Highly phenylated polyarylenes: Synthesis, properties, and applications

The syntheses of highly phenylated polyarylenes (polyphenylenes, polyalkylenephenylenes, poly(phenylene oxides), poly(phenylene sulfides), poly(phenylene ketones), and poly(phenylene ethynylenes)) based on the interaction of hexaphenyl-substituted bis(cyclopentadienes) of the appropriate structure with diethynylarylenes via the Dields-Alder reaction are considered. Polymers containing no less than six phenyl substituents per repeating unit and characterized by the isomerism of backbone chains combine unique solubility in common organic solvents with excellent thermal characteristics. Highly phenylated polyarylenes are of interest as materials for electronics, microelectronics, membrane techniques, and fuel cells.     

Impact,Thermal, and Morphological Properties of Poly(Lactic Acid)/Poly(Methyl Methacrylate)/Halloysite Nanotube Nanocomposites

Poly(lactic acid)/poly(methyl methacrylate) blends containing halloysite nanotube (2 and 5 phr) and epoxidized natural rubber (5–15 phr) were prepared by melt mixing. The impact strength of poly(lactic acid)/poly(methyl methacrylate) blend was slightly improved by the addition of halloysite nanotube. Adding epoxidized natural rubber further increased the impact strength of poly(lactic acid)/poly(methyl methacrylate)/halloysite nanotube nanocomposite. Single T_g of poly(lactic acid)/poly(methyl methacrylate) is observed and this indicates that poly(lactic acid)/poly(methyl methacrylate) blend is miscible. The addition of halloysite nanotube into poly(lactic acid)/poly(methyl methacrylate) slightly increased the T_g of the blends. The epoxidized natural rubber could encapsulate some of the halloysite nanotube and prevent the halloysite nanotube from breaking into shorter length tube during the melt shearing process.     

A methacrylate monomer bearing nitro,aryl, and hydroxyl side groups: Homopolymerization,characterization, dielectric,and thermal degradation behaviors

2‐Hydroxy‐3‐(4‐nitrophenoxy)propyl methacrylate (HNPPMA) monomer was synthesized. The poly(HNPPMA) was prepared by free radical polymerization (FRP) method. The characterization of poly(HNPPMA) was carried out using FT‐IR, NMR, differential scanning calorimetry, and GPC techniques. The thermal stability and degradation behavior of this polymer have been studied by using thermogravimetry (TG), GC‐MS, NMR, and FT‐IR. The results were in comparison to poly[2‐hydroxy‐3‐(1‐naphtyloxy)propyl methacrylate] sample with α‐naphtyloxy side group prepared by the same method in the our previous study. The effect of thermal activation on non‐isothermal decomposition kinetics of poly(HNPPMA) was investigated using thermogravimetric analysis according to Flynn‐Wall‐Ozawa method. The dielectric measurements of poly(HNPPMA) and doped with europium(III)chloride (EuCI₃) were investigated by impedance analyzer technique in range of 10–4000 Hz frequency by depending on the alternating current conductivities. The mode of thermal degradation including formation of the main products of poly(HNPPMA) degraded from ambient temperature to 500 °C was identified. S°, the cold ring fraction (CRF) was collected from room temperature to 500 °C. The structure of the degradation products has also been studied depending on the GC‐MS analysis. The thermal degradation mechanism for poly(HNPPMA) with radical degradation processes thought to dominate at high temperature was proposed based on GC/MS, NMR, FT‐IR, and taking into account the new products and differences in stability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43925.     

Poly(azomethine-imide)s containing siloxane moities: Optical,thermal, mechanical,and morphological properties

A new series of poly(azomethine-imide)s having siloxane moities in backbone was prepared using different dianhydrides.Thermal, optical, and morphological properties of these polymers were clarified. Also, bulky  CO and  CF₃ group effects and meta or para-substituted aldeyhde effects on the mentioned properties were evaluated. The structural characterization of poly(azomethine-imide)s was carried out using a FT-IR spectroscopy. The optical properties of the polymers were performed via an UV–Vis spectrophotometer. Optical band gap of the poly(imide)s containing azomethine was calculated between 2.20 and 2.33 eV. Thermal behavior of poly(azomethine-imide)s was also studied using TG-DTA, DSC, and DMA techniques. The onset degradation temperature and percentage char values of the polyimides were found in the range from 429 to 545 °C and 22 to 35%, respectively. Thermal stability results demonstrated that benzophenone bearing poly(azomethine-imide)s have higher onset temperature, percentage char, and the glass transition temperature than poly(azomethine-imide)s derived from hexafluoroisopropylidene. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48364.     

Synthesis,Chiroptical, and Redox Properties of Ferrocene‐Containing Optically Active Polymers

The Sonogashira–Hagihara coupling polymerization of ferrocene‐containing l ‐phenylalanine‐derived optically active o‐, m‐, p‐substituted bis(iodophenylene) monomers 1o , 1m , 1p with 1,4‐diethynylbenzene ( 2 ) and 1,4‐diethynyl‐2,5‐bis[2‐(2‐methoxyethoxy)ethoxy]benzene ( 3 ) is carried out to obtain the corresponding polymers consisting of ferrocene, amino acid, and phenyleneethynylene moieties. In the solution state, poly( 1o ‐ 2 ), poly( 1o‐3 ), and poly( 1m ‐ 2 ) exhibit no circular dichroism (CD) signals in N,N‐dimethylformamide (DMF), while poly( 1m‐3 ), poly( 1p ‐ 2 ), and poly( 1p ‐ 3 ) exhibit CD signals assignable to the main chain chromophore, indicating the formation of certain chiral structures. In the solid state, poly( 1o ‐ 2 ), poly( 1o‐3 ), poly( 1m ‐ 2 ), and poly( 1m‐3 ) exhibit CD signals in the solid state, while poly( 1p ‐ 2 ), poly( 1p ‐ 3 ) does not, indicating the different aggregation manners of the polymers in the solution and solid states. The monomer and the polymers exhibit redox properties assignable to the ferrocene moieties. Thermal gravimetry analysis (TGA) measurements reveal that a 30% weight reduction occurs at 500 °C yielding black ferromagnetic solids.     

CuO and MWCNTs Nanoparticles Filled PVA–PVP Nanocomposites: Morphological,Optical, Thermal,Dielectric, and Electrical Characteristics

Journal of Inorganic and Organometallic Polymers and Materials - Copper dioxide (CuO) nanoparticles and Multiwall carbon nanotubes (MWCNTs) filled poly(vinyl alcohol) (PVA) and poly(vinyl...     

Postsynthetic surface functionalization,encapsulation, and releasing studies of a novel polymer nanocapsule

Postsynthetic surface functionalizations of the amphiphilic poly(allyamine)‐g‐poly(t‐butylacrylate) nanocapsule of 50–100 nm diameters are reported. The hydrophobic poly(t‐butylacrylate) surface of the polymer nanocapsules were successfully functionalized with poly(acrylate) and poly(ethylene glycol). These new nanocapsules were investigated for their water dispersibility, encapsulation and controlled releasing properties with fluorescein, an anionic fluorescence probe, and 5‐fluorouacil, an anticancer drug as the model compounds. The postsynthetic surface funcitionalization approach of the cross‐linked polymer nanocapsules shows promise for improving the biocompatibility and aqueous dispersibility of the nanocapules without disrupting the encapsulation and releasing properties of the polymer nanocapsules. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The dominant factor for mechanical property of polyimide films containing heterocyclic moieties: In‐plane orientation,crystallization, or hydrogen bonding

Crystallization, in‐plane orientation, and hydrogen bonding interactions are three vital factors for enhancing mechanical properties of polyimide (PI) films. However, which is the dominant factor? In this study, three PI films containing heterocyclic moiety, poly(benzoxazole‐imide), poly(benzimidazole‐imide), and poly(pyrimidine‐imide) were chosen to comparative study. The crystallinity of poly(benzoxazole‐imide), poly(benzimidazole‐imide), and poly(pyrimidine‐imide) PI films are 36, 24, and 15%, respectively. The results of small angle X‐ray scattering indicate poly(benzoxazole‐imide) and poly(benzimidazole‐imide) films show periodical lamellar structures, while poly(pyrimidine‐imide) shows no long period due to low crystallinity. In‐plane orientation (P₂₀₀) is calculated from polarized attenuated total reflection (ATR)‐Fourier transform infrared and refractive indices. The order of in‐plane orientation is poly(benzimidazole‐imide) < poly(benzoxazole‐imide) < poly(pyrimidine‐imide). Hydrogen bonding interactions, which restrict chain motion and hinder spontaneous in‐plane orientation, are only formed in poly(benzimidazole‐imide). The relationship between mechanical properties and three influence factors are discussed, and the order of influence extent for mechanical properties of PI films is hydrogen bonding interactions < degree of crystallization < in‐plane orientation. Two structure models for PI films are proposed in order to further confirm the dominant effect of in‐plane orientation on the mechanical properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44000.     

Drying of Multilayer Polymeric Coatings,Part I: An Experimental Study

Designing of multilayer coatings of poly(styrene)-tetrahydrofuran and poly(methyl methacrylate)-tetrahydrofuran has been studied. Multilayers were prepared by layer-by-layer and simultaneous methods. Several binary polymeric coatings of poly(styrene)-tetrahydrofuran and poly(methyl methacrylate)-tetrahydrofuran systems have been dried under quiescent drying conditions. Gravimetric analyses were performed using an analytical weighing balance. The initial amount of polymer was kept constant in both solution coatings. Coating which is likely to go through the glass transition temperature should be applied on the bottom side in order to minimize the residual solvent. For instance, residual solvent content is high in multilayer coating having poly(methyl methacrylate)-tetrahydrofuran coating on the top and poly(styrene)-tetrahydrofuran coating on the bottom, as compared to multilayer coatings having poly(styrene)-tetrahydrofuran on the top of poly(methyl methacrylate)-tetrahydrofuran coating.     

Understanding polyanhydride blend phase behavior using scattering, microscopy, and molecular simulations

The phase behavior of a biocompatible binary polyanhydride blend system composed of poly[1,6-bis(p-carboxyphenoxy)hexane] (poly(CPH)) and poly(sebacic acid) (poly(SA)) is described. The phase behavior is determined from the CPH-SA segmental interaction parameter, χ, obtained from in situ small angle X-ray scattering (SAXS) experiments. The predicted phase diagram has an upper critical solution temperature (UCST) with a critical point of 114 °C. The phase diagram is validated by optical microscopy (cloud point determination) of blend films. However, the full range of blend compositions is not accessible via cloud point measurements, because the melting point of poly(CPH) is above the critical point. Additionally, the poly(CPH) crystallinity interferes with cloud point determination because the length scale of the amorphous phase separation and that of the crystallinity are both near the limit of resolution of the optical microscope. The poly(CPH)-rich region of the phase diagram was investigated by ex situ atomic force microscopy on thin blend films. Finally, in order to validate the use of molecular simulations to study energetic and structural properties of this system, χ is also computed from molecular dynamics both above and below the critical point. Excellent agreement is obtained for all three experimental methods and the computational technique. The results are compared to a simple group contribution method for computing the solubility parameters of the polymers. This technique fails to accurately predict the phase diagram.     

Poly(di-1H,1H,2H,2H-perfluoroalkylitaconate) films: surface organisation phenomena, surface energy determinations and force of adhesion measurements

The significance of the Liftshitz/van der Waals, Lewis-acid, and Lewis-base contributors to the total surface energy of an homologous series of poly(di-1H,1H,2H,2H-perfluoroalkylitaconate)s is discussed in terms of the molecular design features and surface organisation phenomena characterising these, comb-like, polymers. Comparison of the characteristics specific to films prepared from this class of materials with those of the previously-studied homologous series of poly(perfluoroalkylacrylate)s, poly(perfluoroalkylmethacrylate)s and poly(methylpropenoxyalkyl siloxane)s suggests that, of the molecular design requirements for low-surface-energy polymers, an increase in the packing density of pendent side-chains has little effect on the contributors to surface energy but an adverse effect on the roughness of the film.     

Interpenetrating polymer networks based on polyol modified castor oil polyurethane and poly(2‐ethoxyethyl methacrylate): Synthesis,chemical, mechanical,thermal properties,and morphology

Interpenetrating polymer networks (IPNs) of glycerol modified castor oil polyurethane (GC‐PU) and poly(2‐ethoxyethyl methacrylate) poly(2‐EOEMA) were synthesized using benzoyl peroxide as initiator and ethylene glycol dimethacrylate (EGDM) as crosslinker. GC‐PU/poly (2‐EOEMA) interpenetrating polymer networks were obtained by transfer molding. The novel GC‐PU/poly (2‐EOEMA) IPNs are found to be tough films. These IPNs are characterized in terms of their resistance to chemical reagents thermal behavior (DSC, TGA) and mechanical behavior, including tensile strength, Young's modulus, shore A hardness, and elongation. The morphological behavior was studied by scanning electron microscopy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1029–1034, 2004     

Synthesis,characterization, and thermal degradation kinetics of poly(decamethylene 2‐oxoglutarate)

Poly(decamethylene 2‐oxoglutarate) [poly (DMOG)] was synthesized by a melt polycondensation reaction. The structure of poly(DMOG) was confirmed by means of Fourier transform infrared, ¹H‐NMR, and ¹³C NMR spectroscopies. The molecular weight distribution values of poly(DMOG) were determined with size exclusion chromatography. The number‐average molecular weight, weight‐average molecular weight, and polydispersity index values of poly(DMOG) were found to be 13,200, 19,000, and 1.439, respectively. Also, characterization was made by thermogravimetry (TG)–dynamic thermal analysis. The kinetics of the thermal degradation of poly (DMOG) was investigated by thermogravimetric analysis at different heating rates. TG curves showed that the thermal decomposition of poly(DMOG) occurred in one stage. The apparent activation energies of thermal decomposition for poly(DMOG), as determined by the Tang method, the Flynn–Wall–Ozawa method, the Kissinger–Akahira–Sunose method, and the Coats–Redfern method were 122.5, 126.8, 121.4, and 122.9 kJ/mol, respectively. The mechanism function and pre‐exponential factor were also determined by the master plots method. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Self-crosslinked poly-L-ornithine and poly-L-arginine networks: Synthesis,characterization, pH-responsibility,biocompatibility, and AIE-functionality

A pH-responsive hydrogel consists of polypeptides only is a promising biomaterial with the advantages of good biocompatibility and non-toxicity. This work reports the synthesis of poly-L-ornithine(poc) (polyLOpoc) serving as the precursor for hydrogels of poly-L-ornithine (polyOrn) and poly(L-arginine-r-L-ornithine) (poly(Arg-r-Orn)). Their controllable degree of crosslinking, good mechanical properties, good biocompatibility, and pH-responsibility are detailedly investigated. The swelling ratio of polyOrn hydrogel in acidic aqueous solution is 5.7 times higher than that in a basic environment. In the deprotection of phenoxycarbonyl group, polyLOpoc releases amino pendant groups, which attack the remaining poc-protected amino groups to fulfill self-crosslinking without any crosslinking agent. In addition, the pH-responsive behavior of hydrogels is visualized by aggregation-induced emission phenomena with polyOrn and poly(Arg-r-Orn) containing tetrakis(4-aminophenyl)ethene moisture.     

Crystallization,Morphological, and Mechanical Response of Poly(Lactic Acid)/Lignin-Based Biodegradable Composites

Green/bio-based composites of poly(lactic acid) and lignin were prepared by melt blending in a twin-screw extruder. Thermal and mechanical properties, phase interaction, and morphology of the composites have been investigated. Fourier transform infrared studies elucidated the existence of intermolecular hydrogen bonding between poly(lactic acid) and lignin. Scanning electron microscopy studies revealed an extent of diffused phase boundaries between poly(lactic acid) and lignin which also indicated significant interaction between them. Tensile properties showed significant increase over neat poly(lactic acid) with lignin loading (0–0.28 volume fraction) which further justified using theoretical models. Izod impact strength decreased with lignin content.     

Investigation of surface molecular orientation of poly(dimethylsiloxane-co-diphenylsiloxane)-modified poly(amic acid) films using dynamic contact angle measurements,NEXAFS and XPS

Since poly(dimethylsiloxane)-modified poly(amic acid) was not wetted by the photoresist, poly(dimethylsiloxane-co-diphenylsiloxane)-modified poly(amic acid) was synthesized to improve the wettability of photoresist. From a study on dynamic contact angles of water, the initial advancing contact angles on poly(dimethylsiloxane)-modified poly(amic acid) and those on poly(dimethylsiloxane-co-diphenyl-siloxane)-modified poly(amic acid) are almost the same, but the equilibrium advancing contact angles on poly(dimethylsiloxane-co-diphenylsiloxane)-modified poly(amic acid) are much smaller than those on poly(dimethylsiloxane)-modified poly(amic acid). The decrease in equilibrium advancing contact angles on poly(dimethylsiloxane-co-diphenylsiloxane) appears to indicate migration of phenyl groups to the surface in the polar environment. Thus, photoresist could be wetted on the poly(dimethylsiloxane-co-diphenylsiloxane)-modified poly(amic acid) film. Near-edge X-ray absorption fine structure spectroscopy (NEXAFS) and X-ray photoelectron spectroscopy (XPS) were used to investigate the orientation and surface migration of molecules in poly(dimethylsiloxane-co-diphenylsiloxane).     

Acyl Poly(Glycerol-Succinic Acid) Oligoesters: Synthesis,Physicochemical and Functional Properties,and Biodegradability

Biobased surfactants were synthesized using poly(glycerol-succinate) as the polar head group and variable acyl groups as hydrophobic tails. Acyl chain lengths ranged from 8 to 14 carbon atoms. The resulting oligomeric surfactants were characterized by quantitative ¹³C nuclear magnetic resonance (NMR), acid values and size exclusion chromatography. Investigation of the physicochemical properties of the acyl poly(glycerol-succinate) surfactants revealed their potential for use in a wide array of applications. The acyl poly(glycerol-succinate) functional properties appeared to be particularly concentration-dependent. This study highlights the relative impact of acyl chain length on the polymeric structure, physicochemical and functional behaviors, and biodegradability of the acyl poly(glycerol-succinate) surfactants.     

Synthesis of poly(N,N-dimethylcarbamoylmethylene) as a polymer homolog of N,N-dimethylacetamide

Summary A novel polymer homolog of N,N-dimethylacetamide (DMAc) having amide groups on all main chain carbons, poly(N,N-dimethylcarbamoylmethylene) 1, was prepared by heating poly(di-t-butyl fumarate) 2 at 180 °C for 2 hours followed by treatment with hexamethylphosphoramide at 180 °C for 5 hours. The structure of the obtained polymer 1 was confirmed by ¹H-, ¹³C-NMR and IR spectroscopy. The polymer 1 actually showed the properties based on its repeating structures. 1 had the amphiphilicity and was soluble both in protic and aprotic solvents. Furthermore, 1 showed the miscibility with commodity polymers such as poly(N-vinylpyrrolidone), poly(vinyl alcohol) and poly(vinyl chloride). In comparison with another polymer homolog of DMAc, poly(2-methyl-2-oxazoline), the polymer 1 exhibited better miscibility with poly(N-vinylpyrrolidone). Received: 24 June 1999/Accepted: 19 July 1999     

Mechanically Strong and Ductile Polypropylene/Poly(ethylene-co-octene) Blends Prepared Through Multistretched Extrusion: Morphological Evolution,Toughening, and Reinforcing Mechanism

In this paper, polypropylene matrix with densely stacked shish-kebab crystalline structure and dispersed poly(ethylene-co-octene) phase with micro/nanofibers were formed simultaneously in polypropylene/poly(ethylene-co-octene) blends through multistretched extrusion. The as-obtained highly oriented and densely stacked shish-kebab crystalline structure can provide blends with greatly enhanced tensile yield strength. The as-formed poly(ethylene-co-octene) micro/nanofibers can toughen polypropylene matrix effectively through deflecting the crack, which is different from the toughening mechanism in polypropylene/poly(ethylene-co-octene) blends filled with spherical poly(ethylene-co-octene) particles. Compared with that of conventional polypropylene/poly(ethylene-co-octene) blends, the tensile yield strength of multistretched blends increased approximately 300%, while the notched impact strength declined slightly.     

Synthesis,characterization, and degradation of poly(ester-anhydride) for particulate delivery

A series of poly(ester-anhydride) from poly(lactic acid) and poly(sebacic acid) have been synthesized and characterized. Poly(lactic acid) of molecular weight 2,550 Da has been synthesized from pharmaceutical grade lactic acid. The copolymers are in the molecular weight range of 3,000-15,000 Da, with the higher molecular weights obtained for the polymers with higher sebacic acid content. With increase in sebacic acid content, the melting point is also found to increase. The polymers with 50% or more poly(sebacic acid) content melt between 80 and 84 °C. These polymers have been formulated into microspheres and their degradation studied. Due to their biodegradability and the flexibility to alter their degradation profile, they find a wide application in drug delivery.