Cationic Polymerizable Surfactant Research Articles

Synthesis of New Anionic and Cationic Polymerizable Surfactants for Emulsion Polymerization of Styrene

AbstractNew anionic and cationic maleic surfmers containing a benzyl or p‐vinylbenzyl hydrophobic tail were prepared and characterized. The behaviour of benzyl maleate hemiester in the emulsion polymerization process of styrene has been studied in the presence of potassium persulfate as initiator. The effect of surfmer concentration on particle diameter was particularly investigated.

New piperazine‐based polymerizable monoquaternary cationic surfactants: Synthesis, polymerization, and swelling characteristics of gels

AbstractMonoquaternary cationic polymerizable surfactants of type N‐acryloyl‐N′‐methyl‐N′‐alkyl piperazinium bromide based on piperazine heterocycle was synthesized by reacting N‐acryloyl‐N′methyl piperazine with the corresponding n‐alkyl bromide (decyl, dodecyl, tetradecyl, and hexadecyl) in anhydrous acetone at room temperature. The resulting surfactants were deliquescent to display any sharp melting points. The surface activity was studied by surface tension measurements. Due to the complex head group geometry of these surfactants, the critical micelle concentration value was high in comparison to the analogous alkyltrimethyl ammonium bromides of similar alkyl chain length. The surfactants were polymerized by micellar (in water) and isotropic (in benzene) conditions and the resulting polymers were characterized by solubility and viscosity studies. The polymers prepared in water showed higher viscosity than the ones prepared in benzene as a result of micellar aggregation in water. The reduced viscosity of the polymers in polar solvents such as methanol and dimethyl formamide (DMF) showed polyelectrolyte‐like behavior, whereas nonelectrolyte behavior was observed in chloroform. pH‐responsive hydrogels were prepared by polymerizing the surfactants in the bicontinuous phase of a microemulsion. The resulting polymers did not exhibit any definite micro/nanostructure due to cross‐polymerization of the hydrophilic oil in the bicontinuous network structure. The gels were highly responsive to changes in pH of the medium and showed high‐swelling degree in acidic media owing to the protonation of the tertiary nitrogen of the piperazine ring. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2059–2072, 2009

Preparation of highly monodisperse fluorescent polymer particles by miniemulsion polymerization of styrene with a polymerizable surfactant

Miniemulsion polymerization of styrene (St) in the presence of a hydrophobe (hexadecane:HD) using a cationic polymerizable surfactant ( N , N -dimethyl- N - n -dodecyl- N-2-methacryloyloxyethylammonium bromide:C 12Br) and a cationic initiator (2,2′-azobis(2-amidinopropane) dihydrochloride:V50), called St/C 12Br/V50 hereafter, proceeded efficiently compared with that using sodium dodecyl sulfate (SDS) and potassium persulfate (KPS), i.e., St/SDS/KPS, providing monodisperse polystyrene latex particles with a narrower particle size distribution. In St/C 12Br/AIBN, where an oil-soluble initiator, i.e., 2,2′-azobisisobutyronitrile (AIBN), was used in place of V50, little changes in polymerization kinetics or in particle size distribution were observed, while a significant drop in polymerization rate and a broad particle size distribution were observed with St/SDS/AIBN. A polymerizable pyrene derivative (1-pyrenylmethyl methacrylate: PyMMA) was quantitatively incorporated into monodisperse latex particles in St/PyMMA/C 12Br/V50 compared to pyrene (Py) in St/Py/C 12Br/V50. Contrary to our expectation, however, increased excimer emission was observed with St/PyMMA/C 12Br/V50 particles, indicating less evenly distributed pyrene chromophores in the particles. The fluorescence lifetime of pyrene chromophores in St/Py/C 12Br/V50 particles was determined to be 286 ns, which was 17 times longer than that of pyrene in THF solution.

Radical generation process studies of the cationic surfactants in ultrasonically irradiated emulsion polymerization

Without any chemical initiators added, ultrasonically irradiated emulsion copolymerization of styrene and a cationic polymerizable surfactant (methacryloxyethyl dodecydimethyl ammonium bromide, C12N+) was successfully employed to prepare copolymer nanolatexes. Compared with the conventional ionic surfactants, C12N+ has much higher initiation efficiency and C12N+ system exhibits shorter induction period, much higher styrene conversions and polymerization rate Rp in short reaction time. A radical trapping experiment and gas chromatograph–mass spectrograph analysis proved that under ultrasonic irradiation, C12N+ undergoes bond scission between the two alkyl and ionic group, where both C–N bonds are weak along the chain, thereby producing much more original radicals to initiate the emulsion polymerization.

High purity nanolatex prepared by ultrasonically irradiated emulsion polymerization

Ultrasonically initiated emulsion copolymerization of styrene and a cationic polymerizable surfactant (methacryloxyethyl dodecydimethyl ammonium bromide, C12N+) was successfully employed to prepare high purity copolymer nanolatex. C12N+ can play the roles of an emulsifier, an initiator, and a comonomer at the same time. It has an excellent initiation efficiency and reactivity. The rate of copolymerization was high and styrene conversion achieved 95% in an hour. Nanoscale latex particles with average diameter 40nm were obtained easily under ultrasonic irradiation. Results of FTIR, 1H NMR and surface tension tests proved almost all surfmers had copolymerized with styrene when the C12N+ concentration was more than 0.030g/mL, indicating high purity nanolatex without residual emulsifiers was obtained.

Synthesis and polymerization of tail-type cationic polymerizable surfactants and hydrophobic counter-anion induced association of polyelectrolytes

A series of tail-type cationic surface-active monomers with the cationic charge at the ω-end (1; ST-C m -AB, m=5, 7, and 9, where ST is a styrenic group, C m the alkylene chain at the 4-position of styrene, and AB is alkyltrimethylammonium bromide) have been synthesized as a novel cationic polymerizable surfactant. Their fundamental physicochemical properties such as critical micelle concentration (cmc) and weight-average aggregation number of the micelle (N w(agg)) have been characterized in water at 25 °C by static light-scattering measurements. The cmc values determined for the tail-type surfactant monomers are two-orders of magnitude smaller than those of the corresponding head-type cationic surfactant monomers (2; ST-C1-AC-C m ). The N w(agg) of ST-C m -AB is 68 for m=5, 156 for m=7, and 413 for m=9. Free-radical homopolymerization of ST-C7-AB proceeds very rapidly in water as a result of organization in the micelle to afford the corresponding amphiphilic cationic polyelectrolyte with M w=3.63×106 and 23 nm hydrodynamic radius at 25 °C. Emulsion copolymerization of styrene with ST-C m -AB also proceeds rapidly to afford very stable cationic polystyrene latex particles of 30–60 nm diameter. The amphiphilic cationic polyelectrolyte of poly(ST-C7-AB) is likely to assume a compact conformation with high segment density in 0.1 mol L−1 NaCl in water. Addition of hydrophobic aromatic counter-anions with an weak acid group, for example potassium hydrogen phthalate (PHK) and sodium salicylate, to a salt-free aqueous solution of poly(ST-C7-AB) induces intermolecular aggregation and increases the solution viscosity substantially, often producing gels and precipitation at high polymer concentration.

Synthesis and characterization of nanosized polypyrrole–polystyrene composite particles

AbstractNanosized polypyrrole–polystyrene (PPy–PS) composite particles were synthesized by the polymerization of pyrrole on PS nanoparticles in the presence of FeCl3. The PS nanoparticles were prepared from microemulsion polymerizations using the cationic nonpolymerizable surfactant cetyltrimethylammonium bromide (CTAB), the nonionic polymerizable surfactant ω‐methoxy[poly(ethylene oxide)40]undecyl α‐methacrylate (PEO–R–MA‐40), or the cationic polymerizable surfactant ω‐acryloyloxyundecyltrimethylammonium bromide (AUTMAB). For the latexes stabilized by CTAB, the resulting PPy–PS composite particles exhibited relatively poor colloidal stability and the pressed pellets exhibited relatively low electrical conductivities (∼10−7–10−3 S cm−1). However, for the latexes stabilized by polymerizable surfactants, the resulting PPy–PS composite particles exhibited relatively good colloidal stability and relatively high conductivities (∼10−5–10−1 S cm−1). The effect of polymerizable surfactants on the colloidal stability of composite particles and the conducting mechanism of the composites are discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1360–1367, 2004

Polymerizable Surfactants and Micellar Polymers Bearing Fluorocarbon Hydrophobic Chains Based on Styrene

Cationic polymerizable surfactants based on styrene with fluorocarbon chains and their hydrocarbon analogues were synthesized, and copolymerized to give micellar polymers of the polysoap type. Characteristically, the fluorocarbon polymers show a higher tendency for self-organization, but also much less mobile hydrophobic associations in aqueous media than their hydrocarbon counterparts. In contrast to statistical terpolymers of similar average composition, block copolymers made of a fluorocarbon polysoap block and a hydrocarbon polysoap block via the radical addition fragmentation chain transfer (RAFT) method give rise to not only microphase separation between the hydrophilic polar parts and the hydrophobic apolar parts of the macromolecules, but also seem to be able to undergo additional microphase separation between hydrophobic domains made of fluorocarbon chains and those made of hydrocarbon chains, at least in the solid state.

Copolymerization Behaviour and Structure of Styrene and Polymerizable Surfactants in Three-Component Cationic Microemulsion

The copolymerization and structural properties of the ternary o/w-microemulsions formed from water, styrene and (11-(acryloyloxy)undecyl)trimethylammonium bromide or (2-(methacryloyloxy)ethyl)dodecyldimethylammonium bromide as cationic polymerizable surfactants are investigated. The two surfactants contain the polymerizable group either at the hydrophobic tail (T-type) or at the hydrophilic head group (H-type) and form micellar structures in aqueous solution. Upon addition of styrene, transparent, globular o/w-microemulsions are formed without any addition of a cosurfactant. The microemulsions can be polymerized upon γ-irradiation at room temperature. Copolymers with completely different morphology are obtained. With styrene and the T-type surfactant, very small nanolatex particles are formed similar to microemulsion polymerization of styrene and nonpolymerizable surfactants. In contrast, copolymerization of styrene and the H-type surfactant monomer results in transparent nanogels with high water content. The structure of the micelles and o/w-microemulsions before and after polymerization was studied using small-angle neutron scattering (SANS), while the copolymer structure was analyzed using NMR and IR spectroscopy. SANS experiments show that in the water/H-type surfactant/styrene system the overall structure of the parent microemulsion is largely preserved whereas in the T-type system distinct changes are observed. Structure models are presented which take into account the different properties of the resulting polymer materials at both a macroscopic and a microscopic length scale.

The influence of salicylate counterions on the aggregation behaviour of a polymerizable cationic surfactant

The aggregation behaviour of the cationic polymerizable surfactant dimethylhexadecyl-(2-acrylamidoethyl)ammonium bromide (AM16) has been studied with time-resolved fluorescence quenching (TRFQ) and viscometry. The quencher-averaged aggregation number N q was determined in the absence and presence of strongly binding salicylate ions using TRFQ. In the absence of sodium salicylate (NaSal) AM16 behaves very much like other cationic surfactants with an aggregation number increasing with surfactant concentration and decreasing with increasing temperature. In the presence of NaSal at constant temperature, N q first increases slowly with NaSal concentration C Sal, until the critical concentration C ∗ Sal above which N/ q increases sharply. At constant C Sal, with increasing temperature N q decreases more strongly at C Sal > C ∗ Sal than at C Sal < C ∗ Sal. Viscosity measurements have confirmed the trends observed with TRFQ. The values of C ∗ Sal, as determined with the two different techniques, agree well. The copolymerization of the surfactant with acrylamide leads to water-insoluble copolymers, because of the large compositional drift during copolymerization.

Mechanism of copolymerization of acrylamide with a polymerizable surfactant

AbstractAssociating polymers have been prepared by radical copolymerization in water of acrylamide with a micelleforming cationic polymerizable surfactant. To estimate the locus of initiation, the polymerizations were carried out in the presence of initiators and radical inhibitors of various solubilities (water‐soluble or oil‐soluble), and the decay of inhibitor concentration has been monitored by electron spin resonance spectroscopy. Conversion–time curves simultaneously determined. The experimental data have been interpreted by taking into account the concentration and lifetime of the different radical species (primary radicals, oligoradicals, inhibitors), their partitioning between the micelles and the aqueous continuous phase, and the dynamics of the micellar system. Analysis of the data provided some insight into the copolymerization mechanism of these micellar systems.

Forces between Surfaces Coated with a Polymerizable Surfactant before and after Polymerization

Abstract The forces between layers of a cationic polymerizable surfactant, cetyl p -vinylbenzyl dimethyl ammonium chloride (CVDAC), adsorbed onto muscovite mica have been measured with a surface force technique. The forces were measured both before and after partial UV polymerization of the adsorbed layers, and the stability of adsorbed bilayers after dilution of the adsorption solution was studied for these two cases. Due to their large headgroup, CVDAC molecules do not pack efficiently into monolayers and bilayers. This can be observed by, for instance, the lower surface potential of adsorbed bilayers and the lower pull-off force from monolayer contact, compared to what is found for simpler surfactants like CTAB. It was also found that surface aggregates build up on top of the bilayer, due to the partly hydrophobic headgroup. When the bilayer structure, including the surface aggregates, is polymerized, it is stabilized both with respect to mechanical forces and with respect to dilution of the surrounding solution.