Hemiesters and hemiamides of maleic and succinic acid: synthesis and application of surfactants in emulsion polymerization with styrene and butyl acrylate

Hemiesters and hemiamides of maleic acid with different chain lengths of the hydrophobic alkyl group (R = C₈H₁₇, C₁₀H₂₁, C₁₂H₂₅, C₁₆H₃₃) have been synthesized and used as surfactants in the emulsion polymerization of styrene and butyl acrylate. The same polymerization experiments were also carried out using nonreactive surfactants with an analogous succinic structure. The chemical structure of the surfactants was confirmed by 1H nuclear magnetic resonance. The melting point and critical micelle concentration of the reactive surfactants described herein were measured. All of the surfactants studied provided good stability of styrene/butyl acrylate latexes, when compared with a reference latex of a styrene/butyl acrylate copolymer prepared with a surfactant sodium dodecyl sulfate. The amount of surfactant grafted onto the particles of the final latex was estimated by conductimetric titration. Between 33 and 68% of surfactant used in emulsion polymerization was found on the surface of latex particles. Electrolyte addition at high concentration and freeze/thaw cycle cause flocculation of latexes. Copyright © 1999 John Wiley & Sons, Ltd.     

The use of selected acrylate and acrylamide-based surfmers and polysoaps in the emulsion polymerization of styrene

Polymerizable surfactants (surfmers) 12-acryloyloxy-dodecanoic acid and 11-acrylamidoundecanoic acid and their respective sodium salts were prepared and then polymerized to form their corresponding oligomers using reversible addition-fragmentation chain transfer (RAFT). Different concentrations of both the surfmers, their sodium salts, and their RAFT oligomers were used as polysoaps in the emulsion polymerization of styrene. Stabilities of the pre-emulsions before polymerization were determined and compared. After polymerization, particle sizes and polydispersities of the resulting polystyrene latices were determined. Sodium dodecyl sulfate (SDS) was used as a reference surfactant to compare the particle sizes and stabilities of the pre-emulsions prepared using surfmers and polymeric surfactants (polysoaps) as particle stabilizers. Emulsion polymerization of styrene using these surfmers and polysoaps all led to latices which were stable for a period of more than six months, as indicated by constant particle sizes, whereas latices prepared using the conventional surfactant, SDS, were not as stable.     

The morphology of the monomer–polymer particle in styrene emulsion polymerization

A heterogeneous model for the monomer–polymer particle in styrene emulsion polymerization is presented. In this model, the growing particle consists of an expanding polymer-rich core surrounded by a monomer-rich shell which serves as the major locus of polymerization. This core-shell model was suggested by kinetic studies with continuously uniform latices which showed that the systems of interest were of the Smith-Ewart case II type but that the dynamic—as opposed to equilibrium swelling—particle monomer concentrations were continuously variable. Supporting evidence for the suggested morphology was obtained by electron microscope observation of ultrathin sections of latex particles.     

Nanopore microspheres prepared by a cationic surfmer in the miniemulsion polymerization of styrene

A polymerizable cationic quaternary ammonium surfactant (CQAS) based on 2‐(dimethylamino)ethyl methacrylate (DMAEMA) was successfully synthesized via quaternization reaction. The product was characterized by FTIR and ¹H NMR spectroscopy, and its critical micelle concentration (CMC) was obtained by surface tension measurement. The surfmer acted well as comonomer and surfactant to stabilize monomer droplets during miniemulsion polymerization. To identify whether this system undergoes miniemulsion nucleation mechanism, surface tension, particle size, and N_droplet/N_particle of the system were also measured. The effect of concentration and counter‐ion of the surfmer, and pH value of the system were systematically investigated by kinetic analysis and dynamic light scattering (DLS). The resulting nanopore microspheres were observed by transmission electron micrograph (TEM) and field emission scanning electron micrograph (FESEM) and showed the nanopore morphology with reasonable stability. Another cationic surfactant cetyltrimethylammonium bromide (CTAB) was used for comparative studies. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5800–5810, 2007     

Organocobalt chelates as initiators of emulsion polymerization of styrene

The kinetics of decomposition of organocobalt chelates in the pH range of 2.2–7.0 has been studied. It has been shown that the rate constant of decomposition of the octyl chelate complex at 20°C changes from ～3 × 10^?3 to ～6 × 10^?6 s^?1 in the above pH range. The rate constants of decomposition of complexes with ethyl, octyl, and cetyl ligands, as estimated at 20°C and pH 8.3, are 1.69 × 10^?4, 1.39 × 10^?4, and 2.42 × 10^?5 s^?1, respectively. As evidenced by emission spectrometry measurements, ～100% of organocobalt chelates with ethyl and isopropyl ligands occur in the aqueous phase, while organocobalt chelates with octyl and cetyl ligands are partitioned between monomer and aqueous phases. The rates of initiation of the emulsion polymerization of styrene have been measured by the inhibited polymerization procedure. It has been demonstrated that among three tested compounds (diphenyl picryl hydrazyl, hydroquinone, and benzoquinone), benzoquinone has been found to be a suitable inhibitor for the polymerization under study. The rates of initiation of styrene polymerization at 30°C for organocobalts with ethyl, octyl, and cyclohexyl ligands are 1.0 × 10^?7, 1.04 × 10^?7, and 3.7 × 10^?6 mol/(l s), respectively. The rate constant of decomposition of the organocobalt complex with the octyl ligand at 30°C is 2.28 × 10^?5 s^?1, and the efficiency of initiation with this complex is 0.95.     

Preparation of PEG-modified urethane acrylate emulsion and its emulsion polymerization

In order to improve stability and reduce droplet size, the PEG-modified urethane acrylates were synthesized by the reaction of polyethylene glycol (PEG) with residual isocyanate groups of urethane acrylate to incorporate hydrophilic groups into the molecular ends. The droplet sizes of the PEG-modified urethane acrylate emulsions were much smaller than those of unmodified urethane acrylate emulsions at the same surfactant composition, and the droplet sizes of these emulsions were significantly effected not by surfactant compositions and types, but by the reaction molar ratio of PEG, because the urethane acrylate containing polyoxyethylene groups as terminal groups aided the interfacial activity of surfactant molecules and acted as a polymeric surfactant. The actions of PEG-modified urethane acrylate were confirmed by the investigation of adsorption of urethane acrylate in a water/benzene interface.For polymerization of emulsions, the stability of emulsion in the process of emulsion polymerization was changed by the type of surfactant or initiator. In the case of emulsion polymerization with a water soluble initiator (K₂S₂O₈), the emulsions prepared using TWEEN 60 were broken in the process of polymerization. However, polymerization of these emulsions could be carried out using an oil soluble initiator (AIBN). The conversion of emulsion polymerization changed with the type of urethane acrylates, that is, the reaction molar ratio of PEG to 2-HEMA.     

Preparation of highly concentrated carboxyl-containing butyl acrylate based polymer dispersions by emulsion polymerization

A study of the influence exerted by the structure of oxyethylated and sulfooxyethylated alkylphenols on the features of emulsion polymerization of butyl acrylate with methacrylic acid showed that the use of mixtures of an ionic emulsifier with nonionic emulsifiers allows preparation of stable low-viscosity dispersions of butyl acrylate-methacrylic acid copolymers with no less than 65 wt % content of the main substance.     

Effect of dose rate on emulsion and microemulsion polymerization of styrene

Emulsion and microemulsion polymerization of styrene were initiated with a gamma ray to study the effect of dose rate on polymerization. In both systems, there is an apparent plateau of polymerization rate in the curve of reaction rate vs. conversion. It was shown that emulsion polymerization conformed to the Smith–Ewart theory very well. Changing the dose rate in interval 2 had no great influence on polymerization rate, but it changed the average lifetime of radicals in polymer particles and affected the molecular weight of polymer produced. For microemulsion polymerization it was assumed that in the plateau it is the number of growing polymer particles being kept constant, not the number of polymer particles. When the dose rate was changed while the polymerization came into the constant period, the polymerization rate and the molecular weight of the polymer varied with the dose rate. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 257–262, 1998     

Automated batch emulsion copolymerization of styrene and butyl acrylate

This article describes a method for carrying out emulsion copolymerization using an automated synthesizer. For this purpose, batch emulsion copolymerizations of styrene and butyl acrylate were investigated. The optimization of the polymerization system required tuning the liquid transfer method, sufficient oxygen removal from the reaction medium and setting a proper sampling procedure. The monomer conversion‐time plots obtained with gas chromatography revealed a good reproducibility of the automated reaction kinetics. Furthermore, the particle size distributions and the properties of the final products were found to be highly reproducible. The performance of the automated reactions was subsequently compared with the conventional ones: similar reproducibility of either synthetic method was observed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Effect of a bi-unsaturated monomer on the emulsion polymerization of ethyl acrylate

The emulsion polymerization and copolymerization of ethyl acrylate with a bi-unsaturated comonomer (divinylbenzene, 1,6-hexamethylene diacrylate), present in small proportions, in the presence of anionic emulsifier sodium dodecyl sulfate have been kinetically investigated at 60°C under batch conditions by gas chromatograhy and gravimetric methods. The rate of polymerization in interval 2 was found to be proportional to the 0,37, 0,23, and 0,5 power of the emulsifier concentration for the system A (ethyl acrylate), the system B (ethyl acrylatedivinylbenzene), and the system C (ethyl acrylate/1,6-hexamethylene diacrylate). Divinylbenzene was found to decrease both the rate of polymerization and the polymer particle size. Addition of 1,6-hexamethylene diacrylate slightly increases both the rate of polymerization and the polymer particle size.     

Nitroxide-mediated miniemulsion polymerization of n-butyl acrylate: synthesis of controlled homopolymers and gradient copolymers with styrene

Controlled free-radical homopolymerization of n-butyl acrylate and its copolymerization with styrene have been studied in aqueous miniemulsion, using an acyclic β-phosphonylated nitroxide as a mediator, the N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl) nitroxide, also called SG1. Polymerization kinetics have been studied and characterization of the (co)polymers has been performed, demonstrating the successful synthesis of well-defined poly(n-butyl acrylate) homopolymers and poly(n-butyl acrylate-co-styrene) gradient copolymers.     

Surfactants with transfer agent properties (transurfs) in styrene emulsion polymerization

Styrene emulsion polymerization has been carried out at 70°C using 2–2 Azobis (2 methyl, N-(2 hydroxyethyl) propionamide as initiator and thiol-ended surfactants (I) HS-C₁₁ H₂₂- (OCH₂ CH₂) _n OH withn from 17 to 90 units. The kinetics of monomer conversion, the evolution of particle size, particle size distribution, molecular weight, and molecular weight distribution have been studied. After washing the final latex, the incorporation yield of the surfactant moieties in the particles has been measured. Most of the experiments have been carried out in batch; complementary experiments used semi batch or seeded process. In some experiments the two functions of transfer agent and surfactants have been decoupled using either dodecylmercaptan (oil soluble) or thioglycolic acid (water soluble) as transfer agent and the bromine ended precursor of (I) as surfactant. The discussion of the results is chiefly oriented towards both the molecular weight distribution and the incorporation of the surfactant to the latex.     

Mixtures of organocobalt chelates as initiators of emulsion polymerization of styrene

The emulsion polymerization of styrene has been investigated in the presence of the mixture of alkylcobalt(III) chelates with a tridentate Schiff base containing linear or branched alkyl ligands and characterized by different decomposition constants. The addition of as low as 10 wt % of the complex with the isopropyl ligand to the mixture has been shown to decrease the induction period by a factor of 5 compared with the ethylcobalt complex. The optimal mass ratio between organic cobalt complexes containing isopropyl and ethyl ligands is 1: 3. It has been established that the use of a pair of initiators containing alkyl ligands of different structures, with one of them (more active) efficiently initiating the polymerization at the initial stage and the other (with a lower decomposition rate constant) providing the presence of free radicals in the reaction zone until complete conversion of the monomer, makes it possible to carry out the process to high conversions (>99%) within the optimal period.     

Synthesis of polystyrene-block-polyoxyethylene for use as a stabilizer in the emulsion polymerization of styrene

Five well-defined polystyrene-block-polyoxyethylene copolymers were synthesized by anionic polymerization for use as stabilizers in the emulsion polymerization of styrene. The size of the blocks and their relative weight ratios to each other were the main variables. The molecular weights of the blocks varied from M?_n = 1000–7000 for polystyrene, and M?_w = 3000–9000 for polyoxyethylene. The results of the styrene emulsion polymerization with these block copolymers as stabilizers indicate that for efficient anchoring the block length need not be more than 10 monomer units, possibly even less, and that the polyoxyethylene block M?_w = 3000 is just as capable of stabilizing the polystyrene particle as the higher molecular weight blocks. A very important factor was found to be the weight ratio of the two blocks: block copolymers with a polyoxyethylene content between 75 and 90 wt % were effective stabilizers for the emulsion polymerization of styrene © 1992 John Wiley & Sons, Inc.     

Kinetics of styrene emulsion polymerization in the presence of montmorillonite

The effect of the pristine sodium montmorillonite (Na⁺-MMT) on the styrene emulsion polymerizations with different concentrations of SDS ([SDS]) was investigated. At constant [SDS], the polymerization rate is faster for the run with 1 wt.% Na⁺-MMT compared to the counterpart without Na⁺-MMT. Micelle nucleation predominates in the polymerizations with [SDS] ≧ 13 mM. On the other hand, the contribution of the polymerization associated with the Na⁺-MMT platelets increases significantly when [SDS] decreases from 13 to 9 mM. At [SDS] (e.g., 2 mM) < CMC, homogeneous nucleation controls the particle formation process and polymerization kinetics. Moreover, the contribution of the Na⁺-MMT platelets that act as extra reaction loci to the polymerization kinetics is even comparable to the run in the absence of Na⁺-MMT. The resultant polymer particle size, polymer molecular weight and zeta potential were characterized and a preliminary model was developed to qualitatively study the differences between the polymerizations in the presence and absence of 1 wt.% Na⁺-MMT.     

Seeded semibatch emulsion polymerization of butyl acrylate: Effect of the chain‐transfer agent on the kinetics and structural properties

The effect of dodecane‐1‐thiol on the kinetics, gel fraction, level of branches, and sol molecular weight distribution of the seeded semibatch emulsion polymerization of n‐butyl acrylate carried out at 75 °C was investigated. The gel fraction was strongly affected by the content of the chain‐transfer agent (CTA). The sol weight‐average molecular weights decreased with increasing CTA concentration, whereas no effect on the kinetics and the level of branches was observed. The experimental data were analyzed with a mathematical model of the process that was able to catch fairly well the effect of the process variable. In addition, adhesive tests were carried out to check the effect of the gel fraction on the adhesive properties. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1106–1119, 2001     

Allyl phthalazinone synthesis,polymerization and polymer properties

A phthalazinone monomer with an allyl group, i.e. 4-（3-allyl-4-hydroxyphenyl）phthalazin-1（2H）-one, was synthesized and then copolymerized with 4-（4-hydroxylphenyl）（2H）-phthalazin-1-one and 2,6- diflurobenzonitrile by means of aromatic nucleophilic polycondensation to provide a series of crosslinkable poly（aryl ether nitrile）s. The virgin copolymers exhibited good solubility in polar organic solvents with relative high molecular weights （Mw： 45,130-58,403, inherent viscosities： 0.58-0.75 dL/ g）. After cross-linking, the thermal stability and solvent resistance of the polymer increased.     

Modification of the properties of gelatin of emulsion layer of photographic film with styrene acrylate latex

The problems of modification of the gelatin properties, the polymer for the adhesion of emulsion layer of photographic films are considered. For enhancing the physicochemical parameters of emulsion layer is used styrene acrylate latex in conjunction with hydrophilic synthetic polymer for the modification of gelatin. A method is proposed that simplifi es technology of introducing the gelatin modifying polymer to the emulsion layers.