Large-scale and narrow dispersed latex formation in batch emulsion polymerization of styrene in methanol–water solution

This work is an extension of previous research results reported by our team (Colloid Polym Sci 291:2385–2389, 2013), where monodisperse, large-scale, and high-solid-content latexes of poly(n-butyl acrylate) were obtained with the particle coagulation method induced by the electrolyte. However, large-scale polystyrene latex particle is difficult to synthesize with this approach; moreover, demulsification phenomena easily take place especially in high solid content. In this article, a new approach to prepare large-scale polystyrene latex particle was proposed. Methanol was added to aqueous phases to decrease the interfacial tension between the polymer particle surface and continual phases, further decreasing interfacial free energy. Consequently, the surfactant molecules would loosely pack on the polymer particle surface, which is favored by particle coagulation. Experimental investigations showed that the final polystyrene particle scale only reaches to 93.5 nm when the methanol/water ratio is equal to 0:100, but the particle size attains 270 nm when the methanol/water ratio is equal to 30:70. These results indicated that polystyrene particle coagulation can be induced by methanol by varying the surfactant molecule adsorption on the particle surface. This investigation also provided a new simple approach to prepare large-scale, stable latex particles.     

Enhanced properties of poly(lactic acid) with silica nanoparticles

The objective of this article is to fabricate poly(lactic acid) (PLA) and nano silica (SiO₂) composites and investigate effect of SiO₂ on the properties of PLA composites. Surface‐grafting modification was used in this study by grafting 3‐Glycidoxypropyltrimethoxysilane (KH‐560) onto the surface of silica nanoparticles. The surface‐grafting reaction was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis. Then the hydrophilic silica nanoparticles became hydrophobic and dispersed homogeneously in PLA matrix. Scanning electron microscope and Dynamic thermomechanical analysis (DMA) results revealed that the compatibility between PLA and SiO₂ was improved. Differential scanning calorimetry and polarized optical microscope tests showed that nano‐silica had a good effect on crystallization of PLA. The transparency analysis showed an increase in transparency of PLA, which had great benefit for the application of PLA. The thermal stability, fire resistance, and mechanical properties were also enhanced because of the addition of nano silica particles. Copyright © 2016 John Wiley & Sons, Ltd.     

丙烯酸丁酯－苯乙烯－丙烯腈共聚物的结构与力学性能

丙烯酸丁酯－苯乙烯－丙烯腈共聚物的结构与力学性能张会轩，韩业，张会良，冯之榴（吉林工学院化工系长春１３００１２）（中国科学院长春应用化学研究所长春）关键词ＡＳＡ，乳液聚合，粒子，力学性能丙烯酸丁酯－苯乙烯－丙烯腈共聚物（ＡＳＡ）是两相结构，聚丙烯酸丁...     

Accumulation of Silver(I) Ion and Diamine Silver Complex by <Emphasis Type="Italic">Aeromonas</Emphasis> SH10 biomass

The biomass of Aeromonas SH10 was proven to strongly absorb Ag⁺ and [Ag(NH₃)₂]⁺. The maximum uptake of [Ag(NH₃)₂]⁺ was 0.23 g(Ag) g⁻¹(cell dry weight), higher than that of Ag⁺. Fourier transform infrared spectroscopy spectra analysis indicated that some organic groups, such as amide and ionized carboxyl in the cell wall, played an important role in the process of biosorption. After SH10 cells were suspended in the aqueous solution of [Ag(NH₃)₂]⁺ under 60°C for more than 12 h, [Ag(NH₃)₂]⁺ was reduced to Ag(0), which was demonstrated by the characteristic absorbance peak of elemental silver nanoparticle in UV-VIS spectrum. Scanning electron microscopy and transmission electron microscopy observation showed that nanoparticles were formed on the cell wall after reduction. These particles were then confirmed to be elemental silver crystal by energy dispersive X-ray spectroscopy, X-ray diffraction, and UV-VIS analysis. This study demonstrated the potential use of Aeromonas SH10 in silver-containing wastewater treatment due to its high silver biosorption ability, and the potential application of bioreduction of [Ag(NH₃)₂]⁺ in nanoparticle preparation technology.     

Kinetics and mechanism of dissolved organic phosphorus (DOP) digestion by the UV/O3 process

In this study, the kinetics and mechanism of UV/O₃ synergistic oxidative digestion of dissolved organic phosphorus (DOP) were investigated, focusing on the ozone direct oxidation and hydroxyl radical oxidation parts of glufosinate and triphenyl phosphate (TPhP). The p-chlorobenzoic acid (p-CBA) was selected as the probe compound, and two kinds of reaction kinetic models were proposed by competitive kinetic method with R_ct according to the different scale of rate constants of hydroxyl radical oxidation. Under the condition of weakly alkaline (pH = 9.0) and weakly acidic environment (pH = 5.0), the second-order rate constants of glufosinate and TPhP was determined indirectly to be ko_{3/glufosinate} = (2.903 ± 0.247)M⁻¹s⁻¹ and ko_3/TPhP = (3.307 ± 0.204) M⁻¹s⁻¹ by ozone direct oxidation, and k_{·OH/glufosinate} = (1.257 ± 1.031) × 10⁹ M⁻¹s⁻¹ and k_·OH/TPhP = (7.120 × 10⁸ ± 0.963) M⁻¹s⁻¹ by hydroxyl radical oxidation, respectively. The comparison of the contribution levels of the two parts to the digestion process showed that the contribution levels in the digestion of glufosinate and TPhP processes both the contribution of ·OH were higher than those of ozone, 86.3% and 72.6%, respectively.     

Structural evolution of poly(acrylonitrile‐co‐dimethyl itaconate) copolymer during thermal oxidative stabilization

The structural evolution of poly(acrylonitrile‐co‐dimethyl itaconate) [P(AN‐DMI)] copolymer was investigated by Fourier transform infrared spectroscopy (FTIR) in detail and compared with the polyacrylonitrile (PAN) homopolymer. The extent of cyclization reactions was calculated from the FTIR data. It was found that DMI comonomer had the ability to promote the cyclization reactions significantly at the temperature of 240°C, compared to the PAN homopolymer. The results of quantitative FTIR analysis in the range of 1000–1800 cm^?1 showed that the DMI comonomer not only promoted the cyclization reactions, but also facilitated the oxygen uptake reactions, especially the conjugated carbonyl group in an acridone ring in the ladder polymer chains, which proved that DMI comonomer had the potential ability to make successful thermal oxidative stabilization (TOS) process. The positive effects of DMI comonomer on TOS reactions and carbon yield were further confirmed by the dynamic thermogravimetry (TG) analysis. Copyright © 2015 John Wiley & Sons, Ltd.     

Properties of Poly(butylene terephthalate)/Bisphenol A Polycarbonate Blends Toughening with Epoxy-Functionalized Acrylonitrile–Butadiene–Styrene Particles

Glycidyl methacylate functionalized acrylonitrile–butadiene–styrene particles (ABS-g-GMA) prepared via an emulsion polymerization method were used to toughen poly(butylene terephthalate) (PBT)/bisphenol A polycarbonate (PC) blends. DMA results showed PBT was partially miscible with PC and the addition of ABS-g-GMA improved the miscibility between PBT and PC. DSC tests further testified that the introduction of ABS-g-GMA improved the miscibility of PBT and PC according to the T_m depression criterion. SEM displayed a very good dispersion of ABS-g-GMA particles in the PBT/PC blends and the dispersed phase size of PC decreased due to the compatibilization effect of ABS-g-GMA. The mechanical properties showed that the addition of 10 wt% ABS-g-GMA was sufficient to induce a super-tough fracture behavior to the PBT/PC blends and a notched impact strength of more than 1000J/m was achieved. The Vu-Khanh test showed that stable crack propagation took place for PBT/PC blends with the addition of ABS-g-GMA and led to ductile failure.     

Miscibility and crystallization behavior of PBT/epoxy blends

The miscibility and the isothermal crystallization kinetics for PBT/Epoxy blends have been studied by using differential scanning calorimetry, and several kinetic analyses have been used to describe the crystallization process. The Avrami exponents n were obtained for PBT/Epoxy blends. An addition of small amount of epoxy resin (3%) leads to an increase in the number of effective nuclei, thus resulting in an increase in crystallization rate and a stronger trend of instantaneous three‐dimensional growth. For isothermal crystallization, crystallization parameter analysis showed that epoxy particles could act as effective nucleating agents, accelerating the crystallization of PBT component in the PBT/Epoxy blends. The Lauritzen–Hoffman equation for DSC isothermal crystallization data revealed that PBT/Epoxy 97/3 had lower nucleation constant K_g than 100/0, 93/7, and 90/10 PBT/Epoxy blends. Analysis of the crystallization data of PBT/Epoxy blends showed that crystallization occurs in regime II. The fold surface free energy, σ_e = 101.7–58.0 × 10^?3 J/m², and work of chain folding, q = 5.79–3.30 kcal/mol, were determined. The equilibrium melting point depressions of PBT/Epoxy blends were observed and the Flory–Huggins interaction parameters were obtained. It indicated that these blends were thermodynamically miscible in the melt. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1320–1330, 2006     

Synthesis of Sub-100 nm and Narrow Particle Size Distribution Cationic Latex by One-Step Emulsion Polymerization

A novel approach to synthesize narrow particle size distribution cationic latex particles based on styrene and butyl acrylate was proposed. The effect of monomer/water ratios, surfactant (cetyltrimethylammonium chloride) concentrations, and monomer compositions on the evolution of particle size, distribution, number, and morphology as a function of monomer conversion was concerned in order to confirm the optimum polymerization condition. As expected, the particle size of the ultima latex increased with monomer/water ratios and styrene contents decreased with increasing surfactant concentrations. Continuous nucleation phenomena occurred when monomer/water ratio was lesser than 30/70, resulting in a gradual increase in the number of particles in the whole polymerization process. Combined with the previous work (Colloid and Polymer Science, 2014, 292: 519–525), it was concluded that particle coagulation easily took place in cationic emulsion polymerization of styrene. Thus, the narrow particle size distribution cationic latexes with particle scale between 50 nm and 80 nm, 30 wt% solid content could be prepared in a short reaction time.