A novel hyperbranched aromatic polyamide containing bithiazole: Synthesis,metal complexation and magnetic properties

Based on the polycondensation of bifunctional 2,2′-diamino-4,4′-bithiazole(DABT) and trifunctional 1,3,5-benzenetricarbonyl trichloride (BTC),a novel hyperbranched aromatic polyamide PBD was synthesized with excellent solubility and good thermal stability.The structure of the polymer was confirmed by FT-IR and 1H NMR spectrum.The calculated degree of branching of our product was 52%.By exploring the influence of several different solvent systems,the yield of the polymer increased in the solvent system of DM...     

Synthesis,structure and catalytic activity of complexes [Ln(EDBP)_2(DME)Na(DME)_3](Ln=Er,Yb,Sm) for ring-opening polymerization of ε-caprolactone

Discrete ion-pair complexes [Ln(EDBP)2(DME)Na(DME)3] [Ln=Er (1), Yb (2), Sm (3)] have been synthesized by the reaction between sodium salt of 2,2'-ethylidene-bis(4,6-di-tert-butylphenol)(EDBPH2) and Ln(BH4)3·3THF (Ln=Er, Yb, Sm) followed by centrifugation and recrystalization. The complexes were characterized by elemental analysis and FT-IR, and the bonding model of these compounds was confirmed by X-ray single crystal diffraction for complex 1. It was found that four O atoms in two biphenol ligands as well...     

Synthesis,characterization of neodymium chloride complex of amine-bis(phenolate) ligand and its reactivity in the ring-opening polymerization of ε-caprolactone

The neodymium chloride complex[Nd(ONN'O)Cl(THF)]_2 supported by amine-bis(phenolate) ligand was synthesized by the metathesis reaction of anhydrous NdCl_3 with Li_2(ONN'O)[H_2ONN'O = Me_2NCH_2CH_2N(CH_2-3-Bu_2~t-5-Me-C_6H_2OH)_2]in high yield.X-ray structural determination shows[Nd(ONN'O)Cl(THF)]_2 complex consists of two seven-coordinate neodymium centers linked throughμ-Cl bridges.And this complex was successfully used to initiate the ring-opening polymerization(ROP) ofε-caprolactone.     

Surface-grafted block copolymer brushes with continuous composition gradients of poly(poly(ethylene glycol)-monomethacrylate) and poly(N-isopropylacrylamide)

Surface-grafted block copolymer brushes with continuous composition gradients containing poly(poly(ethylene glycol) monomethacrylate) (P(PEGMA)) and poly(N-isopropylacrylamide) (PNIPAAm) chains were fabricated by integration of the surface-initiated atom transfer radical polymerization (SI-ATRP) and continuous injection method.Three types of copolymer gradients were prepared: (1) a uniform P(PEGMA) layer was block copolymerized with a gradient PNIPAAm layer (PP1);(2) a gradient P(PEGMA) layer was block copo...     

温敏性丙烯腈共聚物纳米纤维膜的制备与性能

采用可逆加成断裂链转移可控/活性聚合方法合成了丙烯腈与N-异丙基丙烯酰胺(NIPAM)的嵌段共聚物,通过调控嵌段聚合反应时间可以获得一系列不同嵌段链长的共聚物,分子量分布在1.3左右.运用静电纺丝技术制备了所合成嵌段共聚物的纳米纤维膜,扫描电镜照片表明纳米纤维膜较为均匀且直径可调.研究了纳米纤维膜表面水接触角与荧光标记牛血清清蛋白的吸附现象,接触角结果证实共聚物纳米纤维膜具有一定的温度响应性,且疏水性嵌段的引入导致响应温度较PNIPAM有所降低;蛋白质吸附结果则表明温度较低时纳米纤维膜表面更亲水,蛋白质吸附较少.所制备的温敏性纳米纤维膜可望用作智能分离与吸附材料.     

Preparation of chitosan rods with excellent mechanical properties: One candidate for bone fracture internal fixation

Chitosan (CS) is one promising material as a temporary mechanical supporter for bone fracture internal fixation.In our previous work,we successfully fabricated CS rods through one in situ precipitation route.But bending strength and bending modulus of CS rods need to be improved to match the commercially available devices used for bone fracture internal fixation.In this research,CS rods were reinforced effectively through cross-linking reaction by using glutaraldehyde as the coupling reagent.Schiff’s base w...     

Observation of negative differential resistance in diketopyrrolopyrrole-based copolymer films

Remarkable and repeatable negative differential resistance (NDR) phenomenon was observed in a metal-polymer-metal structure diode based on bishexyloxy-divinyl-benzene-alt-diketopyrrolopyrrole (C6DPPPPV),a type of donor-acceptor (D-A) conjugated copolymer.Thickness dependence of the devices implied that the observed NDR characteristics were bulk-controlled.The device performance was considered to depend on the slow trapping and releasing processes related to the local deep states,which was enhanced by the gr...     

Graphene nanosheets decorated with Pd,Pt,Au,and Ag nanoparticles:Synthesis,characterization,and catalysis applications

We report that noble metal nanopartcles (Pd,Pt,Au,and Ag) decorated-graphene nanosheets can be synthesized with the template of graphene oxide by a one-pot solution-based method.The resulting hybrid materials are characterized by transmission electronic microscopy,energy dispersive X-ray spectroscopy,scanning electronic microscopy,atomic force microscopy,X-ray diffraction,and Raman spectroscopy,which demonstrate that the metal nanoparticles have been uniformly deposited on the surfaces of graphene nanosheet...     

Thermo-responsive stick-slip behavior of advancing water contact angle on the surfaces of poly(N-isopropylacrylamide)-grafted polypropylene membranes

Wettability of a solid surface is highly important to its practical application,especially for the surface that shows thermoresponsive properties.In this paper,we describe a thermo-responsive stick-slip behavior of water droplets on the surfaces of poly(N-isopropylacrylamide)(PNIPAM)-grafted polypropylene membranes.Field emission scanning electron microscope(FESEM) images elucidate that the morphology of PNIPAM-grafted membrane surface is thermo-responsive,i.e.,the surface becomes rougher above the lower cr...     

In situ generated,tetrahydrosalen stabilized yttrium borohydride complex:Efficient initiator for the ring-opening polymerization of ε-caprolactone

In this paper,we report the preparation of a new tertrahydrosalen-stabilized yttrium complex which was employed as an initiator-precursor for the polymerization ofε-caprolactone(ε-CL) in the presence of NaBH_4 to give interesting hydroxytelechelic poly(ε-caprolactone)(PCL).The effect of[monomer]/[initiator]([CL]/[I]),temperature and time on the polymerization was investigated.It was found that under the condition:[CL]/[I]= 1200,55℃,toluene:0.5 mL,ε-CL:0.5 mL,PCL with M_w = 32,600 and PDI = 1.47 was obtai...