PEO Macromonomer Research Articles

New aspects in chemistry and characterization of poly(ethylene oxide) hydrogels

AbstractTo extend the variability of poly(ethylene oxide) (PEO) hydrogels in their swelling behaviour, ability to bind various subjects, and possible applications, some new synthetic approaches have been elaborated recently: (i) PEO networks with ionic and reactive groups were prepared by the reaction of P‐OH groups of poly(oligoethylene glycol phosphate)s with diepoxide. The swelling degree of these hydrogels is strongly affected by salts, what is typical of polyelectrolyte networks. The structure parameters of the network evaluated from the swelling data are discussed.(ii) A series of hydrogels with controlled structure was obtained by radical polymerization of methacrylate PEO macromonomers of various molecular weights and average functionality (0.99–1.85) in aqueous media. The networks prepared are characterized by means of elastic modulus and swelling pressure measurements as well as with the help of microparticles of liquid‐crystalline dispersion of DNA as probes highly sensitive to the network structure and state.

Synthesis and characterization of amphiphilic networks obtained by copolymerization of poly(ethylene oxide) macromonomers with methylmethacrylate

Hydrogels whose elastic chains are constituted of hydrophilic Poly(ethylene oxide) (PEO) segments were obtained through free radical homopolymerization with methylmethacrylate (MMA) of α,ω-methacryloyloxy PEO macromonomers. This reaction can be conducted in water solution or in organic solvent. These networks were investigated as gels swollen to equilibrium in THF or in water. The influence of the preparation solvent on the properties of these networks was studied. The mechanical properties of the networks obtained in water are better than those of networks obtained under exactly the same conditions in organic solvents. This result can be explained by the preferential formation in water of micellar structures containing a higher concentration of polymerizable units. The influence of the concentration of the hydrophobic comonomer on the properties of these PEO networks was also examined.

Dispersion polymerization of styrene in aqueous ethanol media using poly(ethylene oxide) macromonomer as a polymerizable stabilizer

The kinetics of dispersion polymerization of styrene with a small amount of ω-methoxy poly(ethylene oxide)40 undecyl-α-methacrylate macromonomer (PEO-R-MA-40) in the ethanol-water media was studied. A maximum and constant rate of polymerization for this system appeared at the 18%—55% conversion of styrene to polystyrene. However, only 50% of the amphiphilic PEO macromonomer was found to be grafted in the copolymer (stabilizer) after 10 h of polymerization at 65°C. But as high as 98.5% conversion of styrene to polymer was attained. The initial rate of polymerization follows the scaling relationship, (Rp)i ∞ [PEO-R-MA-40]00 [styrene]00.92 [AIBN]00.90. It increased with increasing temperature but decreased with increasing water content because of the solvency effect in the reaction medium. The molecular weight Mw of polymer increased with increasing conversion of styrene up to about 55%. It then decreased slightly towards higher conversions, leading to a broader molecular weight distribution. The activation energies for the dispersion polymerization in the initial stage (< 6% conversion) and in rate interval II were 122.3 and 66.7 kJ mol−1 respectively. The characterization of the monodisperse latex particles of about 250 nm in diameter was carried out by the transmission electron microscope (TEM), FTi.r., n.m.r. and X-ray photoelectron spectroscope (XPS). The XPS result shows that the grafted PEO macromonomers were enriched and anchored on the surface of polystyrene latex particles with a top surface composition of 28% macromonomer. © 1997 Elsevier Science Ltd.

The particle size of latexes from dispersion polymerization of styrene using poly(ethylene oxide) macromonomer as a polymerizable stabilizer

The particle sizes and their size distributions of latexes from the dispersion polymerization of styrene using a small amount of ω-methoxy poly(ethylene oxide)n undecyl-α-methacrylate macromonomer (PEO-R-MA-40) as a polymerizable stabilizer in ethanol–water media have been studied. Monodisperse or/and nearly monodisperse latex particles from 0.1 to 1 μm in diameter were readily obtained. The diameter of latex particles follows the relationship Dvad ∝︁ θ0.33 [PEO-R-MA-40]−0.60 [styrene]01.02 [AIBN]o−0.09, where θ is the fractional conversion of styrene. Except for the styrene concentration dependency, this relationship is in excellent agreement with the model developed by Paine11 and modified by Kawaguchi et al.13 When the surface composition of the grafted PEO macromonomer on the latex particles exceeded 16% as analyzed by X-ray photoelectron spectroscopy (XPS), the particles were nearly monodisperse. In terms of polymerization, this occurred around 18% conversion of styrene. Beyond this critical state of polymerization, the latex particles grew bigger with more PEO macromonomer–styrene copolymers situated on the particle surface. The effect of various factors on the particle size distribution is also discussed. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3575–3583, 1997

The particle size of latexes from dispersion polymerization of styrene using poly(ethylene oxide) macromonomer as a polymerizable stabilizer

The particle sizes and their size distributions of latexes from the dispersion polymerization of styrene using a small amount of ω-methoxy poly(ethylene oxide)n undecyl-α-methacrylate macromonomer (PEO-R-MA-40) as a polymerizable stabilizer in ethanol–water media have been studied. Monodisperse or/and nearly monodisperse latex particles from 0.1 to 1 μm in diameter were readily obtained. The diameter of latex particles follows the relationship Dvad ∝︁ θ0.33 [PEO-R-MA-40]−0.60 [styrene]01.02 [AIBN]o−0.09, where θ is the fractional conversion of styrene. Except for the styrene concentration dependency, this relationship is in excellent agreement with the model developed by Paine11 and modified by Kawaguchi et al.13 When the surface composition of the grafted PEO macromonomer on the latex particles exceeded 16% as analyzed by X-ray photoelectron spectroscopy (XPS), the particles were nearly monodisperse. In terms of polymerization, this occurred around 18% conversion of styrene. Beyond this critical state of polymerization, the latex particles grew bigger with more PEO macromonomer–styrene copolymers situated on the particle surface. The effect of various factors on the particle size distribution is also discussed. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3575–3583, 1997

Nanostructured Polymeric Materials from Microemulsion Polymerization Using Poly(ethylene oxide) Macromonomer

Transparent nanostructured polymeric materials have been produced from the direct polymerization of bicontinuous microemulsions using the macromonomer ω-methoxy−poly(ethylene oxide)40−undecyl−α-methacrylate (C1−PEO−C11−MA-40) as a polymerizable nonionic surfactant. Besides the PEO macromonomer, the system also consisted of methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), water, and the cross-linker ethylene glycol dimethacrylate (EGDMA). Most of the bicontinuous microemulsions investigated could be gelled within 10 min at 30 °C using a redox initiator. The transparent microemulsions were eventually transformed to transparent solid polymers. These polymeric materials were characterized by thermoporometry, SEM observation, and the pore size evaluation for the polymer films by PEG filtration. The pore size of these transparent polymeric materials ranges from about 1 to 10 nm in diameter. It was larger for the systems containing higher ratios of water to HEMA or water to C1−PEO−C11−MA-40 and smaller for higher ratios of HEMA to C1−PEO−C11−MA-40. The results from PEG filtration provide the direct evidence that bicontinuous nanostructured polymeric materials can readily be prepared via the polymerization of these nonionic bicontinuous microemulsions.

Synthesis, polymerization, and dispersion copolymerization of poly(ethylene oxide) macromonomers carrying methacryloyloxyalkyl end groups

Poly(ethylene oxide) macromonomers carrying methoxy group on the one (α-) end and methacryloyloxyhexyl or methacry-loyloxydecyl group on the other (ω-) end were prepared, homopolymerized in water, and dispersion-copolymer-ized with styrene or methyl methacrylate in a methanol-water mixture. They were found to polymerize more rapidly and to produce stable polystyrene dispersions more effectively, as compared to the corresponding macromonomers carrying either α-methoxy and or α-dodecyloxy and ω-methacryloyloxy end groups. Thus, the amphiphilic constitution of the macromonomers such that favors the polymerizing methacrylate end groups to locally concentrate into the micelle core or to the particle surface while the poly(ethylene oxide) chains extending to the medium appears to be most important in enhancing their polymerizability and effectiveness as reactive steric stabilizers. On the other hand, stable poly(methyl methacrylate) particles with a number of craters or pleats on the surface were produced with a PEO macromono-mer with α-methoxy and co-methacryloyloxy end groups.

Copolymerization of Styrene with Nonionic Surfactants: Poly(Ethylene Oxide) Macromonomers

Abstract A series of macromonomers of ω-methoxy poly(ethylene oxide)n undecyl-α-methacrylate (PEO-R-MA-n, where n = 10, 15, 40) was synthesized. The copolymerization of styrene (M1) with the macromonomers (M2) was carried out in benzene solution and in an emulsion. The apparent reactivity (1/r1) of the macromonomer decreased with an increase of its PEO chain length. The results are discussed in terms of the incompatibility between PEO macromonomer and polystyryl radicals. Stable emulsion latices with monodisperse particles were obtained from the copolymerization of styrene with PEO-R-MA-40. The particle sizes ranged from about 30 to 300 nm in diameter depending on the amount of styrene used and the PEO chain length of the macromonomer. The molecular weights of the copolymers produced by the emulsion copolymerization of PEO-R-MA-40 with styrene were around half a million, and their molecular weight distributions ( M w/ M n) were relatively narrow (1.6–1.9) as determined by gel-permeation chromatography.

Control of Particle Size in Dispersion Polymerization Using Poly(Ethylene Oxide) Macromonomers

Dispersion copolymerization of styrene with a small amount of PEO macromonomer having p-styrylbutyl end group (Mn = 2000) in methanol/water (90/10 vol%) produced monodisperse microspheres of 0.5 to 3 μ in diameter. The particle size increased in proportion to Θ l/3 W o 2/3 (r1/W Do S crit ) 1/2 , a theoretical model based on particles formation sterically stabilized by graft-copolymerized PEO chains on the particle surface, where Θ = styrene conversion, W o = styrene weight in feed, W Do = macromonomer weight in feed, S crit = critical occupancy area per grafted PEO chain, and r 1 = monomer reactivity ratio of styrene before critical conversion. Quantitave agreement between theory and experiment was obtained with S crit /r 1 = 10 nm 2 .

Synthesis and study of poly(ethylene oxide) membranes obtained from homopolymerization of peo macromonomers

AbstractHydrogels were obtained by free‐radical polymerization of bifunctional macromonomers. This reaction can be conducted in water solution or in organic solvent. The kp value is yet strongly depending on the solvent used. The properties of these networks will be compared to those of networks obtained by end‐linking procedures. These materials were also used as a semi‐permeable membrane in the conception of an artificial pancreas.

A method for rubber toughening powder coatings

This paper describes a new method for rubber toughening brittle powder coatings. The design involves the use of toughening agents with specific physical and chemical properties. The modifiers are low-to-medium molecular weight polymers with polymerizable end groups (macromonomers). To achieve the physical properties required for fabrication into fine powders for subsequent deposition using conventional powder coating equipment, semi-crystalline polymers with Tg's well below room temperature and melting points above ≈70°C were required. Upon copolymerization with a thermosetting resin, crystallization of the modifier was precluded provided that low ethylene oxide compositions were employed. This scheme, in principle, yields an amorphous low Tg modifier chemically bound to the cured network. Poly(ethylene oxide), PEO, was found to be an excellent candidate, since it has a Tg of -68°C and a Tm of 70°C, sufficient crystallinity for friability and functional end groups for copolymerization. Free radical polymerization of 2,2-bis[4-vinylbenzoyloxyphenyl] hexafluoropropane and step-growth polymerization of 4,4′-(hexafluoroisopropylidene)diphenyl cyanate were utilized to demonstrate the feasibility of this approach. An electrostatic powder coater was used to co-deposit the PEO macromonomers with either of the thermosetting precursor monomers, followed by thermal curing to produce the modified networks. The resulting networks showed multiphase morphologies with improved toughness.

Coating porous silica by in situ polymerization of peo macromonomers for size exclusion separation of proteins

A coating method using comb-like polymers with poly(ethylene oxide) (PEO) grafts is described and studied in order to use porous silica as phase in size exclusion chromatography (SEC) of proteins. The coating is carried out by in situ polymerization and crosslinking of methacrylates of PEO with OH end groups (macromonomers) after deposition from a solution. A series of phases was prepared using two different graft lengths and two different crosslinking agents in different proportions. The efficiency of the coatings to mask the silanol groups of the matrix is characterized by pH metric titration and the best coating conditions are deduced. From calibration with PEO standards and with proteins, the SEC behavior of each phase is analyzed from column experiments and compared to results of pH metric measurements. A close interdependence between the two methods is observed. The optimized phases exhibit very good performance in SEC, except with low molecular weight basic proteins which interact with some residual unmasked silanol groups. The presence of these groups is attributed to the intrinsic porosity of the polymeric layer which increases with the length of the grafts.

Influence of the peo macromonomers on the ionic transport and aging processes in heterogeneous solid polymer electrolytes: A fractal approach

Macromonomer-based solid polymers electrolytes are fully investigated by ac impedance measurements in order to have a better insight into the contribution of the macromonomer in the ionic transfer processes, either in the bulk electrolyte or at the electrolyte-electrode interfaces. A physical meaning of some relevant parameters of the impedance spectrum (bulk conductivity, transfer resistance, relaxation times, phase angle) is proposed in the framework of a heterogeneous electrolytic medium. The deviations of the impedance spectra with respect to the theoretical ones are interpreted in terms of an ionic transfer across a fractal interface. Finally, the behaviour of these electrolytes upon aging is examined and the evolution of the electrochemical performances is discussed.

Macromonomer synthesis. New functionalization methods

AbstractSo far, the syntheses of macromonomers by end‐capping of “living” anionic polymers with unsaturated electrophiles, were not always quantitative. Now, we found that macromonomers with unsaturated end groups can be smoothly prepared with quantitative yields from ω‐hydroxy‐poly(ethyleneoxide)s (PEO) applying methods of peptide synthesis. The intermediate PEO with carboxylic, p‐toluenesulfonate or chlorocarbonyl end groups were prepared with quantitative yields. They were transformed into the 4‐vinylphenyl substituted PEO macromonomers by reaction with 2‐(4‐vinylphenyl)ethanol or 4‐vinyl‐aniline, in quantitative yields, in the presence of dicyclohexylcarbodiimide and 1‐hydroxybenzotriazole or triethylamine, respectively. PEO with methacryloyl end groups were prepared from ω‐hydroxy‐PEO and 2‐isocyanato ethyl methacrylate. The resulting macromonomers were characterized by determination of the double bond content and by 1H NMR spectroscopy.