Search results for "emulsion"
showing 10 items of 344 documents
Cationic and Zwitterionic Polymerizable SurfactantsQuaternary Ammonium Dialkyl Maleates. 2. Emulsion Polymerization of Styrene and Butyl Acrylate
1998
Polymerizable cationic and zwitterionic dialkyl maleates with different hydrophobic chain lengths (R = C10H21, C12H25, C16H33, C18H37) and different counterions (I, Br, HSO4) for the cationic hydrophilic part, as well as some similar surfactants, dialkyl succinates, were used in batch and seeded emulsion polymerization of styrene and butyl acrylate. All surfactants, when used in emulsion polymerization, provide good stability to the styrene/butyl acrylate latices. A styrene/butyl acrylate latex prepared with sodium dodecyl sulfate (SDS) was used as a reference. Some stability tests for latices were performed, and the glass transition temperatures, as well as the molecular weights of the pol…
Hydrophobically Modified Halloysite Nanotubes as Reverse Micelles for Water-in-Oil Emulsion.
2015
An easy strategy to obtain inorganic reverse micelles based on halloysite nanotubes (HNTs) and alkyltrimethylammonium bromides has been developed. The selective modification of the HNTs external surface with cationic surfactants endows to generate tubular nanostructures with a hydrophobic shell and a hydrophilic cavity. The influence of the surfactants alkyl chain on the HNTs functionalization degree has been investigated. The dynamic behavior of the surfactant/HNT hybrids in solvents with variable polarity has been correlated to their affinity toward hydrophobic media explored through partition experiments. The water-in-oil emulsion is able to solubilize copper sulfate, proving the incorpo…
Controlling the Polymer Microstructure in Anionic Polymerization by Compartmentalization.
2018
An ideal random anionic copolymerization is forced to produce gradient structures by physical separation of two monomers in emulsion compartments. One monomer (M) is preferably soluble in the droplets, while the other one (D) prefers the continuous phase of a DMSO-in-cyclohexane emulsion. The living anionic copolymerization of two activated aziridines is thus confined to the DMSO compartments as polymerization occurs selectively in the droplets. Dilution of the continuous phase adjusts the local concentration of monomer D in the droplets and thus the gradient of the resulting copolymer. The copolymerizations in emulsion are monitored by real-time 1 H NMR kinetics, proving a change of the re…
Efficiency Boosting of Surfactants with Poly(ethylene oxide)-Poly(alkyl glycidyl ether)s: A New Class of Amphiphilic Polymers
2020
Twenty years ago, it was found that adding small amounts of amphiphilic block copolymers like poly(ethylene propylene)-co-poly(ethylene oxide) (PEP-b-PEO) to microemulsion systems strongly increases the efficiency of medium-chain surfactants to solubilize water and oil. Although being predestined to serve as a milestone in microemulsion research, the effect has only scarcely found its way into applications. In this work, we propose new types of efficiency boosters, namely, poly(ethylene oxide)-poly(alkyl glycidyl ether carbonate)s (PEO-b-PAlkGE) and their "carbonated" poly(ethylene oxide)-poly(carbonate alkyl glycidyl ether) analogs. Their synthesis via anionic ring-opening polymerization (…
Maleic diamide polymerizable surfactants. Applications in emulsion polymerization
2003
Abstract A series of new polymerizable non-ionic and ionic surfactants (surfmers) with amides groups on both sides of the C=C double bonds have been prepared upon reaction of maleic isoimide carrying a long alkyl chain (or a benzyl group) with a hydrophilic amine derivative. Their critical micellar concentration (CMC) was measured with a surface tensiometer. They have been engaged in batch emulsion polymerization of styrene, and semi-batch seeded copolymerization of styrene and butyl acrylate, giving stable latexes during the polymerization process, and upon extraction with ethanol, showing a high rate of incorporation at the particle surface. However these surfmers do not confer good steri…
Radiation synthesis of polyaspartamide functionalised hydrogels for sustained release of fragrances
2005
The aim of the present investigation is to assess the possibility of obtaining a biocompatible material device which is able to deliver oil-soluble fragrances in air over a length of time. Aqueous solutions of polyaspartamide functionalised with glycidyl methacrylate have been cross linked through gamma irradiation in the presence of a lipophilic model fragrance, emulsified prior to irradiation. Two emulsification conditions have been considered at two different concentrations of both fragrance and surfactant in water. Chemical hydrogels have been obtained in correspondence to two irradiation absorbed doses and have been characterised for their solubility properties and swelling ability in …
Molekulargewichtsverteilungen einiger emulsionspolymerisate von styrol
1965
An einigen unter normalen Bedingungen hergestellten Emulsionspolymerisaten werden die Verteilungen durch Fallungschromatographie bestimmt. Die Uneinheitlichkeit ist erheblich hoher als bei unter homogenen Bedingungen hergestellten Polymerisaten, und die Verteilungskurven weisen einige Besonderheiten auf. Einige Schlusse uber die Kinetik der Emulsionspolymerisation konnen daraus gezogen werden. Vergleichende Viskositats- und Lichtstreuungsmessungen im Bereich der Molekulargewichte 106 bis 107 ergeben, das die [η]-M-Beziehung bei Emulsionspolymerisaten und homogen polymerisierten Polystyrolen innerhalb der Fehlergrenzen ubereinstimmt. The molecular-weight distributions of several polymers pre…
Creep and recovery experimental investigation of low oil content food emulsions
2008
Abstract Creep and recovery tests have been performed to study the viscoelastic behavior of low oil content food emulsions. Formulations of salad dressings usually include modified starch (MS) due to its low cost and the special creamy texture if affords. The combination of starch with other natural gums may improve the quality of the product. A reference emulsion containing 4% MS, and four other formulations in which the starch was partially replaced by xanthan gum (XG), locust bean gum (LBG) and two synergistic blends of these gums were formulated. Gels prior to emulsification were studied for comparative purposes. The viscoelastic behavior of all the systems was characterized by means of…
Influence of hydrocolloid nature on the structure and functional properties of emulsified edible films
2009
Abstract To investigate the influence of polymer behaviors on the structure and the functional properties of emulsified films, agar (AG) and cassava starch (CAS) were used as hydrocolloid continuous phases in which hydrogenated vegetable oil (VGB81) was dispersed. Different ratios of hydrophilic/hydrophobic materials (HB/HL) were also used in film formulations to study the evolution of film-emulsion structure. Microscopically observed, VGB–CAS emulsified films exhibit a similar bilayer structure. However, there was just a migration and an aggregation of lipid particles. There was no coalescence which could form a continuous “lipid layer” necessary for an effective barrier. Moreover, they co…
Tomographic and Topographic Investigation of Poly-D,L-Lactide-Co-Glycolide Microspheres Loaded with Prostaglandine E<sub>2</sub> for Exte…
2010
Polymeric, biodegradable microspheres represent a good reliable system to investigate the release of bioactive substances in both in vitro and in vivo applications. Common biomaterials for the synthesis of these microspheres are aliphatic polyesters of the poly(α-hydroxy)acids, especially poly-L-lactides (PLA) and polyglycolides (PGA) or their copolymers poly-D,L-lactide-co-glycolides (PLGA). In our own previous studies we have developed PLGA microspheres with integrated PGE2 as model substance for a wide range of biomedical applications, especially in angiogenesis, fracture healing and cartilage repair. The synthesis is based on a binary solvent in water emulsion approach, where two differ…