Synthesis and properties of conjugated copolymers having a tricarbonyl(arene)chromium and thiophene units in the main chain

Summary Palladium-catalyzed polymerization of η ⁶-(1,4-diethynylbenzene)tricarbonyl chromium (1) with 3-alkyl-2,5-dibromothiophene (2a-c) was carried out to give the corresponding alternating conjugated copolymers (5a-c) in good yields. The structures of the polymers were supported by ¹H NMR and IR spectra. The polymers obtained were soluble in common solvents such as THF, CH₂Cl₂, CHCl₃ and toluene. The molecular weights of the polymers were determined by GPC. Their thermal, optical and electrical properties were investigated in detail. Received: 18 March 2002 /Accepted: 1 April 2002     

Branched polysilanes from tetrafunctional monomers

Tetrafunctional silicon monomers have been incorporated into soluble branched polysilanes. Tetrakis(chlorodimethylsilyl)silane has been homopolymerized to form an irregular branched polymer which may contain some spiro and some bicyclic units. This polymer shows weak absorption at 300 nm, the region of the linear polysilane chains. It emits broadly in the region from 400 to 500 nm. The copolymers of tetrakis(chlorodimethylsilyl)silane with dichlorodimethylsilane are also soluble and in the presence of l ge amount of the tetrakis monomer emit in the region from 400 to 500 nm. By contrast, copolymers with phenyltrichlorosilane emit strongly at 450 to 650 nm, due to the phenylsilane hyperbranched structure. Small amounts of tetrachlorosilane can be incorporated into soluble polysilanes. Incorporation of =Si=units into polymers withn-hexyl substituents is very inefficient but leads to minor changes in emission spectra. Incorporation into polymers with phenyl substituents affects luminescence and increases molecular weights and broadens polydispersities. Reaction with dimethyldichlorosilane provides soluble low molecular weight oligomers and polymers. Polymers prepared with a small proportion of tetrachlorosilane show absorption and emission typical for linear polymers. Polymers synthesized with higher proportion of tetrachlorosilanes emit broadly at 400 to 500 nm, indicating the presence of Si clusters. The silicon clusters entrapped into soluble polymers are very easily oxidized as seen by the siloxane peaks in²⁹Si NMR spectra and they should be treated under complete exclusion of oxygen.     

Synthesis of A<Subscript>2</Subscript>B<Subscript>2</Subscript> miktoarm star copolymers from a new heterobifunctional initiator by combination of ROP and ATRP

Abstract  

A new heterobifunctional initiator, 2,3-bis(2-bromo-2-methylpropionyloxy) succinic acid, was synthesized and used in preparation of A₂B₂ miktoarm star copolymers, (polystyrene)₂(poly(ε-caprolactone))₂, by combination of atom transfer radical polymerization (ATRP) and Controlled ring-opening polymerization (ROP). The structures of products were confirmed by the ¹H NMR, ¹³C NMR, FT–IR, elemental analysis, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). GPC traces show that the obtained polymers have a relatively narrow molecular weight distribution. The compositions of resulting miktoarm star copolymers were very close to theoretical.     

Separation and characterization of the vinyl side chains from grafted polyacrylonitrile–cotton copolymers

A method of separation of polyvinyl side chains from grafted polyacrylonitrile–cotton copolymers was developed in order to study the effect of length of side chain on copolymer properties. The method consists of dispersion of the copolymer (1 g.) containing 20% polyacrylonitrile in 75% aq. ZnCl₂ (100 ml.), addition of 6N HCl (100 ml.), heating for 1 hr. at 100°C., and precipitation and purification of the resulting vinyl polymer. The effect of hydrolysis on the intrinsic viscosity, the nitrogen content, and the infrared absorption spectra of the polyacrylonitrile polymers was investigated. It was concluded that this method of separation of the grafted polymers permitted a comparison of samples grafted by various techniques. A series of grafted copolymers was hydrolyzed, and the molecular weights of the isolated products were determined by measurements of intrinsic viscosity. Copolymer samples prepared by a post-irradiation grafting technique had the longest polyacrylonitrile side chains (molecular weight, 1 × 10⁶). Samples grafted by a simultaneous irradiation technique varied in side-chain length, depending upon the monomer-solvent system used in the preparation of the copolymer (molecular weight, 3 × 10⁴?5 × 10⁵). Chemically initiated grafting to cotton resulted in a copolymer containing relatively short side chains (molecular weight, 9 × 10⁴).     

Macromonomers by activated polymerization of oxiranes. Synthesis and polymerization

Macromonomers were obtained by cationic polymerization of propylene oxide and epichlorohydrin proceeding by the activated monomer mechanism with hydroxyethyl acrylate as initiator. Up to DP _n ～ 15 for propylene oxide and DP _n ～ 20 for epichlorohydrin, polymerization proceeds as a living process, giving with quantitative yields macromonomers with functionality equal to one, controlled molecular weight and narrow molecular weight distribution (M _wM _n<1.2) free of side products. In the higer molecular weight region, side reactions become increasingly noticeable. Propylene oxide macromonomers undergo radical homopolymerization. Homopolymerization of macromonomer with M _n = 8×10² gives graft copolymers with M _n up to 7.2×10³ in copolymerization with styrene, completely soluble graft copolymers with M _n ～ 2×10⁴ were obtained. Radical copolymerization of epichlorohydrin macromonomers with styrene gives initially soluble products with M _n ～ 6×10⁴ were obtained. Radical copolymerization of epichlorohydrin macromonomers with styrene gives initially soluble products with M_n～ 6×10⁴, which are converted in the later stages into insoluble gels, apparently due to the chain transfer to chloromethly groups of the polyepichlorohydrin chains.     

Synthesis, characterization, and reactivity ratio studies on new sulfide copolymers containing ethylbenzene units

Soluble new sulfide copolymers were synthesized readily by the polycondensation of ethylene dibromide (EDB) (or methylene dibromide (MDB)) with styrene dibromide (SDB) and sodium sulfide (Na₂S) in the presence of phase transfer catalyst. The copolymers were characterized by using Fourier transform-infrared, ¹H NMR, ¹³C NMR, gel permeation chromatography, and thermogravimetric analysis (TGA) techniques. The copolymer composition obtained from the ¹H NMR spectra led to the determination of reactivity ratios. The analysis of reactivity ratios revealed that both EDB and MDB are more reactive than SDB towards Na₂S, and copolymers formed are random in nature. Furthermore, it also gave an insight on the microstructure of the copolymers that both poly (ethylene sulfide-co-styrene sulfide) (p(ES-co-SS)), and poly(methylene sulfide-co-styrene sulfide) (p(MS-co-SS)) copolymers have more of blocky structure with increase in the concentration of ethylene sulfide (ES) or methylene sulfide (MS) units in the respective copolymers. The TGA was used to find out the thermal stability of these polymers. The XRD data indicated an increase in the amorphous content of the copolymers with an increase in the concentration of styrene sulfide (SS) units and thereby resulting in most of these copolymers being soluble in common organic solvents. The solubility and molecular weight of the polymers formed were dependent on the concentration of SDB taken in the feed.     

New luminescent 1,2,4-triazole/thiophene alternating copolymers: Synthesis, characterization, and optical properties

New five-membered ring heteroaromatic copolymers composed of 1-alkyl-1H-1,2,4-triazole and thiophene or bithiophene units were prepared by palladium-catalyzed polycondensation. The copolymers were soluble in organic solvents, and showed number-average molecular weights of 6200-23,700 in the GPC analysis. NMR spectroscopy revealed that the copolymers had a regio-random molecular structure. The optical properties, as well as the electrochemical properties, of the copolymers in solutions and films were determined. The polymers exhibited blue photoluminescence (PL) with an emission peak at about 420 nm and quantum yields of 36-43% in solutions, and the PL peak shifted to 470-480 nm in films. X-ray diffraction data suggested that the polymers formed a π-stacked structure in solid state.     

Associating behaviour of polyacrylamide modified with a new hydrophobic zwitterionic monomer

The nucleophilic ring opening of dicyanoketene ethylene acetal by tertiary amino monomers leads to an hydrophobic zwitterionic monomer [(dimethylammonioethoxy)dicyanoethenolate]propylmethacrylamide (DADPMA) characterized by a very high dipole moment. Hydrophobically modified water soluble polymers have been prepared by classical radical polymerization of acrylamide and DADPMA either in homogeneous medium (water/ethanol mixtures) or in micellar solution (water containing sodium dodecylsulphate (SDS)). The copolymers obtained have a high molecular weight (M _w = 2–5 × 10⁶ g mol^?1) and are water soluble for a content of DADPMA lower than 1% mole/mole. The properties of the copolymers in aqueous solution depend on the synthesis conditions, especially on the ratio ethanol:zwitterionic monomer. © 2001 Society of Chemical Industry     

One-Step Synthesis of Thermoplastic Phenylsilsesquioxane Polymer and Its Copolymers with Diphenylsiloxanes

The preparation of reversibly softening polymers and copolymers of phenylsilsesquioxane in a one-step synthesis has been studied. The synthetic methods are based on hydrolytic polycondensation of PhSiCl₃ or copolycondensation of PhSiCl₃ with Ph₂SiCl₂ using moistened or hydrated salts: (1) moistened Na₂CO₃, K₂CO₃, (2) Na₂B₄O₇·10H₂O, (3) Na₃PO₄·12H₂O. Syntheses (1) and (2) gave products as reversibly softening and soluble materials, whereas synthesis (3) produced partially cross-linked resins from which a soluble material might be extracted. Polycondensation using borax gave polymers and copolymers with incorporated boron atoms. The polysilsesquioxanes were characterized by size exclusion chromatography (SEC), ¹H and ²⁹Si NMR, IR spectroscopy, and elemental analysis. Thermal properties were studied by DSC and thermogravimetry.     

One‐step synthesis of star‐block copolymers via simultaneous free radical polymerization of styrene and ring opening polymerization of ε‐caprolacton using tetrafunctional iniferter

Star‐block copolymers comprised of poly(styrene) (S) core and four poly(ε‐caprolacton) (ε‐CL) arms were synthesized by the combination of free radical polymerization (FRP) of S and ring opening polymerization (ROP) of ε‐CL in one‐step in the presence of tetrafunctional ineferter. The block copolymers were characterized by ¹H‐NMR and FTIR spectroscopy, gel permeation chromatography (GPC), and fractional precipitation method. ¹H ‐NMR and FTIR spectroscopy and GPC studies of the obtained polymers indicate that star‐block copolymers easily formed as result of combination FRP and ROP in one‐step. The γ values (solvent/precipitant volume ratio) were observed between 1.04–2.72 (mL/mL) from fractional measurements. The results show that when the initial S feed increased, the molecular weights of the star‐block copolymers also increased and the polydispersities of the polymers decreased. M_w/M_n values of the products were measured between 1.4 and 2.86 from GPC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis,characterization, and thermal properties of poly(methylvinylsilylene‐co‐styrene)

The copolymerization of methylvinyldichlorosilane (MVDCS) and styrene was carried out with various monomer feed ratios under dechlorination conditions with sodium in toluene at 110°C. The copolymers were obtained in 84–95% yields. The copolymerization of MVDCS and styrene with monomer feed ratios of 1 : 0.25 and 1 : 0.5 mainly gave insoluble polymers. The copolymers synthesized with monomer feed ratios of 1 : 1, 1 : 3, and 1 : 7 contained soluble fractions of 3, 26, and 47%, respectively. The copolymers were characterized with infrared, ¹H‐NMR, gel permeation chromatography, thermogravimetric analysis, pyrolysis/gas chromatography (PGC), X‐ray diffraction, and elemental analysis (silicon content). ¹H‐NMR and PGC studies suggested that the soluble fractions were mainly polystyrene. PGC studies indicated that the copolymers obtained with monomer feed ratios of 1 : 0.25 and 1 : 0.5 did not have any significant amount of polystyryl blocks, whereas the copolymers obtained with higher styrene feed ratios contained appreciable amounts of polystyryl blocks. The composition of the insoluble fractions of the copolymers was obtained from PGC data and was in good agreement with the composition calculated from the silicon content of the copolymers.© 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3774–3784, 2004     

Synthesis and optical properties of polyacetylenes containing nonlinear optical chromophores

High molecular weight polyacetylenes bearing nonlinear chromophoric pendants poly[4-ethynyl-4′-(N,N-diethylamino)azobenzene-co-phenylacetylene]s [poly(EAAB-co-PA)s] were synthesized in moderate yields by [Rh(nbd)Cl]₂-Et₃N. The azo unit in the copolymers can be effectively controlled by the monomer feed ratio. Whereas the homopolymer of EAAB possessed low solubility, all the copolymers, however, dissolved readily in common organic solvents when the poly(EAAB) molar content was less than 41.7%. The structures and properties of the polymers were characterized and evaluated by UV, NMR, optical limiting, and nonlinear optical analyses. All the copolymers possessed high stereoregularity and thermal stability (≥300 °C). They can attenuate intense laser pulses, with solutions of high concentrations showing better performances. The third-order nonlinear susceptibility of the copolymers was as high as 4.62×10⁻¹¹ esu, which are two orders of magnitude larger than those of poly(PA), and larger than that of poly(N-carbazoylacetylene), and poly(1-naphthylacetylene).     

Molecular structure-property engineering for photovoltaic applications: Fluorene-acceptor alternating conjugated copolymers with varied bridged moieties

A series of novel soluble conjugated copolymers consisting of electron-accepting 2-pyran-4-ylidenemalononitrile (PM) and electron-donating fluorene connected by different electron-donating ability conjugated moieties were synthesized by Suzuki coupling polymerization. The structures of the copolymers were characterized and their physical properties were investigated. High molecular weight (M_n up to 43.8 kg/mol) and thermostable copolymers were obtained. The conjugated bridge between PM and fluorene building block with gradually increased electron-donating ability moieties results in enhanced intramolecular charge transfer (ICT) transition bands, which lead to an extension of their absorption spectral range. Cyclic voltammetry measurement displayed that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the copolymers can be fine-tuned. The resulting copolymers possessed relatively low HOMO energy levels, promising good air stability and high open circuit voltage (V_oc) for photovoltaic application. Bulk heterojunction photovoltaic devices were fabricated by using the copolymers as donors and (6,6)-phenyl C₆₁-butyric acid methyl ester (PCBM) as acceptor. The power conversion efficiencies (PCE) of the devices were in the range of 0.02-0.52% under simulated AM 1.5 solar irradiation of 100 mW/cm², and the highest V_oc reached 0.82 V. The significant improvement of PCE indicates a novel concept for developing donor-acceptor (D-A) conjugated copolymers with high photovoltaic performance by adjusting electron-donating ability of conjugated bridge.     

p-benzoquinone diimines and thiophene based alternating copolymers: organometallic catalyzed syntheses and elementary characterization

A series of alternating polymers, which were prepared by coupling of N, N’-dichloro-benzoquinonediimine (a) or 2, 5-dimethyl-N, N’-dichloro-benzoquinonediimine (b) with Grignard reagents of thiophene, were successfully prepared using Ni(II) complexes as catalyst with moderate yields (54–88%) and molecular weights (4.3–7.0 × 10³). The basic properties of the obtained copolymers were characterized by FT-IR, ¹H NMR, UV-vis absorption, cyclic voltammetry, thermal analysis and Gel permeation chromatography (GPC). The maximum UV–vis absorption of these polymers appears in the range of 410–430 nm and 437–494 nm in DMF and CF₃COOH, respectively. XRD patterns of these polymers suggest the low crystallinty. After doped by iodine, conductivity of obtained polymers was improved five-eight orders of magnitude relative to their corresponding neutral precursors (the conductivity of them was <10⁻¹³ S/cm). The electrochemical activity of iodine-doped polymers was greatly improved as compared to un-doped ones. The reduction of pristine benzoquinone polymers was also studied in order to tune their properties conveniently.     

Creep rupture properties of homopolymer,copolymer, and terpolymer based on poly(oxymethylene)

Polyacetal copolymers were prepared by cationic ring‐opening copolymerizations of 1,3,5‐trioxane (TOX) with 1,3‐dioxolane (DOX), and polyacetal terpolymers were prepared by terpolymerizations of TOX, DOX, and 2‐ethylhexyl glycidyl ether (EHGE). Polyacetal polymers with three different structures such as polyacetal homopolymers, polyacetal copolymers, and polyacetal terpolymers were compared in the mechanical properties and the creep characteristics, and discussed from the view point of the polymer structure. The polyacetal copolymers and the polyacetal terpolymers were determined by ¹H‐MNR measurement. About 80 mol % of DOX and EHGE amounts in feed were incorporated randomly into the each polymer. From the plots of the degree of crystallinity (X_c) versus the tensile strength, the tensile strength and crystallintiy of the polyacetal homopoymers are higher than those of the polyacetal copolymers and the polyacetal terpolymers. However, the tensile strength does not decrease linearly with a decrease in the crystallinity among the polyacetal polymers with three different structures, the polyacetal homopolymer, the polyacetal copolymers, and the polyacetal terpolymers. Creep rupture was characterized by the activation volume, υ_c, value in Zhurkov's equation, which can be estimated from the slope in the plots of load versus log (rupture time) at 80°C. The polyacetal polymers with higher molecular weight have larger values of the activation volume than those with lower molecular weight. When the activation volume values are compared among the polyacetal polymers with the same molecular weights, they increase in the following order: the polyacetal homopolymers < the polyacetal copolymers < polyacetal terpolymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of copolymers from 3,5-dioxo-4,10-dioxatricyclo-[5.2.02,6]dec-8-ene and vinyl monomers by photopolymerization and their biological activities

Photocopolymerizations of 3,5-dioxo-4,10-dioxatricyclo[5.2.0^2,6]dec-8-ene (DDTD) with methacrylic acid (MA) acrylamide (AAm) and vinyl pyrrolidone (VP) were carried out in 2-butanone using dimethoxy benzoin (DMB) as an initiator at 25°C. The structures of the polymers obtained from photopolymerizations of corresponding monomer pairs were confirmed to be poly(DDTD-co-MA), poly(DDTD-co-AAm) and poly(DDTD-co-VP) by ¹H NMR and ¹³C NMR spectroscopies, and the average molecular weights were determined by gel permeation chromatography (GPC). The weight average molecular weights (M_w) of the polymers were in the range 9500–17300. The polymers were soluble in water, dimethyl sulphoxide (DMSO) and dimethyl formamide (DMF). The contents of DDTD units in the copolymers were 19, 37 and 45%. The in vitro cytotoxicities of the polymers were evaluated using mouse mammary carcinoma (FM-3A), mouse leukaemia (P-388) and human histiocytic lymphoma (U-937) cell lines. The in vivo antitumour activities of the polymers were estimated by the survival time of sarcoma 180 tumour-bearing mice. The in vivo antitumour activities of the polymers were greater than those of 5-fluorouracil (5-FU) and monomeric DDTD at a dose of 0·8mgkg^-1. Poly(DDTD-co-AAm) and poly(DDTD-co-VP) showed higher antitumour activity than 5-FU and monomeric DDTD at all doses tested. © 1998 SCI.     

New soluble rigid rod copolymers comprising alternating 2-amino-pyrimidine and phenylene repeat units: Syntheses, characterization, optical and electrochemical properties

A new type - π-conjugated copolymers of 2-amino-pyrimidine was prepared between 2-amino-4,6-diiodidepyrimidine and 1,4-dibromo-2,5-dialkoxybenzene by Sonogashira polycondensation. The structures of the copolymers were elucidated by FT-IR, ¹H NMR and ¹³C NMR, fluorescence spectroscopy, gel permeation chromatography, thermal analysis and element analysis. The derived polymers were soluble in common organic solvents and trifloroacetic acid and exhibited good thermal stability. They emitted green light under UV irradiation in solid state and blue or green light in solution phase, respectively. Electrochemical behavior of these new polymers depicted facile p-doping and good electron-transporting properties. These polymers displayed bathochromic shift when protonated with CH₃SO₃H acid in chloroform solutions or m-cresol solutions and the red-shifted peaks were observed from 490 nm to 652 nm. XRD patterns of copolymers showed that the intensity of peaks was enhanced with increasing alkyloxy chain length.     

Synthesis and characterization of greenish‐blue emitting vinyl copolymer containing pyrene and triarylamine moieties

Two fluorescent monomers N‐phenyl‐N‐(4‐vinylphenyl)pyren‐1‐amine (vinyl‐PyPA) and 1‐vinyl pyrene (VPy) were synthesized in good yields. A series of soluble conductive vinyl copolymers P(PyPA‐co‐VPy) containing vinyl‐PyPA and VPy moieties in different composition ratios were prepared by free radical solution polymerization. These copolymers showed high T_g (190?201 °C) and good thermal stability. The photoluminescence emission maxima of the copolymers were all in the range 474.5?478.5 nm, which was similar to the poly(N‐phenyl‐N‐(4‐vinylphenyl)pyren‐1‐amine) (P(PyPA)) (475 nm) but blue shifted compared with poly(1‐vinyl pyrene) (PVPy) (490.5 nm). The lifetime of the copolymers increased from 10.2 to 29.7 ns with an increase in pyrene content. The copolymers had higher quantum yields (0.51) than those of the homopolymers of P(PyPA) (0.48) and PVPy (0.13). The highest occupied molecular orbital of the copolymers remained relatively unchanged from P(PyPA), while the lowest unoccupied molecular orbital varied from ?2.41 eV to ?2.51 eV with an increase in pyrene ratio in the copolymers. The energy bandgaps of the copolymers (from 2.70 eV to 2.81 eV) were smaller than those of P(PyPA) (2.82 eV) and PVPy (3.47 eV). Two polymer light‐emitting diode (PLED) series were attempted including indium tin oxide (ITO) (fluorocarbon (CFx) treated)/P(PyPA‐co‐VPy)/LiF/Al and ITO(CFx treated)/P(PyPA‐co‐VPy)/1,3,5‐Tri(1‐phenyl‐1H‐benzo[d]imidazol‐2‐yl)phenyl (TPBi)/LiF/Al. The results suggested that the PyPA moiety is hole conducting and the PLEDs can achieve high luminance from 650 to 1150 cd m^?2 (at 100 mA cm^?2) only when an electron injecting layer TPBi is employed. © 2013 Society of Chemical Industry     

Synthesis and characterization of (star po1ystyrene)-block- (linear polydimethylsi1oxane)-block-(star polystyrene) triblock copolymers

Summary (Star po1ystyrene)-block-(linear polydimethy1siloxane)-block-(Star polystyrene) triblock copolymers were synthesized by making living Star-shaped polystyrenes through a convergent living anionic polymerization procedure, followed by ring-opening polymerization of hexamethylcyclotrisiloxane (D₃) then difunctional coupling. The molecular weights of the resulting polymers were characterized by gel permeation chromatography (GPC), multi angle laser light scattering (MALLS) and ¹H NMR spectroscopy. Triblock copolymers with relatively narrow molecular weight distributions were obtained. Received: 22 April 2002/ Revised version: 15 August 2002/ Accepted: 16 August 2002 Correspondence to Daniel M. Knauss Email: dknauss@mines.edu, Fax: (303) 273 3629     

Reactive polymers in diagnostics: Syntheses and characterizations of nucleic acid probes and maleic anhydride-co-methyl vinyl ether polymers

Maleic anhydride-co-methyl vinyl ether copolymers were used as reactive polymers to link oligodeoxyribonucleotides (ODN) to make oligonucleotide-copolymer conjugates of potential applications in diagnostics. The anhydride moieties of the copolymers were used for the covalent binding, via the formation of a peptide bond, on reaction with DNA probes that were amino modified at the 5′ position. The best coupling yields were obtained by carrying out the reaction in a DMSO-borate buffer (95/5 volume ratio) mixture at high ionic strength. Copolymers and ODN-copolymer conjugates were characterized by size exclusion chromatography and multiangle laser light scattering detection. The average molecular weights of the formed conjugates were relatively high, in the 10⁶ g/mol range, resulting from the crosslinking of several copolymer molecules during coupling. Coupling DNA probes onto smaller molecular weight polymers did not result in the formation of very high molecular weight conjugates showing that copolymer chain interpenetration was a determining factor of the crosslinking process that occurs during the coupling reaction. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2567–2577, 1997