As-synthesized Polymers Research Articles

Synthesis and photovoltaic performances of 2,5-dioctyloxy-1,4-phenylenevinylene and terthiophene copolymers with di( p-tolyl)phenylamine and oxadiazole side groups

Three novel conjugated polymers ( P1, P2, and P3), comprised of 2,5-dioctyloxy-1,4-phenylenevinylene and terthiophene derivatives with/without di( p-tolyl)phenylamine (TPAV) and oxadiazole (OXD) side groups, have been synthesized via the Witting–Horner reaction. The effect of TPAV and OXD side groups on the optical, electrochemical and photovoltaic properties has been investigated. It is found that the introduction of TPAV and OXD side groups to the backbone of P2 and P3 exhibits broader and stronger absorption than that of P1 without TPAV and OXD side groups. Photovoltaic cells have been fabricated with the as-synthesized polymers as the donors and [6,6]-phenyl-C 61-butyric acid methyl ester (PCBM) as the acceptor in a 1:4 weight ratio. The device based on P2 shows a maximum power conversion efficiency of 1.75% under simulated AM 1.5 G solar irradiation (100 mW/cm 2).

Synthesis, one- and two-photon properties of poly[9,10-bis(3,4-bis(2-ethylhexyl-oxy)phenyl)-2,6-anthracenevinylene-alt-N-octyl-3,6-/2,7-carbazolevinylene

The synthesis, one- and two-photon absorption (TPA) and emission properties of two novel 2,6-anthracenevinylene-based copolymers, poly[9,10-bis(3,4-bis(2-ethylhexyloxy)phenyl)-2,6-anthracenevinylene-alt-N-octyl-3,6-carbazolevinyl-ene] (P1) and poly[9,10-bis(3,4-bis(2-ethylhexyloxy)phenyl)-2,6-anthracenevinyl-ene-alt-N-octyl-2,7-carbazolevinylene] (P2) were reported. The as-synthesized polymers have the number-average molecular weights of 1.56 × 104 for P1 and 1.85 × 104 g mol−1 for P2 and are readily soluble in common organic solvents. They emit strong bluish-green one- and two-photon excitation fluorescence in dilute toluene solution (ϕP1 = 0.85, ϕP2 = 0.78, λem(P1) = 491 nm, λem(P2) = 483 nm). The maximal TPA cross-sections of P1 and P2 measured by the two-photon-induced fluorescence method using femtosecond laser pulses in toluene are 840 and 490 GM per repeating unit, respectively, which are obviously larger than that (210 GM) of poly[9,10-bis-(3,4-bis(2-ethylhexyloxy) phenyl)-2,6-anthracenevinylene], indicating that the poly(2,6-anthracenevinylene) derivatives with large TPA cross-sections can be obtained by inserting electron-donating moieties into the polymer backbone. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 463–470, 2010

Effect of gamma radiation on dilute aqueous solutions and thin films of N-succinyl chitosan

N-Succinyl chitosan ( N-SC) products with various degrees of substitution were synthesized by a direct reaction between chitosan and succinic anhydride. The susceptibility of the as-synthesized polymers to degradation upon their exposure to γ-ray radiation was investigated. The results were compared with the as-received chitosan. The size exclusion chromatographic results showed that chitosan and N-SC products in their dilute aqueous solution state were more subservient to degradation by γ-ray radiation than in their solid film state, despite the much less exposure to the radiation (i.e., 5–30 kGy for the solutions versus 20–100 kGy for the films). Increasing the radiation dose resulted in the rather monotonous decrease in the molecular weights of the polymers. Structural analyses of the irradiated polymers by Fourier-transformed infrared spectroscopy (FT-IR) and UV–visible spectrophotometry indicated the increase in the amount of carbonyl groups with the radiation dose. The formation of the carbonyl groups suggested that the radiolysis of chitosan and N-SC products occurred at the glycosidic linkages. In addition, FT-IR, elemental analysis and proton nuclear magnetic resonance spectroscopy ( 1H NMR) results suggested that γ-ray radiation affected both the N-acetyl and N-substituted groups on the polymer chains.

Synthesis of a novel biodegradable and electroactive polyphosphazene for biomedical application

To prepare one electroactive and biodegradable biomaterial for biomedical application, a new synthetic strategy was developed to synthesize a novel electrically conductive biodegradable polyphosphazene polymer containing parent aniline pentamer (PAP) and glycine ethyl ester (GEE) as side chains by a nucleophilic substitution reaction. The electrical conductivity of the polymer is ∼2 × 10−5 S cm−1 in the semiconducting region upon preliminarily protonic-doped experiment. The degradation and RSC96 Schwann cells experiments in vitro prove that the polymer is biodegradable and beneficial to the cell adhesion and proliferation. The as-synthesized polymer also shows good solubility in common organic solvent and good film-forming properties. This new type of polymer has potential applications as scaffolds for neuronal and cardiovascular tissue engineering or other biomedical devices that require electroactivity.

Rapid fabrication and formation mechanism of cyclotriphosphazene-containing polymer nanofibers

Cyclotriphosphazene-containing polymer nanofibers with uniform diameters, high aspect ratios, and high specific surface area have been synthesized rapidly at high yields under ultrasonic irradiation via a self-directing template approach. During the polymerization, triethylamine (TEA) as an acid acceptor absorbed a byproduct hydrogen chloride (HCl) to afford triethylamine hydrochloride (TEACl), acting as structure-directing template and guiding the formation of nanofibrous structures. The mechanism was confirmed by means of SEM, TEM, FTIR, XRD, TG, and N 2 adsorption method. The molecular structure of as-synthesized polymer nanofibers was characterized by solid state NMR and elemental analysis.

Self-Assembly and Encoding of Polymer-Stabilized Gold Nanoparticles with Surface-Enhanced Raman Reporter Molecules

Polymer-stabilized gold nanoparticles (AuNPs) were prepared and encoded with a range of surface-enhanced Raman reporter molecules. A range of as-synthesized polymers produced by reversible addition fragmentation chain transfer (RAFT) polymerization were demonstrated to self-assemble at the surface of AuNPs dispersed in water. The method involved the coprecipitation of polymer-gold conjugates by the addition of polymer dissolved in a water-miscible solvent to gold AuNPs dispersed in water. This method represents a simplification of the preparation of polymer-stabilized AuNPs compared with other published methods, in that the AuNPs do not need to be first transferred to an organic solvent. The process enabled the polymer stabilized AuNPs to be easily recovered by filtration or by phase transfer of the AuNPs to an organic solvent in which the RAFT polymer was soluble. The polymer-stabilized AuNPs were characterized by a range of methods including UV-visible spectrophotometry, transmission electron microscopy, thermogravimetric analysis, dynamic light scattering, and attenuated total reflection Fourier transform infrared spectroscopy. Furthermore, 1H pulsed field gradient spin echo NMR was utilized to characterize the self-diffusion of the polymer-stabilized AuNPs. Finally, we then demonstrated that these polymer-stabilized AuNPs maintained their ability to be encoded with surface-enhanced Raman spectroscopy reporter molecules.

Direct fluorination of various poly( p-phenylene): Effects of the polymer synthesis and thermal post-treatment

In order to complete a preliminary work about the direct fluorination of poly( p-phenylene) (PPP), the main parameters of the process were investigated. The molecular (chain length and crystallinity) and morphological effects (B.E.T. surface, granulometry) were studied. So, two new starting samples were studied in addition to PPP synthesized by the Kovacic's method (i) a commercial PPP (Polysciences) and (ii) a pyrolyzed PPP, which is similar to an amorphous hydrogenated carbon. Moreover, an annealed PPP (Kovacic's synthesis and post-treatment at 400 °C for 36 h) was compared to the as-synthesized polymer. The reactions with F 2 gas differ significantly in accordance with the synthesis way and the post-treatment (annealing or pyrolysis). Investigations about the direct fluorination of PPPs were carried out for a better understanding of their behavior with respect to molecular fluorine. An extensive characterization was performed by complementary techniques ( 19F and 13C NMR, FT-IR, and EPR). The fluorine content in the fluorinated PPPs is evaluated by these methods and a reaction mechanism is proposed.

Preparation of organic/inorganic hybrid nanomaterials using aggregates of poly(stearyl methacrylate)- b-poly(3-(trimethoxysilyl) propyl methacrylate) as precursor

A novel brush-type amphiphilic copolymer of PSMA- b-PTMSPMA was synthesized via ATRP technique. As-synthesized polymer was characterized by GPC and 1H NMR. It was of interest that the resultant polymer could self-assemble into micelles with different morphologies and sizes in selective solvents by adjusting the copolymer concentrations. These aggregates could be prepared into novel stable organic/inorganic hybrid nanomaterials by the gelation process. The size and structure of these aggregates and the corresponding hybrid nanomaterials were observed by TEM.

Supramolecular Polypseudorotaxanes Composed of Star-Shaped Porphyrin-Cored Poly(ε-caprolactone) and α-Cyclodextrin

Star-shaped porphyrin-cored poly(epsilon-caprolactone) (SPPCL) was synthesized using a tetrahydroxyethyl-terminated porphyrin as a core initiator and stannous octoate as a catalyst in bulk at 120 degrees C. The molecular weight of as-synthesized polymer could be adjusted linearly by controlling the molar ratio of epsilon-caprolactone to porphyrin core initiator, and the molecular weight distribution was reasonably narrow. Supramolecular polypseudorotaxanes were prepared by inclusion complexation of SPPCL with alpha-cyclodextrin (alpha-CD) and thoroughly characterized by means of FT-IR, 1H NMR, 13C CP/MAS NMR, DSC, TGA, and WAXD. The results demonstrated that the porphyrin-cored polypseudorotaxanes formed through alpha-CD molecules threading onto the branch chains of star-shaped SPPCL polymers, and they had a channel-type crystalline structure. Meanwhile, the original crystallization of SPPCL polymers within the polypseudorotaxanes was completely suppressed in the alpha-CD cavities. Moreover, inclusion complexation between SPPCL and alpha-CD enhanced the thermal stability of both the guest SPPCL polymers and the host alpha-CD. Furthermore, both the SPPCL polymers and the polypseudorotaxanes showed similar fluorescent and UV-vis spectra compared with porphyrin core initiator. Consequently, this will not only provide potentially porphyrin-cored poly(epsilon-caprolactone) and its polypseudorotaxanes for photodynamic therapy but also improve the compatibility between poly(epsilon-caprolactone) and peptide drugs for drug delivery.

A novel family of ordered, mesoporous inorganic/organic hybrid polymers containing covalently and multiply bound microporous organic hosts.

We have prepared a new family of periodic hybrid polymers containing microporous cavities provided by covalently bound organic hosts. Cyclodextrin (CD) or calixarene (CX) hosts are attached to four or more trialkoxysilyl groups, which are polymerized to form a polysilsesquioxane matrix. Structural integrity is provided by copolymerization with tetraethoxysilane, which produces a polysilicate co-matrix. Periodic order is created by carrying out the polymerization in the presence of a surfactant, cetyltrimethylammonium bromide. The resulting as-synthesized polymers from these three starting materials were characterized by solid-state nuclear magnetic resonance spectroscopy. The (13)C and (29)Si spectra provided evidence for intact polysilsesquioxane, polysilicate, organic host, and surfactant. Removal of the surfactant by washing produced a polymer containing cavities of mesoporous dimensions, in addition to the microporous host cavities. The purpose of introducing mesoporosity is to allow enhanced access of guests to the microporous hosts. Transmission electron microscopy demonstrated that both as-synthesized and solvent-extracted polymers have a periodic structure. All polymers are completely insoluble in water. The as-synthesized CD-containing polymers extracted up to >99% of 4-nitrophenol from aqueous solution, and the solvent-extracted CX-containing polymers extracted up to 67% of Fe(3+) and lesser amounts of other metal cations from aqueous solution, with interesting selectivity patterns. Simple filtration then removes the polymer containing the extracted organic molecule or metal cation. These extraction abilities are superior to previous materials.

A nanoporous metal-organic framework based on bulky phosphane ligands.

No interpenetration: The use of bulky phosphane ligands allows the preparation of a non-interpenetrating two-dimensional nanoporous structure with hexagonal channels (see picture). In the as-synthesized polymer these channels are saturated with solvent, however, this solvent can be exchanged for other solvents which in turn can be removed by heating under vacuum without collapse of the structure.

Pristine and Overoxidized Polypyrrole by XPS

An x-ray photoelectron spectroscopy (XPS) analysis was performed of polypyrroles (PPy) electrosynthesized on Pt in aqueous solution. Spectra were recorded both for the as-synthesized (pristine) polymer (specimen 1) and for the so-called “overoxidized” PPy (specimen 2). Electrosynthesis was accomplished potentiostatically at +0.7 V vs SCE in KCl 10 mM containing pyrrole 0.4 M. Overoxidized PPy was obtained by keeping the pristine polymer at the electrosynthesis potential for 5 h, in phosphate buffer solution (pH 7). C, N, O (1s), and Cl 2p (pristine) spectra are included. Some minor elements, P (in the overoxidized polymer), Na (in some overoxidized samples), and Si (in other samples of both types of PPy, but not in those here reported), were also detected.

Thermal and mechanical characterization of poly[bis(4-benzylphenoxy)phosphazene

In this paper we report the thermal and mechanical characterization of poly[bis(4-benzylphenoxy)phosphazene] (PBPP). Glass transition and melting temperatures of 13.8 and 88.2°C respectively, and heat of fusion of 7.0 J g −1 were measured by differential scanning calorimetry (d.s.c.) for the as-synthesized polymer. Crystallization studies from the melt, in both isothermal and dynamic regimes, showed a low crystallizability of PBPP, due to the high mobility and steric hindrance of lateral substituents, with a heat of fusion no higher than 9 J g −1. Activation energies of about 70 kJ mol −1 were calculated both for the crystallization process and for the rubber-glass transition in the amorphous state. The highest crystallization rate in isothermal experiments occurred at a temperature of 45°C. Thermodegradation of PBPP in air was found to start with the probable formation of the hydroperoxide group on the methylene site at about 233°C, as demonstrated from both thermogravimetric and d.s.c. analyses. PBPP film behaved as an elastomeric polymer with a strain at break higher than 350%. A tensile modulus of 1.2 MPa and a stress at break of 4.8 MPa for the amorphous polymer were measured, whereas crystalline polymers exhibited higher tensile modulus and stress at break, ranging from 34 to 48 MPa and from 7 to 12 MPa, respectively.

Polymerization and properties of poly(3-chlorodiphenylamine): a soluble electrochromic conducting polymer

Poly(3-chlorodiphenylamine) was prepared by electrochemical and chemical polymerization in acetonitrile solutions. The as-synthesized polymers are soluble in organic solvents and concentrated acid and exhibited a room temperature electrical conductivity of 1.6 × 10 −3 S cm −1. Electropolymerized and solution cast films are electroactive and displayed reversible colour changes when cycled in organic or acid electrolytes between 0.0 V and 1.3 V versus Ag AgCl .

Synthesis and Characterization of New Electroactive Polymers

ABSTRACTA general scheme for the preparation of soluble electroactive polymers is reviewed with emphasis that polymers so prepared permit investigation of the effects of π-electron delocalization and lattice charge upon nonlinear optical activity. Particular attention is focused upon six membered ring polymer derivatized in 1,4 positions with vinylamine substituents. Such substituents influence rates of polymerization reactions and electronic properties as well as solubility. Preliminary measurement of χ(3) for as-synthesized polymers is effected by DFWM.