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.     

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.     

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。     

稀土三元催化剂催化二氧化碳/环氧丙烷/环氧环己烷的三元共聚合研究

在稀土三元催化剂(三氯乙酸稀土配合物/二乙基锌/甘油)催化下实现了二氧化碳、环氧丙烷及环氧环己烷的三元共聚合.该催化剂对二氧化碳与环氧环己烷共聚的催化活性比对二氧化碳与环氧丙烷共聚的高.增加反应单体中环氧环己烷的比例可提高共聚物中环己撑碳酸酯的含量,大幅度改善共聚物的耐热性.     

二氧化碳/环氧丙烷/马来酸酐三元共聚物对PPC/PHB共混物力学性能的影响

采用稀土三元催化剂制备了二氧化碳-环氧丙烷-马来酸酐三元共聚物(PPCMA).用红外和核磁谱图确定了PPCMA的结构及马来酸酐单元的含量,3 wt％马来酸酐投料量的PPCMA(共聚物中马来酸酐单元含量4.1％)的玻璃化转变温度(Tg)和起始热分解温度(Td-5％)分别为13.4℃和217℃,拉伸强度为2.88 MPa,断裂伸长率为1669％,与二氧化碳-环氧丙烷共聚物(PPC)相比,引入少量马来酸酐的PPCMA有望成为一种韧性材料,并可对PPC和聚3-羟基丁酸酯(PHB)共混体系进行改性.当在PPC/PHB共混体系中添加10 wt％的PPCMA时,所得共混材料的拉伸强度为18.2 MPa,断裂伸长率则提高到85％,较没有添加PPCMA的样品提高了4.25倍,因此PPCMA的加入能有效提高PPC/PHB共混体系的韧性,改善PPC/PHB共混体系的力学性能.偏光显微镜的研究表明PPC/PHB共混体系加入PPCMA后,很快形成大量尺寸小的PHB球晶,且结晶速度大幅度提高,因此PPCMA在一定意义上可视为一种特殊的“成核剂”.     

二氧化碳与环氧化物的三元共聚反应动力学过程控制

二氧化碳共聚物的分子结构调控有助于改善其物化性能,尤其是对深受低玻璃化温度困扰的二氧化碳(CO₂)-环氧丙烷(PO)共聚物(PPC).引入氧化环己烯(CHO)为第三单体进行三元共聚是提高PPC耐温性能的重要途径,但是三元共聚反应过程复杂,其动力学研究还处于探索阶段.本文以均相的卟啉铝配合物为催化剂,利用Fineman-Ross方程和在线红外光谱研究CO₂/PO/CHO的三元共聚反应.实验发现较低共聚温度(60～70℃)下PO与CHO的单体竞聚率均小于1,因此通过调整单体投料比即可制备出无规共聚物,进而调整三元共聚物的热力学性能.当共聚温度高于70℃时,CHO竞聚率大幅提高,更容易生成嵌段共聚物.在线红外反应动力学研究表明,此催化体系70℃即使在极低黏度下依然可以快速引发聚合反应,但聚合温度提高后,环状碳酸酯生成量会大幅提升,可明显观察到聚合物的解拉链反应.     

聚乳酸基可降解形状记忆聚合物的制备、结构与性能

以三枝化低不饱和度聚环氧丙烷/聚乳酸两嵌段共聚物(POLA)为原料, 甲苯二异氰酸酯(TDI)交联制备可降解聚环氧丙烷/聚乳酸基聚氨酯(POLA-PU). 通过对POLA共聚物序列结构的调控, 制备了由高模量低断裂伸长率的脆性到低模量高断裂伸长率的韧性POLA-PU可降解形状记忆材料. 由TMA测得POLA-PU的形变温度为96～153 ℃. POLA-PU试样在140 ℃的形状记忆恢复时间不超过20 s. 在200%拉伸形变条件下, POLA-PU的形变固定率在65%～100%之间, 形变回复率均可达100%. 实验表明, 形状记忆行为取决于链的交联密度, 记忆效应归属于不同温度下柔性链的构象熵变化. 降解实验结果表明, 聚乳酸链段的引入赋予了该形状记忆材料良好的降解性能, 且随着聚乳酸含量的降低而下降.     

双金属氰化物/稀土配合物催化二氧化碳和环氧丙烷的共聚合

使用双金属氰化物/稀土配合物复合催化剂催化二氧化碳和环氧丙烷共聚合,其催化效率比双金属氰化物催化剂有显著提高,得到了数均相对分子质量大于1.0×105的聚合物。研究了复合催化剂的组成(如稀土的种类、稀土与锌的比例(Ln/Zn)、稀土配合物中酸根离子的酸性等)对共聚反应的影响,同时研究了反应体系的压力及反应时间对催化活性的影响。采用Y(CCl3COO)3稀土金属配合物有利于共聚反应的进行。当n(Y)/n(Zn)=6、聚合4 h后,其催化活性比单纯的双金属氰化物提高了31.5%,聚合物的相对分子质量则没有太大变化,而副产物碳酸丙烯酯的质量分数低于2%,而在该温度下单独采用稀土三元催化剂时副产物碳酸丙烯酯的生成量通常在10%以上。聚合物中碳酸酯含量低于双金属氰化物的催化产物,说明稀土配合物只是起到活化金属与环氧丙烷配位的作用,没有提高共聚物的碳酸酯含量,整个共聚合反应依然遵循双金属氰化物催化的共聚反应机理。     

苯乙烯-N-苯基马来酰亚胺-马来酸酐三元共聚物的合成与性能

以过氧化对苯二甲酸二叔丁酯为引发剂, 以一次投料方式, 采用溶液聚合法合成了苯乙烯-N-苯基马来酰亚胺-马来酸酐三元共聚物. 通过控制单体配比, 实现产物中N-苯基马来酰亚胺质量分数在48%~63%之间可调. 采用FTIR, ¹H NMR, ¹³C NMR和GPC技术对三元共聚物的化学组成、链序列结构和分子量进行了测试. 利用FOX方程计算的共聚物NPMI含量与¹H NMR核磁测试结果一致. DSC和TGA测试的结果表明, 当N-苯基马来酰亚胺质量分数>48%时, 共聚物的玻璃化转变温度(T_g)从202 ℃提高到215 ℃, 5%热失重温度高于363 ℃, 所以三元聚合物是一种优异的聚合物耐热剂.     

Crosslinkable poly(propylene carbonate): High‐yield synthesis and performance improvement

A crosslinking strategy was used to improve the thermal and mechanical performance of poly(propylene carbonate) (PPC): PPC bearing a small moiety of pendant C?C groups was synthesized by the terpolymerization of allyl glycidyl ether (AGE), propylene oxide (PO), and carbon dioxide (CO₂). Almost no yield loss was found in comparison with that of the PO and CO₂ copolymer when the concentration of AGE units in the terpolymer was less than 5 mol %. Once subjected to UV‐radiation crosslinking, the crosslinked PPC film showed an elastic modulus 1 order of magnitude higher than that of the uncrosslinked one. Moreover, crosslinked PPC showed hot‐set elongation at 65 °C of 17.2% and permanent deformation approaching 0, whereas they were 35.3 and 17.2% for uncrosslinked PPC, respectively. Therefore, the PPC application window was enlarged to a higher temperature zone by the crosslinking strategy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5329–5336, 2006     

耐紫外光老化CO2共聚物的合成与性能

CO₂基塑料(PPC)是通过CO₂与环氧丙烷共聚所得的生物降解高分子,由于PPC的耐紫外老化性能较差,随紫外线的照射不仅PPC的相对分子质量快速下降,且其拉伸强度和断裂伸长率等力学性能也迅速降低,而农用地膜长期处于紫外线照射的环境中,因此亟待改善PPC的耐紫外老化性能。 本文设计合成了含紫外吸收基团的单体2-羟基-4(2,3-环氧丙氧基)二苯甲酮(HEB),与CO₂和环氧丙烷进行三元共聚制备了耐紫外光老化的CO₂共聚物(PPCH)。 在保证PPCH相对分子质量不低于5.0×10⁴的前提下,PPCH中HEB单元的摩尔分数最高可达0.32%,相应地其玻璃化转变温度(T_g)和起始热分解温度(T_d-5%)分别为26.7和216.9 ℃,拉伸强度达到30.97 MPa。 普通PPC经过240 h的紫外辐照后,其数均相对分子质量下降了67.8%,相应地其拉伸强度和断裂伸长率分别下降了10.1%和40.1%。 即使PPCH中的HEB摩尔分数仅为0.06%,经过240 h辐照后其数均相对分子质量仅下降了6.2%,相应地其拉伸强度和断裂伸长率也仅分别下降了1.7%和13.3%,证明PPCH具有较强的耐紫外老化性能,原因在于其主链含有HEB单元,对紫外光具有较好的吸收性能。 PPCH的紫外吸收性能随HEB单元在聚合物中含量的增加而增强,因此随着共聚物中引入的HEB单元含量增加,PPCH的相对分子质量和力学性能的保持率均得到了大幅度提高。 另一方面,对PPCH共聚物与相同二羟基二苯甲酮(BP)含量的PPC/BP共混物进行120 h的50 ℃热水萃取实验,PPCH显示出稳定的紫外光吸收性能,而PPC/BP共混物的紫外吸收性能随热水萃取时间的增长而快速下降,表明三元共聚反应能够有效解决普通共混物面临的小分子紫外吸收剂的外迁移问题。     

A general approach to controlling the surface composition of poly(ethylene oxide)-based block copolymers for antifouling coatings

To control the surface properties of a polystyrene-block-poly(ethylene oxide) diblock copolymer, perfluorinated chemical moieties were specifically incorporated into the block copolymer backbone. A polystyrene-block-poly[(ethylene oxide)-stat-(allyl glycidyl ether)] [PS-b-P(EO-stat-AGE)] statistical diblock terpolymer was synthesized with varying incorporations of allyl glycidyl ether (AGE) in the poly(ethylene oxide) block from 0 to 17 mol %. The pendant alkenes of the AGE repeat units were subsequently functionalized by thiol-ene chemistry with 1H,1H,2H,2H-perfluorooctanethiol, yielding fluorocarbon-functionalized AGE (fAGE) repeat units. (1)H NMR spectroscopy and size-exclusion chromatography indicated well-defined structures with complete functionalization of the pendant alkenes. The surfaces of the polymer films were characterized after spray coating by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS), showing that the P(EO-stat-fAGE) block starts to compete with polystyrene to populate the surface after only 1 mol % incorporation of fAGE. Increasing the incorporation of fAGE led to an increased amount of perfluorocarbons on the surface and a decrease in the concentration of PS. At a fAGE incorporation of 8 mol %, PS was not detected at the surface, as measured by NEXAFS spectroscopy. Water contact angles measured by the captive-air-bubble technique showed the underwater surfaces to be dynamic, with advancing and receding contact angles varying by >20°. Protein adsorption studies demonstrated that the fluorinated surfaces effectively prevent nonspecific binding of proteins relative to an unmodified PS-b-PEO diblock copolymer. In biological systems, settlement of spores of the green macroalga Ulva was significantly lower for the fAGE-incorporated polymers compared to the unmodified diblock and a polydimethylsiloxane elastomer standard. Furthermore, the attachment strength of sporelings (young plants) of Ulva was also reduced for the fAGE-containing polymers, affirming their potential as fouling-release coatings.     

Dynamically vulcanized ethylene propylene diene terpolymer/nylon thermoplastic elastomers

A thermoplastic elastomer (TPE) of ethylene propylene diene terpolymer (EPDM) and nylon with excellent mechanical properties was prepared by dynamic vulcanization. The effects of the curing systems, compatibilizer, nylon content and reprocessing on the mechanical properties of EPDM/nylon TPEs were investigated in detail. Experimental results indicate that maleic anhydride (MAH) grafted EPR has a better performance in compatibilizing the EPDM/nylon blends compared with other compatibilizers containing acid group. Tensile strength and elongation at break go through a maximum value at a compatibilizer resin content (on total rubber dosage) of 20%. EPDM/nylon TPE using sulfur as curative has higher tensile strength and elongation than that of TPE using phenolic resin or peroxide as curatives. Tensile strength and elongation at break increase with increasing nylon content. Scanning electron microscopy results show that rubber particles distributed at an average size of 1 μm in dynamic vulcanized EPDM/MAH-g-EPR/nylon TPE.     

Effect of surface modification of colloidal silica nanoparticles on the rigid amorphous fraction and mechanical properties of amorphous polyurethane–urea–silica nanocomposites

Colloidal silica nanoparticles (NPs) modified with eight different silane coupling agents were incorporated into an amorphous poly(tetramethylene oxide)‐based polyurethane–urea copolymer matrix at a concentration of 10 wt % (4.4 vol %) in order to investigate the effect of their surface chemistry on the structure–property behavior of the resulting nanocomposites. The rigid amorphous fraction (RAF) of the nanocomposite matrix as determined by differential scanning calorimetry and dynamic mechanical analysis was confirmed to vary significantly with the surface chemistry of the NPs and to be strongly correlated with the bulk mechanical properties in simple tension. Hence, nanocomposites with an RAF of about 30 wt % showed a 120% increase in Young's modulus, a 25% increase in tensile strength, a 15% decrease in elongation at break with respect to the neat matrix, which had no detectable RAF, whereas nanocomposites with an RAF of less than 5% showed a 60% increase in Young's modulus, a 10% increase in tensile strength and a 5% decrease in the elongation at break. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2543–2556     

聚丁二酸丁二醇酯与氯醚弹性体协同增韧改性聚乳酸多元共混体系

以来源于可再生资源聚丁二酸丁二醇酯(PBS)和氯醚橡胶(ECO)作为聚乳酸(PLA)的增韧改性剂,通过熔融共混的方法制备了PLA/PBS/ECO三元共混体系。动态力学分析和扫描电子显微镜结果表明,ECO促进了PBS和PLA之间的相容性。力学性能测试表明,ECO与PBS可实现对聚乳酸基体的协同增韧: PLA/PBS/ECO(70/20/10)显示出最优的拉伸性能,断裂伸长率高达270%;PLA/PBS/ECO(70/10/20)的冲击强度提高至23.7 kJ/m²,是纯聚乳酸的12倍。结合形态结构和冲击断面形貌分析表明ECO的存在可起到增容/增韧双重作用, 与柔性PBS产生良好的协同效应,有效改善聚乳酸材料的韧性。我们的研究表明,构造PLA-柔性生物聚酯和生物基弹性体多元共混体系是一种获得高性能生物基材料简单高效的手段。     

Reactive compatibilization of poly(styrene-Co-maleic anhydride)/poly(phenylene oxide) blends

Primary amine terminated polystyrene (PS-NH₂), with Mn=12,000 g/mol and Mw=23,000 g/mol, was applied as a reactive compatibilizer for poly(styrene-co-maleic anhydride)/poly(phenylene oxide) (SMA/PPO) blends, in which both an impact modifier for the continuous SMA phase, viz. ABS, and the dispersed PPO phase, viz. SEBS, was incorporated. During melt blending, SMA-g-PS copolymers are generated at the interface between the SMA/ABS and the PPO/SEBS phases. The addition of 10 wt % of the reactive PS-NH₂ compatibilizer to a SMA/ABS/PPO/SEBS 30/30/30/10 blend results in a more significant refinement of the dispersed PPO/SEBS particles than 10 wt % of a commercially available, bulky PS-graft-PMMA copolymer with Mn=45,300 and Mw=293,400 g/mol. In addition, PS-NH₂ gives a more pronounced enhancement of the yield stress, the stress at break and the notched Izod Impact than the PS-g-PMMA. On the other hand, the elongation at break is higher in the case of the non-reactive PS-g-PMMA. It was demonstrated that surface imperfections, probably introduced by an observed strongly elastic character due to partial crosslinking of the SMA/ABS phase by difunctional H₂N-PS-NH₂, are responsible for the lower elongation at break for the PS-NH₂ based blends.     

Structural characteristics of some high density polyethylene/EPDM blends

Blends of ethylene propylene diene terpolymer rubber (EPDM) with high density polyethylene were obtained by melt mixing. Mechanical properties of the composites, tensile strength, hardness, resilience, elongation at break, 100% modulus and tear strength were determined. Differential scanning calorimetry and wide angle x-ray diffraction were employed to study melting behavior and crystalline structure. The surface properties were analyzed using contact angle determinations. Also, compatibilization with PE-g-MA or dynamical vulcanization using phenolic resins was applied to obtain improved mechanical properties. It was found that the crystalline structure of HDPE was not changed during blending. The vulcanized composite presents a lower degree of crystallinity. Elongation at break and hardness were significantly increased for composites containing compatibilizing agent. The morphology of EPDM composites was studied by atomic force microscopy.     

Synthesis and Characterization of Thermoplastic Polyurethaneureas based on Polyisobutylene and Poly(tetramethylene oxide) Segments

New thermoplastic polyurethaneureas (TPUU) based on polyisobutylene (PIB) and poly(tetramethylene oxide) (PTMO) segments have been synthesized possessing tensile properties comparable to conventional PTMO based TPUs. PIB based TPUU containing 35 weight (wt)% hard segment was synthesized by chain extension of H₂N-Allyl-PIB-Allyl-NH₂ with 4,4′ -methylene bis(phenylisocyanate) (MDI) and 1,4-butanediol (BDO) in toluene. The ultimate tensile strength (UTS) = 12 MPa and ultimate elongation = 70% were inferior to PTMO based polyurethane (UTS = 35 MPa, elongation at break = 600%). H₂N-Allyl-PIB-Allyl-NH₂ and HO-PTMO-OH in different proportions were chain extended in presence of MDI and BDO to obtain TPUUs containing 35 wt% hard segment. The polymers exhibited M _ns = 84000–138000 with polydispersity indices (PDIs) = 1.7–3.7. The UTS = 23–32 MPa and elongation at break = 250–675% was comparable to that of PTMO based polyurethane and significantly higher than the PIB based TPUU with the same Shore hardness. The Young's modulus of the polymers was strongly dependent and directly proportional to the PIB wt% in the SS of the TPUUs.