Block Copolymer Surfactants in Emulsion Polymerization: Influence of the Miscibility of the Hydrophobic Block on Kinetics, Particle Morphology, and Film Formation (original) (raw)
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Block copolymers as polymeric surfactants in latex and microlatex technology
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1999
Ž. Polystyrene-poly ethylene oxide PS-PEO di-and triblock copolymers were used as non-ionic stabilizers in the emulsion polymerization of styrene and styrene-butyl acrylate for the preparation of 'hairy latexes'. The efficiency of these polymeric surfactants was 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. Acrylic microlatexes with a particle size below 50 nm could be obtained with PS-PEO and PMMA-PEO diblock copolymers. Crosslinking of these microlatexes leads to the formation of microgels dispersible with adjustable swelling in organic Ž. Ž. solvents. 'Hairy' latexes are also prepared with poly methyl methacrylate-poly acrylic acid PMMA-PAA diblock copolymers as ionic surfactants. The swelling of the PAA fringe of the latex by neutralization is demonstrated.
e-Polymers, 2006
Ab initio emulsion copolymerization of styrene with 2-hydroxyethyl methacrylate (HEMA) at weight ratios of the hydrophilic monomer of 1 and greater was investigated at various temperatures in dependence on the concentration of sodium dodecylsulfate (SDS) and potassium peroxodisulfate as emulsifier and initiator, respectively. Both the course of the polymerization and the latex properties are strongly influenced by the hydrophilic monomer. For instance, transparent or highly translucent latexes are obtained resembling the appearance of microemulsion latexes with polymer contents as high as 10 weight-% but at much lower surfactant concentration. Moreover, polymerization rate, average particle size, and particle morphology depend on the surfactant and initiator concentration, monomer feed composition, and polymerization temperature.
Macromolecules, 2009
Described is the synthesis of diblock copolymers generated via sequential atom transfer radical polymerization (ATRP) of poly(n-butyl acrylate) (PnBA) followed by chain augmentation with either sulfonated poly(2-hydroxyethyl methacrylate) (PHEMA) or poly(2-hydroxyethyl acrylate) (PHEA) blocks. ATRP of PHEMA or PHEA from PnBA macroinitiator was conducted in acetone/methanol 50:50 (v/v) and produced diblock copolymers of low PDI (<1.3). Hydroxyl functional groups were converted to sulfonate through esterification using excess 2-sulfobenzoic acid cyclic anhydride (SBA). TEM images of aqueous block copolymer solutions reveal an array of polymer micelle morphologies including monodisperse spheres, cylinders, and cylinder aggregates. Surface tensions and critical micelle concentrations appear to be dependent more on hydrophile structure as opposed to its length. Application of the synthesized block copolymers as stabilizers for batch emulsion polymerization of n-butyl acrylate showed the polymeric surfactant effectively stabilizes latex particles and produces a lower polydispersity when compared with commonly applied commercial emulsifiers.
Journal of Applied Polymer Science, 2006
The evolution of the main colloidal parameters in the seeded starved-feed semi-continuous emulsion polymerization of butyl methacrylate (BMA) was investigated, with the main purpose of assessing the effectiveness of the semi-empirical relationship S ¼ K Á S S Á DA/A S as a tool to define the surfactant/monomer feed ratio (! K) best suited to achieve a target particle size. In particular, the effect of the type and amount of surfactant [i.e., anionic, sodium dodecyl sulfate (SDS), or nonionic, Brij 58P] added during the semi-continuous stage was considered. Coagulum formation was never observed under the adopted experimental conditions. To detect the occurrence of secondary nucleation or particle aggregation, or both, the particle size and number of particles, the surface tension and the particle surface cov-erage ratio were correlated. The best results were obtained with SDS and 0.8 K 3. In fact, under the selected experimental conditions, only with SDS did the number of particles remain nearly constant throughout the polymerization at the value defined by the seed latex; the particle size distribution was highly monodisperse, and the final particle diameter closely matched the calculated one ($ 120 nm). The above semi-empirical relationship based on the adjustable parameter K was validated by running test polymerizations aimed at lattices with well-defined particle size.
Journal of Applied Polymer Science, 2009
Monodisperse styrene/methyl methacrylate/acrylic acid (St/MMA/AA) copolymer microspheres have been prepared with surfactant-free emulsion polymerization in air. The presence of oxygen in the system not only caused an induction period but also decreased the average particle size (D p ). However increasing AA concentration ([AA]) gave a reduction in the induction period. The FTIR and NMR analysis of the latex copolymer confirmed that the correlation of the copolymer compositions with the feed compositions was much better at the lower [AA] than at the higher levels. The AA contents of the copolymers obtained in air were much lower than those of the copolymers obtained under N 2 protection.
Colloid and Polymer Science, 2014
This work is an extension of previous research results reported by our team (Colloid Polym Sci 291:2385-2389, where monodisperse, large-scale, and highsolid-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.
Role of alkali-soluble random copolymer in emulsion polymerization
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1999
Ž. Ž. Alkali-soluble random copolymer ASR , poly styreneralpha-methylstyreneracrylic acid was used as a polymeric emulsifier in the emulsion polymerization of styrene and methyl methacrylate, respectively. ASR could form aggregates like micelles and the solubilization ability of the aggregates was dependent on the neutralization degree of ASR. The rate of polymerization of styrene decreased as the neutralization degree of ASR was increased with little change in particle size. This result can be explained by the solubilization ability of ASR aggregate and the entry rate of radicals into the particle. As the degree of neutralization of ASR increased, the ASR aggregate was less efficient in solubilizing the monomer, and it was more difficult for radicals to enter the particle through the extended ASR Ž. layer on the particle surface, which led to a decrease in the rate of polymerization. The polystyrene PS latexes prepared using ASR showed the monodispersed particle size distribution. On the other hand, the particle size Ž. Ž. distribution of poly methyl methacrylate PMMA latexes became broader as the neutralization of ASR increased. This could be explained by the effects of the water solubility of the monomer and the neutralization degree of ASR on particle formation.
Materials Today: Proceedings, 2018
This investigation reports the synthesis of block copolymer of poly(ethylene glycol) methyl ether methacrylate (PPEGMA) with poly(heptafluorobutyl acrylate) (PHFBA). The blockcopolymer was prepared via reversible addition-fragmentation chain transfer polymerization (RAFT). The RAFT end-capped poly[poly(ethylene glycol) methyl ether methacrylate] (PPEGMA) macro-chain transfer agent (CTA) was prepared using 2-cyano-2-propyl dithiobenzoate (CPBT) as RAFT agent. The synthesized PPEGMA was later used as macro-RAFT agent for the polymerization of 2,2,3,3,4,4,4-heptafluorobutyl acrylate (HFBA) which yielded well-defined block copolymers of varied lengths. The PPEGMA-b-PHFBA block copolymer self-assembles in water produces spherical micelles with core-shell nano-structure where the core made of hydrophobic block (PHFBA) and shell is of hydrophilic block (PPEGMA). The synthesized block copolymers, PPEGMA−b−PHFBA, an amphiphilic block copolymers were used as surfactant in the surfactant free emulsion polymerization of styrene. Aqueous micellar solutions of the block copolymers were characterized by DLS and TEM analyses. The CMC value of polymeric surfactant was 0.046 mg. mL −1 , determined by surface tension analysis. The block copolymers were characterized by GPC, 1 H NMR, FT-IR, DSC analyses.
Novel polymerizable surfactants: synthesis and application in the emulsion polymerization of styrene
Polymer Journal, 2010
A series of anionic maleic surfactants were synthesized, and their chemical structures were characterized by NMR. The synthesized surfmers were then used in emulsion polymerization of styrene in the presence of potassium persulfate as an initiator. The polymerization kinetics were investigated, and the obtained latex particles were characterized in terms of particle size and size distribution. The results obtained were compared with the emulsion polymerization of styrene in the presence of an SDS surfactant. The influences of the nature and concentration of surfmers on polymerization conversion and particle size in particular were investigated and discussed.
Die Angewandte Makromolekulare Chemie, 1998
Amphiphilic block and graft copolymers with polysiloxane and poly[(acetylimino)ethylene] sequences were used as nonionic surfactants in the emulsion polymerization of some vinyl monomers (styrene, methyl methacrylate, butyl methacrylate). The peculiarities of the systems (polymerization kinetics and emulsion characteristics) were related to the structural features of the studied emulsifiers and suggested their ability to participate in initiation and transfer reactions and respectively clouding phenomena in aqueous phase. ZUSAMMENFASSUNG: Block-und Pfropfcopolymere mit Polysiloxan-und Poly(acetyliminoethylen)-Bestandteilen wurden als nichtionische Emulgatoren bei der Emulsionspolymerisation von einigen Vinylmonomeren (Styrol, Methylmethacrylat, Butylmethacrylat) benutzt. Die Polymerisationssysteme (kinetische Aussagen, Teilchengröße, Teilchengrößenverteilungen, usw.) wurden charakterisiert und die Emulgatorstruktur-Polymerisationseigenschaft-Beziehungen wurden untersucht. Die Teilnahme der Copolymeren an der Initiierungs-und Ü bertragungsreaktion wurde festgestellt.