Perfluoromethacrylate-styrene statistical copolymers synthesized in CO2-expanded monomers

Statistical copolymers of perfluoroalkyl ethyl methacrylate (Zonyl-TM) and styrene (S) were synthesized in CO₂-expanded monomer medium at a low initial pressure of 25 MPa. Different Zonyl-TM/S feed ratios were used during copolymerizations, and it was determined that the increase in the Zonyl-TM content and decrease of the CO₂ amount in the comonomer feed resulted in a decrease of the molecular weights of copolymers due to earlier precipitation of copolymers giving shorter chains. The cloudy CO₂-expanded liquid monomer phase was found to be the main loci of copolymerization. In addition, the increase in the Zonyl-TM feed ratio resulted in an increase in the critical degree of the polymerization time (J _crit) as the time when the copolymer chains start to precipitate. The higher the Zonyl-TM content used in the feed, the higher the J _crit time and the lower the weight-average molecular weight (M _w) of the copolymer obtained. Thermal analysis results of the copolymer indicated that the copolymers are stable up to 387–403 °C.     

Mechanical and thermal properties of perfluoroalkyl ethyl methacrylate-methyl methacrylate statistical copolymers synthesized in supercritical carbon dioxide

Poly(methyl methacrylate-ran-perfluoroalkyl ethyl methacrylate) copolymers having varying perfluoroalkyl ethyl methacrylate ester (Zonyl-TM) contents were synthesized in supercritical CO₂. Complete amorphous structures of the copolymers were verified by XRD. Young's modulus (Y_mod) of the copolymers was decreased linearly from 1.57 to 1.08 GPa and T_g values from 102 to 77 °C with the increase of Zonyl-TM content. A linear relationship between the Y_mod and the T_g values of the copolymer was also found. The increase of the large branched pendant groups resulted in the increase of the free volume and a corresponding decrease in Y_mod and T_g of the copolymers. A good fit was found when the Schneider equation was used. Negative deviation from the Gordon-Taylor equation was observed when Zonyl-TM content was lower than 14% due to rapid increase in free volume and then a positive deviation was found due to the dipole-dipole interactions between the methyl ester and fluoroalkyl ester groups.     

Creation of low hysteresis superhydrophobic paper by deposition of hydrophilic diamond-like carbon films

The creation of low hysteresis superhydrophobic paper is reported using a combination of oxygen plasma etching and plasma deposition of an 80 nm non-fluorinated, hydrophilic diamond-like carbon (DLC) coating. The DLC has an equilibrium (flat surface) contact angle (θ _e ) of 68.2° ± 1.5°, which is well below the 90° contact angle that is typically believed to be a prerequisite for superhydrophobicity. Coating of paper substrates with the DLC film yields an advancing contact angle of 124.3° ± 4.1°, but the surface remains highly adhesive, with a receding contact angle <10°. After 60 min of plasma etching and DLC coating, a low hysteresis, superhydrophobic surface is formed with an advancing contact angle of 162.0° ± 6.3° and hysteresis of 8.7° ± 1.9°. To understand the increase in contact angle and decrease in hysteresis, atomic force microscopy and optical profilometry studies were performed. The data demonstrates that while little additional nanoscale roughness is imparted beyond the first 5 min of etching, the roughness at the microscale continually increases. The hierarchical structure provides the appropriate roughness to create low hysteresis superhydrophobic paper from a hydrophilic coating.     

Copolymerization of ethylene with a vinyl ether bearing a fluorinated group

The copolymerization of ethylene (E) with 1H,1H,2H,2H-perfluorodecyl vinyl ether (FAVE8) by oxidative addition of salicylaldimine ligand to bis(1,5-cyclooctadiene)nickel(0)/methylaluminoxane (MAO) at room temperature and at different ethylene pressures is reported. The homopolymerization of ethylene is known to be highly active with this catalyst in contrast to the fluorinated vinyl ether which does not homopolymerize. The copolymerization of E with FAVE8 led to linear poly(E-co-FAVE8) statistic copolymers that were characterized by means of various techniques. The obtained copolymers, analyzed by FT-IR and solid state NMR spectroscopy, showed a small incorporation of the fluorinated vinyl ether. Three copolymerization reactions were investigated with different ethylene pressures (5, 10 and 50 bar) and the copolymer compositions indicated that the content of FAVE8 units depends on the ethylene pressure. The lower this pressure, the higher the content of such a fluorinated comonomer and for a 50 bar-pressure, no FAVE8 was incorporated. Thermogravimetric and differential scanning calorimetry analyses of these resulting copolymers exhibited high thermal stability, the thermal degradation starting from ca. 300 °C whereas high melting point (T_m = 129 °C) were achieved with these copolymers. Original films processed from these poly(E-co-FAVE8) copolymers illustrated hydrophobic and oleophilic characters as evidenced by water and diiodomethane contact angles of 104° and 49°, respectively.     

Introduction of hydrophilicity of polyacetylene film surfaces

Polyacetylene films have been rendered hydrophilic by treatment with aqueous KMnO₄. The treated films were characterized by contact angle measurement, infrared spectroscopy, and x-ray photoelectron spectroscopy. We found that it is possible to lower the contact angle of H₂O on polyacetylene from 72° to ca. 10° without significantly affecting the electrical conductivity afforded after I₂ doping compared with similar doping of untreated films. The treated, hydrophilic films were found to be more permeable to aqueous ionic solutions than pristine polyacetylene.     

Preparation and characterization of TiO2 sols and their UV-cured hybrid thin films on plastic substrates

In this research, TiO₂ sols were synthesized via a sol?Cgel reaction at room temperature followed by heating under reflux. Hybrid thin films were prepared using the TiO₂ sols and dipentaerythritol hexacrylate on poly(methyl methacrylate) substrates via spin coating followed by UV-curing. The images of transmission electron microscopy (TEM) and results of dynamic light scattering (DSL) showed that some originally synthesized TiO₂ nanoparticles aggregated while many small-sized (~5?nm) TiO₂ nanoparticles still existed after reflux heating. The synthesized TiO₂ sols showed poor photocatalytic ability, which might avoid degradation of organic moieties in the hybrids. The refractive indices of the hybrid thin films were increased from 1.66 to 1.82 while the water contact angles on the thin films were increased from 70.2° to 87.7° with the increment of TiO₂ content. Increasing the heating time of the TiO₂ sol resulted in an increase in the refractive index and contact angle.     

Effect of butyl lactate methacrylate content on the properties of acrylic acid copolymers

In the present work, the effect of butyl lactate methacrylate (BLM) content on the properties of acrylic acid (AA) copolymers was investigated. The BLM monomer was synthesized by reacting butyl lactate with methacrylic acid through azeotropic distillation method, which was confirmed by Mass spectrometric technique. Copolymers were synthesized by free-radical solution polymerization technique to obtain poly(BLM-co-AA). BLM monomer and copolymers were characterized by Fourier transform infrared (FTIR), ¹H-nuclear magnetic resonance (¹H-NMR) and proton decoupled ¹³C-NMR spectroscopic techniques. The Finemann-Ross method was used to determine the reactivity ratio of AA and BLM and the values were found to be 0.79 and 0.39, respectively. The wide angle X-ray scattering (WAXS) studies exhibited that the increase in BLM content in copolymers, shifted the amorphous halo from 21.34° to 15.39° and also increased the average molecular interchain spacing (〈R〉) from 5.20 to 7.18 Å, which was calculated from 2θ values of amorphous halo of copolymers. Moisture absorption of polymers followed Fickian absorption. Depending upon the copolymer composition, relative humidity and time, the moisture absorption of copolymers can be tuned to a wide range from 11 to 35% (wt/wt). Glass transition temperature of copolymers decreased from 106 to 72.1°C with increase in BLM content. Copolymers were thermally stable up to 150°C and thereafter exhibited three-step thermal degradation in nitrogen atmosphere. Thermal stability of copolymers can be explained on the basis of 〈R〉 value.     

Copolymers of 2-hydroxyethyl methacrylate and alkyl methacrylates. I. Synthesis and characterization

Copolymerization of 2-hydroxyethyl methacrylate (HEMA) with ethyl methacrylate (EMA) and n-butyl methacrylate (BMA) was carried out in bulk at 70°C ± 1°C using 0.2% benzoyl peroxide as initiator in nitrogen atmosphere. Number average molecular weight (M _n) of the copolymers was determined by dynamic osmometry. Intrinsic viscosity [η] of HEMA-BMA copolymers was evaluated at 35°C in dimethyl formamide. These copolymers were also characterized by infrared spectroscopy and density measurements. Cohesive energy densities (CED) of these polymers were determined by observing their swelling behavior in different solvents. It was found that a decrease in alkyl methacrylate content resulted in an increase in the CED values of the copolymers.     

Preparation and properties of a novel waterborne fluorinated polyurethane–acrylate hybrid emulsion

The waterborne fluorinated polyurethane–acrylate hybrid emulsion (WFPUA) was prepared by two steps, including the preparation of the fluorinated alcohol blocked polyurethanes (FBPU) in the mixtures of vinyl monomers and fluorinated monomers and then the free radical polymerization after the pre-emulsification of the said system. The effects of hydrophilic monomer (MDEA) on the surfactivity and the emulsifiability of the FBPU were firstly reported. Then, the particle size (d), zeta potential (ζ), and viscosity (η) of the WFPUA hybrid emulsion were characterized, respectively. At the same time, the surface properties and the mechanical properties of the films were investigated. The results show that the increase of MDEA is good for the emulsifiability and the lower surface tension of the FBPU. This increase improves the stability, the ζ and η, yet decreases the d of the WFPUA emulsion. However, it has disadvantages to the hydrophobic performance of the WFPUA films. When the content of the MDEA in the WFPUA is increased from 4.67 to 14.89 %, the surface free energies are increased from 22.22 to 27.28 mJ m^?2 and the attenuation rate of the contact angle–time curve is increased from 0.3051° to 0.6290°/min. Also, with the increase of MDEA, the tensile strength and the shore hardness of the film are increased, but its elongation at break is decreased. The storage moduli of the film are enhanced remarkably. Meanwhile, the glass transition temperature of the soft segment [T_g(s)] is reduced and that of the hard segment [T_g(h)] is raised.     

Optically transparent superhydrophobic TEOS-derived silica films by surface silylation method

Optically transparent silica films were prepared at room temperature (~27°C) by keeping the molar ratio of TEOS:MeOH:H₂O (0.001 M NH₄F) constant at 1:19.29:6.20, respectively. A surface chemical modification of the films was done with alkylchlorosilanes at different concentrations from 0 to 1 vol. % and aging times varied from half to 2 h. The DMCS and TMCS surface modified silica films showed the static water contact angle of 146° and 162°, respectively. When the DMCS and TMCS modified films were cured at temperatures higher than 240 and 275°C, respectively, the films became superhydrophilic. Further, the humidity study was carried out at a relative humidity of 90% at 30°C temperature over 60 days. We characterized the water repellent silica films by Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, % of optical transmission, humidity tests and contact angle measurements.     

Poly(N-acylethylenimine) copolymers containing pendant pentamethyldisiloxanyl groups. III. Surface properties and abhesion

The surface properties and abhesion of both N/Si and U/Si series of random copolymers were studied by contact angle and peel strength measurements. When these copolymers are coated on clean glass slides, the contact angles of water on the polymer films are over 105° for copolymers with less than 50 mol % of Si , and 98-104° for those with more than 50 mol % of Si. All the polymers have similar critical surface energies, 21 dyn/cm (from hydrocarbon probes) and 20 dyn/cm (from EtOH/H₂O probes), within the experimental error. This demonstrates that the amide groups in the polymer backbones are buried and all the polymers have methyl surfaces. The copolymers with less than 50 mol % Si (for N/Si copolymers) or 20 mol % (for U/Si copolymers) are stable and show good abhesive properties toward Scotch magic tape at or below 50°C. The peel strengths of Scotch magic tape with the copolymer coated slides rise dramatically as the annealing temperatures approach to the melting points of the polymers.     

Hydrophobic and Oleophobic Epoxy Surfaces Prepared by a Facile Process with Fluorosilicone Copolymer and SiO2 Nano-Particle

Hydrophobic and oleophobic surfaces with multi-scale structures were prepared on epoxy coating surfaces by using a facile process with fluorosilicone copolymer and SiO₂ nano-particles. The fluorosilicone copolymers were synthesized using perfluoroalkyl acrylate (FA), vinyltriethoxysilane (VTES) and styrene (St) as comonomers via radical emulsion polymerization. In this paper, the surface properties of epoxy coating modified by fluorosilicone copolymer and SiO₂ nano-particles were analyzed by using the contact angle measurement. The results showed that the modified epoxy coating surface exhibited not only excellent hydrophobicity but also oleophobicity, the water contact angle reached as high as 149° and the oil (atoleine) contact angle 101°, respectively.     

Influence of O2 Plasma on Surface Properties of PC-TiO2 Nanocomposite Film

In this work, polycarbonate-TiO₂ nanocomposite films were prepared with different percentages. The aim was to consider the effect of O₂ LF plasma (50 Hz) on the hydrophilicity, surface energy, and surface morphology of polycarbonate and polycarbonate-TiO₂ nanocomposite. Structure of samples was determined by using X-ray diffraction analysis. In comparison with the reference sample, the samples’ structure did not change after plasma treatment. Surface properties of polycarbonate and polycarbonate-TiO₂ nanocomposite films were studied by X-ray photoelectron spectroscopy (XPS), contact angle measurement, atomic force microscopy (AFM), and Vickers microhardness tester. XPS analysis showed that the surface of samples became more oxidized due to plasma treatment. The water contact angle significantly decreased from 88° to 15° after plasma treatment. It was observed that the hardness of the nanocomposite films was not modified after plasma treatment.     

Synthesis and properties of copolymers of methyl methacrylate with 2,3,4,5,6‐pentafluoro and 4‐trifluoromethyl 2,3,5,6‐tetrafluoro styrenes: An intrachain interaction between methyl ester and fluoro aromatic moieties

2,3,4,5,6‐Pentafluoro and 4‐trifluoromethyl 2,3,5,6‐tetrafluoro styrenes were readily copolymerized with methyl methacrylate (MMA) by a free radical initiator. The copolymers were soluble in tetrahydrofuran and acetone. The films obtained were transparent and flexible. The glass transition temperatures (T_gs) of the copolymers were found positively deviated from the Gordon–Taylor equation. The positive deviation could be accounted for by dipole–dipole intrachain interaction between the methyl ester group of MMA and the highly fluorinated aromatic moiety, which resulted in a decrease in the segmental mobility of the polymer chains and the enhanced T_g values of the copolymers. The water absorption of PMMA was greatly decreased by copolymerization of MMA with the highly fluorinated styrenes. With as little as 10 mol % of pentafluoro styrene content in the copolymer, the water absorption was decreased to one‐third of that for pure PMMA. The fluorinated styrenes‐MMA copolymers were thermally stable up to 420 °C under air and nitrogen atmospheres. With 50 mol % of MMA in the copolymer, the copolymer was still stable up to 350 °C. Since these copolymers contain a large number of fluorine atoms, the light absorption in the region of the visible to near infrared is decreased in comparison with nonfluorinated polymers. Thus, these copolymers may be suitable for application in optical devices, such as optical fibers and waveguides. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis and characterization of a new fluorinated macroinitiator and its diblock copolymer by AGET ATRP

A new fluorinated macroinitiator of poly 2,2,3,4,4,4-hexafluorobutyl methacrylate-Br (PHFMA-Br) was prepared via activator generated by electron transfer atom transfer radical polymerization (AGET ATRP), and then a series of fluorinated block copolymers with different fluorine content were successfully synthesized from the macroinitiator by the second step AGET ATRP. GPC, FTIR and ¹H NMR data obtained verified the synthesis. Contact angle measurement indicated that proper fluorine content could decrease the surface energy and increase the contact angle of the copolymer films. XPS characterization showed that the large difference in surface energy between the block and random copolymer film resulted from the difference of the fluorine content on the surface, although the fluorine content of the two copolymers in bulk was similar. The self-assembly behavior of the fluorinated block copolymer in selective solvents was evaluated by the TEM study, and the stable micelles with a core-shell structure were observed when the copolymer content was about 1 wt%.     

Polyimide/polyoxometalate copolymer thin films: synthesis,thermal and dielectric properties

A mono‐lancunary keggin‐type decatungstosilicate (SiW₁₁) polyoxometalate (POM) modified by γ‐aminopropyltriethoxysilane (KH550) was incorporated into polyimide (PI) through copolymerization. Nuclear magnetic resonance (NMR), fourier transition infrared spectroscopy (FTIR), and wide angle X‐ray diffraction (WAXD) were used to characterize the structure and composition of the polyoxometalate–organosilane hybrid (SiW₁₁KH550) and PI/SiW₁₁KH550 copolymers. The differential scanning calorimetry (DSC) studies indicate that the glass transition temperature (T_g) of PI/SiW₁₁KH550 copolymers increases from 330°C (for neat PI) to 409°C (for the copolymer sample with 10 wt% of SiW₁₁KH550). Dielectric measurement showed that both the dielectric constant and the dielectric loss for the copolymer thin films decreased with the increase in SiW₁₁KH550 content, and the dielectric constant and dielectric loss values decreased to 2.1 and 3.54 × 10^?3, respectively, for the copolymer sample with 10 wt% of SiW₁₁KH550. The incorporation of SiW₁₁KH550 into polymer matrices is a promising approach to prepare PI films with a low dielectric constant and low dielectric loss. Copyright © 2009 John Wiley & Sons, Ltd.     

Controlled copolymerization of vinyl acetate with 1‐alkenes and their fluoro derivatives by degenerative transfer

The degenerative transfer copolymerization of vinyl acetate with ethene and higher 1‐alkenes, as well as their fluoro derivatives (R_fCH?CH₂), under mild conditions was carried out using AIBN as the initiator and ethyl iodoacetate as the control agent. The obtained random copolymers were fairly high in alkene content, with high molecular weights and relatively narrow polydispersities. The quasi‐living nature of the copolymerization allowed the synthesis of a block terpolymer by sequential addition of two different 1‐alkene comonomers to a vinyl acetate copolymerization system. The fluorinated side chains of vinyl acetate/fluoro alkene copolymers segregate toward the air‐side of thin films, resulting in advancing water contact angle as high as 114°. 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3728–3736, 2005     

Temperature‐induced aggregation of the copolymers of N‐isopropylacrylamide and sodium 2‐acrylamido‐2‐methyl‐1‐propanesulphonate in aqueous solutions

A series of random copolymers of N‐isopropylacrylamide (NIPAM) and sodium 2‐acrylamido‐2‐methyl‐1‐propanesulphonate (AMPS) was synthesized by free‐radical copolymerization. The content of AMPS in the copolymers ranged from 1.1 to 9.6 mol %. The lower critical‐solution temperature (LCST) of copolymers in water increased strongly with an increasing content of AMPS. The influence of polymer concentration on the LCST of the copolymers was studied. For the copolymers with a higher AMPS content, the LCST decreased faster with an increasing concentration than for copolymers with a low content of AMPS. For a copolymer containing 1.1 mol % of AMPS the LCST dropped by about 3 °C when the concentration increased from 1 to 10 g/L, whereas for a copolymer containing 9.6 mol % of AMPS the LCST dropped by about 10 °C in the concentration range from 2 to 10 g/L. It was observed that the ionic strength of the aqueous polymer solution very strongly influences the LCST. This effect was most visible for the copolymer with the highest content of AMPS (9.6 mol %) for which an increase in the ionic strength from 0.2 to 2.0 resulted in a decrease in the LCST by about 27 °C (from 55 to 28 °C), whereas for the copolymer containing 1.1 mol % of AMPS the LCST decreased only by about 6 °C (from 37 to 31 °C) when the ionic strength increased from 0.005 to 0.3. The reactivity ratios for the AMPS and NIPAM monomer pairs were determined using different methods. The values of r_AMPS and r_NIPAM obtained were 11.0–11.6 and 2.1–2.4, respectively. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2784–2792, 2001     

Wetting properties of aqueous solutions of hydrophobically modified inulin polymeric surfactant

The contact angles of aqueous solutions of a polymeric surfactant namely hydrophobically modified inulin (INUTEC®SP1) were measured on hydrophilic and hydrophobised quartz glass surfaces using the sessile drop technique. These measurements showed a large difference (>10°) between the advancing contact angle θ ₁ (that is measured immediately after placing the drop on the surface) and the constant contact angle θ ₂ (that is measured 30 minutes after placing the drop). In all the results only the contact angle θ ₂ was subsequently measured. θ versus INUTEC®SP1 concentration C _s curves were obtained at various NaCl concentrations both on hydrophilic and hydrophobic glass surfaces. On hydrophilic glass surface the θ versus C _s curves showed a maximum at a concentration range of 10^–6 to 2?×?10^–5 mol dm^-3 INUTEC®SP1. These curves were shifted to lower values as the NaCl concentration was increased. On such hydrophilic surface the INUTEC®SP1 molecule adsorbs with the polyfructose loops and tails oriented towards the surface leaving the alkyl chains in solution. Saturation adsorption with this orientation occurs at 2?×?10^–5 mol dm^-3 INUTEC®SP1. However, the contact angles remain quite small (<18°) indicating the presence of several hydrophilic glass patches uncovered by surfactant molecules. At C _s?>?2?×?10^–5 mol dm^-3 θ decreases with further increase of the INUTEC®SP1 concentration reaching 5° at the Critical Association Concentration (CAC) of the polymer. This indicates the formation of a bilayer of INUTEC®SP1 molecules with the alkyl chains hydrophobically attached to those of the first layer. On a hydrophobic glass surface, adsorption of INUTEC®SP1 occurs by multi-point attachment with the alkyl chains on the surface leaving the hydrophilic polyfructose loops and tails dangling in solution. This results in a gradual decrease of the contact angle with increase in INUTEC®SP1 concentration, reaching a plateau value (>85°) between 2?×?10^–5 and 2?×?10^–4 mol dm^-3. The large contact angles obtained on adsorption of the polymeric surfactant on a hydrophobic surface indicate the presence of several uncovered hydrophobic patches. These results give a reasonable picture of the adsorption and orientation of the INUTEC®SP1 molecules on both hydrophilic and hydrophobic solid surfaces.     

Alternating polyester/fluoroalkene copolymers: Combining high hydrophobicity with degradability

2‐Methylene‐1,3‐dioxepane (MDO) was copolymerized with fluoroalkenes (R_fCH?CH₂) using azobis(isobutyronitrile) AIBN as an initiator. NMR spectroscopy confirmed that the obtained polymers are effectively alternating copolymers of caprolactone and fluoroalkene. Angle resolved XPS of copolymer films revealed that the outer layers have higher CF_x:COO ratio relative to the subsurface, indicating that the perfluoroalkyl tails segregate to the air‐side, thereby presenting a hydrophobic surface with water contact angle as high as 130°. Blends of this material with polycaprolactone and polycarbonate polymers also form hydrophobic films. In the presence of trifluoroacetic acid, the copolymer undergoes complete degradation through hydrolysis. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1225–1232, 2006