Amine-containing olefin copolymer with CO2-switchable oil absorption and desorption

Global decrease in crude oil resources and frequent crude oil leaks cause the energy crisis and ecological pollution. The absorption and release of leaked crude oil through absorption materials are a necessary process for environmental protection and recycling. In this article, a CO₂-responsive olefin copolymer was obtained by copolymerization of styrene and an amine-containing olefin monomer. The structure of resultant copolymer was characterized by FTIR; thermal properties and CO₂-responsive morphology changes were determined by DSC/TGA and SEM, respectively. Copolymers had certain absorption capacity for toluene with absorption rate up to 180.0%. The absorbed toluene could be released upon CO₂ stimulation with desorption rate up to 84.6%. The CO₂-responsive copolymer could be regenerated through a simple heating process and showed stable absorption–desorption performance even after being recycled for 4 times. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47439.     

Modeling of sequence length distribution for olefin copolymerization with vanadium-based catalyst

Some thermodynamic and mechanical properties of a polyolefin, such as the melting temperature and the rigidity, are dependent on the nature of its sequence distribution. Accurate modeling of sequence length distribution (SLD) is important in precisely tuning and optimizing the properties of polymers produced. In this article, we proposed a model to predict the molecular weight distribution (MWD) and SLD for olefin copolymerization with vanadium-based catalyst. Due to the 2,1-insertion of α-olefin with vanadium-based catalyst, the SLD is expressed by uninterrupted methylene sequence distribution instead of conventional triad sequence distribution. To obtain a reliable model, parameter estimation with experimental data is first conducted. The SLD model along with the estimated kinetic parameters can be used to predict unmeasurable sequence length fraction. For the experimental conditions studied, the average methylene sequence length is predicted to change from 10 to 4 units as the propylene/ethylene mole feed ratio increases from 1.1 to 3.4.     

Study of Compatibilized Liquid Crystalline Polymer/Cyclic Olefin Copolymer Blends

The technology to produce compatibilized blends of liquid crystalline polymer and highly amorphous cyclic olefin copolymers through two novel approaches were studied. The first approach was to use silane-functionalized halloysite nanotube as nonspecific compatibilizer and the second method was reactive compatibilization. The study of blends and their resulting microstructure; their thermal, mechanical, and viscoelastic properties were investigated. The kinetic study of blends compatibilized through both routes was performed.     

甲醇制烯烃催化剂积炭的形成机理

采用二氯甲烷超声波萃取,提取甲醇制烯烃(MTO)待生催化剂和不完全再生催化剂外表面可溶性积炭,采用氢氟酸溶解及碳酸钠溶液中和后再用二氯甲烷超声波萃取,提取待生催化剂和不完全再生催化剂孔道内可溶性积炭,结合气相色谱-质谱(GC-MS)分析了其组成,并对MTO催化剂积炭形成的机理和再生烧炭的机理进行了分析探讨。结果表明:MTO待生催化剂外表面可溶性积炭主要是饱和烃和芳烃,其中饱和烃以C23~C31的正构烷烃为主,芳烃以一环和二环芳烃为主;孔道内可溶性积炭均为芳烃,以三环和四环芳烃为主,从质谱峰强度计算约占总量的80%,菲和芘约占总量的50%。MTO不完全再生催化剂外表面可溶性积炭主要是沸点较高的C23~C31正构烷烃;孔道内可溶性积炭主要是几个高含量组分如芘和菲等的残留。在催化剂外表面的饱和烃可能是由小分子烯烃类化合物经过一系列聚合而成,而催化剂外表面的一环和二环芳烃应该是从分子筛孔道内形成并溢出,在分子筛孔道口吸附。分子筛催化剂孔道内的多环芳烃,是由小分子烃类化合物经过一系列低聚、氢转移、环化和脱氢等反应生成。     

烯烃复分解法制备端基官能化液体橡胶研究进展

用烯烃复分解法制备端基官能化液体橡胶具有分子量可控、易于引入多种官能团、反应条件较温和等优势。本文即综述了利用烯烃复分解法制备端羟基、端羧基、端酯基等官能化液体橡胶的研究新进展,并提示了其今后的发展方向。     

聚烯烃弹性体技术进展

聚烯烃弹性体为一类新型乙烯与高级α-烯烃共聚物，由于应用茂金属催化技术且分子结构中引入大量高级α-烯烃共聚单体并保留一定聚乙烯结晶相而兼备可塑性和弹性，具有良好的机械性能、加工性能和热性能。聚烯烃弹性体主要生产商有Exxon公司、Dow化学公司、Mitsui公司和LG公司，均采用溶液法聚合工艺及茂金属催化技术，其中,以Dow化学公司的Insite聚合工艺与CGC茂金属催化技术为代表，限定几何构型（CGC）催化剂为桥联单茂结构催化剂，其自身结构变化对催化性能影响较大，改变桥基团、Cp环上的烷基取代基和配位基团均可得到不同结构和性能的催化剂。Exxon公司采用Exxpol茂金属催化剂开发Exact塑性体［密度(0.860~0.915) g·cm^-3］，包括乙烯-辛烯共聚物、乙烯-己烯共聚物和乙烯-丁烯共聚物;采用同种催化技术，溶液法生产丙烯基弹性体，商品名为Vitamaxx。2003年，日本Mitsui公司-三井弹性体新加坡公司100 kt·a-1的乙丙橡胶弹性体装置投产，装置采用茂金属催化技术和独有的溶液法聚合工艺，商品名为Tafmer［密度(0.862~0.905) g·cm^-3］。韩国LG公司将独特的茂金属催化剂与溶液法聚合工艺相结合，生产聚烯烃弹性体［密度(0.865~0.903) g·cm^-3］，商品名为LUCENE。我国目前没有聚烯烃弹性体生产企业，开展过一些高共聚性能茂金属催化剂的研发，应用于聚烯烃弹性体技术开发。     

聚烯烃嵌段共聚物技术的研究进展

综述了聚烯烃嵌段共聚物(OBC)的制备方法,包括链穿梭聚合法、活性聚合法、短周期停流聚合法和管式反应器技术。重点介绍了链穿梭聚合法的基本原理、催化体系及生产工艺,该方法在制备OBC产品方面具有很大的优势。介绍了OBC的表征方法、产品的性能及应用。对利用链穿梭聚合法制备OBC提出了展望。     

Well‐Defined End‐Functionalized Conjugated Polymers/Oligomers Exhibiting Unique Emission Properties through the End Groups: The Exclusive Synthesis by Combined Olefin Metathesis with Wittig‐type Coupling

Acyclic diene metathesis polymerization using ruthenium–carbene catalysts affords defect‐free, high molecular weight poly(arylene vinylene)s containing all trans olefinic double bonds. The exclusive end‐functionalization in the resultant poly(fluorene vinylene)s or poly(phenylene vinylene)s can be attained by treating the vinyl end groups using a molybdenum–alkylidene catalyst/reagent (through olefin metathesis) followed by addition of various aldehydes (Wittig‐type coupling). Some of these end‐modified conjugated materials display unique emission properties, which are different from the original ones, through an interaction (energy transfer or structural change in the excited state) between the conjugated main chain and the end groups [oligo(thiophene)s, F‐BODIPY, etc.]. Exclusive synthesis of well‐defined, all‐trans end‐functionalized oligo(2,5‐dialkoxy‐1,4‐phenylene vinylene)s [(oligo(phenylene vinylene), alkoxy = O(CH₂)₂OSiⁱ Pr₃, up to 31 repeat units] is demonstrated by adopting a stepwise synthetic approach (olefin metathesis and the subsequent Wittig‐type cleavage). It is clearly demonstrated that their optical properties (especially the fluorescence spectra including photoluminescence quantum yields) are strongly affected by the end groups as well as the conjugation repeat units.     

Effect of metal loading on catalytic activity and selectivity of ZSM-5 zeolite catalyst in conversion of methanol to olefins and aromatics

Effect of ZSM-5 zeolite promotion using potassium, strontium, and cerium metals on conversion of methanol to light olefins and aromatics was investigated. ZSM-5 catalyst was promoted using wet impregnation of metal salts and its activity was tested in methanol to hydrocarbons process under optimum operational condition obtained in our group previously. Zeolite samples were characterized by X-ray powder diffraction, scanning electron microscopy, N₂ adsorption-desorption, acid sites distribution, and strength using temperature programmed desorption of NH₃. Results showed that presence of these metals could significantly affect acid site distribution and therefore influence the catalyst activity and selectivity to olefins and aromatics.