Carbon fiber as an initiator of cationic polymerization of N-vinylcarbazole

Summary Carbon fibers were found capable of initiating the cationic polymerization of N-vinylcarbazole (NVC) at 6080°C. The activation energy of the polymerization was estimated to be 13.4 kcal/mol. The carbon fiber lost the initiating activity of the polymerization upon the blocking of carboxyl groups on the surface by the treatment with potassium bicarbonate or diazomethane. Therefore, it was concluded that carboxyl groups on carbon fiber play an important role in the initiation of the polymerization. Furthermore, it was found that during the polymerization, poly-NVC was grafted onto the surface; the grafting ratio was determined to be 39.7% (60°C, 24 h).     

Grafting of polyesters onto carbon black. III. Polymerization of β-propiolactone initiated by quaternary ammonium carboxylate groups on the surface of carbon black

By use of carbon black containing quaternary ammonium carboxylate (COO^?N⁺R₄) groups as catalyst, the anionic ring opening polymerization of β-propiolactone (PL) was carried out at 50°C. Although carbon black itself was unable to initiate the polymerization of PL, carbon black containing COO^?N⁺R₄ groups, which was prepared by the reaction of carboxyl groups with corresponding quaternary ammonium hydroxide, was found to be able to initiate the polymerization. The carbon black obtained from the polymerization gave a stable colloidal dispersion in an organic solvent, and it was confirmed that the polyester formed was effectively grafted onto the surface. In addition, the effect of quaternary ammonium countercation on the polymerization was investigated.     

Ring-opening polymerization of 2-oxazolines initiated by chloromethyl groups introduced onto carbon black surface

Summary The ring-opening polymerization of 2-oxazolines (OXZs) was found to be initiated by chloromethyl groups introduced onto carbon black surface. The introduction of chloromethyl groups onto the surface was achieved by the reaction of carbon black with 3,3-bischloromethylbenzoyl peroxide in carbon tetrachloride. During the polymerization, poly-OXZs were grafted from carbon black based on the propagation of the polymers from the surface: percentage of grafting increased with an increase of conversion and reached 40–60%. The polymerization was accelerated by the addition of potassium iodide. Poly-OXZ-grafted carbon black produced stable colloidal dispersions in both hydrophobic and hydrophilic solvents.     

Grafting of poly-β-alanine onto carbon black: The hydrogen transfer polymerization of acrylamide catalyzed by n-butyllithium in the presence of carbon black

The hydrogen transfer polymerization of acrylamide (AAm) catalyzed by n-butyllithium in the presence of carbon black was carried out at 80–100°C and the grafting of poly-β-alanine (nylon 3) was investigated. It was suggested that the growing polymer anion was captured by the quinonic oxygen group on the surface of carbon black. Furthermore, the growing polymer anion reacted with the phenolic hydroxyl group on the surface to give ungrafted polymer and the lithium phenolate (? O^?Li⁺) group (chain transfer to phenolic hydroxyl group). The ? O^?Li⁺ group formed was considered to be capable of initiating the hydrogen transfer polymerization of AAm. Accordingly, during the hydrogen transfer polymerization in the presence of carbon black, poly-β-alanine was effectively grafted by the termination of growing polymer anion and the propagation of the polymer from the ? O^?Li⁺ group on the surface. The grafting ratio was determined to be 60–80%. The carbon black obtained from the polymerization gave a stable colloidal dispersion in water, N,N-dimethylformamide, and formic acid. Furthermore, it was found that the ratio of hydrogen transfer polymerization to normal vinyl polymerization (T ratio) increased with an increase in polymerization temperature.     

Cationic graft polymerization of polymers from carbon fiber initiated by acylium perchlorate groups introduced onto the surface

The cationic graft polymerization of several monomers initiated by acylium perchlorate groups introduced onto the carbon fiber surface was investigated to modify the surface. The introduction of acylium perchlorate groups was successfully achieved by the reaction of silver perchlorate with acyl chloride groups, which were introduced by the reaction of surface carboxyl groups with thionyl chloride. It was found that the cationic polymerization of styrene is initiated by acylium perchlorate groups on the carbon fiber. In the polymerization, polystyrene was grafted onto the carbon fiber surface through the propagation of polystyrene from the surface. Ungrafted polymer was also formed by the chain transfer reaction of growing polymer cation to the monomer. The acylium perchlorate groups have the ability to initiate cationic ring-opening polymerization of tetrahydrofuran (THF) and ε-caprolactone (CL), polyTHF and polyCL being grafted onto the carbon fiber surface, respectively. Polyacetals, such as poly(1,3-dioxolane) and polyoxymethylene, were able to graft onto the carbon fiber by cationic ring-opening polymerization of the corresponding monomers.     

The polymerization of styrene catalyzed by n-butyllithium in the presence of carbon black

The polymerization of styrene catalyzed by n-butyllithium has been carried out in the presence of carbon black at 0°C in toluene. A large portion of the catalyst was consumed by the reaction with the carbon black surface and thus the growth of polystyrene anions on the surface was hindered to a considerable extent. The typical retardation of conversion of styrene monomer to polymer does not change even in the presence of carbon black pretreated with sodium borohydride solution. The intrinsic viscosities of the homopolymers formed in the presence of carbon black were found to be higher than those of the ones formed in the absence of carbon black. On the other hand, the addition of carbon black during the anionic polymerization of styrene was found to promote grafting the growing polymer anions onto the surface of carbon black, consequently giving polymer-grafted particles, while hindering the conversion of styrene into polymer. However, little grafting was observed when the carbon black pretreated with sodium borohydride solution was used. The phenomena indicate that quinonic groups present on the surface of carbon black may be responsible for the capture of growing polymer anions.     

Reactive carbon black having acyl imidazole or acid anhydride groups: Preparation and reaction with functional polymers having hydroxyl or amino groups

The introduction of acyl imidazole groups onto a carbon black surface was achieved by the reaction of the carboxyl groups on the surface with N N′-carbonyldiimidazole, the loading of acyl imidazole groups introduced was determined to be 0.28 mmol/g. In addition, reactive carbon black having acid anhydride groups was prepared by the reaction of phenolic hydroxyl groups with trimellitic anhydride chloride; the amount of acid anhydride groups introduced onto the surface was determined to be 0.20 mmol/g. The reaction of acyl imidazole groups on carbon black with commercially available polymers having hydroxyl or amino groups such resulted in polymers that were found to be grafted onto the surface via ester or amide bonds. The percentage of grafting of diol-type poly(propylene glycol) and diamine-type polydimethylsiloxane was increased to 27.2 % and 42.5 %, respectively. Furthermore, acid anhydride groups on carbon black also reacted with functional polymers having hydroxyl or amino groups to give polymer-grafted carbon blacks. The grafting reaction was accelerated by the addition of tertiary amines. These polymer-grafted carbon blacks produced a stable colloidal dispersion in good solvents for the grafted polymer, but readily precipitated in poor solvents.     

炭黑表面聚合物接枝改性的研究进展

介绍了各种单体通过自由基聚合、阴离子聚合、阳离子聚合等机理在炭黑表面的接技改性及活性聚合物在炭黑表面的接枝反应的研究进展,归纳了改性炭黑的性能及其表征方法。     

The polymerization of N-vinylcarbazole in the presence of carbon black

In order to obtain more detailed information on the mechanism of the polymerization of N-vinyl-carbazole (N-VC) in the presence of carbon black, a comparison of the rates of conversion under various conditions was made and the following results were obtained. The phenolic hydroxyl groups on the surface of carbon black were found to have an ability to initiate the polymerization, and an increase in dielectric constant of the solvent increased the rate of polymerization. Using the mixture of N-VC and comonomers such as styrene or methyl methacrylate, we found that styrene gives a copolymer with N-VC, while methyl methacrylate gives no copolymer during the early stage of polymerization. The phenomena observed here indicate that the nature of polymerization of N-VC initiated by carbon black is cationic.     

炭黑亲水性改性的研究进展

从炭黑的元素组成和表面官能团出发,介绍了增强炭黑亲水性改性的3种方法:氧化改性、接枝改性和包覆改性。氧化改性分为气相氧化、液相氧化、阳极氧化和等离子体氧化,接枝改性分为捕获性接枝、引发性接枝和反应性接枝,包覆改性的方法有微乳液聚合包覆和相分离法包覆。亲水性改性后的炭黑对水的润湿性增强,在水中分散更稳定。     

Modification of carbon black through grafting multihydroxyl hyperbranched polyether onto its surface

The hydroxy methyl groups were introduced onto the pristine carbon black surface through the reaction between unsaturated hydrogen atoms of the polycondensed aromatic rings of carbon black and formaldehyde in alkali condition. Using the resultant hydroxy methyl groups on the carbon black surface as the growth point, multihydroxyl hyperbranched polyether was grafted onto the carbon black surface by cationic ring‐opening polymerization of 3‐ethyl‐3‐(hydroxymethyl)‐oxetane in the presence of BF₃·OEt₂ to improve its dispersion ability in solvents. It was found that the modified carbon black could be dispersed in polar solvents, such as ethanol, chloroform, and DMF. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2086–2092, 2007     

Filler-elastomer interactions: influence of oxygen plasma treatment on surface and mechanical properties of carbon black/rubber composites

In this work, the influence of oxygen plasma treatment on the surface and adsorption properties of carbon blacks was investigated using X-ray photoelectron spectroscopy (XPS), ζ-potential, and BET isotherms. Then the mechanical properties [tensile strength and tearing energy (G_IIIC)] of carbon black/acrylonitrile butadiene rubber (NBR) composites were measured. As a result, it was found that oxygen plasma treatment generated oxygen-containing functional groups, such as, carboxyl, hydroxyl, lactone, and carbonyl groups, on the carbon black surfaces, resulting in a decrease in the equilibrium spreading pressure or London dispersive component of surface free energy. The tearing energy of the carbon black/NBR composites improved as the oxygen-containing functional groups on the carbon black surfaces increased. This revealed that there is a relatively high degree of interaction between the polar NBR and the oxygen-functional groups of carbon blacks.     

Surface grafting of polymer onto carbon thin film

The surface grafting of polymers onto carbon thin film deposited on a glass plate was achieved by two methods: the graft polymerization initiated by initiating groups introduced onto the surface; and the trapping of polymer radicals by surface aromatic rings of the thin film. It was found that the radical and cationic graft polymerization of vinyl monomers are initiated by azo and acylium perchlorate groups introduced onto the surface, respectively, and the corresponding polymers are grafted onto the surface: the surface grafting of polymers were confirmed by the contact angle of the surface with water. In addition, the anionic ring-opening alternating copolymerization of epoxides with cyclic acid anhydrides was found to be initiated by potassium carboxylate groups on the carbon thin film to give the corresponding polyester-grafted carbon thin film. On the other hand, polymer radicals formed by the decomposition of azo polymer, such as poly(polydimethylsiloxane-azobiscyanopentanoate) and poly(polyoxyethylene-azobiscyanopentanoate), were successfully trapped by the surface aromatic rings of carbon thin film and polydimethylsiloxane and polyoxyethylene were grafted onto the surface. © 1995 John Wiley & Sons, Inc.     

炭黑的物化性质及表征

炭黑是一种微观结构，粒子形态和表面性能都极为特殊的炭素材料，炭黑原生粒子是由同心石墨层排列组成，炭黑含有氢，氧及硫等元素，它们基本上位于炭黑表面，形成具有化学活性的表面官能团，决定了炭黑的化学性质，仪器分析技术的发展，为人们研究炭黑表面性质提供了有效的手段，进一步认识了炭黑粒子的表面形态。     

Preparation and characterization of carbon adsorbents from furfural

Carbon adsorbents with different properties were obtained from furfural with variations in the activation reagents and conditions of treatment. They possess insignificant ash and sulfur contents. Pore volume, pore size distribution and the chemical character of the surface of the obtained carbon adsorbent depend on the activation reagent and temperature of treatment. Various oxygen-containing groups of acidic character (carboxyl groups, carboxyl groups in lactone-like binding, phenolic hydroxyl and carbonyl groups) and different chemical properties are present on the surface of carbon oxidized with air. The sample activated with water vapour contains predominantly oxygen-containing groups with basic character.     

Hydrophilic carbon onions synthesized by millisecond pulsed laser irradiation

Carbon onions with hydrophilic characteristics were synthesized through irradiating carbon black suspension using millisecond pulsed laser at room temperature. Laser energy absorption resulted in the structure transformation of carbon black and the formation of hydrophilic groups on the surface of carbon onion. Carbon onions with hollow cores and the incomplete graphitic shells were produced from the starting materials under high and low laser power density, respectively.     

超临界二氧化碳改性活性炭及其对载体性能的影响

以氯化钌为活性前驱体,活性炭为载体,采用超临界CO2处理制备钌/炭催化剂。以超临界二氧化碳流体对活性炭进行预处理,并使用联碱中和法、XPS等手段表征活性炭表面官能团数量,发现处理后活性炭表面羧基和酚羟基的数量明显减少,内酯基的数量增多,这是由于在超临界二氧化碳条件下活性炭表面的羧基和酚羟基发生酯化反应生成内酯基造成的。活性炭表面官能团的改变,改善了它的负载性能。结果表明,使用超临界CO2预处理活性炭作催化剂载体,能提高葡萄糖加氢制备山梨醇的反应催化活性。     

CB-g-WPU/WPU复合材料的制备与气敏响应性能

通过对导电填料炭黑（CB）进行官能化，在CB表面引入羧基官能团，利用CB表面的羧基等活性官能团与端异氰酸酯基聚氨酯预聚物反应得炭黑接枝水性聚氨酯（CB-g-WPU），采用乳液共混法制备得CB—g-WPU／WPU气敏导电复合材料，并对CB—g-WPU／WPU复合材料的气敏响应行为进行了研究。X射线光电能谱（XPS）、傅立叶变换红外光谱（FTIR）、热重分析（TGA）等分析结果表明聚氨酯接枝到了炭黑表面；SEM分析表明，炭黑经过接枝改性后均匀分散在基体WPU中。该法制备的CB—g-WPU／WPU复合材料逾渗值低、气敏响应度大、响应范围广，是一种综合性能优异的气敏导电复合材料。     

Synthesis,characterization of polyacrylate‐g‐carbon black and its application to soap‐free waterborne coating

Polyacrylate‐g‐Carbon Black (abbrev. as gCB) was prepared by free radical polymerization of acrylate monomers on the carbon black surface, which was initiated by a redox system consisting of cerium ammonium nitrate and hydroxymethyl carbon black. gCB was ascertained by X‐ray Photoelectron Spectrometry (XPS). The optimum conditions of synthesis were studied. The stabilities of gCB dispersing in water were studied by zeta potential measurement and spectrophotometric analysis. The results showed that gCB could disperse in water better than the ungrafted carbon black. gCB could be dispersed in the soap‐free hydrosol forming a colored soap‐free water‐borne coating with satisfactory comprehensive performance. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1100–1106, 2001     

提高炭黑分散性能的硝酸氧化研究

为了得到具有优良分散性的炭黑,利用硝酸长时间氧化。作沉降实验,用稳定系数检测炭黑的分散稳定性;用红外光谱、激光粒度仪、元素分析仪、光电子能谱检测其表面的物化性质;用单晶X射线衍射仪确定炭黑的晶相结构。研究表明：通过硝酸氧化,增加了炭黑的表面含氧量,使炭黑的分散性得到了极大的提高;硝酸氧化在炭黑表面引入了羧基、羟基等酸性含氧基团。