Stabilization of water/n‐hexane emulsions by amphiphilic copolymers based on vinyl ethers and their polycomplexes with poly(acrylic acid)

Amphiphilic random copolymers based on vinyl ether of ethylene glycol and vinyl butyl ether as well as their polycomplexes with poly(acrylic acid) were studied as polymeric reagents for the stabilization of water/n‐hexane emulsions. The emulsion stability strongly depended on the content of vinyl butyl ether in the copolymers as well as their concentration in solution. The more hydrophobic copolymers stabilized emulsions more efficiently. An increase in the temperature and the addition of inorganic salts reduced the emulsion lifetime. The formation of interpolymer complexes between the copolymers and poly(acrylic acid) significantly influenced the stability of the emulsions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2625–2632, 2004     

Amphiphilic hydrogel nanoparticles. Preparation, characterization, and preliminary assessment as new colloidal drug carriers

Inverse emulsion photopolymerization of acrylated poly(ethylene glycol)-bl-poly(propylene glycol)-bl-poly(ethylene glycol) and poly(ethylene glycol) was successfully employed to prepare stable, cross-linked, amphiphilic nanoparticles. Even at low emulsifier concentrations (2%) and high water-to-hexane weight ratios (35/65), the stability of the inverse emulsion allowed for the formation of well-defined colloidal material. Inverse emulsion characteristics and polymerization conditions could be controlled to vary the size of the nanoparticles between 50 and 500 nm. The presence of hydrophobic nanodomains within these otherwise hydrophilic nanoparticles was verified by using pyrene as a microenvironmentally sensitive probe. The hydrophobic poly(propylene glycol)-rich domains appear to be suitable for incorporation of hydrophobic drugs, encapsulating Doxorubicin up to 9.8% (w/w). We believe that the complex nano-architecture of these materials makes them a potentially interesting colloidal drug delivery carrier system and that the method should be useful for a number of amphiphilic macromolecular precursors.     

Water-Containing Cured Resin from Inverted Emulsion of Unsaturated Polyester Based on Divalent Metal Salt of Mono(hydroxyethyl)phthalate

Inverted emulsion, i.e., water-in-oil (W/O) type emulsion, was prepared from styrene solution of unsaturated polyester obtained from Mg salt of mono(hydroxyethyl)phthalate, ethylene glycol (EG), maleic anhydride (MA), phthalic anhydride (PA), and propylene oxide (PO). The inverted emulsion was much more stable than that of blank polyester obtained from EG, MA, PA, and PO, and further than the usual inverted emulsion prepared by treating styrene solution of commercial unsaturated polyester with triethanolamine. By polymerization, the inverted emulsion was transformed to a white solid which was dry to the touch. The water-containing cured resin obtained showed considerably higher physical and other properties than those of commercial unsaturated polyester.     

Thermodynamics of crystalline linear high polymers. IV. The effect of ethyl,acetate, and hydroxyl side groups on the properties of polyethylene

Copolymers of ethylene with vinyl acetate, vinyl alcohol, and butene-1 have been investigated by differential thermal analysis. The method of fast heating is used to approximate a zero entropy production heating path. The activity of crystallizable units in the melt, the crystallinity, and the a-axis spacings are determined and compared with previous results for copolymers of ethylene and propylene and carbon monoxide. Carbonyl and hydroxyl groups form point defects, forming solutions in both the crystalline and amorphous regions. Methyl, ethyl, and acetate groups form large amorphous defects. The maximum melting point of polyethylene is calculated to be 142.6°C.     

Application of New Modified Poly(ethylene Oxide)-Block-Poly(propylene oxide)-Block-Poly(ethylene oxide) Copolymers as Demulsifier for Petroleum Crude Oil Emulsion

Water soluble nonionic amphiphilic block copolymers based on hydrophilic poly(ethylene glycol) (PEG) and hydrophobic poly(propylene glycol) (PPG) were prepared. Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) copolymers, PEG-PPG-PEG, were prepared in the normal condition. The chemical composition and molecular weights of the prepared copolymers were determined from ¹H NMR and GPC techniques. The surface properties of the prepared surfactants were determined by measuring the surface tension at different temperatures. The prepared nonionic surfactants were evaluated as demulsifiers for water in crude-oil emulsions that were pronounced at different ratios of crude oil: water at 318 K and 333 K. The experimental results showed that the dehydration rate of the prepared demulsifiers reached 100% based on demulsifier chemical compositions and concentrations.     

Pretreatment of sugarcane bagasse by acidified aqueous polyol solutions

Pretreatments of sugarcane bagasse by three high boiling-point polyol solutions were compared in acid-catalysed processes. Pretreatments by ethylene glycol (EG) and propylene glycol solutions containing 1.2 % H₂SO₄ and 10 % water at 130 °C for 30 min removed 89 % lignin from bagasse resulting in a glucan digestibility of 95 % with a cellulase loading of ~20 FPU/g glucan. Pretreatment by glycerol solution under the same conditions removed 57 % lignin with a glucan digestibility of 77 %. Further investigations with EG solutions showed that increases in acid content, pretreatment temperature and time, and decrease in water content improved pretreatment effectiveness. A good linear correlation of glucan digestibility with delignification was observed with R² = 0.984. Bagasse samples pretreated with EG solutions were characterised by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction, which confirmed that improved glucan enzymatic digestibility is mainly due to delignification and defibrillation of bagasse. Pretreatment by acidified EG solutions likely led to the formation of EG-glycosides. Up to 36 % of the total lignin was recovered from pretreatment hydrolysate, which may improve the pretreatment efficiency of recycled EG solution.     

Ethylene–vinyl acetate semi-batch emulsion copolymerization: Use of factorial experiments for improved process understanding

A good working knowledge of the mechanism and an appreciation of the effects the process variables have on the properties of interest are required for optimization and control of polymerization processes. Despite the importance of ethylene-vinyl acetate emulsion copolymers, limited kinetic information is available. Results from a series of factorial experiments are presented here which examine the emulsion polymerization of ethylene with vinyl acetate. Copolymers of up to 32 wt % ethylene have been produced at an ethylene pressure of 500 psig and a temperature of 20°C. The effects of the process variables on the rate of polymerization, copolymer composition, particle size and number, molecular weight averages, and gel content are discussed. The kinetic results obtained suggest process improvements for the production of homogeneous copolymer. Mechanistically, the locus of polymerization has been verified as the polymer particles and little water phase polymerization was observed. © 1993 John Wiley & Sons, Inc.     

Ethylene-vinyl acetate semi-batch emulsion copolymerization: Use of factorial experiments for process optimization

The application of factorial experiments to optimize the ethylene-vinyl acetate emulsion polymerization process is described herein. A prior extensive experimental phase identified those variables that are most important for ethylene-vinyl acetate emulsion copolymer production. The effects of temperature, pressure, added co-solvent, vinyl acetate feed rate and emulsifier type, and concentration on the rate of polymerization, cumulative copolymer composition, molecular weight averages, and particle size and number are described in this article. The primary objectives of this research were to increase the amount of ethylene that could be incorporated into the copolymer at reduced temperatures and pressures (our target was a copolymer with an ethylene content of 30% by weight at 500 psig and 20°C versus the commonly employed industrial conditions in excess of 1000 psig), to achieve an improved process understanding, and to accumulate reliable data for modelling purposes. A copolymer containing 34% by weight of ethylene has been achieved at a pressure of 500 psig and a temperature of 20°C. The confusion present in the literature surrounding emulsifier effects has also been clarified. A discussion of hydrolysis, experimental reproducibility, and glass transition temperatures is also included. The sequential nature of the experimental process is illustrated throughout these optimizing experiments. © 1994 John Wiley & Sons, Inc.     

Phase Diagram of the Ethylene Glycol–Dimethylsulfoxide System

The phase diagram of ethylene glycol (EG)–dimethylsulfoxide (DMSO) system is studied in the temperature range of +25 to ?140°C via differential scanning calorimetry. It is established that the EG–DMSO system is characterized by strong overcooling of the liquid phase, a glass transition at ?125°C, and the formation of a compound with the composition of DMSO · 2EG. This composition has a melting temperature of ?60°C, which is close to those of neighboring eutectics (?75 and ?70°C). A drop in the baseline was observed in the temperature range of 8 to ?5°C at DMSO concentrations of 5–50 mol %, indicating the existence of a phase separation area in the investigated system. The obtained data is compared to the literature data on the H₂O–DMSO phase diagram.     

Organocatalytic depolymerization of poly(ethylene terephthalate)

We describe the organocatalytic depolymerization of poly(ethylene terephthalate) (PET), using a commercially available guanidine catalyst, 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD). Postconsumer PET beverage bottles were used and processed with 1.0 mol % (0.7 wt %) of TBD and excess amount of ethylene glycol (EG) at 190 °C for 3.5 hours under atmospheric pressure to give bis(2‐hydroxyethyl) terephthalate (BHET) in 78% isolated yield. The catalyst efficiency was comparable to other metal acetate/alkoxide catalysts that are commonly used for depolymerization of PET. The BHET content in the glycolysis product was subject to the reagent loading. This catalyst influenced the rate of the depolymerization as well as the effective process temperature. We also demonstrated the recycling of the catalyst and the excess EG for more than 5 cycles. Computational and experimental studies showed that both TBD and EG activate PET through hydrogen bond formation/activation to facilitate this reaction. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis of bromine-functionalized polyolefins by scandium-catalyzed copolymerization of 10-bromo-1-decene with ethylene,propylene, and dienes

By use of a THF-containing trimethylsilylmethyl scandium catalyst system (C₅Me₄SiMe₃)Sc(CH₂SiMe₃)₂(THF)/[Ph₃C][B(C₆F₅)₄], the multi-component copolymerization of 10-bromo-1-decene (BrDC) with ethylene, propylene, and dienes has been achieved to afford a new family of bromine-functionalized polyolefins with controllable composition and high molecular weight. The copolymerization of BrDC with ethylene afforded the well-defined BrDC–ethylene copolymers with high BrDC incorporation (up to 12 mol%) and high molecular weight (M_w > 100 kg mol⁻¹). The terpolymerization of propylene, ethylene with BrDC afforded random ethylene–propylene–BrDC terpolymers with controllable bromine content (2 ~ 11 mol%), high molecular weight (M_w > 100 kg mol⁻¹) and low glass transition temperature (T_g = −51 °C ~ −67 °C). Moreover, the tetrapolymerization of ethylene, propylene, BrDC, and ethylidene norbornene or conjugated dienes such as isoprene and myrcene has been achieved for the first time to afford selectively the bromine-functionalized ethylene–propylene–diene rubbers containing various types of double bonds.     

Oxidative stability and effect of stress factors on flaxseed oil-in-water emulsions stabilized by sodium caseinate–sodium alginate–chitosan interfacial membrane

The susceptibility of heart healthy ω-3 fatty acids to lipid oxidation has hindered its incorporation into healthful foods and beverages. In this study, plant-based flaxseed oil rich in ω-3 fatty acids were dispersed into primary, secondary and tertiary emulsion system. A primary emulsion containing sodium caseinate-stabilized cationic droplets was prepared by homogenizing flaxseed oil as oil phase and sodium caseinate solution as the aqueous phase in an ultrasonicator. A secondary emulsion comprising of sodium caseinate–sodium alginate anionic droplets were produced by diluting appropriate primary emulsion with alginate solution. Further, a tertiary emulsion composed of sodium caseinate–sodium alginate–chitosan-coated cationic droplets was produced by diluting secondary emulsion with chitosan solution. The resistance of primary, secondary and tertiary emulsions with the same lipid concentration to destabilization by thermal treatment (30–90 °C for 30 min), sodium chloride addition (≤70 mM NaCl) and oxidative degradation (hydroperoxide concentration and TBARS) was determined. The results showed that secondary emulsions could resist variation in environmental stresses of salt and heat as well as protect the oil phase from decomposition better than primary and tertiary emulsions. Interfacial engineering could be used to design emulsion system with desirable characteristics.     

Multidimensional chromatographic techniques for hydrophilic copolymers II. Analysis of poly(ethylene glycol)-poly(vinyl acetate) graft copolymers

A large variety of hydrophilic copolymers is applied in different fields of chemical industry including bio, pharma and pharmaceutical applications. For example, poly(ethylene glycol)-poly(vinyl alcohol) graft copolymers that are used as tablet coatings are responsible for the controlled release of the active compounds. These copolymers are produced by grafting of vinyl acetate onto polyethylene glycol (PEG) and subsequent hydrolysis of the poly(ethylene glycol)-poly(vinyl acetate) graft copolymers. The poly(ethylene glycol)-poly(vinyl acetate) copolymers are distributed with regard to molar mass and chemical composition. In addition, they frequently contain the homopolymers polyethylene glycol and polyvinyl acetate. The comprehensive analysis of such complex systems requires hyphenated analytical techniques, including two-dimensional liquid chromatography and combined LC and nuclear magnetic resonance spectroscopy. The development and application of these techniques are discussed in the present paper.     

Preparation and biodegradation of sugar-containing poly(vinyl acetate) emulsions

To accelerate the biodegradability of poly(vinyl acetate)-based emulsions, emulsion copolymerizations of vinyl sugars, including triacetylated N-acetyl-D-glucosamine (GlcNAc)-substituted 2-hydroxyethyl methacrylate (GlcNAc(Ac)3-substituted HEMA), glucose-substituted HEMA (GEMA) and 6-O-vinyladipoyl-D-glucose (6-O-VAG) with vinyl acetate (VAc), were carried out using poly(vinyl alcohol) as an emulsifying agent in the presence of poly[(butylene succinate)-co-(butylene adipate)] [poly(BS-co-BA)]. Copolymerization with GEMA produced a stable emulsion and that with 6-O-VAG also produced a homogeneous emulsion. Their biodegradation tests indicated that PVAc main chain scission was accelerated by copolymerization with vinyl sugars.     

Functionalization of a poly(vinyl alcohol) in the solid state with a swelling agent by methacrylic anhydride

Poly(vinyl alcohol‐co‐vinyl acetate) was functionalized by methacrylic anhydride to introduce functional groups by a new process that consisted of modifying a polymer directly from a powder form in the solid state. To favor the diffusion of the reagents, a swelling agent composed by a mixture of ethylene carbonate and propylene carbonate was used. N‐methylimidazole was used as a basic catalyst of the esterification reaction, adjusting the reaction times. This work presents the process and the effects of the formulation on anhydride conversion. The side reactions were also determined; they all involved N‐methylimidazole. Decarboxylation reactions of the carbonates were characterized, that is, going from ethylene carbonate to ethylene glycol, which is able to react with two anhydride molecules by esterification reactions to, respectively, form 2‐hydroxyethyl 2‐methylpropenoate and ethyl 1,2‐bis(2‐methyl propenoate). The same side reactions are possible with propylene carbonate but are less reactive than the starting ethylene carbonate. Model anhydrides such as hexanoic and heptanoic anhydrides, less reactive than methacrylic anhydride, were used to characterize a new anhydride decarboxylation reaction. The homogeneity of the grafting is also discussed, especially its dependence on the polymer properties, the diffusion modes of the reagents (carbonate mixture and the anhydride), and the competition between the diffusional and chemical kinetics of methacrylic anhydride. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1618–1629, 2004     

Controlling the gelation temperature of biomimetic polyisocyanides

The gelation temperature and mechanical properties of aqueous ethylene glycol-decorated polyisocyanide solutions strongly depends on the length of the glycol tail. Copolymerisation of monomers with different tail lengths allows for precise engineering of the gel properties.     

Studies on the formation of PEN. I. Kinetic aspects of catalyzed reaction in transesterification of dimethylnaphthalate with ethylene glycol

The transesterification of dimethyl naphthalate (DMN) with ethylene glycol (EG) was kinetically investigated in the presence of various catalysts at 185°C. The transesterification was assumed to obey first-order kinetics with respect to DMN and EG, and a rate equation was derived. The rate constant of transesterification which was calculated from the quantity of methanol which distilled from the reaction vessel was used to evaluate the activity of each metal compound. The first-order dependence on the catalyst concentration is valid below a critical concentration which was found to be dependent on the catalyst type. The order of decreasing catalytic activity of various metal ions was found to be: Pb ≥ Zn > Co > Mg > Ni ≥ Sb, but in the case of highly basic metal salts, the rate constants were found to be extremely large at the initial stage of the reaction, and then rapidly decreased with the progress of the reaction. Effects of reaction temperature were also discussed. The activation energies for zinc acetate and lead acetate were 97.84 and 108.8 kJ/mol, respectively, which were calculated from the Arrhenius equation. © 1994 John Wiley & Sons, Inc.     

Study of cryostructuring of polymer systems. 32. Morphology and physicochemical properties of composite poly(vinyl alcohol) cryogels filled with hydrophobic liquid microdroplets

Cryogenic treatment (freezing at −20°C for 12 h followed by defrosting at a rate of 0.03°C/min) of decane, dodecane, or tetradecane emulsions in a poly(vinyl alcohol) solution (80 g/l) is employed to prepare composite cryogels containing microdroplets of liquid hydrophobic fillers entrapped into a macroporous hydrogel matrix. The effects of the type of a hydrocarbon, the degree of filling, and the addition of a surfactant (decaethylene glycol cetyl ether) on the physicomechanical properties, heat endurance, and morphology of the composites are studied. It is shown that, an increase in the content of liquid hydrophobic fillers within some range of their volume fraction enhances the rigidity of corresponding cryogels. Incorporation of the nonionic surfactant into the initial emulsions results in a complex dependence of the rigidity of the resulting composite cryogels on surfactant concentration and variations in the morphology of pores in the gel phase. At the same time, the heat endurance of all examined composite cryogels weakly depends on the type and concentration of the hydrocarbon fillers, as well as the presence of surfactant additives.     

Copolymerization of propylene with 1,3‐butadiene using isospecific zirconocene catalysts

Poly(propylene‐ran‐1,3‐butadiene) was synthesized using isospecific zirconocene catalysts and converted to telechelic isotactic polypropylene by metathesis degradation with ethylene. The copolymers obtained with isospecific C₂‐symmetric zirconocene catalysts activated with modified methylaluminoxane (MMAO) had 1,4‐inserted butadiene units ( 1,4‐BD ) and 1,2‐inserted units ( 1,2‐BD ) in the isotactic polypropylene chain. The selectivity of butadiene towards 1,4‐BD incorporation was high up to 95% using rac‐dimethylsilylbis(1‐indenyl)zirconium dichloride (Cat‐A)/MMAO. The molar ratio of propylene to butadiene in the feed regulated the number‐average molecular weight (M_n) and the butadiene contents of the polymer produced. Metathesis degradations of the copolymer with ethylene were conducted with a WCI₆/SnMe₄/propyl acetate catalyst system. The ¹H NMR spectra before and after the degradation indicated that the polymers degraded by ethylene had vinyl groups at both chain ends in high selectivity. The analysis of the chain scission products clarified the chain end structures of the poly(propylene‐ran‐1,3‐butadiene). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5731–5740, 2007     

Phase Diagram of an Ethylene Glycol–Hexamethylphosphorotriamide System

The phase diagram of an ethylene glycol (EG)–hexamethylphosphorotriamide (HMPT) system is studied over two wide temperature intervals (+25°С…?90°С…+40°С) and (?150°С…+40°С) by means of differential scanning calorimetry using INTERTECH DSC Q100 and METTLER TA4000 DSC instruments (Switzerland) in the DSC30 mode with variable cooling/heating rates. Substantial overcooling of the liquid phase, a glass transition, and different types of interaction are observed in the system. No thermal effects are observed in intermediate range of concentrations during the slow cooling/heating processes, and the system remains liquid until the glass transition. The presence of such a metastable phase is attributed to a sharp rise in the viscosity of the system due to different kinds of interaction between the components. HMPT: 2EG and HMPT: EG compounds with crystallization temperatures of +5 and ?0.5°С, respectively, are observed upon rapid cooling and slow heating. Changes in enthalpy are calculated for all of the observed thermal effects. The distinction from the phase diagram of H₂O–HMFT (literary data) is explained by the difference in the interactions between system components and by the structural differences between EG and H₂O.