscopic ellipsometry and subsequent modeling made it possible to extract the dielectric function in the range of 260-1200 nm. Semiempirical quantum chemical calculations (ZINDO) revealed the character of the main electronic transitions in the studied spectral region. The spectral band just above 400 nm was assigned to a delocalized pi-pi* transition for both polymers. The red band lying at 622 and 767 nm in the two polymers corresponds to an electronic state mainly occupying the acceptor units and having a strong charge-transfer character. We show that the ZINDO transition energies are valuable input to the application of Lorentz oscillators in modeling of the dielectric function of the polymer material.     

Treatment of aperiodicity and correlation in polymers

The negative factor counting method (in its simple and matrix block form) for the determination of the density of states of disordered polymer chains and its applications to different aperiodic organic polymers are reviewed. The problems of the calculation of the correlation energy in large systems like polymers will be discussed. Different ways for the partitioning of an energy band into regions make it possible to perform Møller–Plesset perturbation theoretical calculations on polymers. Applications to hydrogen chains are presented. Finally, possible applications to disordered polymers are also discussed.     

Green-emitting Polyfluorenes Containing Hexylthiophen-dibenzothiophene-<Emphasis Type="Italic">S</Emphasis>,<Emphasis Type="Italic">S</Emphasis>-dioxide Unit with Large Two-photon Absorption Cross Section

Green light-emitting polyfluorenes containing 3,7-bis(4-hexylthiophen-2-yl)dibenzo[b,d]thiophene 5,5-dioxide (DHTSO) unit were synthesized.All the resulted polymers show high thermal stability with the decomposition temperatures (Td) over 420 ℃ and the glass transition temperatures (Tg) over 75 ℃.The polymers exhibit the enhanced highest occupied molecular orbital (HOMO) energy levels and the depressed lowest unoccupied molecular orbital (LUMO) energy levels with the increase of DHTSO unit in polymers.The photoluminescence (PL) spectra of the polymers show positive solvatochromism in solution with the variation of solution polarities,indicating remarkable intramolecular charge transfer (ICT) effect in the polymers containing DHTSO moiety.The fluorescence quantum yields (ΦPL) are in the range of 34％-67％ for PF-DHTSOs in film.All polymers possess two photon absorption (TPA) properties,and the TPA cross sections (δ2) are enhanced with increasing DHTSO unit in polymers.The highest δ2 is 2392 GM for PF-DHTSO 15 in chloroform solution upon 740 nm excitation.The device of PF-DHTSO15 shows green emission with the Commission Intemationale de L'.Eclairage (CIE) coordinates of (0.26,0.59),and the maximum luminous efficiency (LEmax) of 10.8 cd·A-1 with the configuration of ITO/PEDOT:PSS/EL/CsF/Al.These results indicate that introducing DHTSO unit into polyfluorene backbone could be a promising molecular design strategy for TPA and effective green-light emission.     

Natural Polymers-Based Materials: A Contribution to a Greener Future

Natural polymers have emerged as promising candidates for the sustainable development of materials in areas ranging from food packaging and biomedicine to energy storage and electronics. In tandem, there is a growing interest in the design of advanced materials devised from naturally abundant and renewable feedstocks, in alignment with the principles of Green Chemistry and the 2030 Agenda for Sustainable Development. This review aims to highlight some examples of the research efforts conducted at the Research Team BioPol4fun, Innovation in BioPolymer-based Functional Materials and Bioactive Compounds, from the Portuguese Associate Laboratory CICECO–Aveiro Institute of Materials at the University of Aveiro, regarding the exploitation of natural polymers (and derivatives thereof) for the development of distinct sustainable biobased materials. In particular, focus will be given to the use of polysaccharides (cellulose, chitosan, pullulan, hyaluronic acid, fucoidan, alginate, and agar) and proteins (lysozyme and gelatin) for the assembly of composites, coatings, films, membranes, patches, nanosystems, and microneedles using environmentally friendly strategies, and to address their main domains of application.     

Phosphorescence quenching by conjugated polymers

Energy transfer between phosphors and conjugated polymers was investigated using a fluorene trimer (F3) as a model conjugated material. The phosphors studied were bis-cyclometalated iridium complexes (FP, PPY, BT, PQ, and BTP), with triplet energies of 2.6, 2.4, 2.2, 2.1, and 2.0 eV, respectively (based on phosphorescence spectra). Stern-Volmer analysis of luminescent quenching shows that energy transfer from either FP or PPY to F3 is an exothermic process with Stern-Volmer quenching constants (kqSV) of near 109 M-1 s-1 while energy transfer from BT, PQ, and BTP is endothermic (kqSV = 107-106 M-1 s-1). On the the basis of above results, the triplet energy of F3 is estimated to be less than 2.3 eV (530 nm). This study suggests that conjugated polymers, which typically have lower T1 energies than F3, should also quench phosphorescent emission in thin films and organic light-emitting diodes (OLEDs) incorporating these and related phosphorescent dopants.     

Fracture mechanics analysis of arc shaped specimens for pipe grade polymers

Instrumented three-point bend impact fracture tests are widely used to evaluate pipe grade polymers. Often specimens cut from small-diameter pipe are used, and these are necessarily arc-shaped. Because the orientation and thermal history may differ between extruded pipe and compression moulded plaque material, this additional difference in geometry must be properly accounted for, or it may mask any effects on material properties. This paper modifies a previously published solution for the geometry-dependent energy correction factor for arc-shaped specimens, and extends it to a wider range of standard pipe geometries. When the results are properly corrected, the effects of processing on a commercial PE100 appear to be minor.     

可持续高分子-纤维素新材料研究进展

21世纪"绿色"化学已成为世界各国社会经济发展中的研究与开发战略方向.纤维素是自然界中储量最丰富的天然高分子,是重要的可再生资源以及未来的主要工业原料.然而由于纤维素存在着大量的分子内以及分子间氢键,其结构致密,难以溶解或熔融进一步加工.本文简要介绍了近几年来关于直接使用物理溶剂方法(非衍生化)对纤维素材料开发利用的新进展,主要包括以下4个方面:(1)纤维素在"绿色"溶剂-碱/尿素以及离子液体体系中的溶解和再生;(2)纳米纤维素的制备以及组装;(3)木材纳米技术的开发及利用;(4)细菌纤维素基材料等,旨在推进"绿色"技术实现纤维素资源的研究开发及利用.     

Zwitterionic Polymeric Sulfur Ylides with Minimal Charge Separation Open a New Generation of Antifouling and Bactericidal Materials**

Zwitterionic polymers are widely employed hydrophilic building blocks for antifouling coatings with numerous applications across a wide range of fields, including but not limited to biomedical science, drug delivery and nanotechnology. Zwitterionic polymers are considered as an attractive alternative to polyethylene glycol because of their biocompatibility and effectiveness to prevent formation of biofilms. To this end, zwitterionic polymers are classified in two categories, namely polybetaines and polyampholytes. Yet, despite a fundamental interest to drive the development of new antifouling materials, the chemical composition of zwitterionic polymer remains severely limited. Here, we show that poly(sulfur ylides) that belong to the largely overlooked class of poly(ylides), effectively prevent the formation of biofilms from pathogenic bacteria. While surface energy analysis reveals strong hydrogen-bond acceptor capabilities of poly(sulfur ylide), membrane damage of pathogenic bacteria induced by poly(sulfur ylides) indicates toxicity towards bacteria while not affecting eucaryotic cells. Such synergistic effect of poly(sulfur ylides) offers distinct advantages over polyethylene glycol when designing new antifouling materials. We expect that our findings will pave the way for the development of a range of ylide-based materials with antifouling properties that have yet to be explored, opening up new directions at the interface of chemistry, biology, and material science.     

Recent advances in epoxy resins and composites derived from lignin and related bio-oils

This short critical review gives an insight on the potential that lignin and its bio-oils present towards the production of thermosetting epoxy polymers and composites. Green and sustainable ways of producing monomers and polymers from renewable sources are critical and lignin, as an underutilized bio-based waste material, presents a high exploitation potential. Due to its versatile and highly functional phenolic structure, the utilization of lignin or its depolymerized fractions (bio-oils) has been investigated in the last years as alternative for fossil-based epoxy resin pre-polymers and crosslinkers. Lignin can in fact be considered as a crosslinker for epoxy resins, especially after appropriate functionalization with amine groups or with additional hydroxyl groups, or it can be modified with epoxide groups towards the replacement of toxic BPA-based epoxy prepolymers. Furthermore, lignin derived pyrolysis or hydrogenolysis bio-oils may offer highly reactive soluble oligomers that after appropriate functionalization could be utilized as bio-based epoxy prepolymers. The lignin-based epoxy resins and composites exhibit similar or even better and novel properties, compared to those of pristine epoxy polymers, thus rendering lignin a highly valuable feedstock for further utilization in the thermoset polymer industry.