Preparation and solubility of a partial ladder copolymer from p-phenylenediamine and o-phenetidine

A series of copolymers were synthesized by chemically oxidative polymerization of p-phenylenediamine (PPD) and o-phenetidine (PHT) in acidic aqueous media. The polymerization yield, intrinsic viscosity, and solubility of the copolymers were comprehensively studied by changing the comonomer ratio, polymerization time and temperature, oxidant, monomer/oxidant ratio, and acidic medium. As-prepared fine powder of the PPD/PHT copolymers was characterized by FT-IR, UV-vis, high-resolution ¹H-NMR, and DSC techniques. A circular dichroism technique was firstly used to characterize the macromolecular structure of the copolymers. The results showed that the oxidative copolymerization from PPD and PHT is exothermic and the resulting copolymers exhibit an enhanced solubility in most of the organic solvents as compared with poly(p-phenylenediamine), sometimes also with poly(o-phenetidine). The polymer obtained is a real copolymer containing PPD and PHT units, and the actual PPD/PHT ratio calculated by ¹H-NMR spectra of the polymers is very close to the feed ratio. The DSC measurement indicates that the copolymers are amorphous and chemically instable at elevated temperature.     

Facile synthesis of oxidative copolymers from aminoquinoline and anisidine

Oxidative copolymerization of 8-aminoquinoline (AQ) and o-anisidine (AS) using ammonium persulfate as oxidant was studied under various polymerization conditions and fine and uniform copolymer particles of several micrometers, determined by laser particle size and atomic force microscopic analyses, were synthesized simply. The polymerization yield, molecular weight, solubility, electroconductivity, and thermostability of the copolymers were systematically studied by changing the comonomer ratio, polymerization temperature, monomer/oxidant ratio, and acidic medium. Single chain configuration of the copolymers with various AQ/AS ratios was simulated and well related to the intrinsic viscosity. The macromolecular structure of the resulting copolymers was wholly characterized by elementary analysis, IR, UV-vis, high-resolution ¹H NMR, and solid-state high-resolution ¹³C NMR. The results show that the oxidative copolymerization of AQ and AS is exothermic. All copolymers are totally soluble in H₂SO₄, HCOOH, m-cresol but their solubility in other solvents depends significantly on the comonomer ratio, and also on the polymerization conditions. The oxidative polymer obtained is a real copolymer containing AQ and AS units rather than a mixture of two homopolymers. The AQ content calculated based on the ¹H NMR spectra of the copolymers is slightly higher than feed AQ content when feed AQ content is lower than 70 mol%. However, the AQ content calculated based on the ¹³C NMR and elementary analyses is lower than the feed AQ content when the AQ feed content is higher than 50 mol%. A peculiar dependency of molecular weight and electroconductivity of the copolymers on the AQ/AS ratio was observed. The decomposition temperature of the copolymers rises with increasing AQ content. Therefore, the thermostability of the copolymers increases with increasing AQ content due to its high aromaticity.     

Preparation and identification of a soluble copolymer from pyrrole and o-toluidine

A series of copolymers were prepared by chemically oxidative polymerization of pyrrole (PY) and ortho-toluidine (OT) in HCl aqueous medium. The yield, intrinsic viscosity, and solubility of the copolymers were studied by changing the monomer molar ratio. The resulting PY/OT copolymers were identified by FTIR, ¹H–NMR, DSC, and WAXD techniques. The experimental results showed that the oxidative polymerization of pyrrole and o-toluidine is exothermic and the resulting polymers exhibit an enhanced solubility in most organic solvents compared with that of pyrrole homopolymer. The polymer obtained is a real and amorphous copolymer containing pyrrole and o-toluidine units. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 510–518, 2001     

Chemically oxidative polymerization of aromatic diamines: The first use of aluminium-triflate as a co-catalyst

Aromatic diamine monomers, including o-phenylenediamine (oPD), p-phenylenediamine (pPD), 4,4′-diaminodiphenylenemethane (DADPM) and benzidine (BZN), were polymerized by chemical oxidation using sodium persulfate, potassium persulfate, and ammonium persulfate as oxidant catalysts. Aluminium-triflate (Al(OTf)₃) was also used for the first time as a co-catalyst under various polymerization conditions. The homopolymers obtained are characterized by FT-IR, ¹H and ¹³C NMR, GPC, WAXD, DSC and TGA. The yield, solubility, structure and molecular weight of the polymers are significantly dependent on the oxidative catalyst and polymerization conditions. The polymers show different molecular structures, good thermal stability and decompose above 400 °C in nitrogen.     

Effect of polymerization conditions on o‐phenylenediamine and o‐phenetidine oxidative copolymers

A series of new o‐phenylenediamine (OPD)/o‐phenetidine (PHT) copolymers with partly phenazine‐like structures has been successfully synthesized at three polymerization temperatures by chemically oxidative polymerization in four different polymerization media. The molecular structures and properties of the resulting OPD/PHT polymers were investigated by IR, UV–vis and high‐resolution ¹H NMR spectroscopies, and DSC, in order to ascertain the effect of reaction temperature, comonomer ratio and acid medium. The copolymerization mechanism of OPD with PHT monomers has been proposed. It is found that the statistical OPD/PHT copolymer obtained at a temperature of 118 °C has a higher degree of polymerization than that obtained at 12–17 °C. The OPD content in the copolymers calculated from NMR spectroscopic analysis is higher than that in the feed OPD content, whereas the OPD content calculated from element analysis is slightly lower than the feed OPD content. It can be predicted that denitrogenation takes place in the OPD units during the polymerization process at OPD/PHT molar ratios of 90/10 and 100/0. These OPD/PHT copolymers exhibit a much better solubility than the OPD homopolymer, hence suggesting an incorporation of PHT units into the phenazine structure of the homopolymer. The thermal behavior of the copolymers was also studied. Copyright © 2004 Society of Chemical Industry     

Facile synthesis of highly soluble copolymers and sub-micrometer particles from ethylaniline with anisidine and sulfoanisidine

Two series of copolymers were synthesized by an oxidative polymerization of 2-ethylaniline (EA) with 2-anisidine (AS) or 5-sulfonic-2-anisidine (SA) for a detailed comparative study between EA/SA and EA/AS copolymers. The preparation, structure, and properties of the copolymers were systematically studied by FT-IR, high-resolution ¹H NMR, UV-vis, elementary analysis, GPC, laser particle size analysis, atomic force microscope, and thermogravimetry. Significant dependences of the yield, molecular weight, solubility, and thermostability of the copolymer particles on the comonomer ratio and oxidant/monomer ratio have been observed. The molecular weight increases continuously with increasing EA content in the two copolymers. Quinoid structures favor on the EA units in EA/AS copolymers with the whole oxidation rate of larger than 0.5 in the molecular chain. Although the EA/AS copolymers exhibit only external doping, the EA/SA copolymers exhibit not only external doping on EA units but also self-doping on SA units. The monomer reactivity increases in the order of EA≤SA<AS. The size and its distribution of the particles are highly dependent on polymerization time and comonomer ratio. The sub-micrometer particles with the smallest diameter of 120 nm are easily prepared by an in situ EA/SA (70/30) polymerization. A relationship between the particle diameter and macromolecular steric model is founded. A new simple method of preparing sub-micrometer particles of aniline derivative polymers without adscititious stabilizer is established. A possible formation mechanism of the sub-micrometer particles during a non-emulsion EA/SA polymerization is proposed. The polymer particles obtained are completely soluble in many solvents and exhibit a very good film-forming ability. A regular variation of the thermostable characteristics of the copolymers with comonomer ratio is found and a three-step process of the thermal degradation is assigned.     

Synthesis and nitrosation of processible copolymers from pyrrole and ethylaniline

A series of copolymers were prepared by an oxidative polymerization of pyrrole (PY) and 2-ethylaniline (EA) in HCl. The polymerization process was followed by tracking open-circuit potential and temperature of the reaction solutions. The fine particles of the PY/EA copolymers obtained in situ were further N-nitrosated for the first time in order to improve their solubility. The size, structure, and properties of the fine particles and their N-nitroso products were systematically characterized by laser particle size analyzer, FTIR, UV-vis, GPC, solution casting, and TG techniques. It is found that both the open-circuit potential and temperature of the solutions exhibit a maximum during the copolymerization, while the particle size of the copolymers will decrease monotonically with prolongating polymerization time or doping. Both the polymerization yield and molecular weight of the copolymers exhibit a minimum with PY/EA ratio, indicating a mutual retarding effect between the PY and EA monomers. The top potential and top temperature of the copolymerization as well as the particle size and its distribution, solubility, film-forming ability, electroconductivity, and thermostability of the copolymers all depend significantly on the PY/EA ratio. The PY/EA copolymers have good solubility in the solvents with the solubility parameter from 23 to 27 J^1/2/cm^3/2, dielectric constant greater than 12 and polarity index from 6.4 to 7.4 and their solubility becomes further better with increasing EA content. The N-nitrosation of copolymers can also improve their solubility in polar solvents furthermore. The copolymers with PY content of less than 30 mol% in NMP and THF exhibit good thin-film formability. The copolymer films become smoother and tougher with increasing EA content and by N-nitrosation. With increasing PY content, the decomposition temperature, maximum decomposition rate, char yield at 500 °C, and activation energy all decrease but decomposition order increases. The temperature at the maximum weight-loss rate of the copolymers has a maximum at the PY/EA molar ratio of 30/70. These results suggest that the polymer obtained is a real copolymer containing two comonomer units.     

Preparation and characterization of poly(p-phenylenediamine-co-xylidine)

p-Phenylenediamine (PPDA) homopolymer and its copolymers with 2,3-xylidine (XY) were synthesized by oxidative polymerization using potassium persulfate as an oxidant in HCl medium at room temperature. The yield, intrinsic viscosity, and solubility of the polymers were significantly dependent on the monomer ratio. The resulting polymers were characterized by Fourier transform IR spectroscopy, ¹H-NMR spectroscopy, wide-angle X-ray diffraction, and thermogravimetry methods. The results showed that the number-average degree of polymerization of the PPDA homopolymer was 33 and the actual content of XY units in the copolymer was slightly higher than the feed XY unit content. The polymers were substantially amorphous and showed the strongest diffraction at a Bragg angle of 3°. The polymers exhibited a thermal decomposition temperature higher than 436°C, the maximum weight-loss rate was slower than 4%/min, and the char yield was larger than 24 wt % at 600°C in nitrogen. The activation energy of thermal decomposition for the polymers increased from 19 to 25 kJ/mol with increasing XY unit contents from 0 to 10 mol %. The polymers showed higher thermostability but lower activation energy of decomposition in nitrogen than in air. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3107–3116, 2001     

Synthesis and properties of a functional copolymer from N-ethylaniline and aniline by an emulsion polymerization

A series of functional copolymers was synthesized by an emulsion polymerization of N-ethylaniline (EA) and aniline (AN) in the presence of sodium dodecylbenzene sulfonate in HCl. Several important polymer parameters including the polymerization yield, molecular weight, solubility, film formability, solvatochromism, thermochromism, and alterable electrical conductivity were systematically studied by changing the comonomer ratio, emulsifier/monomer ratio, oxidant/monomer ratio, solvent, and temperature. The resulted copolymers were characterized in detail by infrared and UV-vis spectroscopies. It is found that these copolymers exhibit narrow molecular weight distribution, good solubility, excellent film flexibility, colorful solvatochromism in various solvents, reversible thermochromism in a wide temperature range, and widely controllable conductivity from 2.03×10⁻¹⁰ to 0.161 S/cm with changing the polymerization conditions and doping states.     

Chemical synthesis,characterization, and properties of conducting copolymers of imidazole and pyridine

A series of conducting copolymers were synthesized by chemical oxidative polymerization of imidazole (Imi) and pyridine (Py) in acetonitrile medium at ambient temperature. The yield, solubility, and conductivity of the copolymers were measured by changing the Imi/Py molar ratio from 0/100 to 100/0. The as‐prepared Imi/Py conducting copolymers were characterized by UV‐Visible, FTIR, ¹H‐NMR, DSC, TGA, and XRD. The results suggest that the resulting copolymers were more easily soluble in most of the organic solvents than in polyimidazole. The polymer obtained is a real copolymer containing imidazole and pyridine units, but the Imi content calculated on the basis of the proton NMR spectra is lower than feed Imi content. The thermostability of the Imi/Py copolymer increases with increasing Imi unit content. The copolymers show comparatively higher conductivity and higher thermal stability than the homopolymer polypyridine and are lower than those of polyimidazole. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Chemical synthesis,characterization, and properties of conducting copolymers of imidazole and carbazole

Conducting copolymers of imidazole and carbazole were chemically synthesized in various molar ratios of the imidazole and carbazole by chemical oxidative polymerization in acetonitrile medium using ammonium persulphate as oxidant. The selection and composition of solvent, concentration of the monomer, polymerization time, and temperature were optimized to obtain better quality and yield of the copolymers. The synthesized conducting copolymers were characterized by various techniques such as UV–visible, Fourier transform infrared, ¹H‐NMR, and X‐ray diffraction spectroscopy. The solubility of the copolymers was tested in various solvents. Their conductivity was tested at various temperatures. The thermodynamic stability of the copolymers was examined by differential scanning colorimetric and thermogravimetric analysis. The copolymers show comparatively higher conductivity, better solubility, and higher thermal stability than the homopolymer poly(carbazole) and lower than that of poly(imidazole). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermo-, and pH dual-responsive poly(N-vinylimidazole): Preparation,characterization and its switchable catalytic activity

A monomer, 2-(isobutyramido)-3-methylbutyl methacrylate (IMMA) was synthesized through a two-step reaction. When a few of IMMA (less than 4 mol%) was copolymerized with N-vinylimidazole (VIm) under free radical polymerization condition, water-soluble P(VIm-co-IMMA) copolymers were obtained. Their structural information was verified and interpreted from ¹H NMR, FTIR and GPC. Kinetic analyses from ¹H NMR demonstrated that one-batch addition of IMMA into the polymerization system led to an inhomogeneous distribution of IMMA units in the copolymers, whereas homogeneous distribution of IMMA units in the copolymers could be obtained through the portion-wise addition of IMMA monomer. The thermal properties of such copolymers were measured by DSC. Compared with PVIm homopolymer, the few IMMA units in the P(VIm-co-IMMA) copolymer had little influence on the T_g values. The obtained P(VIm-co-IMMA) copolymers were thermoresponsive in water, and their phase transition temperatures could be efficiently raised through reducing the IMMA content in the copolymers, raising the addition times of IMMA monomers or lowering the pH of media. Dynamic light scattering analysis showed that unlike the traditional thermoresponsive linear polymers, obvious size shrinkage around the phase transition temperature could not be observed in such P(VIm-co-IMMA) copolymers. Such copolymers could be used as smart organocatalysts in the hydrolysis of p-nitrophenyl acetate. Below the phase transition temperature the reaction rate followed the Arrhenius law, but above the phase transition temperature the reaction rate increased much slower than the prediction from the Arrhenius law. Moreover, the catalytic transition temperature could be tuned through utilizing the P(VIm-co-IMMA) copolymers with different phase transition temperature. The mechanism was discussed accordingly.     

Block copolymer grafted-silica particles: a core/double shell hybrid inorganic/organic material

Hybrid inorganic/organic materials consisting of a poly(n-butyl acrylate)-b-poly(styrene) diblock copolymer anchored to silica particles were synthesized via ‘grafting from’ technique using a controlled/living free radical polymerization named stable free radical polymerization. XPS and FTIR analysis were used to control the effectiveness of the chemical modification of the silica particles. Thermal characterizations were performed by thermal gravimetric analysis (TGA) and by differential scattering calorimetry (DSC). The TGA permitted the determination of the quantity of grafted polymer and thus the grafting density; DSC was used to study the influence of the silica and blocks of the copolymer on their thermal behaviors. The glass transition temperature of the grafted copolymers was compared to these of free polymers or copolymers homologues.     

Chemical synthesis and characterization of self-doped N-propanesulfonic acid polyaniline derivatives

In chemical oxidative homopolymerization of aniline-N-propanesulfonic acid, ammonium persulfate has been used as an oxidant to obtain water-soluble and self-acid-doped polyanilines. Copolymerization of aniline-N-propanesulfonic acid with aniline, using three feed molar ratios of comonomers has been studied, as well. The polymers and copolymers had moderate molecular weights and were soluble in water and polar solvents. They have been obtained in self-acid-doped form, as has been evidenced by UV?CVis spectroscopy, as green-colored materials, and can be de-doped with alkaline solutions. The propanesulfonic groups had not cleaved during the oxidative polymerization and the atomic ratio between nitrogen and sulfur atoms (N/S) was determined by X-ray photoelectron spectroscopy which was consistent with the chemical structure. The chemical structures and morphologies of the homo- and copolymers have been studied by FTIR, ¹HNMR, UV?CVis, thermogravimetric analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, and X-ray diffraction methods. The X-ray diffraction patterns of the homo- and copolymers have showed a high degree of crystallinity which can be explained by the ionic interaction between propanesulfonate anions and the amine nitrogen atoms of the main chain, resulting in the layering structure of the polyaniline chains. Electrical conductivity of the homopolymer determined at room temperature on pressed pellet was 0.0038?S/cm, while the copolymers show higher conductivities compared with homopolymer.     

Preparation and characterization of a type of ladder‐like poly(phenyl silsesquioxane) based hybrid star‐shaped copolymer of ε‐caprolactone

Combination of the organic–inorganic hybrid such as silsesquioxane with ε‐caprolactone will lead to materials expected to be environmentally friendly and applicable to biomedical usages. A ladder‐like poly(phenyl silsesquioxane) based hybrid star‐shaped copolymer of ε‐caprolactone was prepared by ring opening polymerization of ε‐caprolactone catalyzed by Sn(Oct)₂ with hydroxyl terminated ladder‐like poly(phenyl silsesquioxane) as initiator. The copolymers were characterized by proton nuclear magnetic resonance (¹H‐NMR), silicon nuclear magnetic resonance (²⁹Si‐NMR), Fourier‐transform infrared spectrometer (FT‐IR), size exclusion chromatography (SEC), thermo gravimetric analysis (TGA), and differential scanning calorimetry (DSC) in detail. Furthermore, the enzymatic degradation property of the copolymers was also investigated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42335.     

Synthesis of polysulfone-b-polystyrene block copolymers by mechanistic transformation from condensation polymerization to free radical polymerization

Synthesis of polysulfone-b-polystyrene (PSU-b-PS) block copolymers by a combination of condensation polymerization and free radical polymerization processes are described. First, a new macroazoinitiator (MAI) containing polysulfone (PSU) units was prepared by direct esterification of 4,4-azobis(4-cyanopentanoic acid) with α,ω-hydroxyl PSU telechelics at ambient conditions. The macroinitiator was then used in conventional free radical polymerization of styrene leading to the formation of desired block copolymers. In this process, initiating macroradicals were generated by thermal cleavage of the azo group present in the macroazoinitiator structure. The precursor polysulfone macroazoinitiator (PSU-MAI) and resulting block copolymers were characterized by spectral analysis using FT-IR, ¹H-NMR, GPC, TGA, and DSC.     

Preparation of hyperbranched copolymers of maleimide inimer and styrene by ATRP

Novel hyperbranched copolymers were prepared by the atom transfer radical copolymerization of N-(4-α-bromobutyryloxy phenyl) maleimide (BBPMI) with styrene in 1-methyl-2-pyrrolidone (NMP) using the complex of CuBr/2,2′-bipyridine as catalyst. The copolymerization behavior was investigated by comparison of the conversion of double bond of BBPMI determined by ¹H NMR with that of styrene. The hyperbranched structure of resulting copolymers was verified by gel permeation chromatography (GPC) coupled with multi-angle laser light scattering (MALLS). The influences of dosage of catalyst and monomer ratio on the polymerization rate and structure of the resulting polymers were also investigated. The glass transition temperature of the resulting hyperbranched copolymer increases with increasing mole fraction of BBPMI, f_BBPMI. The resulting copolymers exhibit improved solubility in organic solvents; however, they show lower thermal stabilities than their linear analogues.     

Electrosyntheses and characterizations of novel electrochromic copolymers based on pyrene and 3,4-ethylenedioxythiophene

The copolymers based on pyrene and 3,4-ethylenedioxythiophene (EDOT) are electrochemically synthesized in acetonitrile (ACN) containing tetrabutylammonium perchlorate (TBAP) via the direct oxidation of pyrene/EDOT mixtures. FT-IR and ¹H NMR characterizations confirm that the obtained polymers contain both pyrene and EDOT units. Elemental analyses results show that the ratio of pyrene/EDOT units in polymers decreases as the feed ratio of pyrene/EDOT decreases in ACN. The effects of pyrene/EDOT feed ratio and polymerization potential on the electrochemical properties of the obtained copolymers are studied by cyclic voltammetry (CV). Compared with polypyrene, the copolymers perform reversible redox process, and their UV–vis absorption peaks exhibit obvious red-shift. It is interesting that the obtained copolymer films present a property of tunable electrochromism, smooth morphology and good thermal stability.     

Synthesis and properties of the copolymers based on aniline and 2-aminobenzyl alcohol

A kind of novel conducting copolymer with different compositions based on aniline and 2-aminobenzyl alcohol was prepared by chemical oxidative polymerization method. The copolymers were characterized by the methods of FT-IR, UV–Vis, XRD and DSC. It indicated that 2-aminobenzyl alcohol could copolymerize with aniline by this method. In addition, the solubility and conductivity of the copolymers were also studied in detail. The results showed that the copolymers had better solubility in pyridine than pure HCl doped polyaniline and the conductivities were decreased with the increase of the molar ratio of 2-aminobenzyl alcohol in copolymer.     

Improving water solubility of poly(acrylic acid‐co‐styrene) copolymers by adding styrene sulfonic acid as a termonomer

Acrylic acid is often used to make water‐soluble polymers while styrene is often modified to add special functions to polymers. However, when styrene and acrylic acid are copolymerized, the resulting polymer is much less water soluble. To regain water solubility, the effect of styrene sulfonic acid on solubility of poly(acrylic acid‐co‐styrene) copolymers was investigated. Even though acrylic acid polymers are known for their water solubility, the presence of styrene units within acrylic acid copolymers reduces the solubility of the copolymer substantially at the natural pH of the solutions. By adding styrene sulfonic acid as a termonomer, polymers that are water soluble at the natural pH of the polymerization could be obtained. The solubility of the polymer after removal of the solvent and by redissolving at different concentrations and pH levels is also reported. Solubility increases at higher pH especially with low styrene concentration in the copolymer. It was found that incorporation of as little as 5 mol % of styrene into poly(acrylic acid) reduced the aqueous solubility to less than 0.5 g dL^?1 at pH 7. Upon adding 7 mol % styrene sulfonic acid as a termonomer, the water solubility increased to 5 g dL^?1 at pH 7. At higher levels of styrene, more styrene sulfonic acid was needed, especially at low pH. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013