Surface characterization of flat and rough films of perfluoromethacrylate-methylmethacrylate statistical copolymers synthesized in CO2-expanded monomers

Statistical copolymers of perfluoroalkyl ethyl methacrylate (Zonyl-TM) and methylmethacrylate were synthesized in CO₂-expanded monomer mixture at a low pressure of 10–13 MPa for the first time. M _w of the copolymers was found to decrease with the increase of Zonyl-TM content. Flat films of these copolymers were obtained by dip coating from their chloroform solutions and were characterized using contact angle measurements, optical microscopy, and 3D profilometry. The increase in the Zonyl-TM content of the copolymers resulted in a decrease of the total surface free energy. Superhydrophobic and oleophobic rough copolymer films were also prepared by applying a phase-separation process where THF was used as the solvent and ethanol as the non-solvent. Surface roughness increased with the increase in the nonsolvent ratio resulting in an increase in the water contact angle from 103° to 151° and hexadecane contact angle from 49° to 73°.     

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.     

CO2-expanded bio-based liquids as novel solvents for enantioselective biocatalysis

For the first time, CO₂-expanded bio-based liquids were reported as novel and sustainable solvents for biocatalysis. Herein, it was found that by expansion with CO₂, 2-methyltetrahydrofuran (MeTHF), and other bio-based liquids, which were not favorable solvents for immobilized Candida antarctica lipase B (Novozym 435) catalyzed transesterification, were tuned into excellent reaction media. Especially, for the kinetic resolution of challenging bulky secondary substrates such as rac-1-adamantylethanol, the lipase displayed very high activity with excellent enantioselectivity (E value > 200) in CO₂-expanded MeTHF (MeTHF concentration 10% v/v, 6 MPa), whereas there was almost no activity observed in conventional organic solvents.     

Microstructure and association property of hydrophobically modified polyacrylamide of a new family

A new family of hydrophobically modified polyacrylamides was synthesized via copolymerization of acrylamide (AM) and anionic surface-active monomer of acrylamide-type, sodium 2-acrylamido-tetradecane sulfonate (NaAMC₁₄S), in aqueous solution. In the copolymerization, by varying various factors, such as the feed ratio of NaAMC₁₄S to AM and the amount of added electrolyte NaCl and initiator, we prepared copolymers NaAMC₁₄S/AM with different block structures. The relationship between structures and hydrophobic association properties of copolymer chains was studied by using fluorescence probe and viscosimetry. Effects of the content and length of the hydrophobic blocks and the total molecular weight on hydrophobic association of the copolymers in pure water and in brine solution were examined, respectively. The results show that in pure water, hydrophobic association of the copolymers was enhanced as the content and length of the hydrophobic block increase. On the other hands, for a given content and length of the hydrophobic block, the hydrophobic association of the copolymers was enhanced as the total molecular weight increases. For all the copolymers studied, the apparent viscosity of their solutions in pure water has a limited value, but the apparent viscosities of the copolymer brine solutions are much higher than that of their corresponding water solutions, and show strong positive salinity sensitivity. Similarly, the hydrophobic association of the copolymer in brine solutions was enhanced as the content and length of the hydrophobic block increase.     

Novel Copolymers of Styrene and Alkyl Ring‐Substituted Methyl 2‐Cyano‐3‐phenyl‐2‐propenoates

Electrophilic trisubstituted ethylene monomers, alkyl ring substituted methyl 2‐cyano‐3‐phenyl‐2‐propenoates, RC₆H₄CH[dbnd]C(CN)CO₂CH₃, where R is 2‐methyl, 3‐methyl, 4‐methyl, 4‐isopropyl, and 2,5‐dimethyl were synthesized by piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and methyl cyanoacetate, and characterized by CHN elemental analysis, IR, ¹H and ¹³C NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (AIBN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 260–400°C range.     

Radical Copolymerization of Fluorine Ring-Substituted 2-Phenyl-1,1-dicyanoethylenes with 4-Fluorostyrene: Synthesis and Characterization

Novel copolymers of trisubstituted ethylene monomers, fluorine ring-substituted 2-phenyl-1,1-dicyanoethenes, RC₆H₄CH[dbnd]C(CN)₂ (where R is 2-F, 3-F, and 4-F) and 4-fluorostyrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C-NMR. High T _g of the copolymers, in comparison with that of poly(4-fluorostyrene) indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decomposed in two stages in the range 210–600°C.     

Amphiphilic polymer gel electrolytes. I. preparation of gels based on poly(ethylene oxide) graft copolymers containing different ionophobic groups

Amphiphilic graft copolymers were prepared via the radical copolymerization of poly(ethylene oxide) (PEO) macromonomers with fluorocarbon or hydrocarbon acrylates in toluene with 2,2′‐azobisisobutyronitrile (AIBN) as an initiator. ¹H NMR spectroscopy confirmed that the composition of the graft copolymers corresponded well to the monomer feed. For gel electrolytes prepared from the amphiphilic copolymers, the nature of the ionophobic parts of the amphiphilic graft copolymers had a great influence on the ion conductivity. Gel electrolytes based on graft copolymers containing fluorocarbon side chains showed significantly higher ion conductivity than electrolytes based on graft copolymers containing hydrocarbon groups. The ambient‐temperature ion conductivity was about 2.6 mS/cm at 20 °C for a gel electrolyte based on an amphiphilic graft copolymer consisting of an acrylate backbone carrying PEO and fluorocarbon side chains. Corresponding gels based on graft copolymers with PEO side chains and hydrocarbon groups showed an ambient‐temperature ion conductivity of about 1.2 mS/cm. The gel electrolytes contained 30 wt % copolymer and 70 wt % 1 M LiPF₆ in an ethylene carbonate/γ‐butyrolactone (2/1 w/w) mixture. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2223–2232, 2001     

Monitoring the formation of polystyrene/silica nanocomposites from vinyl triethoxysilane containing copolymers

Random copolymers of polystyrene-co-polyvinyl triethoxysilane (PS-co-PVTES) were prepared via semi-batch emulsion polymerization with different feed monomer compositions and evaluated as precursors of polystyrene (PS)/silica nanocomposites. Small-angle X-ray scattering (SAXS) profiles acquired from 20 °C to 180 °C showed that, at temperatures higher than glass transition temperature (T _g) of PS, the latex particles aggregate. On thermal annealing at 180 °C, silica-rich domains are formed, as corroborated by scanning electron microscopy. Infrared spectroscopy and differential scanning calorimetry analyses showed a reduction of the silanol concentration and an increase in the T _g value, respectively. The silica long domain spacing, measured by SAXS, depends on the concentration of vinyl triethoxysilane (VTES) in the feed; this value varied from 35 to 57 nm when the weight ratio of the monomers (styrene/VTES) was 50:50 and 90:10, respectively.     

Preparation of 4(5)-vinylimidazole-co-acrylic acid copolymer and thermal performances related to applicability as PEM fuel cells

A series of acrylic acid and 4(5)-vinylimidazole copolymers for a non-hydrous proton transferring membrane used in polymer electrolyte membrane for fuel cell (PEMFC) are reported. The feed ratio of each monomer results in the variation of copolymer as evaluated by Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (¹H-NMR). Differential scanning calorimeter and thermal gravimetric analyzer confirm the thermal properties of copolymer films with T_g at 105-177 °C and T_d above 230 °C. The simultaneous analysis of wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) suggests the thermal performance about the decrease in domain size as a consequence of the loss of moisture content in the membrane and the increase in domain size as a consequence of chain mobility after T_g. The proton conductivities under anhydrous condition of the copolymer membranes are in the range of 10⁻² S/cm even up to 120 °C.     

Polymerization of coordinated monomers. XIV. Systematic deviations from alternating regulation in copolymerization of methyl methacrylate with styrene in the presence of metal halides

Methyl methacrylate (MMA) and styrene (St) copolymerize in the presence of zinc chloride at 3°C under photoirradiation. The contents of methyl methacrylate in the copolymers obtained at a [ZnCl₂]/[MMA] molar ratio of 0.4 are systematically larger than 53 mole %, which is the limiting value at a small feed ratio of methyl methacrylate. The resulting copolymers are confirmed as the sole products and not the mixtures by thin layer chromatography. The effect of dilution of the monomer feed mixture with toluene on copolymer composition suggests that it depends chiefly on the feed concentration of styrene and hardly at all on monomer feed ratios. Copolymerizations are also conducted in the presence of stannic chloride at ?17°C under photoirradiation and in the presence of ethylaluminium sesquichloride at 0°C with spontaneous initiation. The contents of methyl methacrylate in both copolymers obtained at feed ratios lower than 60 mole % almost correspond to the 1:1 alternating copolymer and increase systematically with higher feed ratios. The systematic deviations of copolymer composition obtained in the presence of metal halides are reasonably interpreted by the participation of the binary molecular complex composed of metal halide and methyl methacrylate in the polymerization of the ternary molecular complex composed of metal halide, methyl methacrylate, and styrene.     

Random copolymers of N-isopropylacrylamide and methacrylic acid monomers with hydrophobic spacers: pH-tunable temperature sensitive materials

Two series of random copolymers of N-isopropylacrylamide (NIPAAm) and comonomers derived from methacrylic acid with a different number of methylene units as hydrophobic spacers (n=4, 7 and 10) were synthesized via free radicals. The first series was prepared having the acid groups methoxy-protected while the second series have the acid groups free. The NIPAAm-copolymers of both series were prepared varying the comonomer content from 5 to 20 mol%. All the copolymers were characterized by FTIR, DSC, ¹H NMR and SLS. The aqueous solution behaviour of the copolymers having methoxy-protected acid groups shows that the comonomer increases the hydrophobicity of the copolymer chain and decreases its lower critical solution temperature (LCST). For the copolymers having free acid groups, hydrogen-bonding is responsible for a further decrease in the LCST of these copolymers in pure water. In buffer solutions, every acid comonomer have a critical ionization degree (α_crit) above which the LCST increases with increasing comonomer content while at an ionization degree lower than α_crit the LCST decreases with increasing comonomer content. In dependence of comonomer content, number of methylene units in the spacer and the pH of the buffer solution, the LCST of the copolymers can be varied widely, showing that these random copolymers have pH-tunable temperature sensitivity.     

Novel Copolymers of Styrene. 9. Methyl and Methoxy Ring-Substituted 2-Cyano-3-phenyl 2-propenamides

Novel electrophilic trisubstituted ethylene monomers, methyl and methoxy ring- substituted 2-cyano-3-phenyl-2-propenamides, RPhCH=C(CN)CONH₂, where R is 2,3-dimethyl, 2,4-dimethyl, 2,5-dimethyl, 2-(3-methoxyphenoxy), 2-(4-methoxyphenoxy), 3-(4-methoxyphenoxy), 4-(4-methylphenoxy), 2,3-methylenedioxy were prepared and copolymerized with styrene. The monomers were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and cyanoacetamide, and characterized by CHN elemental analysis, IR, ¹H- and ¹³C-NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ABCN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H- and ¹³C-NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (5.8–33.8 wt%), which then decomposed in the 500–800°C range.     

Novel Copolymers of Styrene. 10. Halo Ring-Substituted 2-Cyano-3-phenyl-2-propenamides

Novel electrophilic trisubstituted ethylene monomers, halo ring-substituted 2-cyano-3-phenyl-2-propenamides, RPhCH ? C(CN)CONH₂, where R is 2-bromo, 3-bromo, 2-fluoro, 3-fluoro, 2-iodo, 3-iodo, and 4-iodo were prepared and copolymerized with styrene. The monomers were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and cyanoacetamide, and characterized by CHN elemental analysis, IR, ¹H- and ¹³C-NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ABCN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H- and ¹³C-NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (7-19 wt%), which then decomposed in the 500–800°C range.     

Novel Copolymers of Styrene. 11. Ring-Substituted 2-Cyano-3-phenyl-2-propenamides

Novel electrophilic trisubstituted ethylene monomers, halo ring-disubstituted 2-cyano-3-phenyl-2-propenamides, RPhCH = C(CN)CONH₂, where R is 2,3-difluoro, 2,4-difluoro, 2,5-difluoro, 2,6-difluoro, 3,4-difluoro, 3,5-difluoro, 2-chloro-4-fluoro, 3-chloro-2-fluoro, 3-chloro-4-fluoro were prepared and copolymerized with styrene. The monomers were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and cyanoacetamide, and characterized by CHN elemental analysis, IR, ¹H- and ¹³C-NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ABCN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H- and ¹³C-NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (10–14 wt%), which then decomposed in the 500–800°C range.     

An alternating copolymer of maleimide and atropic acid with narrow molecular weight distribution prepared by radical mechanism

Three basic conditions for preparation of alternating copolymer with narrow molecular weight distribution were derived from the element kinetic equations of binary radical copolymerization. Using maleimide (MI) and atropie acid (ATA) as model monomer pairs and dioxane as the solvent the alternating copolymer with molecular weight distribution in the range of 1.09--1.20 was prepared successfully by charger transfer complex (CTC) mechanism in the presence of benzoyl peroxide at 85℃. The monomer reactivity ratioes r_1(MI)=0.05±0.01 and r_2(ATA)=0.03±0.02 were measured. The alternating eopolymerization was carried out through formation of a contact-type CTG and then alternating addition of MI and ATA monomers. The molecular weight of the copolymers is nearly independent of the feed ratio in a large range and the polymerization rate dropped with an increase in ATA in feed ratio.     

Novel Copolymers of Styrene and Alkyl and Alkoxy Ring‐Trisubstituted Methyl 2‐Cyano‐3‐phenyl‐2‐propenoates

Electrophilic trisubstituted ethylene monomers, akyl and alkoxy ring‐trisubstituted methyl 2‐cyano‐3‐phenyl‐2‐propenoates, RC₆H₂CH[dbnd]C(CN)CO₂CH_3, (where R is 2,3‐dimethyl‐4‐methoxy, 2,5‐dimethyl‐4‐methoxy‐, 2,3,4‐trimethoxy‐, 2,4,5‐trimethoxy, 2,4,6‐trimethoxy, and 2,4‐dimethoxy‐3‐methyl), were synthesized by the piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and methyl cyanoacetate, and characterized by CHN elemental analysis, IR, ¹H‐ and ¹³C‐NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (AIBN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 283–306°C range.     

CERIC ION INITIATED GRAFTING ON CELLULOSE FROM BINARY MIXTURE OF ACRYLONITRILE AND METHYLACRYLATE

The Ce(IV)-ion induced grafting on cellulose from the binary mixture of acrylonitrile-methylacrylate has been investigated in heterogeneous and acidic conditions at 25 ± 0. 1°C. Various grafting parameters were evaluated as a function of molarity, feed composition, reaction time, and concentration of ceric ion at constant concentration of nitric acid in the feed. The higher fraction of acrylonitrile in the grafted chains than the feed has indicated the synergistic effect of methylacrylate taken in the feed along with acrylonitrile. IR and elemental analysis for nitrogen contents in the synthesized copolymers were used to determine the composition of the grafted copolymers. The reactivity ratios of acrylonitrile and methylacrylate have been determined by the Mayo and Lewis method and are found to be 1.45 and 0.9, respectively. The grafting parameters have shown increasing trends on varying feed composition (f_AN) from 0.25 to 0.80 and varying monomer concentration from 0. 6 to 5 4 mol dm^?3. The number of grafted moles of synthetic polymer (N_g) on cellulose were found to be dependent on molarity, feed composition, and ceric ion concentration. The experimental results have clearly indicated that maximum fraction of the feed was consumed in the formation of grafted copolymer chains in comparison to the homocopolymers and homopolymers. Estimation of ceric ion disappearance as a function of reaction time has clearly suggested that grafting on cellulose is initiated by the reactive sites generated through hydrogen ion abstraction by single electron transfer process.     

Exploring the influence of acceptor content on semi‐random conjugated polymers

A family of diketopyrrolopyrrole (DPP)‐incorporated P3HT based semi‐random copolymers was synthesized and their optical, electronic and photovoltaic properties were investigated. For the first time, the influence of acceptor content on semi‐random copolymers was explored in the broad range of 10–40% acceptor. A mixture of DPP acceptor units with different side chains (ethylhexyl and decyltetradecyl) was incorporated into each copolymer to improve solubility and film quality. Increased DPP content in the polymer backbone resulted in broadened absorption between 350 and 900 nm, resulting in a monotonic decrease in optical band gap (E_g) of the polymers from 1.49 to 1.37 eV. Highest occupied molecular orbital (HOMO) energy levels showed an increase from 10% DPP to 20–30% DPP, while decreasing for 40% DPP. V_oc values followed a consistent trend with HOMO energy levels. Semi‐random copolymers showed significantly improved photovoltaic properties compared with P3HT. Bulk heterojunction solar cells fabricated from the semi‐random copolymers blended with PC₆₁BM exhibited high short‐circuit current densities (J_sc) up to 10.29 mA/cm² and efficiencies up to 4.43%. A new method of methanol treatment was developed and applied to the semi‐random copolymers resulting in high fill factors approaching 0.70 under ambient conditions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3884–3892     

Novel anhydrous proton conducting copolymers of 1‐vinyl‐1,2,4‐triazole and diisopropyl‐p‐vinylbenzyl phosphonate

Phosphonic acid functional polymers are currently of interest because of their high proton conductivity in humidified and anhydrous systems. In addition, heterocyclic compounds are used in anhydrous proton conducting polymer membranes. In that study, a new copolymer based on 1‐vinyl‐1,2,4‐triazole (VTri) and diisopropyl‐p‐vinylbenzyl phosphonate (VBP) was synthesized, and their thermal, chemical, and proton conducting properties were investigated. The copolymers were synthesized by free radical copolymerization of the corresponding monomers at several monomer feed ratios to obtain P(VTri‐co‐VBP) copolymers. The copolymer samples were then hydrolyzed to produce poly(vinyl triazole‐co‐vinyl phosphonic acid) copolymers. The composition of the copolymers was determined by elemental analysis. The copolymerization and hydrolysis reactions were verified by Fourier transform infrared spectroscopy and ion exchange capacity measurements. Thermogravimetry analysis indicates that the copolymers are thermally stable up to 300°C. In order to increase the proton conductivity, the copolymers were doped with H₃PO₄ at several stoichometric ratios. The proton conductivity increases with triazole and phosphoric acid content. In the absence of humidity, the copolymer electrolyte, P(VTri‐co‐VBPA)1:0.5 X = 2, showed a proton conductivity of 0.005 S/cm at 150°C. Copyright © 2013 John Wiley & Sons, Ltd.     

Greffage radiochimique de l'acrylonitrile sur le poly(methacrylate de methyle)

The radiation-induced polymerization of acrylonitrile with dissolved PMMA exhibits kinetics similar to those found with the pure monomer. The addition of PMMA to the monomer at first leads to an increase in polymerization rate; a maximum in rate is observed for 60 per cent acrylonitrile in the mixture. The unreacted PMMA was quantitatively extracted by toluene from the reaction mixture. In contrast, polyacrylonitrile could not be separated from the graft copolymer by fractional precipitation, presumably due to association of the graft copolymer with the precipitated homopolymer. The free radical yield of PMMA “G_R effective” derived from these results was found to be 8 to 10 in mixtures containing small amounts of monomer. It rapidly decreased as the monomer concentration increased.The solubilities of the graft copolymers were characterized by the precipitation γ determined for several precipitants in DMF solutions. A maximum in solubility was found for copolymers containing 25 to 35 per cent acrylonitrile in DMF-alcohol mixtures. The glass transition temperatures (T_g) of the graft copolymers were measured using a penetrometer. T_g increased with the MMA content in the copolymer. A small minimum of T_g appeared to exist for copolymers containing 90 per cent acrylonitrile.