Polymerization in microemulsion. 2. Surface control and functionalization of microparticles

Antonietti, Markus; Lohmann, Sabine; Niel, Cornelius Van

doi:10.1021/ma00029a021

Cited by 75 publications

(37 citation statements)

References 1 publication

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“…Table 3 summarizes the systems used for the present examination including their ion exchange grade. Polymerization procedure: The technique and procedure of polymerization in the microemulsions have been described in previous publications [3,4] and are only summarized here. For example, 5.19 g of CTMAZ-tartate was dissolved in 1M) ml deionized water, and a mixture of 10 g styrene, 0.38 g m-diisopropenylbenzene (cross-linker), and 150 mg AIBN was added.…”

Section: Communicationsmentioning

confidence: 99%

Microemulsion polymerization: New surfactant systems by counterion variation

Antonietti

Hentze

1996

Advanced Materials

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Communications d D V A N C E D MATERIALSand side (b-d) views of 3 cm-long waveguides of polyurethane (NOA 73) fabricated on a silicon wafer covered with a 2 pm-thick layer of thermal silicon dioxide (Sil Si02). Light from a laser was coupled into a waveguide by butting the end of the optical fiber against the end of the waveguide.'"] These waveguides (n = 1.545) with cross-sections of -3 pm2 supported multi-mode transmission of light with I= 633 nm or 488 nm. We have made 3 cm-long waveguides using polyurethanes, epoxies, and rhodamine-doped polyurethanes and epoxies. A dye-doped waveguide emitted green light from fluorescence when light (A = 0.488 pm, blue) propagating in a waveguide excited the dopant. p T 1 has limitations. Microstructures fabricated on a flat surf; :e using pTM may have a thin ( < 0.1 pm) film betwee I polymeric features; we assume this film is formed by somc combination of transfer of prepolymer from the raist 1 surfaces of the mold, and capillary wicking of prepolymer from the relief structures. The film is sometimes too thin to be visible under a SEM, but it prevents the underlying substrate, such as Si, from being attacked by chemical etchant. When we wished to use the polymeric microstructures as resists to control selective etching of the underlying substrate, we removed this interfering film successfully using 0 2 reactive ion etching (RIE) (44 W, 13 sccm, 180 mTorr). Even without removing this film, however, pTM is successful in applications that are insensitive to its existence. One example is the fabrication of multilayer structures or microstructures on contoured surfaces (Fig. 2c-e). In this type of fabrication, any small amount of liquid prepolymer left on the raised areas of the mold appears to retract to the preexisting contoured surface by capillarity.We believe that pTM has a number of features that make it attractive as a technique in fabrication of microstructures: simplicity; the ability to fabricate both single-and multi-layer microstructures; applicability to non-planar substrates, and to substrates supporting preexisting complex microstructures; speed applicability to the fabrication of structures over large areas; compatibility with a broad range of materials; insensitivity to the viscosity of these materials-all suggest the potential for broad applications in microfabrication. ExperimentalThe elastomeric mold was made from poly(dimethylsiloxane), (PDMS, Sylgard 184, Dow Corning, Silicone Elastomer) as described previously [12,13]. The filled thin ( < 2 mm thick) PDMS mold was brought carefully into contact with the substrate to prevent air bubbles from being trapped between the mold and the substrate. We have used UV-curable polyurethanes (NOA 73, Norland Products; J-91, Summer Optics), heat-curable epoxies (FIOYCLR, F109, F114, Tra-Con), rhodamine-doped polymers (NOA 73, J-91, or FIOYCLR, saturated with rhodamine 590 chloride, Exciton), and precursors for S O z , and Z r 0 2 to make microstructures on various substrates, such as Ag. Au, glass, Si, and Si/SiOz. Photo-...

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Section: Communicationsmentioning

confidence: 99%

Microemulsion polymerization: New surfactant systems by counterion variation

Antonietti

Hentze

1996

Advanced Materials

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“…At medium or high conversion the reaction loci are in the interface zone. Here the polymerization is slower Rpp X lo2* Q X lo2 D N X 10" (mol dm-3) (mol dm-3 s-') (mol particle-' s-') (particle) (nm) (dm3) 1 due to the lower concentration of monomer (a dilution approach").…”

Section: Variation Of Kinetic and Colloidal Parameters Inmentioning

confidence: 99%

“…Oil-in-water-type (O/W) microemulsion homopolymerizations of unsaturated monomers have already been intensively investigated (see, e.g., Refs. [1][2][3][4][5][6][7][8]. Very little has been done, however, on the kinetics of O/W microemulsion copolymerizations.…”

Section: Introductionmentioning

confidence: 99%

“…It was reported that the microemulsion polymerization in the presence of coemulsifiers is very complex because (1) they partition between the monomer and aqueous phases and can change the partitioning and location of monomers, (2) they can act as chain-transfer agents, and (3) they can destabilize the latex by desorbing the coemulsifier from the surface of the polymer particles. For these reasons the three simple component microemulsions (but with a higher concentration of emulsifier) are more convenient for the kinetic studies.…”

Section: Introductionmentioning

confidence: 99%

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On kinetics of microemulsion copolymerization of butyl acrylate and acrylonitrile

Capek

Juraničová

1996

J. Polym. Sci. A Polym. Chem.

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The oil‐in‐water microemulsion copolymerizations of butyl acrylate and acrylonitrile initiated by water (ammonium peroxodisulfate, AP)—and oil (dibenzoyl peroxide, DBP)—soluble radical initiators were investigated. Copolymerizations show two distinct nonstationary rate regions. The maximum rate of polymerization is found to be proportional to the 0.48th and 0.65th power of the AP and DBP concentration, respectively. The rate per particle is found to be proportional to the 0.05th and 0.2nd power of the AP and DBP concentration, respectively. The rate of polymerization decreases with increasing the acrylonitrile concentration. The number of particle increases with increasing conversion up to 50–70%. The number‐average molecular weight increases with conversion up to ca. 20% and then decreases. The number‐average molecular weights were found to decrease with increasing the concentration of both initiator and acrylonitrile. The experimental results were discussed in terms of the water‐phase polymerization, the chain‐transfer and radical desorption events, the particle nucleation during the whole polymerization, and recruiting monomer and emulsifier from the free monomer‐swollen emulsifier micelles. © 1996 John Wiley & Sons, Inc.

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“…Polymerization procedure: The technique and procedure of polymerization in the microemulsions have been described in previous publications [3,4] and are only summarized here. For example, 5.19 g of CTMAZ-tartate was dissolved in 1M) ml deionized water, and a mixture of 10 g styrene, 0.38 g m-diisopropenylbenzene (cross-linker), and 150 mg AIBN was added.…”

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confidence: 99%

The first crystalline hexagonal Si₃N₄ microtubes

1996

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Experimental exchange" lelramethylammonium 339.54 92 DS telrae~ylammonlum 395.65 99 dimethyldiethanolammonium 399.60 90 telrabutylammonium 507.86 96Synthesis of surfactants with diverse organic counterions: Cetyltrimethylammonium chloride (Aldrich) and sodium dodecylsulfate (Serva) were used as supplied. The sodium salts of propionic acid, hydroxybutyric acid, oxalic acid, fumaric acid, maleic acid, terephthalic acid, tartaric acid, and citric acid (all Aldrich) were made by neutralization of a 5 wt.-% acid solution in water with sodium hydroxide. The aqueous solutions of the salts were used as stock solutions. Tetramethylammonium chloride, tetraethylammonium chloride hydrate, and tetrabutylammonium chloride hydrate (Aldrich) were also used as supplied. Diethanoldimethylammonium chloride was synthesized by quarternation of dimethylethanolamine.The surfactants with organic counterions were made by extraction processes. Because the solid-liquid extraction turned out to be rather ineffective for removal of the inorganic salt from the double organic salts, a liquidliquid extraction procedure was performed. For this procedure, stoichiometric amounts of the appropriate organic salts including the targeted counterion were dissolved in a 25 wt-% aqueous solution of the surfactants SDS or CTMA-CI, and 2-butanol was added step-wise until phase separation occurrcd. After separation of the phases, the lower aqueous phase was removed. Repeated addition of small amounts of 2-butanol to the organic phase caused repeated phase separation, until the remainder contained little double inorganic salt, and precipitation stopped. The double organic surfactant was isolated by evaporation of the solvent under reduced pressure. This purification procedure was repeated until the residual amounts of inorganic salt were insignificant. Depending on the hydrophilicity of the organic counterions, ion exchange ratios between 81 % and 99 YO were obtained, as determined by 'H-measurements. Since purity turned out not to be critical for the resulting particle sizes (microemulsions made with the same surfactant with 80-95% purity produced the same particle size, higher salt loads increased the particle size). exhaustive purification was not performed. This contrasts strongly from the influence of salts on standard microemulsions where a decreased particle size with increasing amounts of salt is found [23]. Table 3 summarizes the systems used for the present examination including their ion exchange grade. CTMA-propanoate CTMA.-oxalale CTMA,-terephthalale CTMA-yhydroxvbuwrate CTMAdarfrate CTMA,-maleate CTMA,-fumarate

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Polymerization in microemulsion. 2. Surface control and functionalization of microparticles

Cited by 75 publications

References 1 publication

Microemulsion polymerization: New surfactant systems by counterion variation

Microemulsion polymerization: New surfactant systems by counterion variation

On kinetics of microemulsion copolymerization of butyl acrylate and acrylonitrile

The first crystalline hexagonal Si₃N₄ microtubes

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Polymerization in microemulsion. 2. Surface control and functionalization of microparticles

Cited by 75 publications

References 1 publication

Microemulsion polymerization: New surfactant systems by counterion variation

Microemulsion polymerization: New surfactant systems by counterion variation

On kinetics of microemulsion copolymerization of butyl acrylate and acrylonitrile

The first crystalline hexagonal Si3N4 microtubes

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The first crystalline hexagonal Si₃N₄ microtubes