Effect of the surface-modifying macromolecules on the duration of the surface functionalization

Functionalization of polystyrene films by the preferential surface enrichment of surface-modifying macromolecules (SMM) to achieve a hydrophilic surface with long effective duration is described. The comb-like amphiphilic copolymers (PKG-g-PS) based on styrene-maleic anhydride copolynier (SMA) backbone was synthesized by esterification of SMA with poly(ethylene glycol) (PEG). When PEG-g-PS was melt blended with polystyrene, the preferential surface enrichment of PEG-g-PS was much evident resulting in the large increase of the surface polarity. The effective duration of the surface functionalizatoin was also hugely extended as SMMs were added into the blends. Furthermore, more polyether chain segments on PEG-g-PS could selectively migrate to the surface by the inducement of polar solvent. Compared with the PEG-g-PS/PS and PEG/PEG-g-PS/PS blends, the surface polarity and the effective duration of surface modification both increased greatly when PEG-g-PS was used as the compatibilizer of PEG/PS blends. It was an effective solution to balance the conflict between the duration and efficiency of the surface-modifying additives.     

Polypropylene ionic thermoplastic elastomers: Synthesis and properties

Polypropylene ionic thermoplastic elastomers have been prepared by melt radical grafting of maleic anhydride onto polypropylene in the presence of N-bromosuccinimide followed by neutralization of the resulting elastomeric grafted polypropylene using sodium salts. Sodium hydroxide and sodium acetate were compared in aqueous solution, as anhydrous or hydrated powders. The neutralization reaction was followed by Fourier transform infrared spectroscopy, allowing the development of a method to determine the effective neutralization degree. Important physical changes were recorded upon neutralization. Especially thermal stability, shear storage modulus and complex viscosity in the flow region were largely increased as a function of the neutralization degree.     

A Series of Three‐Dimensional Rare Earth Coordination Polymers with Two Binary Carboxylate as Mixed‐Ligand: Syntheses,Structures, Properties of [LnIII(mal)(ox)0.5(H2O)2]·2H2O (Ln = Pr,Nd, and La)

A series of lanthanide coordination polymers, [Ln^III(mal)(ox)_0.5(H₂O)₂]·2H₂O (Ln = Pr ( 1 ), Nd ( 2 ), and La ( 3 ); H₂mal= maleic acid; H₂ox = oxalic acid), were synthesized firstly by the reaction of Ln^III nitrate salts with maleic anhydrid and oxalic acid under hydrothermal conditions and were characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. X‐ray diffraction analyses reveal that they are crystallized in orthorhombic space group Fddd. Lanthanide metal center atom (Ln) and its corresponding centrosymmtric atom link through two chelating/bridging bidentate carboxyl groups of maleic acid ligands to form an infinite inorganic rod‐shaped building unit. These rod‐shaped building units were linked to each other through the carbon atoms of the maleate anions on the [110] plane to form lanthanide‐maleic acid layers. The oxalic acid pillared lanthanide‐maleic acid layers with intersected channels by free water molecules consist of a 3D framework structure. The thermogravimetric analyses of 1 – 3 were discussed in detail. The courses of the thermal decomposition of complexes are similar.     

Synthesis of polysubstituted 5-hydroxyhydantoins via ring-opening of isatins

A simple and efficient tandem reaction approach was developed for the synthesis of 5-hydroxyhydantoins from one-pot reaction of isatins, phthalic anhydride or succinic anhydride, and 1,3-dimethylurea (1,3-diethylurea). The products were gained through the ring-opening of isatins process. The advantages of this report are simple operation, mild reaction conditions, good yields and easily available raw materials. It was very important for us to obtain the intermediate product and that provided a solid basis for the correct interpretation of the reaction mechanism.     

Room-temperature synthesis of pharmaceutically important carboxylic acids bearing the 1,2,4-oxadiazole moiety

An efficient and mild one-pot protocol has been developed for the synthesis of 1,2,4-oxadiazoles via the reaction of amidoximes with dicarboxylic acid anhydrides in a NaOH/DMSO medium. The method allows the synthesis of diversely substituted carboxylic acids bearing the 1,2,4-oxadiazole motif, – a popular building block for pharmaceutical research, in moderate to excellent yields. The reaction scope includes aromatic and heteroaromatic amidoximes as well as five-, six- and seven-membered anhydrides. The advantages of this procedure are proven gram-scalability and the use of inexpensive starting materials, which from a process chemistry point of view are essential for future industrial applications.     

Synthetic studies on psiguadial B: Construction of bicyclo[4.3.1]decane skeleton via double cyclization reaction of alkyne dicobalt complex

A new method for constructing the polycyclic skeleton of psiguadial B (1), a meroterpenoid isolated from an evergreen shrub of Myrtaceae, was developed. The terpenoid substructure of 1 was constructed on the basis of a cascade double cyclization reaction of an alkyne dicobalt complex, which afforded the bicyclo[4.3.1]decane derivative having a benzyl group with the correct configuration. The substituted aromatic ring was introduced to the bridgehead position of the intermediate, and bromination under radical conditions followed by intramolecular cyclization reaction resulted in formation of the benzopyran moiety in a stereoselective manner.     

Controlled “Grafting-from” of poly[styrene-co-maleic anhydride] onto polydienes using nitroxide chemistry

High-throughput experimentation was used for the functionalization of polybutadiene and polyisoprene with several kinds of nitroxide moieties at 135 °C, as well as for kinetic investigations of the controlled free radical grafting of styrene and maleic anhydride onto the functionalized polydienes at 125 °C. The functionalized polymers were analyzed by GPC, ¹H NMR and FT-IR and the control of the grafting process was assessed by kinetic measurements and GPC analysis. The best control in the molecular weight of the grafts was observed for the polydienes functionalized with 4-oxo-TEMPO. TEMPO functionalization did not render sufficient nitroxide moieties to achieve controlled grafting, while polydienes functionalized with other 4-hydroxy TEMPO derivatives exhibited some level of grafting control at early reaction times, which was lost in later stages of the polymerization reaction. SG1 apparently decomposed at the tested reaction temperatures, as polydienes functionalized with SG1 did not show any level of control during the grafting process.     

微波辐射法合成N-苯基马来酰亚胺

用微波辐射法合成N-苯基马来酰亚胺,在总结前人对原料配比、催化剂用量对反应收率影响的基础上,本实验以顺丁烯二酸酐和苯胺为原料用醋酐作脱水剂、醋酸钠作催化剂采用微波辐射法两步合成N-苯基马来酰亚胺。探讨最佳工艺条件为第一步用微波功率80W熟化3min,第二步用微波以功率400W加热1.5min时N-苯基马来酰亚胺的收率可达75.8%。产品经晶形、熔点和红外光谱分析确定为目标产品。     

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”.