Microtubules of polyaniline doped with HCl and HBF4

Microtubules of polyaniline (PANI) doped with HCl, HBF₄, and β-naphthalene sulfonic acid (NSA) were synthesized by an improved in situ doping polymerization method. Ultraviolet-visible spectra, scanning electron microscopy, ESR, and X-ray diffraction characterized the molecular structure of the resulting PANI microtubules. These microtubules had a diameter of 1 ∼ 10 μm and a conductivity at room temperature of 0.2 ∼ 3.5 S/cm, depending on the molecular structure and concentration of the dopant. The degree of crystallinity of the PANI microtubules was enhanced by increasing the molecular size of the dopant; that is, the order PANI-NSA > PANI-HBF₄ > PANI-HCl was observed in the crystallinity of the microtubules. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4605–4609, 1999     

Polyaniline doped with different sulfonic acids by in situ doping polymerization

Doped polyaniline (PANI) was synthesized by an “in situ doping polymerization” method in the presence of different sulfonic acids, such as methanesulfonic acid (MSA), p‐methylbenzene sulfonic acid (MBSA), β‐naphthalenesulfonic acid (β‐NSA), α‐naphthalenesulfonic acid (α‐NSA), 1,5‐naphthalenedisulfonic acid (1,5‐NSA), and 2,4‐dinitronaphol‐7‐sulfonate acid (NONSA). Morphology, solubility in m‐cresol, and electrical properties of the doped PANI were measured with the variation of the molecular structure of the selected sulfonic acids. Granular morphology was obtained when the sulfonic acids without a naphthalene ring, such as MSA and MBSA, were used. Regular tubular morphology was obtained only when β‐NSA was used. The tubular morphology can be modified by changing the substitutes, the number, and location of sulfo‐group(SOH) on the naphthalene ring. These results indicated that naphthalene ring in the selected sulfonic acids plays an important role in forming the tubular morphology of the doped PANI by the “in situ doping polymerization” method. All resulting PANI salts were soluble in m‐cresol, with the solubility depending on the molecular structure of the selected dopants. Room‐temperature conductivity for the doped PANI ranges from 10⁻¹ to 10⁰S/cm. Temperature dependence of conductivity shows a semiconductor behavior, and it can be expressed by one dimenson Variable Range Hopping (VRH) model. 1 © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1277–1284, 1999     

Tubular polypyrrole synthesized by in situ doping polymerization in the presence of organic function acids as dopants

Tubular polypyrrole (PPy) could be synthesized by in situ doping polymerization in the presence of β‐naphthalene sulfonic acid (NSA) as dopant. The resultant tubular PPy–NSA not only exhibits high room temperature conductivity (ς_RT = 10 S/cm) but is also soluble in m‐cresol. The molecular structure of PPy–NSA is identical to the characteristic structure of PPy synthesized by a conventional method. It has been demonstrated that NSA dopant with large molecular size and plate–lebe structure is a key factor to control formation of tubular PPy–NSA. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1443–1449, 1999     

Universal xanthate‐mediated controlled free radical polymerizations of the “less activated” vinyl monomers

The living free radical polymerizations of three “less activated” monomers (LAMs), vinyl acetate, N‐vinylcarbazole, and N‐vinylpyrrolidone, were successfully achieved in the presence of a disulfide, isopropylxanthic disulfide (DIP), using 2,2′‐azoisobutyronitrile (AIBN) as the initiator. The living behaviors of polymerizations of LAMs are evidenced by first‐order kinetic plots and linear increase of molecular weights (M_ns) of the polymers with monomer conversions, while keeping the relatively low molecular weight distributions, respectively. The effects of reaction temperatures and molar ratios of components on the polymerization were also investigated in detail. The polymerization proceeded with macromolecular design via interchange of xanthate process, where xanthate formed in situ from reaction of AIBN and DIP. The architectures of the polymers obtained were characterized by GPC, ¹H NMR, UV–vis, and MALDI‐TOF‐MS spectra, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

“Living” radical polymerization of methyl methacrylate with diethyl 2,3-dicyano-2,3-diphenylsuccinate as a thermal iniferter

The bulk polymerization of methyl methacrylate (MMA) initiated with diethyl 2,3-dicyano-2,3-diphenylsuccinate (DCDPS) was studied. This polymerization showed some “living” characteristics; that is, both the yield and the molecular weight of the resulting polymers increased with reaction time, and the resultant polymer can be extended by adding MMA. The molecular weight distribution of PMMA obtained at high conversion is fairly narrow (M_w/M_n = 1.24≈1.34). It was confirmed that DCDPS can serve as a thermal iniferter for MMA polymerization by a “living” radical mechanism. Furthermore, the PMMA obtained can act as a macroinitiator for radical polymerization of styrene (St) to give a block copolymer. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4610–4615, 1999     

Poly(ε‐caprolactone) by combined ring‐opening polymerization and azeotropic polycondensation—the role of cyclization and equilibration

Using three different catalysts, water‐initiated polymerizations of ε‐caprolactone were conducted in bulk with variation of the monomer/water ratio. The resulting CH₂OH and CO₂H‐ terminated polylactones were subjected in situ to azeotropic polycondensations. With Bi‐triflate and temperatures, the polycondensations were not much successful and involved side reactions. With ZnCl₂, and especially SnCl₂, considerably higher molar masses were achieved. The substitution of toluene for chlorobenzene for refluxing gave better results. The polycondensations broadened the molar mass distribution of the ROP‐based prepolymers, and polydispersities between 1.4–1.8 were obtained. The MALDI–TOF mass spectra revealed that the polycondensations significantly enhanced the fraction of rings due to efficient “end‐biting” reactions. By comparison with copolymerization experiments and Sn methoxide‐initiated polymerizations, it was demonstrated that equilibration reactions, such as the formation of rings by “back‐biting,” did not occur. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Filler effect on properties of “All‐Acrylic” copolymer/clay elastomeric materials synthesized by “in situ” nitroxide mediated polymerization

In this work, we describe the “in situ” synthesis of “all‐acrylic” copolymer (n‐butyl acrylate‐co‐methyl methacrylate)/clay materials at different low contents of raw and modified Montmorillonite (1–4 wt % versus monomer). The cationic 2,2′ azobis‐(amidinopropane)dihydrochloride initiator was used to modified the clay by cation exchange in combination with the N‐tert‐butyl‐N‐[1‐diethylphosphono‐(2,2‐dimethylpropyl)] (SG1) nitroxide to synthesize the polymer/clay nanocomposite via nitroxide mediated controlled radical polymerization. All synthesized materials are characterized by proton nuclear magnetic resonance, size exclusion chromatography, thermogravimetric analysis and differential scanning calorimetry techniques. The thermo‐mechanical properties of the synthesized materials are also reported. The results show that a decrease in molar masses and/or slight changes in molar compositions of poly (n‐butyl acrylate‐ co‐methyl methacrylate)/clay systems can be balanced by clay loading in polymer matrix, and consequently compensated or masked clay effects on physical properties of obtained materials. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Formation mechanism of polyaniline microtubules synthesized by a template‐free method

A template‐like model, which was an aniline salt formed with β‐naphthalene sulfornic acid (β‐NSA) as a dopant, was proposed to interpret the formation mechanism of polyaniline (PANI) microtubules doped with β‐NSA by a template‐free method. Scanning electron microscope (SEM) and X‐ray diffraction measurements confirmed this model. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2359–2364, 2000     

Graphene oxide‐induced polymerization and crystallization to produce highly conductive polyaniline/graphene oxide composite

Graphene oxide (GO)–polyaniline (PANI) composite is synthesized by in situ polymerization of aniline in the presence of GO as oxidant, resulting in highly crystalline and conductive composite. Fourier transform infrared spectrum confirms aniline polymerization in the presence of GO without using conventional oxidants. Scanning electron microscopic images show the formation of PANI nanofibers attached to GO sheets. X‐ray diffraction (XRD) patterns indicate the presence of highly crystalline PANI. The sharp peaks in XRD pattern suggest GO sheets not only play an important role in the polymerization of aniline but also in inducing highly crystalline phase of PANI in the final composite. Electrical conductivity of doped GO–PANI composite is 582.73 S m^?1, compared with 20.3 S m^?1 for GO–PANI obtained by ammonium persulfate assisted polymerization. The higher conductivity appears to be the result of higher crystallinity and/or chemical grafting of PANI to GO, which creates common conjugated paths between GO and PANI. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1545–1554     

Synthesis,characterization, and morphology of p‐toluene sulfonic acid‐doped polyaniline: A material for humidity sensing application

Polyaniline (PANI) doped with p‐toluene sulfonic acid was synthesized by chemical polymerization method using (NH₄)₂S₂O₈ as an oxidizing agent. This is a single step polymerization process for the direct synthesis of the conducting emeraldine salt (ES) phase, without the need of doping, dedoping, and redoping of the polymer. Presence of a free carrier tail at higher wavelength, characteristic of extended coil conformation along with a sharp polaronic peak is observed in the UV–vis spectrum of doped PANI in m‐cresol solvent. FT‐IR studies show the characteristic peaks of ES phase along with a sharp peak at 1120 cm^?1 representing vibration band of the dopant ion. Clumps of small fibers resulting in a sponge‐like structure was observed under scanning electron microscope. Thermal studies revealed a three‐step decomposition pattern. Conductivity is found to increase with an increase in the temperature showing “thermal activation behavior.” Decrease in resistance with increasing humidity is observed in a broad range of humidity. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2161–2169, 2005     

Iron(III)‐mediated AGET ATRP of styrene using tris(3,6‐dioxaheptyl)amine as a ligand

A commercially available tris(3,6‐dioxaheptyl)amine (TDA‐1) was used as a novel ligand for activator generated by electron transfer atom transfer radical polymerization (AGET ATRP) of styrene in bulk or solution mediated by iron(III) catalyst in the presence of a limited amount of air. FeCl₃ · 6H₂O and (1‐bromoethyl)benzene (PEBr) were used as the catalyst and initiator, respectively; and environmentally benign ascorbic acid (VC) was used as the reducing agent. The polymerizations show the features of “living”/controlled free‐radical polymerizations and well‐defined polystyrenes with molecular weight M_n = 2400–36,500 g/mol and narrow polydispersity (M_w/M_n = 1.11–1.29) were obtained. The “living” feature of the obtained polymer was further confirmed by a chain‐extension experiment. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2002–2008, 2009     

Studies on formation mechanism of polypyrrole microtubule synthesized by template‐free method

The influence of the polymerization time and rate as well as the solution's ionic strength on the morphology, conductivity, and molecular structure of the polypyrrole (PPy) microtubule [synthesized by the template‐free method in the presence of β‐naphthalene sulfonic acid (β‐NSA) as the dopant] were investigated. It was found that the formation of the PPy‐NSA microtubule was a slow and self‐assembled growth process. Moreover, the β‐NSA dopant played a “templatelike” role in the formation of tubular PPy‐NSA, which might be relative to its surfactant characters. This assumption was further confirmed by the phenomenon that the morphology of PPy‐NSA could be modified by increasing the ionic strength by adding inorganic salt. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 997–1004, 2001     

Synthesis of random polyampholyte brushes by atom transfer radical polymerization

We report the synthesis of random polyampholyte brushes containing 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and methacrylic acid (MAA). The preparation of polyampholyte brushes is performed by the “grafting from” strategy using surface‐initiated atom transfer radical polymerization (ATRP). The first step consists in the formation of the self‐assembled monolayer of the ATRP initiator. Secondly, the chains are grown from the surface by controlled/“living” radical polymerization. The random copolymer brushes and the corresponding homopolymers brushes containing 2‐(dimethylamino)ethyl methacrylate and tert‐butyl methacrylate (^tBuMA) are prepared. The last step is the deprotection of the ^tBuMA form to the MAA segment by in situ hydrolysis reaction. The annealed DMAEMA group can also be converted to the quenched form by in situ quaternization reaction. This results in the formation of “annealed” and “semiannealed” polyampholyte brushes. The “annealed” polyampholyte corresponds to the random copolymer that contains only annealed units, weak acid and weak base. The “semiannealed” polyampholyte consists of the mixture of annealed (weak acid) and quenched (quaternized segment) units. Polyampholyte brushes with various grafting densities are synthesized and carefully characterized using surface techniques such as ellipsometry and FTIR‐ATR. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4305–4319, 2008     

Precision synthesis of regioregular poly(3‐hexylthiophene) with low dispersity using a zincate complex catalyzed by nickel with the ligand of 1,2‐bis(dicyclohexylphosphino)ethane

Regioregular poly(3‐hexylthiophene) (P3HT) has been a commonly used p‐type semiconducting material for solution processable organic electronics. To establish a living system of “Negishi‐type catalyst‐transfer polycondensation (NCTP)” using zincate complex as a synthetic method for well‐defined P3HT having predictable molecular weight (MW) and low dispersity (?), the ligands of Ni catalyst were optimized. As a result, a ligand of 1,2‐bis(dicyclohexylphosphino)ethane produced P3HTs with highly controlled number average MWs (1650–32,800) and very low ? values (1.03–1.17). The polymerization results were strongly influenced by steric hindrance based on the factors of cone angle and bite angle of Ni catalysts, and/or electron‐donating ability of phosphine ligands. In addition, we succeeded in the two‐stage polymerization of P3HT and the synthesis of P3HT‐b‐poly(3‐octadecylthiophene), the latter of which is the first demonstration by NCTP using zincate complex. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2287–2296     

Synthesis of graft copolymers with “V‐shaped” and “Y‐shaped” side chains via controlled radical and anionic polymerizations

A combination of nitroxide‐mediated radical polymerization and living anionic polymerization was used to synthesize a series of well‐defined graft (co)polymers with “V‐shaped” and “Y‐shaped” branches. The polymer main chain is a copolymer of styrene and p‐chloromethylstyrene (PS‐co‐PCMS) prepared via nitroxide‐mediated radical polymerization. The V‐shaped branches were prepared through coupling reaction of polystyrene macromonomer, carrying 1,1‐diphenylethylene terminus, with polystyryllithium or polyisoprenyllithium. The Y‐shaped branches were prepared throughfurther polymerization initiated by the V‐shaped anions. The obtained branches, carrying a living anion at the middle (V‐shaped) or at the end of the third segment (Y‐shaped), were coupled in situ with pendent benzyl chloride of PS‐co‐PCMS to form the target graft (co)polymers. The purified graft (co)polymers were analyzed by size exclusion chromatography equipped with a multiangle light scattering detector and a viscometer. The result shows that the viscosities and radii of gyration of the branched polymers are remarkably smaller than those of linear polystyrene. In addition, V‐shaped product adopts a more compact conformation in dilute solution than the Y‐shaped analogy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4013–4025, 2007     

R‐RAFT approach for the polymerization of N‐isopropylacrylamide with a star poly(ε‐caprolactone) core

Reversible addition‐fragmentation chain transfer (RAFT) polymerization is a more robust and versatile approach than other living free radical polymerization methods, providing a reactive thiocarbonylthio end group. A series of well‐defined star diblock [poly(ε‐caprolactone)‐b‐poly(N‐isopropylacrylamide)]₄ (SPCLNIP) copolymers were synthesized by R‐RAFT polymerization of N‐isopropylacrylamide (NIPAAm) using [PCL‐DDAT]₄ (SPCL‐DDAT) as a star macro‐RAFT agent (DDAT: S‐1‐dodecyl‐S′‐(α, α′‐dimethyl‐α″‐acetic acid) trithiocarbonate). The R‐RAFT polymerization showed a controlled/“living” character, proceeding with pseudo‐first‐order kinetics. All these star polymers with different molecular weights exhibited narrow molecular weight distributions of less than 1.2. The effect of polymerization temperature and molecular weight of the star macro‐RAFT agent on the polymerization kinetics of NIPAAm monomers was also addressed. Hardly any radical–radical coupling by‐products were detected, while linear side products were kept to a minimum by careful control over polymerization conditions. The trithiocarbonate groups were transferred to polymer chain ends by R‐RAFT polymerization, providing potential possibility of further modification by thiocarbonylthio chemistry. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Strong activation of MgCl2‐supported Ziegler‐Natta catalysts by treatments with BCl3: Evidence and application of the “cluster” model of active sites

Heterogeneous Ziegler‐Natta precatalysts (with phthalate as internal donor) were modified by treatments with BCl₃ (2 h in heptane; T = 20–90 °C; B/Ti = 0.1–5) before their use in the polymerization of propylene to modify the active sites distribution. If performed on previously “detitanated” precatalysts, the treatment leads to a strong increase of productivity (up to one order of magnitude) without drastic modifications of polypropylenes properties (tacticity, molecular weight distribution). In addition, these findings are in good agreement with the hypothesis of a “cluster” organization of active sites allowing to rationalize activation by BCl₃ by formation of heteronuclear B‐Ti clusters. The activation method was also applied to unmodified precatalysts and gave a significant gain of productivity. The simple and versatile activation process can also be performed under mild conditions (low T and low [BCl₃]). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5784–5791, 2009     

Synthesis of dendritic carbohydrate end‐functional polymers via RAFT: Versatile multi‐functional precursors for bioconjugations

Well‐defined pyridyl disulfide (PDS) end‐functionalized polymer‐dendritic carbohydrate scaffolds are reported as novel precursors for the attachment of biomolecules. This synthetic approach combines reversible addition fragmentation chain transfer (RAFT) polymerization and “click” reactions. Poly(N‐(2‐hydroxypropyl) methacrylamide) (PHPMA) with 2‐mercaptothiozalidine end‐groups was prepared by RAFT polymerization yielding molecular weights of M_n = 4300 and 9900, both with a polydispersity of less than 1.2. These polymers were then attached to dendritic mannose scaffolds preconstructed via consecutive “click” reactions. Finally, the ω‐dithiobenzoate RAFT end‐group of PHPMA was modified to yield PDS functionality, by aminolysis in the presence of 2,2′‐dithiodipyridine. This PDS end‐functionalized PHPMA‐dendritic carbohydrate scaffold is a versatile precursor for bioconjugations, as the synthetic procedure can easily accommodate a range of sugar functionalities. In addition, the PDS groups can be used to react with any thiol present in a biomolecule (e.g., cysteine residue in proteins, or ? SH terminal nucleotides). To demonstrate the utility of these scaffolds we describe their bioconjugation to short interfering RNA. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4302–4313, 2009     

Photo‐initiated thiol–ene “click” hydrogels from RAFT‐synthesized poly(N‐isopropylacrylamide)

Despite the efficiency and robustness of the widely used copper‐catalyzed 1,3‐dipolar cycloaddition reaction, the use of copper as a catalyst is often not attractive, particularly for materials intended for biological systems. The use of photo‐initiated thiol‐ene as an alternative “click” reaction to synthesize “model networks” is investigated here. Poly(N‐isopropylacrylamide) precursors were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization and were designed to have trithiocarbonate moieties as end groups. This structure design provides opportunity for subsequent end‐group modifications in preparation for thiol‐ene “click.” Two reaction routes have been proposed and studied to yield thiol and ene moieties. The advantages and disadvantages of each reaction path were investigated to propose a simple but efficient route to prepare copper‐free “click” hydrogels. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4626–4636     

Efficient synthesis of monodisperse,highly crosslinked,and “living” functional polymer microspheres by the ambient temperature iniferter‐induced “living” radical precipitation polymerization

The facile and efficient one‐pot synthesis of monodisperse, highly crosslinked, and “living” functional copolymer microspheres by the ambient temperature iniferter‐induced “living” radical precipitation polymerization (ILRPP) is described for the first time. The simple introduction of iniferter‐induced “living” radical polymerization (ILRP) mechanism into precipitation polymerization system, together with the use of ethanol solvent, allows the direct generation of such uniform functional copolymer microspheres. The polymerization parameters (including monomer loading, iniferter concentration, molar ratio of crosslinker to monovinyl comonomer, and polymerization time and scale) showed much influence on the morphologies of the resulting copolymer microspheres, thus permitting the convenient tailoring of the particle sizes by easily tuning the reaction conditions. In particular, monodisperse poly(4‐vinylpyridine‐co‐ethylene glycol dimethacrylate) microspheres were prepared by the ambient temperature ILRPP even at a high monomer loading of 18 vol %. The general applicability of the ambient temperature ILRPP was confirmed by the preparation of uniform copolymer microspheres with incorporated glycidyl methacrylate. Moreover, the “livingness” of the resulting polymer microspheres was verified by their direct grafting of hydrophilic polymer brushes via surface‐initiated ILRP. Furthermore, a “grafting from” particle growth mechanism was proposed for ILRPP, which is considerably different from the “grafting to” particle growth mechanism in the traditional precipitation polymerization. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013