Polymer diffusion in high-M/low-M hard-soft latex blends

This paper describes experiments that investigate the use of low glass transition temperature (T _g) latex particles consisting of oligomer to promote polymer diffusion in films formed from high molar mass polymer latex. The chemical composition of both polymers was similar. Fluorescence resonance energy transfer (FRET) was used to follow the rate of polymer diffusion for samples in which the high molar mass polymer was labeled with appropriate donor and acceptor dyes. In these latex blends, the presence of the oligomer (with M _n = 24,000 g/mol, M _w/M _n = 2) was so effective at promoting the interdiffusion of the higher molar mass poly(butyl acrylate-co-methyl methacrylate; PBA/MMA = 1:1 by weight) polymer (with M _n = 43,00 g/mol, M _w/M _n = 3) that a significant amount of interdiffusion occurred during film drying. Additional polymer diffusion occurred during film aging and annealing, and this effect could be described quantitatively in terms of free-volume theory. This paper is dedicated to Professor Haruma Kawaguchi to honor his many contributions to the field of latex particles and their applications.     

Effect of cationic monomer on properties of fluorinated acrylate latex

Cationic fluorinated acrylate latex was prepared via semi-continuous emulsion copolymerization of cationic monomer and other monomers.The resultant latex and its film were characterized with dynamic light scattering detector and contact anglc meter. Influences of amount of DMDAAC on the propcrtics of resultant latex and its film were investigated in detail.Results show that the particle size of the latex has the minimum value and the zeta potential of the latex is increased when the amount of DMDAAC is increased.In addition,the particle size of the latex is unimodal distribution when the amount of DMDAAC is not more than 2.5%. However,the particle size of the latex is bimodal distribution when the amount of DMDAAC is more than 2.5%.The contact angle is varied slightly with the increase of amount of DMDAAC when it is not more than 2.5%.Nevertheless,the contact angle is decreased with the increase of the amount of DMDAAC when it is more than 2.5%.     

多齿双亚胺双膦配位的钌络合物的制备和氢化性能

等摩尔的Ｒｕ（ＯＡｃ）２（Ｐｈ３Ｐ）２和Ｎ，Ｎ＇－双－［邻－（二苯基膦）苯亚甲基］乙二胺（简称Ｐ２Ｎ２）在回流的二氯甲烷或甲苯中反应，分别生成两个新型四齿胺膦配位的钌络合物Ｒｕ（ＯＡｃ）２Ｐ２Ｎ２．２Ｈ２Ｏ和反应式－ＲｕＣｌ２Ｐ２Ｎ２．２Ｈ２Ｏ．对两个络合物进行了元素，ＩＲ和ＮＭＲ表征。在氢压１．０至８．０ＭＰａ和反应温度３０至１５０℃的范围内，研究了它们催化α，β－不饱和酸的氢化性能。结果表明。     

Reactive blends of thermoplastics and latex particles

Monodisperse homogeneous and core–shell latex particles of various sized between 200 and 600 nm were synthesized by emulsion copolymerization. Some of the core–shell particles were functionalized with epoxy groups at their peripheries upon introduction of glycidyl methacrylate (GMA) during the synthesis. The core consisted of crosslinked polybutylacrylate and the shell polymethylmethacrylate. Synthesis conditions at high and low temperatures were optimized to obtain coreshell particles with a well-defined morphology. The particles were characterized by quasi-elastic light scattering, scanning electron microscopy and transmission electron microscopy. The latex particles functionalized with GMA were then dispersed into a reactive matrix (styrene and maleic anhydride copolymer) using a batch mixer to obtain blends with well-defined and stabilized morphology. 4 Dimethylaminopyridine was used as a catalyst. The reaction between the epoxy groups at the particle surface and the maleic anhydride or diacid groups of the matrix was evaluated by torque and extraction techniques. A small amount of conversion generates sufficient amounts of grafted species at the matrix and particle interfaces to ensure a good interfacial adhesion.     

Transmission electron microscopy observations of composite polymer colloid nucleated by functionalized silica

In this work, functionalized nanometric silica particles were engaged in emulsion polymerization of ethyl acrylate. The morphological characterization of this composite material was performed by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). We were particularly interested in the state of encapsulation of the silica particles and their distribution in the latex film. Initialy, we successively studied both components of the composite: polymer beads and silica particles differ by their size and also by their contrast. In addition, it was possible to perfrom dark field TEM to study this system of two amorphous phases because their respective amorphous halos are not too close. Hence, we investigated the colloid material in aqueous media and after film formation. Although no ideal encapsulation is observed in the colloid in aqueous media, the distribution of silica in the latex film is good. SAXS results are in good agreement with TEM observations.     

Emulsion copolymerization of styrene with monomeric emulsifiers

Monomeric emulsifiers with different copolymerization reactivities were used as stabilizers in emulsion polymerization of styrene initiated by 2,2′ azobisisobutyronitrile (AIBN). A significant change in emulsifier function was observed between equal micellar concentrations of surface-active sodium sulfopropyl alkyl maleates and the corresponding sodium sulfopropyl dodecyl fumarate. In the presence of less reactive maleates, copolymerization mainly occurs in the interface of the monomer swollen particles, while copolymerization with the fumarate in the first period of emulsion polymerization leads to polyelectrolyte formation in the water phase.     

Polymeric surfactants in latex technology: polystyrene–poly(ethylene oxide) block copolymers as stabilizers in emulsion polymerization

Polystyrene–poly(ethylene oxide) PS–PEO di- and triblock copolymers have been used as stabilizers in the emulsion polymerization of styrene and styrene–butylacrylate for the preparation of “hairy latexes”. The polymerization kinetics and the efficiency of these polymeric surfactants were correlated with the molecular characteristics of the block copolymer. It was shown that the efficiency decreased with increasing molecular weight and PS content of the block copolymer. The PEO frige, with a thickness of 4–25 nm, on the latex particle surface could be characterized and it was shown by differential scanning calorimetry (DSC) that water is strucured in that PEO layer. Film formation with “hairy latexes” was also examined both by DSC and thermomechanical analysis. The properties and application possibilities, such as in controlled latex flocculation, have been reviewed.     

Miniemulsion polymerization of styrene: Evolution of the particle size distribution

The mechanism of the miniemulsion polymerization of styrene was investiaged through a combination of calorimetry to monitor the polymerization rate and transmission electron microscopy (TEM) to follow the evolution of the particle size distribution. These techniques proved to be a powerful combination for gaining detailed mechanistic information regarding these polymerizations. Particle size analysis of the latexes withdrawn during the course of the reaction revealed that most of the polymer particles were formed by a relatively low conversion (i.e., 10% conversion). However, nucleation continued well past this point (to 40-60% conversion). In fact, it was observed that nucleation in miniemulsion polymerizations using cetyl alcohol continued past the maximum in the rate of polymerization. As a result of these long nucleation periods, the latex particle size distributions produced from these miniemulsion polymerizations were broader than their conventional emulsion polymerization counterparts, and were negatively skewed with a tail of small particles. The amount of negative skewing of the particle size distributions was found to decrease with increasing initiator (potassium persulfate) concentration. Finally, a correlation was observed between the length of time to the maximum polymerization rate and the breadth of the particle size distribution as reflected in the standard deviation. © 1995 John Wiley & Sons, Inc.     

聚合物微球的自组装与微图形材料

苯乙烯;丙烯酸;共聚物;聚合物微球的自组装与微图形材料     

聚氨酯—聚丙烯酸树脂的合成及表征

讨论了在聚氨酯水分散体中进行丙烯酸酯共聚物乳液聚合的一些特征。研究表明,聚氨酯水分散体起着种子乳液的作用,发生了核－壳型事过程;复合乳液中聚氨酯链形成其壳,聚丙烯酸树脂分子链形成其核,二树脂的分子链相贯穿与缠结,形成了互穿网络结构。