Synthesis of block copolymers for surface functionalization with stimuli-responsive macromolecules

Using block copolymers with poly(n-butyl acrylate) (PBA) as anchor block being capable to tether the temperature-responsive block poly(N-isopropylacrylamide) (PNIPAAm) to the surface, polysulfone (PSf) films were functionalized applying an adsorption/surface entrapment process. Homo and block copolymer synthesis was investigated applying atom transfer radical polymerization (ATRP) using tris(2-(dimethylamino)ethyl)amine (Me₆TREN), CuCl and N,N-dimethylformamide (DMF). On basis of the determined critical micelle concentration of the block copolymers, surface functionalization of PSf was performed from an aqueous solution containing 25 vol% dimethylacetamide. These functionalized surfaces exhibit reversible temperature dependent properties due to the lower critical solution temperature (LCST) of PNIPAAm as can be proven by contact angle measurement. Furthermore, the beneficial effect of the PBA block with adjusted molecular weight on the stability of these coatings was proven. This surface functionalization method has various potential applications and the resulting surfaces are anticipated to exhibit actively triggerable ‘chaotic’ properties as basis of an efficient anti-biofouling strategy.     

Elaborate synthesis of biological macromolecules

Egged on: Elaborate syntheses of biological macromolecules consisting of more than two different components is developing. Kajihara and co-workers have used a bio-resource to develop a new strategy for the semisynthesis of glycoproteins.     

Theory of chromatography of complex cyclic polymers: eight-shaped and daisy-like macromolecules

A theory of chromatography of eight-shaped, trefoil-shaped and daisy-like polymers is developed. For a model of an ideal chain in a slit-like pore exact equations and a number of approximate formulae for the distribution coefficient K of these polymers are derived. All modes of chromatography of complex macrocycles of arbitrary molar mass in both narrow and wide pores are covered by the theory. It is shown that complex macrocycles always elute after linear polymers and rings of the same contour length. The effective chromatographic radius of eight-shaped and daisy-like macromolecules, which determines retention in size-exclusion chromatography are calculated. The increase in the retention with molar mass is predicted for all types of macrocycles at the critical interaction condition. Non-monotonous molar mass dependences of K are found at pre-critical interaction. We simulate separation of complex cyclic polymers from linear and ring precursors, discuss possibilities to separate symmetric and asymmetric eights, and speculates on the use of chromatography for separating knotted and unknotted polymer rings. According to the theory, the chromatography under the critical and pre-critical interaction conditions is expected to be especially efficient in these and similar problems. Boundary conditions for the theory and its applicability to real systems are discussed.     

五元环硫酸酯的合成及其在立体合成中的应用

五元环硫酸酯具有较高的反应活性,在有机合成中得到广泛的应用。本文将对五元环硫酸酯化合物的合成及其在有机立体合成中的应用作一综述。     

层状双氢氧化物的可控合成及功能化研究进展

层状双氢氧化物（LDHs）作为一种低成本、表面带正电荷、结构与组成高度可调变并能进行插层反应的二维无机材料备受关注。目前合成出分散性良好、粒径分布范围窄以及可调结构和组成的LDHs具有一定挑战性,再加上为了满足不同应用的实际需求,需要将其他功能组分与含有复杂结构（化学修饰）的LDHs进行组装形成功能化LDHs材料,这对其结构设计和制备方法的策略提出了新的挑战。因此,本文将目光聚焦在LDHs的可控合成、表面化学修饰、功能化复合材料方面的研究上,归类总结了研究者们在设计制备功能化LDHs方面所做的贡献,分析了功能化LDHs复合材料在不同领域应用的特点和作用,提出进行创新结构设计和合成方案简易化将是今后构建功能化LDHs复合材料的研究重点。     

Simultaneous synthesis and functionalization of water-soluble up-conversion nanoparticles for in-vitro cell and nude mouse imaging

Water-solubility and biocompatibility are prerequisites for rare-earth up-converting nanophosphors applied to biological imaging. In this work, we have developed a facile and one-step synthesis technique, through which water-soluble NaYF(4): Yb(3+), Er(3+) nanoparticles (NPs) with functional groups including 3-mercaptopropionic acid, 6-aminocaproic acid and poly(ethylene glycol)methyl ether on their surface can be directly prepared without any further surface treatment. Some inorganic salts will be selected as starting materials, water and some low toxic organic agents have been used as reaction media, which differs from earlier works. Structural and up-converting fluorescence are characterized by a variety of techniques. Cell uptake and in-vitro imaging of the as-synthesized NPs have been investigated using a multiphoton con-focal laser scanning microscope with a near-infrared excitation source. Internalization of the bare and functionalized NPs in human lung carcinoma A549 and human cervical carcinoma HeLa cells are studied at a nanoparticle loading of 10 μg mL(-1) over an exposure period from 30 min to 24 h. The cytotoxicity of modified NPs in HeLa cells is found to be low. In addition, the feasibility of the NPs in animal imaging has been demonstrated by subcutaneously injecting these NPs into nude mouse. The results indicated that our directly synthesized NPs coated with various functional groups are promising as bio-imaging agents due to their easy uptake, long lasting, low cytotoxicity, emissive in various human carcinoma cell lines and small animals through up-conversion with near-infrared excitation.     

A novel cyclic process for synthesis gas production

This paper reports a novel cyclic partial oxidation process for the production of synthesis gas with the in situ separation of oxygen from air. A perovskite-type oxide, La_0.8Sr_0.2Co_0.5Fe_0.5O_3−δ, is employed in the experimental study of the process as an oxygen retaining material. Air and methane are periodically brought into contact with the oxide packed in a fixed-bed reactor. The oxide, during the air step, exclusively retains oxygen while partial oxidation reaction occurs during the methane step utilizing the retained oxygen. Although combustion and cracking reactions occur in addition to the partial oxidation reaction during the methane step, high methane conversion is achieved and hydrogen and CO are produced with high selectivity.     

Recent progress in enzymatic functionalization of carbon-hydrogen bonds for the green synthesis of chemicals

Enzymatic reactions take place with high chemo-, regio-, and stereo-selectivity, appealing for the direct functionalization of abundant and inexpensive compounds with C-H bonds to make fine chemicals such as high-value intermediates and pharmaceuticals. This review summarizes recent progress in the enzymatic functionalization of C-H bonds with an emphasis on heme enzymes such as cytochrome P450s, chloroperoxidase and unspecific peroxygenases. Specific examples are discussed to elucidate the applications of the molecular and process engineering approaches to overcome the challenges hindering enzymatic C-H functionalization. Also discussed is the recent development of the chemo-enzymatic cascade as an effective way to integrate the power of metal catalysis and enzymatic catalysis for C-H functionalization.     

Catalytic asymmetric functionalization of inert bonds and synthesis of bioactive natural products

The direct and enantioselective functionalization of inert bonds such as carbon-hydrogen and carbon-carbon is an emerging tool towards more sustainable and efficient synthetic methods. The individual activation pathways like concerted deprotonation metalations, directed activations, beta-carbon eliminations or retro-allylations proceed by completely different mechanisms and therefore have complementary requirements and different associated challenges. A careful fine-tuning of the transition-metal complex is critical for each mechanism, but a very broad structural space can be covered as well. These methods enhance the synthetic chemist's toolbox allowing more concise, efficient synthetic routes to be executed in target-oriented synthesis. This is illustrated by the examples of a synthesis of largazole and the core of stachyflin from our group.     

Recent progress in enzymatic functionalization of carbon-hydrogen bonds for the green synthesis of chemicals

Enzymatic reactions take place with high chemo-, regio-, and stereo-selectivity, appealing for the direct functionalization of abundant and inexpensive compounds with C-H bonds to make fine chemicals such as high-value intermediates and pharmaceuticals. This review summarizes recent progress in the enzymatic functionalization of C-H bonds with an emphasis on heme enzymes such as cytochrome P450s, chloroperoxidase and unspecific peroxygenases. Specific examples are discussed to elucidate the applications of the molecular and process engineering approaches to overcome the challenges hindering enzymatic C-H functionalization. Also discussed is the recent development of the chemo-enzymatic cascade as an effective way to integrate the power of metal catalysis and enzymatic catalysis for C-H functionalization.     

超分子自组装及其在高分子合成领域中的应用

超分子自组装是近年来倍受重视的国际前沿课题,它将会极大促进信息、能源、生命、环境和材料科学等学科领域的发展,介绍了基于氢键、π键、配位键、双亲分子4种自组装体系,重点综述了这4种自组装体系在高分子合成领域中的最新进展,最后对超分子自组装的发展趋势做了展望。     

Facile functionalization of soybean oil by thiol-ene photo-click reaction for the synthesis of polyfunctional acrylate

Nowadays biosource-based materials have received revitalized interest for their ability to substitute for petrochemical-based materials. In this paper, we report a facile synthetic method of soybean oil-based polyfunctional acrylate (PFA) for UV-curable materials. Specifically, rapid and highly efficient side-chain functionalization of soybean oil was achieved via photoclick thiol-ene reaction, soybean oil-based polycarboxylic acid (PCA) was thus obtained. Next, by DCC (N,N′-dicyclohexylcarbodiimide) catalyzed esterification reaction with hydroxypropyl acrylate, polyfunctional acrylate (PFA) was synthesized at room temperature. Real-FTIR result indicated that almost 100% conversion of double-bond within vegetable oil was observed within 16.7 min, yielding the soybean oil-based polycarboxylic acid quantitatively. Furthermore, the structure of PFA was confirmed by ¹H NMR and FTIR. Finally, the excellent UV-curing rate of PFA was revealed by real-FTIR.     

Bulk functionalization of ethylene-propylene copolymers. IV. A theoretical approach

A theroretical model is developed for the bulk functionalization of ethylene–propylene co-polymers on the basis of the molecular mechanism proposed in previous papers, with certain simplifying assumptions: (1) A steady state regime for all the radical species is hypothesized; (2) a number of termination reaction are neglected; (3) no monomer homopolymerization is allowed to occur. An analytical expression is derived in such a way. A comparison of the theoretical predictions with some experimental data, obtained varying the radical initiator concentration [I]_o and the reaction temperature, T, shows satisfactory agreement at low values of [I]_o and T. At higher values the molecular mechanism becomes more complex and the model is unable to fit the data.     

Flame‐based synthesis and in situ functionalization of palladium alloy nanoparticles

Flame‐driven synthesis and functionalization of palladium‐containing nanoparticles is demonstrated using a high temperature reducing jet (HTRJ) process that decouples flame chemistry from particle formation chemistry and provides a reducing environment that enables synthesis of metal nanoparticles from low‐cost aqueous precursors. Nanoparticles with controlled palladium, copper, and silver content were synthesized and functionalized with amine‐containing ligands using both in situ and ex situ approaches. For in situ functionalization, octylamine was sprayed into the quench section of the HTRJ reactor to cap the nanoparticles in the gas phase. For the ex situ approach, the “bare” nanopowders were heated in various amines (hexylamine, octylamine, and oleylamine) to form stable dispersions. Use of oleylamine at high temperature allowed modification of the nanoparticle size and shape while maintaining the alloy composition. These in situ and ex situ functionalization methods provide flexibility to tailor particles for specific applications such as electrocatalysis or hydrogen purification. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3826–3834, 2018     

Exploring the methods of synthesis,functionalization, and characterization of graphene and graphene oxide for supercapacitor applications

Graphene and graphene oxide, are attracting more attention over the last decades in the area of supercapacitor research and researchers concentrate on extensive exploration, owing to their dominating electrical conductivity, combined with mechanical properties. This review is a panoramic approach, giving insights into various aspects related to graphene and graphene oxide such as their properties, production methods, functionalities, and their applications in supercapacitors. The study ought to be beneficial to novice as well as to the domain experts. Various properties of both materials are explored and both synthesis methods are elaborated. Extra emphasis is given to bring out the role of graphene and graphene oxide in promoting the performance of supercapacitors. Synthesis methods are tabulated based on the evaluation metrics like specific capacitance and capacitance retention. Finally, the application of graphene and graphene oxide in supercapacitors are highlighted. Before concluding, perspectives along with challenges for further development are proposed and are expected to facilitate researchers in shedding light on further studies in this explorative area.     

A convenient method for the synthesis of cyclic polymers by ATRP

Poly (vinylbutyral) (PVB) was synthesized by condensation of poly (vinylalcohol) (PVA) with butyraldehyde. Nanocomposites of PVB with graphene (0.1 to 0.6?wt%) were prepared via solution blending. The structure and properties of prepared compounds were characterized by FT-IR, X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and tensile strength tester (TST). The prepared nanocomposites showed considerable thermal and mechanical properties than PVB and showed good toughness and flexibility.     

基于降冰片烯结构的环状双酰胺的无溶剂微波合成

在无溶剂条件下,利用微波辐射合成法制备了两种含有降冰片烯骨架结构的环状双酰胺化合物,合成过程不需溶剂,反应速度快,操作简便、安全、节能、环保。目标化合物的结构经核磁共振氢谱、核磁共振碳谱、红外光谱和元素分析进行了确认。     

A convenient synthesis of macroporous polymer‐supported supernucleophilic reagent and linear macromolecules

N,N′‐Bis(4‐pyridinyl)piperazine and N‐(4‐pyridinyl)piperazine have been prepared by treatment of piperazine with 4‐chloropyridine. N,N′‐Bis(4‐pyridinyl)piperazine (bis‐DMAP) is similar to a couple of 4‐(N,N‐dimethylamino)pyridine (DMAP). N‐(4‐Pyridinyl)piperazine as reactive group can be linked onto the macroporous polymeric carrier producing a polymer‐bound catalyst. A linear epoxy polymer containing the supernucleophilic functional groups have been synthesized by reaction of epichlorohydrin and 4‐aminopyridine. The linear polymeric catalysts have been braced by the macroporous resin to obtain a polymer‐supported linear polymeric catalyst. It is found that catalytic activity of bis‐DMAP approaches that of DMAP. The activity of the polymer‐supported linear polymeric catalyst is higher than that of the polymer‐bound catalyst in the acetylation of tert‐butyl alcohol, as monitored by gas–liquid chromatography. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 593–597, 2000