Synthetic amphoteric copolymer as a dispersant for aqueous barium titanate slurries

An amphoteric water‐soluble copolymer, i.e., poly(methacrylate‐co‐N‐(4‐vinylbenzyl)‐N,N‐dimethylglycinate) (PMV) was synthesized and used as a dispersion agent for barium titanate (BaTiO₃) (BT) particles. PMV was prepared from methacrylic acid and N‐(4‐vinylbenzyl)‐N,N‐dimethylglycinate in basic conditions through free radical polymerization. The structure of this copolymer was verified by its IR and ¹H‐NMR spectra. The dispersing effects of PMV were examined and evaluated through viscosity and sedimentation measurements. The results indicate that this copolymer could uniformly disperse the particles, make the resulting suspensions less viscous and more stabilized. The dispersing ability of PMV is better than that of a commercial dispersant, ammonium polymethacrylate (PMAAN). Accordingly, the BT compacts with PMV exhibit higher dielectric constant values than those with PMAAN. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and application of an anionic water‐soluble copolymer as a dispersant for barium titanate slurries

An anionic water‐soluble copolymer, poly(acrylamide/4‐carboxylamino‐4‐oxo‐2‐butenate) (PAAM/COB), was synthesized and used as a dispersion agent for BaTiO₃ particles. PAAM/COB was prepared from acrylamide and 4‐carboxylamino‐4‐oxo‐2‐butenate in basic conditions through free‐radical polymerization. The structure of this copolymer was verified by IR and ¹H‐NMR spectra. We examined the dispersion effects of PAAM/COB by measuring the viscosity and sedimentation of BaTiO₃ suspensions and by analyzing the particle sizes. The results indicate that this copolymer was indeed effective in dispersing the particles, for the resulting suspensions were less viscous, more stabilized, and contained powder with smaller particle sizes. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 109–115, 2005     

Amphoteric water‐soluble copolymer for barium titanate slurries. I. Synthesis and dispersing ability

An amphoteric water‐soluble copolymer, polyacrylamide/[α‐N,N‐dimethyl‐N‐(3‐(β‐carboxylate)acrylamino)propyl] ammonium ethanate (PAM/DAE) was synthesized and used as a dispersion agent for BaTiO₃ particles. PAM/DAE was prepared from acrylamide and [α‐N,N‐dimethyl‐N‐(3‐(β‐carboxylate)acrylamino)propyl] ammonium ethanate in a basic condition through a free‐radical polymerization. The structure of this copolymer was verified by IR and ¹H‐NMR spectra. The dispersing effects of PAM/DAE were examined by measuring the viscosity and sedimentation of BaTiO₃ suspensions, and by analyzing the particle size. The results indicate that this copolymer could uniformly disperse the particles, and the resulting suspensions were less viscous, more stabilized, and contained powder with smaller particle size. The dispersing/stabilizing ability of PAM/DAE is close to, or slightly better than, that of a commercial dispersant, ammonium salt of poly(methacrylic acid). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1443–1450, 2005     

Amphibious water‐soluble copolymer. I. Its synthesis and dispersing ability on barium titanate

An amphibious water‐soluble copolymer, polyacrylamide/(α‐N,N‐dimethyl‐N‐acryloyloxyethyl) ammonium ethanate (PAAM/DAAE), was synthesized and used as a dispersion agent for BaTiO₃ particles. PAAM/DAAE was prepared from acrylamide and (α‐N,N‐dimethyl‐N‐acryloyloxyethyl) ammonium ethanate under basic conditions through a free‐radical polymerization. The structure of this copolymer was verified with IR and ¹H‐NMR spectra. The dispersing effects of PAAM/DAAE were examined through the measurement of the viscosity and sedimentation of BaTiO₃ suspensions and the green density. The results indicated that this copolymer could uniformly disperse the particles, reduce the viscosity, stabilize the suspensions, and produce high‐density green compacts. In comparison with a commercial dispersant, the ammonium salt of poly(methylacrylic acid), PAAM/DAAE was clearly more effective. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2232–2239, 2004     

Effects of amphoteric copolymer structure on the properties of barium titanate suspensions

The effect of the molecular structure of an amphoteric copolymer, i.e., poly[acrylamide/(α‐N,N‐dimethyl‐N‐(3‐(β‐carboxylate)acrylamino)propyl)ammonium ethanate)] (PAD) on the interactions with BaTiO₃ (BT) particles in water and on the stability of BT suspensions was examined by means of adsorption, ζ potential, sedimentation, and viscosity measurements. The results indicate that the adsorption of PAD onto BT particles follows the Langmuir adsorption isotherm. As the added PAD containing greater ionic group fraction, both the saturated amount of adsorbed polymer and the amount of the polymer required to reach the minimal ζ potential decrease. Whatever the ionic group fraction in PAD, BT suspensions become stable and less viscous when saturated amount of the polymer was adsorbed on particle surface. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

丙烯酸-丙烯酸丁酯-丙烯酰胺三元共聚物分散剂的制备与分散性能

以丙烯酸(AA)、丙烯酸丁酯(BA)为主单体,与功能单体丙烯酰胺(AM)进行共聚,合成了一系列三元共聚物分散剂,主要研究了链转移剂、引发剂和AM的用量对共聚物粘度的影响,并考察了链转移剂、AM、共聚物分散剂、偶联剂用量、纳米TiO2浓度、pH值等因素对纳米TiO2颜料水性分散体系稳定性的影响。结果表明,随着AM的用量增加,共聚物分散剂对纳米TiO2的分散效果逐渐增强;当n(AM)∶n(BA)∶n(AA)=0.09∶1∶1.5,引发剂(BPO)用量为单体总量的1.2%,链转移剂为单体总量的4%时,所制得AA-BA-AM三元共聚物分散剂的粘度为150 mPa.s,对纳米TiO2颗粒的分散效果最佳;且其优化分散条件为:合成分散剂用量16%,偶联剂用量3%,纳米TiO2水溶液浓度3%,pH值10。     

Effect of pH on the properties of barium titanate slurries with an aniomic dispersant

The colloidal stability of barium titanate (BT) aqueous suspensions with poly(acrylamide/4‐carboxylamino‐4‐oxo‐2‐butenate) (PAAM/COB) at pH 7, 9, and 12 has been investigated by means of ζ potential, adsorption, sedimentation, and particle size measurements. The isoelectric point of BT powder is at pH 4.6 and the value of ζ potential decreases as the pH of suspensions increases. The adsorption of PAAM/COB onto BT particles follows the Langmuir adsorption isotherm. The saturated amount of adsorbed polymer decreases with increasing pH. In general, BT particles in basic solutions with PAAM/COB are more stabilized, and less agglomerated than those without any dispersant present. As pH is increased, the resulting ζ potential becomes more negative, although lower polymer concentration is required for monolayer coverage of particle surface. Consequently, the resulting suspensions become more stabilized, and contain powder with smaller particle size. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1082–1088, 2006     

Hydrothermal synthesis of carbonate-free submicron-sized barium titanate from an amorphous precursor: Synthesis and characterization

In this paper, the amorphous barium titanate precursor was prepared by the peroxo-hydroxide method and post-treated by various drying procedures, such as: room temperature drying, room temperature vacuum drying and vacuum drying at 50 °C. The objective in the latter two treatments was to increase the Ti-O-Ba bonds of the precursor. The post-treated precursors were compared with the untreated (i.e., ‘wet’) precursor. Also, a barium titanate precursor was prepared by an alkoxide route. Afterwards, the precursors were hydrothermally treated at 200 °C in a 10 M NaOH solution. Vacuum drying of the precursor seemingly promoted the formation of Ti-O-Ti bonds in the hydrothermal end-product. The low Ba:Ti ratio (0.66) of the alkoxide-route prepared precursor lead to a multi-phase hydrothermal product with BaTiO₃ as the main phase. In contrast, phase pure BaTiO₃, i.e. without BaCO₃ contamination, was obtained for the precursor which was dried at room temperature. Cube-shaped and highly crystalline BaTiO₃ particles were observed by electron microscopy for the hydrothermally treated peroxo-hydroxide-route prepared precursor.     

Poly(sulfobetaine)s and corresponding cationic polymers. XI. Synthesis and aqueous solution properties of a cationic poly(methyl iodide quaternized ethyl vinyl ether/N,N‐dimethylaminopropyl maleamidic acid) copolymer

A copolymer prepared by the copolymerization of ethyl vinyl ether and maleic anhydride underwent amidoacidation with N,N‐dimethylaminopropylamine. The obtained ethyl vinyl ether/dimethylaminopropyl maleamidic acid copolymer was then reacted with methyl iodide to yield poly(methyl iodide quaternized ethyl vinyl ether/N,N′‐dimethylaminopropyl maleamidic acid) (MIQEDMAPMA). The greatest difference from other polyelectrolytes was the carboxylic group on the polymer chain unit of MIQEDMAPMA. Its aqueous solution properties in various salts and at various pH values were studied by measurements of the reduced viscosity and intrinsic viscosity. The reduced viscosity and intrinsic viscosity of this cationic polyelectrolyte were related to the types and concentrations of the added salts. The tendency of the salt effect was similar to that of other polyelectrolytes; that is, soft salt anions were more easily bound to the quaternary ammonium (R₄N⁺) of MIQEDMAPMA than hard salt anions. Some salt ions strongly attracted the quaternary ammonium of the cationic polymeric side chain for the agglomeration of the polymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2261–2269, 2003     

On the use of bi-variate population balance equations for modelling barium titanate nanoparticle precipitation

In this work barium titanate hydrothermal synthesis is studied from the modelling point of view. In fact, a mathematical model can be used to investigate the origin of the typical multi-crystalline particles obtained during this precipitation process. Their origin is not completely clear, since it is not understood which is the controlling mechanism (i.e., secondary nucleation and/or aggregation). Previous works on this subject tried to retrieve the kinetics underlying this particulate process but being based on mono-varied population balance equations failed to give a definitive answer. In this work a bi-variate model is presented, discussed and solved. Results clearly show that such an approach can overcome the limitations of previous modelling works and provides an useful tool for more detailed kinetic parameters estimation. Moreover the model shows that secondary nucleation is indeed very important but aggregation cannot be neglected.     

双酚F/间苯二酚共聚型环氧树脂的合成

为提高双酚F环氧树脂的综合性能,以双酚F、间苯二酚与环氧氯丙烷反应制得双酚F／间苯二酚共聚型环氧树脂。研究了催化剂用量、反应温度、反应时间以及闭环时的加碱速度等因素对产物性能的影响,并对产物进行了表征。结果显示,其最佳合成工艺条件是:间苯二酚与双酚F质量比为20:80,催化剂摩尔分数为2．0％．醚化温度为80℃,醚化时间为5 h,闭环时加碱速度为0．4g/min。     

Synthesis and application of a new vinyl copolymer superplasticizer

A new vinyl graft copolymer superplasticizer was synthesized by copolymerization of polyethylene glycol acrylate (PEGAA), polyethylene glycol biester of maleic acid and citric acid (PEGMC), acrylic acid (AA), sodium allylsulphonate (SAS), and methyl acrylate (MA). The effects of the vinyl monomers' molar ratio, initiator, reaction temperature, and reaction time on its application properties were investigated. The results show that the new vinyl graft copolymer superplasticizer has excellent application properties when the molar ratio of PEGAA, PEGMC, AA, SAS, and MA is 0.5 : 0.10 : 0.20 : 0.05 : 0.03 and the initiator ammonium persulfate [(NH₄)₂S₂O₈, APS] is 0.8 wt % at 80°C for 3 h. The vinyl monomers' conversion is 98.7%. The applied results show that the water‐reducing ratio and retardation solidification time of the superplasticizer reach 33.5% and 4 h, respectively. The applied concrete has excellent mechanical properties. Its molecular structure was characterized by nuclear magnetic resonance, Fourier transform infrared spectra, and gel permeation chromatography. It is characteristic of the new vinyl graft copolymer superplasticizer that citric acid (CA) and MA are introduced into the copolymer molecules. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

新型阻垢剂MA/AA/AMPS/NaH2PO2共聚物的合成和性能研究

以过硫酸铵为引发剂,在水介质中合成了水溶性马来酸酐（MA）／丙烯酸（AA）／2－丙烯酰胺－2－甲基丙基磺酸（AMPS）／次磷酸钠共聚物,并找到了最佳合成条件。研究了共聚物阻CaCO3垢、Ca3(PO4)2垢及抑制Fe2O3和MgSiO3沉积的能力。     

钇掺杂钛酸锂/石墨烯纳米复合材料的合成与电化学性能

以氧化石墨烯（GO）为基底，钛酸四丁酯、一水合氢氧化锂、六水合硝酸钇为原料，十六烷基三甲基溴化铵为表面活性剂，采用溶剂热法合成前驱体，在N2气氛保护下高温煅烧合成了钇掺杂钛酸锂/氧化石墨烯纳米复合材料。采用SEM、XRD、EDS、Raman对复合材料进行了形貌、结构和成分表征。将复合材料用作锂离子电池负极材料，采用循环伏安法、恒流充放电循环法研究了其电化学性能。结果表明，片状钛酸锂包覆在氧化石墨烯片上形成了钇掺杂钛酸锂/氧化石墨烯纳米复合材料。在100 mA/g的电流密度下，钇掺杂量为8%（以钛酸锂的物质的量为基准，下同）的纳米复合材料的首次放电比容量为145.5mA·h/g，经过100圈充放电循环后容量衰减几乎为0，经过200圈循环后容量衰减1.59%，经过300圈循环后容量衰减3.24%，与目前容量保持率只有80%左右的石墨负极相比有明显的改进。钇元素的掺杂和钛酸锂包覆氧化石墨烯形式的复合材料可以减小钛酸锂电极在充放电循环中的极化程度，从而改善了材料的循环性能。     

Synthesis of new extended surfactants containing a carboxylate or sulfate polar group

New extended anionic surfactants with a carboxylate or sulfate polar head were synthesized from polypropoxylated alcohols, and their structures were confirmed by ¹H and ¹³C nuclear magnetic resonance analysis. The extended surfactant critical micelle concentration was found to decrease with the length of the polypropylene glycol spacer. Surfactants containing a diethylene glycol link to the head group exhibited a higher critical micelle concentration than did their nondiethoxylated homologs.     

Synthesis and application of some oligopolyamines as adhesives for road bitumens

By the amination of a fraction of n‐polychloroparaffins (C_13–19) with 1,2‐ethylenediamine in a basic medium, oligopolyamines were obtained. The obtained products were characterized with spectroscopic, titrimetric, and elemental analyses and tested as adhesives for road bitumens. The samples, containing over 7.0% bound nitrogen in a concentration of 1.0 mass % with respect to the bitumen mixtures, were characterized by maximum effectiveness, that is, 100% adhesion between the bitumen and the mineral fillers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Bisphenol-A polycarbonate/polydimethylsiloxane multiblock copolymers. I. Synthesis and characterization

Aminopropyl-terminated polydimethylsiloxane (PDMS)-bisphenol-A polycarbonate block copolymers were synthesized by interfacial phosgenation reaction of 2,2-bis(4-hydroxyphenyl) propane (BPA) and aminopropyl-terminated PDMS. A new synthetic procedure shows better conversion yield of PDMS oligomer. IR, ¹H, ¹³C, and ²⁹Si nuclear magnetic resonance spectra were used to identify the exact chemical structures of the PDMS-PC block copolymers. The conversions of PDMS of these copolymers were ∼ 90% and independent of the PDMS content. The intrinsic viscosities, IV, [γ] studied were in the range between 0.23 and 2.25 dL/g in dichloromethane at 25°C with different reaction conditions. The intrinsic viscosity and the glass transition temperature decreased with increasing PDMS content at the same reaction temperature, while the melting flow indices increase with increasing PDMS content. Transparent and colorless films, which showed good oxygen-to-nitrogen permselectivity, could be cast from dichloromethane. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 57–66, 1997     

A water‐soluble acrylate/sulfonate copolymer. I. Its synthesis and dispersing ability on cement

A new water‐soluble methacrylate/2‐acrylamido‐2‐methylpropane sulfonate copolymer (PMAMP) was synthesized and evaluated as a dispersion agent for cement particles. PMAMP was prepared from methacrylic acid and 2‐acrylamido‐2‐methylpropane sulfonic acid (AMP). The structure of the prepared polymer was verified by its NMR and IR spectra. The dispersing properties of PMAMP were evaluated by a minislump test on cement pastes. The test results indicated that this copolymer could disperse the cement particles and improve the minislump of cement pastes. Compared with a commercial superplasticizer (sulfonated naphthalene formaldehyde condensates), PMAMP performed better in enhancing the fluidity of the cement pastes. The polymer with about 40–50% AMP and a weight‐average molecular weight of about 5 × 10⁴ was most effective in dispersing cement particles and promoting the fluidity of cement pastes. Nevertheless, PMAMP with a higher AMP content or a higher molecular weight appeared to cause less slump loss. This was related to the interaction of this admixture with the cement particles and its adsorption behavior onto the cement particles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2490–2496, 2006     

An amphoteric water‐soluble copolymer. II. Effect of its molecular weight on the dispersion of barium titanate in water

An amphoteric water‐soluble copolymer, that is, polyacrylamide/(α‐N,N‐dimethyl‐N‐acryloyloxyethyl)ammonium ethanate (PAAM/DAAE) was synthesized and it showed the ability to disperse BaTiO₃ (BT) particles in aqueous solutions. In this work, the effect of molecular weight of this polymer on the dispersing properties was further examined. The results indicate that the effectiveness of three polymer samples with different molecular weights in the dispersion of BT particles is P2 (M_w = 1.1 × 10⁵) > P1 (M_w = 1.2 × 10⁴) > P3 (M_w = 3.0 × 10⁵). Apparently, P2 is most effective in dispersing the particles, reducing the viscosity of the suspensions, and obtaining highest green and sintered densities. This is attributed to the highest adsorption of this polymer onto BT powder, and causes strongest electrostatic and steric repulsions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 886–891, 2006     

Synthesis of polyaniline/polytoluidine block copolymer via the pernigraniline oxidation state

Polyaniline was electrochemically synthesized in the emeraldine oxidation state and then converted to the pernigraniline oxidation state by applying an electric potential under optimized conditions. The stability/reactivity of polyaniline in the pernigraniline oxidation state was evaluated in various aqueous media. The products of the reduction of the pernigraniline oxidation state by o-toluidine were analyzed by gel permeation chromatography, ultraviolet–visible and infrared spectroscopies, and cyclic voltammetry. The results are consistent with the synthesis of a diblock copolymer of polyaniline/poly(o-toluidine) and also of some poly(o-toluidine) homopolymer in the emeraldine oxidation state as a side product.