脂肪族聚碳酸酯共聚物的研究进展

脂肪族聚碳酸酯共聚物是一类可完全生物降解的新型材料,自1969年井上祥平等首次通过二氧化碳与环氧化合物反应合成脂肪族聚碳酸酯以来,人们在将二氧化碳固定为全降解聚合物这一研究领域取得了大量研究成果.本文综述了用于二氧化碳和环氧化合物共聚合成脂肪族聚碳酸酯的各类催化剂及反应机理,讨论了脂肪族聚碳酸酯结构/性能关系,并简要介绍了其在不同领域的应用.     

二氧化碳与环氧化合物直接制备聚碳酸酯

综述了近几年来发展的用于二氧化碳与环氧化合物直接催化合成聚碳酸酯的各类催化剂,并详细讨论了其催化反应机理.利用二氧化碳与环氧化合物来合成聚碳酸酯,对于高分子合成化学、碳资源利用和环境保护都具有重大意义.它是发展聚碳酸酯生产的一个具有很大潜力的方面.     

二氧化碳与环氧环己烷共聚的研究进展

综述了国内外用于二氧化碳与环氧环己烷共聚的各类催化剂的研究现状、进展及研发新动向.指出二氧化碳作为一种廉价、无毒、可循环利用的理想原料,利用其和环氧环己烷共聚可合成具有良好生物降解性能的脂肪族聚碳酸酯.但二氧化碳具有较高的热力学稳定性,其和环氧环己烷共聚过程在一般情况下难以实现,故迫切需要开发高效、高选择性的催化剂.     

二氧化碳与环氧化合物的三元共聚反应

用二氧化碳与环氧化合物共聚合反应制备脂肪族聚碳酸酯,是近几年化学利用二氧化碳研究的重要课题之一.其中最受关注的是二氧化碳与环氧丙烷共聚制备聚碳酸丙烯酯(PPC)和二氧化碳与环氧环己烷共聚制备聚碳酸环己烯酯(PCHC).但是,PPC和PCHC的热性能和力学性能欠佳,限制了它们的规模化生产与应用.利用二氧化碳与环氧化合物进行三元共聚是改善二氧化碳共聚物材料热性能和力学性能的有效途径之一,本文对此项研究的新进展进行了综述.     

二氧化碳合成脂肪族聚碳酸酯

介绍了二氧化碳合成脂肪族聚碳酸酯（APC）的合成工艺、催化剂体系、物理化学性能以及改性,并阐述了共聚物性质和应用前景。     

三亚甲基碳酸酯基响应性脂肪族聚碳酸酯的研究进展

脂肪族聚碳酸酯是一类可生物降解、生物相容性的材料,在生物医药方面引起广泛关注。两亲性脂肪族聚碳酸酯聚合物中,聚碳酸酯部分凭借其疏水性能处于胶束内核部位,且该部分通过物理包覆、化学键合等方式使聚合物与药物相结合,提升了响应环境下药物运输与释放的方式与能力。因此,本工作对近年来响应性脂肪族聚碳酸酯的研究进展进行了综述,主要阐述了具有外环境刺激响应(pH、光、温度和氧化还原)脂肪族聚碳酸酯的合成、响应原理、在药物传递和释放方面的应用。     

脂肪族聚碳酸酯及其在医学中的应用

脂肪族聚碳酸酯具有优良的生物降解性、生物相容性和可功能化性等特点,近十几年来在生物医学领域得到了迅速发展。结合本实验室对生物可降解脂肪族聚碳酸酯的研究工作以及国内外研究现状,根据高分子链的几何形状对脂肪族聚碳酸酯进行了分类介绍,综述了它们的合成方法及其在生物医学领域中的应用,同时展望了脂肪族聚碳酸酯的未来发展趋势。     

聚碳酸亚环己酯及其制备技术研究进展

二氧化碳既(CO₂)是令人头疼的温室气体,更是有价值的碳资源,因此二氧化碳的固定和利用具有重要的理论与现实意义。以二氧化碳和环氧环己烷为原料合成的聚碳酸亚环己酯(PCHC)是一种新型的脂环类可生物降解聚酯材料,相比传统的二氧化碳-环氧烷聚合物,其机械和耐热性能更为优良,有望拓展脂肪类聚碳酸酯的使用范围。本文对PCHC的基本性能及潜在应用领域、合成工艺路线以及交替共聚反应催化剂的发展进行了综述,以期为优质PCHC材料的高效制备提供参考。     

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。     

二氧化碳/1,2-环氧丁烷/ε-己内酯的三元共聚合和表征

以高聚物负载型双金属负离子配位化合物PBM为催化剂,通过二氧化碳(CO2),1,2-环氧丁烷(BO)与ε-己内酯(CL)的三元开环共聚合反应,得到三元共聚物,脂肪族聚碳酸酯(PBCL).对PBCL进行了FTIR1、H-NMR1、3C-NMR、DSC和WAXD等表征,并考察了反应单体比例及反应时间对共聚物性能的影响.结果表明,由于ε-己内酯开环共聚,引入了易水解的羧酸酯单元,PBCL的降解速度和玻璃化转变温度较二氧化碳-环氧丁烷的二元共聚物(PBC)得到了有效地提高.同时,PBCL相对于聚己内酯(PCL)玻璃化转变温度和降解速度明显改善,且PBCL为非晶结构.     

二氧化碳与环氧化物共聚催化剂

综述了二氧化碳与环氧化物共聚催化剂方面的研究进展，重点介绍了90年代后期出现的新型高效率的高位阻型催化剂。     

Tetravalent metal complexes as a new family of catalysts for copolymerization of epoxides with carbon dioxide

New tetravalent metal complexes with a trianionic [ONNO]-tetradentate ligand and an ancillary chloride ligand were synthesized as catalysts for the copolymerization of epoxides with carbon dioxide (CO(2)). All of the titanium, zirconium, germanium, and tin complexes were found to copolymerize epoxides with CO(2). In particular, the copolymerization of propylene oxide with CO(2) gave the almost-completely alternating copolymers by using titanium or germanium complexes. These results are the first example of the copolymerization using tetravalent metal complexes as a main component of catalysts.     

Synthesis and properties of carbon dioxide – epoxides copolymers from rare earth metal catalyst

Ternary rare earth metal coordinate was used to the copolymerization of epoxides and carbon dioxide. Rare earth compound is crucial in raising the catalytic activity and improving the micro-structure of the aliphatic polycarbonates. The Tg of the aliphatic polycarbonate is adjustable by controlling the relative molar ratio of the comonomers.     

稀土三元催化剂对二氧化碳/环氧化合物共聚反应的催化机理研究

采用X射线光电子能谱(XPS)技术研究了二氧化碳与环氧丙烷共聚反应的稀土三元催化剂,探讨了中心金属的X射线光电子能谱与催化活性间的关系,指出稀土三元催化剂的活性中心在于配位活化后的锌氧键,稀土盐通过与烷氧基锌形成双金属桥键,改变了活性中心的电子云分布,从而提高了反应活性.     

Discrete metal-based catalysts for the copolymerization of CO2 and epoxides: discovery, reactivity, optimization, and mechanism

Most synthetic polymers are made from petroleum feedstocks. Given the non-renewable nature of these materials, there is increasing interest in developing routes to polymeric materials from renewable resources. In addition, there is a growing demand for biodegradable polymeric materials. Polycarbonates made from CO(2) and epoxides have the potential to meet these goals. Since the discovery of catalysts for the copolymerization of CO(2) and epoxides in the late 1960's by Inoue, a significant amount of research has been directed toward the development of catalysts of improved activity and selectivity. Reviewed here are well-defined catalysts for epoxide-CO(2) copolymerization and related reactions.     

Study of electronic effect in bifunctional catalysts for the copolymerization of CO2 and PO/CHO

Carbon dioxide (CO₂) is an easily available renewable carbon source that can be used as a comonomer in the catalytic ring-opening polymerization of epoxides to form aliphatic polycarbonates. Herein, a series of new Salen-Co(III) bifunctional catalysts were synthesized for the first time, and they were studied to catalyze the copolymerization of CO₂ and propylene oxide (PO)/cyclohexene oxide (CHO). At the same time, the effects of reaction conditions (electronic effect, temperature, time) on catalytic activity and selectivity were investigated. The results show that the Salen-Co(III) complexes with electron-withdrawing groups have higher selectivity and activity for propylene carbonate (PPC)/cyclohexylene carbonate (PCHC). At the same time, the Salen-Co(III) complexes can better catalyze the copolymerization of CHO and CO₂ than that of PO and CO₂. The catalytic efficiency of the four complexes increased with increasing temperature, and the best reaction condition is 80°C, 30 min and 2 MPa of CO₂.     

Simple yttrium salts as highly active and controlled catalysts for the atom-efficient synthesis of high molecular weight polyesters

The ring-opening copolymerization (ROCOP) of epoxides and cyclic anhydrides is a promising route to sustainable aliphatic polyesters with diverse mechanical and thermal properties. Here, simple yttrium chloride salts (YCl₃THF_3.5 and YCl₃·6H₂O), in combination with a bis(triphenylphosphoranylidene)ammonium chloride [PPN]Cl cocatalyst, are used as efficient and controlled catalysts for ten epoxide and anhydride combinations. In comparison to past literature, this simple salt system exhibits competitive turn-over frequencies (TOFs) for most monomer pairs. Despite no supporting ligand framework, these salts provide excellent control of dispersity, with suppression of side reactions. Using these catalysts, the highest molecular weight reported to date (302.2 kDa) has been obtained with a monosubstituted epoxide and tricyclic anhydride. These data indicate that excellent molecular weight control and suppression of side reactions for ROCOP of epoxides and cyclic anhydrides can coincide with high activity using a simple catalytic system, warranting further research in working towards industrial viability.

Two simple yttrium salts, YCl₃THF_3.5 and YCl₃·6H₂O, are highly active and controlled catalysts for the perfectly alternating ring-opening copolymerization of epoxides and cyclic anhydrides.     

Trinuclear salphen–chromium(III)chloride complexes as catalysts for the alternating copolymerization of epoxides and cyclic anhydrides

Although the alternating copolymerization of epoxides and cyclic anhydrides is a promising route to aliphatic polyesters, improved catalysts are required to realize commercialization of this process. Herein, trinuclear chromium complexes of salicylaldimine, in conjunction with a nucleophilic cocatalyst, are demonstrated as excellent catalysts for epoxide/cyclic anhydride copolymerization, selectively affording perfectly alternating polyesters. The effect of the distance between the chromium species is investigated by varying the bridging skeleton in a series of trinuclear salphen–Cr(III)Cl complexes for obtaining different Cr–Cr distances. Trinuclear salphenCr(III)–complexes with Cr–Cr distances of approximately 7.3 Å are found to be efficient copolymerization catalysts, even at high temperatures and extremely low catalyst loadings. In particular, a high activity of 10,620 h⁻¹ is obtained for the copolymerization of cyclohexene oxide (CHO) and phthalic anhydride (PA) under a low catalyst loading (<0.01 mol%) at 100 °C. In situ infrared spectroscopy studies suggest that the activation energy of the trinuclear Cr(III)–salphen catalyst for CHO/PA copolymerization is 15 kJ mol⁻¹ lower than that of the corresponding mononuclear catalyst owing to an intramolecular synergistic effect among the metal atoms.