Donor-Acceptor Complexes in Copolymerization. XXVI. Effect of Solvent,Temperature, and Complexing Agent on the Polymerization of Comonomer Charge Transfer Complexes

The copolymerization of styrene with methyl methacrylate (S/MMA = 4/1) or acrylonitrile (S/AN = 1/1) in the presence of ethylaluminum sesquichloride (EASC) yields 1/1 copolymer in toluene or chlorobenzene. In chloroform the S-MMA-EASC polymerization yields 60/40 copolymer while the S-AN-EASC polymerization yields 1/1 copolymer. In the presence of EASC, styrene-α-chloroacrylonitrile yields 1/1 copolymer (DMF or DMSO), S-AN yields 1/1 copolymer (DMSO) or radical copolymer (DMF), S-MMA yields radical copolymer (DMF or DMSO), α-methylstyrene-AN yields radical copolymer (DMSO) or traces of copolymer (DMF), and α-MS-methacrylo-nitrile yields traces of copolymer (DMSO) or no copolymer (DMF). When zinc chloride is used as complexing agent in DMF or DMSO, none of the monomer pairs undergoes polymerization. However, radical catalyzed polymerization of isoprene-AN-ZnCl₂ in DMF yields 1/1 alternating copolymer. The copolymerization of S/MMA in the presence of EASC yields 1/1 alternating copolymer up to 100°C, while the copolymerization of S/AN deviates from 1/1 alternating copolymer above 50°C. The copolymerization of S/MMA deviates from 1/1 copolymer at MMA/EASC mole ratios above 20 while the copolymerization of S/AN deviates from 1/1 copolymer at MMA/EASC ratios above 50.     

Propylene sorption and coordinative interactions for poly(N‐vinyl pyrrolidone‐co‐vinyl acetate)/silver salt complex membranes

When poly(N‐vinyl pyrrolidone‐co‐vinyl acetate) (PVP‐co‐PVAc) containing amide and ester groups were complexed with silver salts to form silver polymer electrolyte membranes, their separation performance of propylene/propane mixtures showed the high selectivity of propylene over propane of 55 and the high mixed gas permeance of 12 GPU (1 GPU = 1.0 × 10^?6 cm³(STP) cm^?2 s^?1 cmHg^?1). The separation performance strongly depends on the composition of the copolymer: the higher concentration of PVP in the copolymer, the better separation performance was achieved. These results suggest that the amide group is more effective in facilitated propylene transport than the ester group, primarily due to the stronger interaction of the silver ions with the amide than the ester oxygens, as demonstrated by FT‐IR and FT‐Raman spectroscopies. In‐situ FT‐IR spectra upon propylene sorption also demonstrate that the interaction strength of the silver ions with the ligands is arranged: amide > C?C > ester. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2263–2269, 2007     

Hyperbranched copolymer containing triphenylamine and divinyl bipyridyl units for fluorescent chemosensors

A fluorescent hyperbranched copolymer (HTP) and a linear copolymer (PTP) as a reference sample to HTP both containing triphenylamine and divinyl bipyridyl units were synthesized via Heck coupling reaction from 5,5′‐Divinyl‐2,2′‐bipyridyl with tris(4‐bromophenyl)amine and with 4,4′‐dibromotriphenylamie, respectively. The chemical structure of HTP was confirmed by FTIR, ¹H NMR, and ¹³C NMR. The polymer HTP had a number‐average molecular weight of 1895 and a weight‐average molecular weight of 2315, and good solubility in conventional organic solvents, such as THF, DMF, and chloroform, and exhibited good thermal stability. The UV–vis absorption and photoluminescence (PL) spectra exhibited absorption maximum at 428 nm and emissive maximum at 531 nm for the HTP solution. The spectroscopic results of HTP and PTP indicated that hyperbranched conjugated structure increases the effective conjugation length, as compared with corresponding linear conjugated structure. The fluorescence of the polymer in solution can be quenched by various transition metal ions. The effect of backbone structure of the conjugated polymer‐based chemosensors on the sensitivity and selectivity in metal ions sensing have been investigated, and the quenching effect of HTP is more sensitive toward transition metal than linear copolymer PTP. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 222–230, 2009     

Scope of network polysilanes in the synthesis of fluorescent silver and gold nanoparticles/nanoclusters‐modulations of their optical properties in the presence of Hg(II) ions

The network polysilanes (polysilynes) [RMe₂SiCH₂CH₂Si]_n, [R=Ph ( 1 ), 2‐Furyl ( 2 )] have been synthesized by room temperature reaction of the corresponding organotrichlorosilane with Na dispersion in tetrahydrofuran (THF) medium. The method allows the formation of high molecular weight polymers [M_w/PDI = 10,504/2.2 ( 1 ), 9176/1.5 ( 2 )] in improved yields than those obtained from classical Wurtz coupling reaction (Na, toluene, 110 °C). These polymers act as reducing agents for Ag(I) and Au(III) ions to afford stable metal nanoparticles of 4–8 nm size domains in toluene medium. The corresponding polymer–silver nanocomposites, 1a and 2a , are fluorescent in the green light region (λ_max = ～ 530 nm) due to the formation of silver nanoclusters (AgNCs) along with the nanoparticles (AgNPs). A simple chemical approach has been developed to modulate the plasmonic and emission intensities of the nanocomposite 1a by reacting with varying concentrations (10^?12 to 10^?7M) of HgI₂ in toluene. The method allows enhancement of the fluorescence intensity associated with AgNCs. The results are explained by invoking coupling between the energies of surface plasmon resonance and the nanocluster electronic transition. The polymer–gold nanocomposites, 1b and 2b , are non‐fluorescent and the plasmonic resonance at 530 nm associated with AuNPs is found to be insensitive to Hg(II) ions. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Preparation and properties of conductive silver/photosensitive polyimide nanocomposites

A new electrically conductive photoresist has been developed. It is based on the dispersion of silver nanoflakes in a negative‐tone photosensitive polyimide (PSPI) precursor. 2‐Mercaptopropionic acid was used as the surfactant to modify the silver nanoflake surface for the dispersion of silver nanoflakes in the polymer. The silver/PSPI nanocomposites showed electrical conductivity at a low silver content of 10 wt %. The electrical conductivity of the silver/PSPI nanocomposites ranged from 10 to 10⁴ S/cm, which was dependent on the silver weight fraction in the resist formulation. Patterns with a resolution of 30 μm were obtained from the silver/PSPI nanocomposites. The silver/PSPI nanocomposites had excellent thermal properties. Their glass transition temperatures were above 360 °C and thermal decomposition temperatures were over 420 °C. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1575–1583, 2009     

Synthesis and optical properties of poly(N-isopropylacrylamide) nanogel containing silver nanoparticles

Composite nanoparticles representing silver nanoparticle-containing polymer gels have been synthesized. The synthesis comprises two main stages. Initially, monodisperse hydrogel particles with a controlled diameter of approximately 500 nm are obtained by N-isopropylacrylamide polymerization. Then, silver ions are reduced on the surface of the polymer network. Variations in the concentration ratio between reductants and silver nitrate make it possible to produce silver nanoparticles with sizes in a range of 10–30 nm and different packing densities on the gel particle surface. The resultant nanocomposites have been studied by transmission electron microscopy, spectrophotometry, and dynamic light scattering. Depending on the size and packing density of the silver nanoparticles on the polymer particle surface, the plasmon resonance of the nanocomposites varies in a range of 420–750 nm, which determines variations in the color of the colloid from yellow, orange, and red to blue and blue-green. After the inclusion of silver nanoparticles, nanogels of poly(N-isopropylacrylamide) retain their capability for thermosensitive phase transition with a lower critical mixing temperature of 31°C.     

Synthesis of poly(o‐phenylenediamine) nanofiber with novel structure and properties

The poly(o‐phenylenediamine) (PoPD) was synthesized from the monomer o‐phenylenediamine in various organic solvent medium viz. dimethyl sulfoxide (DMSO), N,N‐dimethyl formamide (DMF) and methanol using ammonium per sulfate as a radical initiator. The structure just like polyaniline derivative with free ?NH functional groups of the synthesized polymers confirmed by various standard characterizations was explained from the proposed polymerization mechanism. All the synthesized polymers were completely soluble in common organic solvent like DMSO and DMF because of the presence of polar free ?NH functional groups in its structure. The formation of polymer nanofiber by reverse salting‐out process was confirmed, and the synthesized polymer in DMSO medium was the best polymer in terms of nano‐morphology as well as conducting properties. Interestingly, the average DC conductivity of undoped polymer film was recorded as 2.21 × 10^?6 Scm^?1 because of induced doping through self charge separation. Moreover, the conductivity of the polymer film was further increased to 1.16 × 10^?3 Scm^?1 after doping by sulfuric acid. Copyright © 2016 John Wiley & Sons, Ltd.     

Kinetics and reactivity of substituted anilines with 2‐chloro‐5‐nitropyridine in dimethyl sulfoxide and dimethyl formamide

The kinetics of the reaction of substituted anilines with 2‐chloro‐5‐nitropyridine were studied in dimethyl sulfonide (DMSO) and dimethyl formamide (DMF) at different amine concentrations and temperatures in the range 45–60°C. In both solvents the reaction was not a base‐catalyzed one. A plot of ΔH^# versus ΔS^# for the reaction in DMSO and DMF gave good straight lines with isokinetic temperatures 128°C and 105°C, respectively. Good linear relationships were obtained from the plots of log k₁ against σ° values at all temperatures with negative ρ values (?1.63 to ?1.28 in DMSO) and (?1.26 to ?0.90 in DMF). © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 645–650, 2002     

Preparation and Free-Radical Polymerizations of Methyl-4-vinylphenylsulfoxide and Methyl-4-vinylbenzylsulfoxide

Methyl-4-vinylphenylsulfoxide (1) was prepared by the selective oxidation of 4-methylthiostyrene with sodium metaperiodate in 87% yield. This monomer was readily homopolymerized in DMSO by AIBN at 60°C. The polymer obtained is soluble in ethanol, chloroform, DMSO, and DMF, but insoluble in water, benzene, and petroleum ether. The inherent viscosity of this polymer was 0.33 dL/g in DMSO. This sulfoxide monomer (1) was copolymerized with styrene, methyl methacrylate, acrylo-nitrile, and acrylamide under radical conditions. From the copolymerization with styrene, copolymerization parameters were obtained as follows; r¹ = 0.56, r_St, = 0.26, and Q¹ = 1.19, e¹ = 0.58. Similarly, methyl-4-vinylbenzylsulfoxide (2) was prepared, and the polymerizability of (2) was also investigated.     

Preparation and characterization of polyacrylamide–silver nanocomposites

Polyacrylamide–silver nanocomposites are successfully prepared by irradiating the aqueous solution of AgNO₃ and acrylamide monomer with ⁶⁰Co γ-ray. The composites are found to contain nanometer silver particles with a narrow size distribution and a homogeneous dispersion. The existing of isopropanol (as a hydroxyl radical scavenger and chain transfer agent) in system affects the properties of both the dispersed phase and matrix of the nanocomposites. The fast-formed polymer chains probably play a key role in preventing the aggregation of silver particles which are reduced later.     

Nanostructure,interactions, and conductivities of polymer electrolytes comprising silver salt and microphase‐separated graft copolymer

Silver polymer electrolytes were prepared by blending silver salt with poly(oxyethylene)₉ methacrylate)‐graft‐poly(dimethyl siloxane), POEM‐g‐PDMS, confining silver salts within the continuous ion‐conducting POEM domains of microphase‐separated graft copolymer. AgClO₄ polymer electrolytes exhibited their maximum conductivity at high silver concentrations as well as higher ionic conductivities than AgCF₃SO₃ electrolytes. The difference in conductivities of the two electrolytes was investigated in terms of the differences in the interactions of silver ions with ether oxygen of POEM and, hence, with the anions of salts. Upon the addition of salt in graft copolymer, the increase of T_g in AgClO₄ was higher than that in AgCF₃SO₃ electrolytes. Analysis of an extended configuration entropy model revealed that the interaction of ether oxygen/AgClO₄ was stronger than that of ether oxygen/AgCF₃SO₃ whereas the interaction of Ag⁺/ClO₄^? was weaker than that of Ag⁺/CF₃SO₃^?. These interactions are supported by the anion vibration mode of FT‐Raman spectroscopy. It is thus concluded that the higher ionic conductivity of AgClO₄ electrolytes was mostly because of higher concentrations of free ions, resulting from their strong ether oxygen/silver ion and weak silver ion/anion interactions. A small angle X‐ray scattering study also showed that the connectivity of the POEM phase was well developed to form nanophase morphology and the domain periodicities of graft copolymer electrolytes monotonically increased with the increase of silver concentration up to critical concentrations, after which the connectivity was less developed and the domain spacings remained invariant. This is attributed to the fact that silver salts are spatially and selectively incorporated in conducting POEM domains as free ions up to critical concentrations, after which they are distributed in both domains as ion pairs without selectivity. The increase of domain d‐spacing in AgClO₄ electrolytes was larger than that in AgCF₃SO₃, which again results from high concentrations of free ions in the former. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1018–1025, 2007     

Polymerization of β‐cyclodextrin in the presence of bentonite clay to produce polymer nanocomposites for removal of heavy metals from drinking water

New hybrid organic–inorganic nanocomposites consist of β‐cyclodextrin (β‐CD)/epichlorohydrin (ECH), and bentonite clay were prepared by direct intercalation through one step emulsion polymerization. The structure and thermal stability of prepared nanocomposites were investigated by Fourier‐transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), field emission‐scanning electron microscopy (FE‐SEM), energy dispersive X‐ray analysis (EDAX), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), differential of differential scanning calorimetry (DDSC), thermogravimetric analysis (TGA) and differential thermogravimetric (DTG) analyses. The observed results show that the β‐CD polymer/clay nanocomposites (β‐CD–ECH polymer/clay) with higher thermal stability than β‐CD–ECH polymer were successfully prepared. The removal of heavy metals such as Cu(II), Zn(II) and Co(II) ions from drinking water was studied using a batch method at ambient temperature. The removal percentage and distribution coefficients (Kd) were determined for the adsorption system. It was found that the β‐CD–ECH polymer/clay nanocomposites showed higher removal capacity for Co²⁺, Cu²⁺ and Zn²⁺ ions in comparison with β‐CD–ECH polymer. The selectivity order could be given as Zn²⁺ > Cu²⁺ > Co²⁺. Copyright © 2016 John Wiley & Sons, Ltd.     

Influence of silver nanoparticles on the order parameter of liquid crystalline polymers

New polymer nematic nanocomposites are prepared containing 1.43–4.64 wt % of silver nanoparticles whose mean dimensions are 2–4 nm. According to ²H NMR spectroscopic measurements, on increasing the content of metallic nanoparticles, the orientational order parameter S_zz of the nematic phase shown by the nanocomposites increases.     

Synthesis and characterization of random hydrophilic/hydrophobic copolymers of styrene and D-lactose-O-vinylbenzylhydroxime

D -Lactose-O-(vinylbenzyl)oxime (LVO), prepared from α-D -lactose and [O-(vinylbenzyl)oxy]amine ( 1 ) was copolymerized with styrene (ST) in dimethylsulfoxide (DMSO)-toluene (1 : 1, v/v) at 65°C using 2,2′-azobisisobutyronitrile (AIBN) as a free radical initiator. The polymerization was rapid when using AIBN as the initiator. The resultant copolymers were characterized by elemental analyses, infrared, viscometry, TGA, DSC, and ¹H-NMR spectroscopy. The poly(ST-co-LVO) had an intrinsic viscosity in the range of 0.11–0.51 dL/g in DMSO at 30°C. The molecular weight was determined by gel permeation chromatography (GPC), and the molecular weight of the resulting polymers ranged from 2.11 × 10⁴ to 6.53 × 10⁷ with low polydispersities. The solubility of the copolymers with different monomer compositions in solvents of varied polarities was also studied. Incorporation of up to 65% (mol %) of lactose-based monomer onto polystyrene backbone led to a water-soluble polymer. Thermal behavior of the synthesized copolymers was evaluated by thermogravimetric analysis (TGA) and correlated very well with the polymer composition. Introduction of a pendant disaccharide compromised the thermal stability of the copolymer. The synthetic approach described in this report provides a route to prepare a novel disaccharide surfactant polymer with well-defined structures and hydrophilic/hydrophobic balances, by adjusting feed ratio of the lactose-based monomer ( 1 ) to styrene. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2971–2978, 1998     

Controlled synthesis of poly(acetone oxime acrylate) as a new reactive polymer: Stimuli-responsive reactive copolymers

Acetone oxime acrylate has been synthesized as a new active ester monomer. Free radical polymerization yielded a reactive polymer soluble in various organic solvents, such as chloroform, dioxane, DMSO, acetone, methanol, dichloromethane, DMF, and ethanol. Controlled radical polymerization of acetone oxime acrylate was successfully conducted using the RAFT, NMP and Iniferter method. Partly polymer analogous reaction with N-isopropylamine resulted in the reactive copolymer poly(N-isopropylacrylamide-co-acetone oxime acrylate), which featured a lower critical solution temperature (LCST) of 61 °C in water. Further, the reactivity of the copolymer was exemplary proven by complete reaction with ammonia yielding poly(N-isopropylacrylamide-co-acrylamide), which does not possess a LCST.     

Synthesis and Evaluation of Thiol Polymers

Thiol polymer, which is known as a reactive and functional polymer, is synthesized and evaluated quantitatively by the modified Ellman method. The synthesis was accomplished by 1) hydrolysis of an isothiouronium salt that is the adduct of 4‐chloromethylstyrene (CMS) homopolymer or CMS‐styrene (St) copolymer with thiourea; 2) hydrolysis of a precursor copolymer made from 4‐vinylbenzyl N‐ethyldithio‐carbamate (VBEC) and St or N‐vinyl‐2‐pyrrolidone (NVP); 3) solvolysis of an iminium salt polymer obtained from the reaction of CMS‐NVP copolymer with N,N‐dimethylthioformamide (TDMF). When a higher thiol content is desired, more severe hydrolysis conditions are required which however, also increase the loss of thiol. Hence, it is clear that the best synthesis of thiol polymers is Method 3. A quantitative yield of functional thiol polymer is obtained by this method, and the product is soluble in DMSO, DMF, and CHCI_3.     

Thermosensitive gels incorporating polythioether units for the selective extraction of class b metal ions

Novel temperature-responsive copolymers of N-isopropylacrylamide and monoaza-tetrathioether derivative, were synthesized for the selective extraction of soft metal ions such as silver(I), copper(I), gold(III) and palladium(II) ion. The ratio between N-isopropylacrylamide group and monoaza-tetrathioether group in the copolymer was determined. The ratio between N-isopropylacrylamide group and monoaza-tetrathioether group varied in the range of 66:1–187:1. Each lower critical solution temperature (LCST) of the polymer solution was determined spectrophotometrically by the relative absorbance change at 750 nm via temperature of the polymer solution. Metal ion extraction using the copolymer with appropriate counter anions such as picrate ion, nitrate or perchlorate ion was examined. Soft metal ions such as silver(I), copper(I), gold(III) and palladium(II) ion were extracted selectively into the solid polymer phase. The extraction efficiency of a metal ion such as silver ion increased as the increase of the ratio of the monoaza-tetrathioether group to N-isopropylacrylamide group in the polymer. The quantitative extraction of class b metal ions as well as the liquid–liquid extraction of metal ions with monoaza-tetrathioether molecule was performed.     

Synthesis and polymerization of long alkyl acetylenic compounds

A variety of long alkyl acetylenic compounds was synthesized and polymerized by using Rh(I) catalysts. Particularly, the monomer having a terminal hydroxyl group was converted into the high molecular weight of polymer in good conversion, which was soluble in THF, DMSO, and DMF. The high stereoregularity (cis) in the main chain was confirmed by ¹H‐NMR in DMSO‐d₆ and the rod‐like structure by wide‐angle X‐ray diffraction. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3419–3427, 2000     

A novel hyperbranched copolymer constituted of triphenylamine and divinyl bipyridyl units

A hyperbranched copolymer (HTP) containing triphenylamine and divinyl bipyridyl units has been synthesized via Heck coupling reaction from 5,5′-divinyl-2,2′-bipyridyl and tris(4-bromophenyl)amine. The polymer had a number-average molecular weight of 1895 and a weight-average molecular weight of 2315, and was readily soluble in common organic solvents, such as THF, DMF and chloroform. The chemical structure of HTP was confirmed by FT-IR, ¹H NMR. Its thermal, electrochemical and optical properties have been investigated. The thermal analysis revealed that the polymer had a good thermal stability with the onset decomposition temperature at ca. 267 °C. The Uv-vis absorption and photoluminescence (PL) spectra exhibited that the Stokes shift between the absorption and emission of HTP was relatively large: 103 for HTP solution and 135 nm for HTP film. The electrochemical analysis showed that the electrochemical band gap of HTP was 0.92 eV. The fluorescence of the polymer in solution can be quenched by various transition metal ions and HTP showed different sensitivity in transition metal ions sensing.     

Fabrication and photoluminescence properties of Ag0 and Ag0–Er3+ containing plasmonic glass nanocomposites in the K2O–ZnO–SiO2 system

Here, we report the preparation of nano silver (Ag) and nano Ag-erbium (Ag–Er) co-embedded potassium–zinc-silicate based monolithic glass nanocomposites by a controlled heat-treatment process of precursor glasses. The nanocomposites were characterized by differential scanning calorimeter, dilatometer, UV–Visible absorption spectrophotometer, X-ray diffractometer and transmission electron microscope and spectroflurimeter. A strong surface plasmon resonance (SPR) band is observed around 430 nm in all the heat-treated glass nanocomposite samples due to the formation of Ag⁰ nanoparticles (NP). The Ag-glass nanocomposite samples display nearly 2-fold enhanced photoluminescence (PL) at 470 nm upon excitation at 290 nm until the size of the NP increases to the value equals to the mean free path of conduction electrons inside the particles. On contrary to this, the photoluminescence spectra of Er³⁺ ions exhibit a gradual decrease of NIR emission at 1540 nm due to ⁴I_13/2 → ⁴I_15/2 transition under excitation at 523 nm in the heat-treated glass nanocomposites which happened due to excitation energy transfer of Er³⁺ ions to the Ag NP, acting as ‘plasmonics diluents’ for Er³⁺ ions. These nanocomposites have huge potential for various nanophotonic applications.