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.     

带双键侧链的二氧化碳三元共聚物的合成及性能研究

二氧化碳和环氧丙烷共聚物的玻璃化温度处于35～40℃,在低于20℃的环境下脆性很大.在稀土三元催化剂Y(CCl3COO)3ZnEt2甘油(glycerine)下实现了CO2、环氧丙烷(PO)和烯丙基缩水甘油醚(AGE)的三元共聚,合成了侧链带双键的二氧化碳共聚物,其玻璃化温度(Tg)为-15.4～36.1℃,大幅度拓展了二氧化碳共聚物的低温区使用范围.     

醋酸锌催化二氧化碳和环氧化合物共聚研究

以醋酸锌为催化剂,在无溶剂条件下实现了二氧化碳和环氧环己烷共聚,研究了反应温度、反应压力和反应时间对共聚的影响.并在优化条件(120℃、5 MPa和24 h)下,用醋酸锌催化了二氧化碳、环氧环己烷和第三单体(环氧丙烷或烯丙基缩水甘油醚)三元共聚,研究了单体物质的量之比对聚合结果的影响.研究结果表明,第三单体的种类和用量对聚合反应结果影响显著,环氧丙烷或烯丙基缩水甘油醚的引入降低了二氧化碳和环氧环己烷二元共聚物的玻璃化转变温度.     

稀土三元催化剂下正辛酸缩水甘油酯-二氧化碳-环氧丙烷的三元共聚合

研究了稀土三元催化剂(三氯乙酸稀土配合物/二乙基锌/甘油)催化下的正辛酸缩水甘油酯、CO2和环氧丙烷三元共聚合. 红外光谱、核磁共振和DSC结果表明,所获得的聚合物是一种新型的三元共聚物. 随着反应单体中正辛酸缩水甘油酯比例的增加,所得聚合物在20 ℃下的断裂伸长率由二氧化碳-环氧丙烷共聚物的31.0%增大至二氧化碳-正辛酸缩水甘油酯共聚物的983.9%,相应的玻璃化转变温度由39.6 ℃降低至-12.3 ℃. 所得三元共聚物中长碳链侧基单元含量为5.6%时,其断裂伸长率就已经达到481.1%,而拉伸强度仍然维持在24.9 MPa的较高水平.     

三元共聚物聚甲基乙撑-环己撑碳酸酯的合成与表征

报道了三元共聚物聚甲基乙撑-环己撑碳酸酯的制备与性能研究. 实验采用高活性的负载戊二酸锌作为催化剂, 在不添加任何溶剂的情况下, 以二氧化碳和环氧丙烷、环氧环己烷为原料, 制备了不同环己撑碳酸酯含量的三元共聚物, 并对其结构和热性能、力学性能进行了表征和分析. 结果表明这些三元共聚物具有较高的分子量, 且玻璃化转变温度随着主链上的环己撑碳酸酯含量增加而逐渐升高. 同时三元共聚物表现出比二元共聚物更好的力学性能.     

稀土三元催化剂作用下正辛酸缩水甘油酯-二氧化碳-环氧丙烷的三元共聚合研究

本工作研究了稀土三元催化剂(三氯乙酸稀土配合物/二乙基锌/甘油)催化下的正辛酸缩水甘油酯、二氧化碳和环氧丙烷三元共聚合。红外光谱、核磁共振和差示扫描结果表明所获得的聚合物是一种新型的三元共聚物。随着反应单体中正辛酸缩水甘油酯比例的增加,所得聚合物在20℃下的断裂伸长率由二氧化碳－环氧丙烷共聚物的31.0%增大到二氧化碳－正辛酸缩水甘油酯共聚物的983.9%,相应的玻璃化转变温度由39.6℃降低至-12.3℃。所得三元共聚物中长碳链侧基单元含量为5.6%时,其断裂伸长率就已经达到481.1％,而拉伸强度仍然维持在24.9MPa的较高水平。     

二氧化碳-环氧乙烷-氧化环己烯三元共聚物的制备与性能

采用稀土三元催化剂实现了二氧化碳、氧化环己烯与环氧乙烷的三元共聚,当环氧乙烷和氧化环己烯等摩尔投料时催化活性达到690 g/(mol Zn h),所得三元共聚物的数均分子量达到7.9×104,远程异核多量子相关核磁谱证明所得共聚物主要是无规三元共聚物,其中环氧乙烷-二氧化碳结构单元与氧化环己烯-二氧化碳结构单元相连的全交替结构占26.9%.二氧化碳-氧化环己烯共聚物的脆性导致其熔体加工十分困难,引入环氧乙烷为第三单体进行三元共聚,实现了二氧化碳-氧化环己烯共聚物的增韧,解决了其熔体加工难题,而且改变环氧单体比率能够调节三元共聚物的耐温性能和力学性能,当环氧乙烷与氧化环己烯等摩尔投料时,所得三元共聚物在20℃下的杨氏模量达到(900±17)MPa,拉伸强度为(38±2)MPa,断裂伸长率为(26.3±9.2)%.     

氧化环己烯连续进料下二氧化碳-环氧丙烷-氧化环己烯三元共聚物的合成

由于氧化环己烯（CHO）与二氧化碳的共聚反应速度比其与环氧丙烷（PO）快,这种竞聚率的差异导致一锅法所得的二氧化碳-环氧丙烷-氧化环己烯三元共聚物的组成难以稳定控制。 为此本文在稀土三元催化剂下,采用氧化环己烯单体连续进料的方法合成了二氧化碳-环氧丙烷-氧化环己烯三元共聚物,催化效率可达575 g/(mol Zn h)。 三元共聚物的玻璃化转变温度随CHO含量升高而增大,当CHO的摩尔投料比从0.19增加到0.59时,玻璃化温度从44.3 ℃提高到70.1 ℃。 CHO连续进料合成的三元共聚物的组成与投料比基本相近,且连续进料法所合成的三元共聚物只有一个玻璃化转变温度,而普通的一锅法所得的三元共聚物通常存在两个玻璃化转变温度,因此连续进料法是制备组成稳定的二氧化碳-环氧丙烷-氧化环己烯三元共聚物的有效方法。     

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.     

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.     

Synthesis and characterization of high molecular weight poly(1,2-propylene carbonate-<Emphasis Type="Italic">co</Emphasis>-1,2-cyclohexylene carbonate) using zinc complex catalyst

Using supported multi-component zinc dicarboxylate catalyst,poly（1,2-propylene carbonate-co-1,2-cyclohexylene carbonate）（PPCHC） was successfully synthesized from carbon dioxide（CO₂） with propylene oxide（PO） and cyclohexene oxide（CHO）.The conversion of epoxides dramatically increased up to 89.7%（yield:384.2 g of polymer per g of Zn） with increasing reaction temperature from 60℃to 80℃.The optimized reaction temperature is 80℃.The chemical structure,the molecular weight,as well as thermal and mechanical properties of the resulting terpolymers were investigated extensively. When CHO feed content（mol%） is lower than 10%,the PPCHC terpolymers have number average molecular weight（M_n） ranging from 102×10³ to 202×10³ and molecular weight distribution（MWD） values ranging from 2.8 to 3.5.In contrast to poly（propylene carbonate）（PPC）,the introduction of small amount of CHO leads to increase in the glass transition temperature from 38.0℃to 42.6℃.Similarly,the mechanical strength of the synthesized terpolymer is greatly enhanced due to the incorporation of CHO.These improvements in mechanical and thermal properties are of importance for the practical application of PPC.     

Differences in Reactivity of Epoxides in the Copolymerisation with Carbon Dioxide by Zinc-Based Catalysts: Propylene Oxide versus Cyclohexene Oxide

The homogeneous dinuclear zinc catalyst going back to the work of Williams et al. is to date the most active catalyst for the copolymerisation of cyclohexene oxide and CO₂ at one atmosphere of carbon dioxide. However, this catalyst shows no copolymer formation in the copolymerisation reaction of propylene oxide and carbon dioxide, instead only cyclic carbonate is found. This behaviour is known for many zinc‐based catalysts, although the reasons are still unidentified. Within our studies, we focus on the parameters that are responsible for this typical behaviour. A deactivation of the catalyst due to a reaction with propylene oxide turns out to be negligible. Furthermore, the catalyst still shows poly(cyclohexene carbonate) formation in the presence of cyclic propylene carbonate, but the catalyst activity is dramatically reduced. In terpolymerisation reactions of CO₂ with different ratios of cyclohexene oxide to propylene oxide, no incorporation of propylene oxide can be detected, which can only be explained by a very fast back‐biting reaction. Kinetic investigations indicate a complex reaction network, which can be manifested by theoretical investigations. DFT calculations show that the ring strains of both epoxides are comparable and the kinetic barriers for the chain propagation even favour the poly(propylene carbonate) over the poly(cyclohexene carbonate) formation. Therefore, the crucial step in the copolymerisation of propylene oxide and carbon dioxide is the back‐biting reaction in the case of the studied zinc catalyst. The depolymerisation is several orders of magnitude faster for poly(propylene carbonate) than for poly(cyclohexene carbonate).     

二氧化碳-氧化环己烯的共聚反应

由CO2 -氧化环己烯 (CHO)配位催化共聚制得高Tg 的脂肪族聚环己基撑碳酸酯 ,并用IR、NMR和DSC等进行了表征 ,用TG对聚合物的热稳定性进行了分析。加入异氰酸苯酯有提高产物特性粘数的作用。     

聚碳酸环己烯酯的研究进展

以CO2和环氧环己烷(CHO)为原料合成的聚碳酸环己烯酯(PCHC),是一种新型可降解材料.本文对聚碳酸环己烯酯的合成、性能及应用研究进行了综述.     

高聚物负载双金属催化剂催化二氧化碳-氧化环己烯的共聚反应

由CO2 氧化环己烯 (CHO)配位催化共聚制得高Tg 的脂肪族聚碳酸亚环己基酯 ,并用IR、NMR和DSC等进行了表征 ,用TG对聚合物的热稳定性进行分析 .加入环氧丙烷 (PO)三元共聚并分析PO/CHO摩尔比对Tg 的影响 .加入异氰酸苯酯有提高产物特性粘数的作用     

Comparative kinetic studies of the copolymerization of cyclohexene oxide and propylene oxide with carbon dioxide in the presence of chromium salen derivatives. In situ FTIR measurements of copolymer vs cyclic carbonate production

The catalysis of the reaction of carbon dioxide with epoxides (cyclohexene oxide or propylene oxide) using the (salen)Cr(III)Cl complex as catalyst, where H(2)salen = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexenediimine (1), to provide copolymer and cyclic carbonate has been investigated by in situ infrared spectroscopy. As previously demonstrated for the cyclohexene oxide/CO(2) reaction in the presence of complex 1, coupling of propylene oxide and carbon dioxide was found to occur by way of a pathway first-order in catalyst concentration. Unlike the cyclohexene oxide/carbon dioxide reaction catalyzed by complex 1, which affords completely alternating copolymer and only small quantities of trans-cyclic cyclohexyl carbonate, under similar conditions propylene oxide/carbon dioxide produces mostly cyclic propylene carbonate. Comparative kinetic measurements were performed as a function of reaction temperature to assess the activation barrier for production of cyclic carbonates and polycarbonates for the two different classes of epoxides, i.e., alicyclic (cyclohexene oxide) and aliphatic (propylene oxide). As anticipated in both instances the unimolecular pathway for cyclic carbonate formation has a larger energy of activation than the bimolecular enchainment pathway. That is, the energies of activation determined for cyclic propylene carbonate and poly(propylene carbonate) formation were 100.5 and 67.6 kJ.mol(-1), respectively, compared to the corresponding values for cyclic cyclohexyl carbonate and poly(cyclohexylene carbonate) production of 133 and 46.9 kJ.mol(-1). The small energy difference in the two concurrent reactions for the propylene oxide/CO(2) process (33 kJ.mol(-1)) accounts for the large quantity of cyclic carbonate produced at elevated temperatures in this instance.     

A Novel [OSSO]-Type Chromium(III) Complex as a Versatile Catalyst for Copolymerization of Carbon Dioxide with Epoxides

A new chromium(III) complex, bearing a bis-thioether-diphenolate [OSSO]-type ligand, was found to be an efficient catalyst in the copolymerization of CO₂ and epoxides to achieve poly(propylene carbonate), poly(cyclohexene carbonate), poly(hexene carbonate) and poly(styrene carbonate), as well as poly(propylene carbonate)(cyclohexene carbonate) and poly(propylene carbonate)(hexene carbonate) terpolymers.