Origin of the methylene bonds in poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenylenevinylene] prepared according to Gilch's method: novel applications

Impurities containing methylene bridges between 2‐((2′‐ethylhexyl)oxy)‐5‐methoxy‐benzene molecules are inevitably formed during the synthesis of 1,4‐bis(chloromethyl)‐2‐((2′‐ethylhexyl)oxy)‐5‐methoxy‐benzene, the monomer used in the preparation of poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenylenevinylene] (MEH‐PPV), but they can be removed by double recrystallization of the monomer prior to polymerization. When impurities containing methylene bridges participate in a Gilch polymerization, the methylene bonds formed in the main chains are prone to break at 200 °C, that is, at least 150 °C below the major degradation temperature of defect‐free MEH‐PPV. Interestingly, the thermal treatment used to break the methylene bonds present reduces the chain aggregation of MEH‐PPV during film formation and induces its blends with poly(2,3‐diphenyl‐5‐octyl‐p‐phenylene‐vinylene) (DPO‐PPV) to form a morphology similar to that of block copolymers. Both significantly enhance the luminescence properties. Copyright © 2006 Society of Chemical Industry     

Micropatterning of poly(p‐phenylene vinylene) by femtosecond laser induced forward transfer

Conjugated polymers are important materials for optical applications, among which poly(p‐phenylene vinylene) (PPV) has a major role due to its applicability in sensors, organic light‐emitting diodes and large area displays. Despite advances on the synthesis of PPV‐based polymers and the improvements of their properties, its printing process, in particular involving the solid phase, remains unsuitable for the development of electro‐optical microcircuits. This paper demonstrates the printing of PPV from the solid phase in 2D micropatterns. Such an achievement was performed using laser induced forward transfer with femtosecond pulses, which allows area‐selective deposition within reduced scales as thin as ca 100 nm and 5 µm wide. Raman, fluorescence and electrochemical impedance spectroscopies confirm that the printed PPV micropatterns have the same structure, emission spectrum and conductivity as the target material, revealing the conservation of their original properties even after laser irradiation. The printing process was carried out using PPV films, overcoming the insolubility issue of this material. The optical and electrical characterization of the transferred PPV demonstrates the potential of this method for the patterning of electro‐optical microdevices, since luminescence and electrical conductivity were preserved. © 2018 Society of Chemical Industry     

Ultrasound‐accelerated dehydrogenation of poly(1,3‐cyclohexadiene): efficient synthesis of poly(para‐phenylene)

The effect of ultrasonication on the dehydrogenation of poly(1,3‐cyclohexadiene) (PCHD) with benzoquinones was examined with the aim of improving the rate of reaction at moderate temperature. The type of solvent and the ultrasound treatment strongly affected the dehydrogenation of PCHD. The rate of reaction of the dehydrogenation of PCHD with 2,3‐dichloro‐5, 6‐dicyano‐1,4‐benzoquinone (DDQ) or 3,4,5,6‐tetrachloro‐1,2‐(o)‐benzoquinone (TOQ) was markedly improved by the use of ultrasound, and poly(para‐phenylene) (PPP) and PPP–TOQ complex, respectively, were successfully obtained. The electron drift mobility for PPP was of the order of 10^?4 cm² V^?1 s^?1 with a negative slope, while that for PPP–TOQ complex was of the order of 10^?3 to 10^?4 cm² V^?1 s^?1 with a negative slope. The dehydrogenation of PCHD with benzoquinones under ultrasonication is thus an effective method to obtain soluble PPP with a well‐defined polymer chain structure. Copyright © 2010 Society of Chemical Industry     

Preparation of polystyrene/poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐p‐phenylenevinylene] fluorescent microspheres by miniemulsion polymerization

Fluorescent microspheres have great potential for use as probes in biological diagnostics. In this context, poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐p‐phenylenevinylene] (MEH‐PPV), a conjugated polymer which has high quantum yield, controllable emitting wavelength and facile processing in manufacture, was used as a fluorescent material for the preparation of polystyrene (PS)/MEH‐PPV fluorescent microspheres via miniemulsion polymerization. We demonstrate that the emitting wavelength of the PS/MEH‐PPV fluorescent microspheres can be regulated by changing the amount of azobisisobutyronitrile initiator in the polymerization process. Using acrylic acid comonomer, poly[styrene‐co‐(acrylic acid)]/MEH‐PPV fluorescent microspheres with functional carboxyl groups were also prepared. All the microspheres were characterized using transmission electron microscopy, scanning electron microscopy, fluorescence microscopy and fluorescence spectrophotometry. The functional carboxyl groups were characterized using Fourier transform infrared spectroscopy. This work provides a novel platform for the preparation of conjugated polymer fluorescent microspheres for biological applications. © 2012 Society of Chemical Industry     

Synthesis and characterization of poly(p‐phenylene)‐graft‐poly(ε‐caprolactone) copolymers by combined ring‐opening polymerization and cross‐coupling processes

2,5‐Dibromo‐1,4‐(dihydroxymethyl)benzene was used as initiator in ring‐opening polymerization of ε‐caprolactone in the presence of stannous octoate (Sn(Oct)₂) catalyst. The resulting poly(ε‐caprolactone) (PCL) macromonomer, with a central 2,5‐dibromo‐1,4‐diphenylene group, was used in combination with 1,4‐dibromo‐2,5‐dimethylbenzene for a Suzuki coupling in the presence of Pd(PPh₃)₄ as catalyst or using the system NiCl₂/bpy/PPh₃/Zn for a Yamamoto‐type polymerization. The poly(p‐phenylenes) (PPP) obtained, with PCL side chains, have solubility properties similar to those of the starting macromonomer, ie soluble in common organic solvents at room temperature. The new polymers were characterized by ¹H and ¹³C NMR and UV spectroscopy and also by GPC measurements. The thermal behaviour of the precursor PCL macromonomer and the final poly(p‐phenylene)‐graft‐poly(ε‐caprolactone) copolymers were investigated by thermogravimetric analysis and differential scanning calorimetry analyses and compared. Copyright © 2004 Society of Chemical Industry     

Synthesis,characterization, and photophysical properties of novel poly(p‐phenylene vinylene) derivatives with conjugated thiophene as side chains

Two novel poly(p‐phenylene vinylene) (PPV) derivatives with conjugated thiophene side chains, P1 and P2, were synthesized by Wittig‐Horner reaction. The resulting polymers were characterized by ¹H‐NMR, FTIR, GPC, DSC, TGA, UV–Vis absorption spectroscopy and cyclic voltammetry (CV). The polymers exhibited good thermal stability and film‐forming ability. The absorption spectra of P1 and P2 showed broader absorption band from 300 to 580 nm compared with poly[(p‐phenylene vinylene)‐alt‐(2‐methoxy‐5‐octyloxy‐p‐phenylene vinylene)] (P3) without conjugated thiophene side chains. Cyclic voltammograms displayed that the bandgap was reduced effectively by attaching conjugated thiophene side chains. This kind of polymer appears to be interesting candidates for solar‐cell applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Interface formation of Ca with poly(p-phenylene α,α′-diphenyl vinylene) and poly(p-phenylene α-phenyl vinylene)

We have investigated the interface formation of Ca with poly(p-phenylene α,α′-diphenyl vinylene) (PPV-DP) and poly(p-phenylene α-phenyl vinylene) (PPV-P) using X-ray photoemission spectroscopy (XPS). Similarly to our earlier findings in metal/PPV interface formation, the O 1s peak shifted toward a lower binding energy as soon as Ca was deposited on to the polymers. This was accompanied by the formation of Ca? O, suggesting a chemical origin for the O 1s shift. By contrast, the C 1s peak shift toward a lower binding energy was observed relatively later, after about 4 Å of Ca deposition. At the same time, a new C 1s component became noticable at about ?1.5 eV relative to the initial C 1s peak. This component signifies the possibility of polymer disruption by the Ca atoms to form Ca? C species. The C 1s peak shift is attributed to Ca induced surface band bending and barrier formation as in the case of metal/PPV interface formation. The disruption of the polymer may also induce changes in the interface electronic states and contribute to the C 1s peak shift. From the intensity attenuation analysis, we conclude that the initial 15 Å of Ca overlayer is contaminated by the Ca? O and Ca? C species and the overlayer is pure beyond 15 Å of Ca coverage.     

New light‐emitting poly{(9,9‐di‐n‐octylfluorenediyl vinylene)‐alt‐[1,5‐(2,6‐dioctyloxy)naphthalene vinylene]}

A new conjugated light‐emitting AB copolymer containing alternating fluorene and naphthalene units, poly{(9,9‐di‐n‐octylfluorenediyl vinylene)‐alt‐[1,5‐(2,6‐dioctyloxy)naphthalene vinylene]} (PFV‐alt‐PNV), was synthesized via Horner‐Emmons polymerization. The polymer is completely soluble in common organic solvents and exhibits good thermal stability up to 400 °C. UV‐visible, fluorescence and photoluminescence measurements of the copolymer show peak maxima at 427, 500 and 526 nm, respectively. A light‐emitting device containing the new polymer was fabricated using a simple indium tin oxide configuration: (ITO)/PEDOT:PSS/PFV‐alt‐PNV/Al. Measurements of current versus electric field were carried out, with an onset of light emission occurring at 2.5 V. The electroluminescence brightness was observed to reach a maximum of 5000 cd m^?2. Copyright © 2011 Society of Chemical Industry     

Inhibition of the thermal degradation of rigid poly(vinyl chloride) using poly(N‐[4‐(N′‐phenyl amino carbonyl)phenyl]maleimide)

Poly(N‐[4‐(N′‐phenyl amino carbonyl)phenyl]maleimide), poly(PhPM), has been investigated for the inhibition of the thermal degradation of rigid poly(vinyl chloride) (PVC) in air, at 180°C. Its stabilizing efficiency was evaluated by measuring the length of the induction period, the period during which no detectable amounts of hydrogen chloride gas could be observed, and also from the rate of dehydrochlorination as measured by continuous potentiometric determination, and the extent of discoloration of the degraded polymer. The results have proved the greater stabilizing efficiency of poly(PhPM) relative to that of the DBLC commercial stabilizer. This is well demonstrated by the longer induction period values and by the lower rates both of dehydrochlorination and discoloration of the polymer during degradation relative to those of the DBLC reference stabilizer. The greater stabilizing efficiency of the poly(PhPM) is most probably attributed not only to its possession of various centers of reactivity that can act as traps for radical species resulting during the degradation process, and replacement of labile chlorine atoms on PVC chains by relatively more thermally stable poly(PhPM) moieties, but also due to the ability of its fragmentation products to react with the evolved hydrogen chloride gas. A radical mechanism is suggested to account for the stabilizing action of this polymeric stabilizer. A synergistic effect is achieved when the poly(PhPM) was blended in various weight ratios with DBLC. This synergism attains its maximum when poly(PhPM) and DBLC are taken at 3 : 1 weight ratio. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Gold(I)‐Catalyzed Cascade for Synthesis of Pyrrolo[1,2‐a:2′,1′‐c]‐/Pyrido[2,1‐c]pyrrolo[1,2‐a]quinoxalinones

An efficient and convenient method was developed for the one‐pot construction of the complex polycyclic heterocycles pyrrolo[1,2‐a:2′,1′‐c]‐/pyrido[2,1‐c]pyrrolo[1,2‐a]quinoxalinones from two simple starting materials via a gold(I)‐catalyzed domino reaction. This strategy presents an atom economical and environmentally friendly transformation, in which two new C N bonds and one new C C bond are formed in a one‐pot reaction process.     

Thermal properties and crystalline structure of liquid crystalline poly(ethylene terephthalate‐co‐2(3)‐chloro‐1,4‐phenylene terephthalate)

Thermal properties and crystalline structure of liquid crystalline (LC) poly(ethylene terephthalate‐co‐2(3)‐chloro‐1,4‐phenylene terephthalate) [copoly(ET/CPT)] were investigated using differential scanning calorimetry (DSC), thermogravimetry (TGA), limiting oxygen index (LOI) measurement, electron dispersive X‐ray analysis (EDX), X‐ray diffractometry, and infrared spectrometry (IR). The thermal transition temperatures of copoly(ET/CPT) were changed with the composition. Copoly(ET/CPT) showed two thermal decomposition steps and the residues at 700°C and LOI values of copoly(ET/CPT) were almost proportional to its chlorine content. The activation energy of thermal decomposition of LC units was very low compared to that of poly(ethylene terephthalate)(PET) units. Crystal structure of copoly(ET/CPT) (20/80) was of triclinic system with the lattice constants of a = 9.98 A?, b = 8.78 A?, c = 12.93 A?, α = 97.4°, β = 96.1°, and γ = 90.8°, which is very close to that of poly(chloro‐p‐phenylene terephthlate) (PCPT) with the lattice constants of a = 9.51 A?, b = 8.61 A?, c = 12.73 A?, α = 96.8°, β = 95.4°, and γ = 90.8°. When copoly(ET/CPT)(50/50) was annealed at 220°C in vacuum, crystallization induced sequential reordering (CISR) was not observed but the heat of fusion was slightly increased due to the increase of the trans isomer content in PET units. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1286–1294, 2002; DOI 10.1002/app.10451     

Synthesis and properties of polyamides based on 5,5′‐bis[4‐(4‐aminophenoxy)phenyl]‐hexahydro‐4,7‐methanoindan

A new diamine 5,5′‐bis[4‐(4‐aminophenoxy)phenyl]‐hexahydro‐4,7‐methanoindan ( 3 ) was prepared through the nucleophilic displacement of 5,5′‐bis(4‐hydroxylphenyl)‐hexahydro‐4,7‐methanoindan ( 1 ) with p‐halonitrobenzene in the presence of K₂CO₃ in N,N‐dimethylformamide (DMF), followed by catalytic reduction with hydrazine and Pd/C in ethanol. A series of new polyamides were synthesized by the direct polycondensation of diamine 3 with various aromatic dicarboxylic acids. The polymers were obtained in quantitative yields with inherent viscosities of 0.76–1.02 dl g⁻¹. All the polymers were soluble in aprotic dipolar solvents such as N,N‐dimethylacetamide (DMAc) and N‐methyl‐2‐pyrrolidone (NMP), and could be solution cast into transparent, flexible and tough films. The glass transition temperatures of the polyamides were in the range 245–282 °C; their 10% weight loss temperatures were above 468 °C in nitrogen and above 465 °C in air. © 2000 Society of Chemical Industry     

Electrosynthesis of free‐standing poly(para‐phenylene) films in mixed electrolytes of boron trifluoride diethyl etherate and trifluoroacetic acid on stainless steel electrode

Free‐standing poly(para‐phenylene) (PPP) films have been electrosynthesized by direct oxidation of benzene on stainless steel electrode in mixed e1ectrolytes of boron trifluoride diethy1 etherate (BFEE) and trifluoroacetic acid (TFA). The oxidation potential of the monomer in these media is lower than those in the neutral media. Increasing the content of TFA in the mixed electrolyte can effective1y decrease the oxidation potential and increase the coup1ing rate of the monomer. The films obtained from these media were very shiny and flexible, and could easily be processed into various shapes by conventional mechanical methods. The films had a 1inear chain structure, and their degree of polymerization could be improved by increasing the TFA content in the mixed electrolyte. Moreover, the films had a fairly good thermal stability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2462–2466, 2002     

Indolo[3,2‐b]carbazole‐based poly(arylene vinylene)s. The influence of substitution position on spectroscopic and electrochemical properties

Three novel soluble poly(arylene vinylene)s containing indolo[3,2‐b]carbazole moiety inserted in the polymer chain at 2,8‐, 3,9‐ and 6,12‐positions were synthesized and used to study the influence of the linking topology on the optical and electronic properties. The new polymers were obtained through a palladium‐catalysed cross‐coupling Stille reaction between bis‐bromine[3,2‐b]indolocarbazoles and trans‐1,2‐bis(tributylstannyl)ethane in toluene. Polymers were soluble in chlorinated, aromatic and aprotic polar solvents. The structures of polymers were investigated using Fourier transform infrared, ¹H NMR and ¹³C NMR spectroscopies. The number‐average molecular weights determined using gel permeation chromatography are in the range (6.3–9.4) × 10³ g mol^?1 while thermogravimetric analysis showed the polymers to possess high thermal stability. UV‐visible and emission spectroscopy evidenced a bathochromic shift of λ_max for indolocarbazole linking topology in the polymer backbone, in the order: 6,12 < 2,8 < 3,9. Electrochemical properties were investigated by cyclic voltammetry using thin films cast on platinum disc working electrodes and highest occupied and lowest unoccupied molecular orbital energy levels were determined. © 2016 Society of Chemical Industry     

Synthesis of poly(ester‐anhydride)s based on poly(ϵ‐caprolactone) prepolymer

The objective of this study was to prepare high molecular weight poly(ester‐anhydride)s by melt polycondensation. The polymerization procedure consisted of the preparation of carboxylic acid terminated poly(?‐caprolactone) prepolymers that were melt polymerized to poly(?‐caprolactone)s containing anhydride functions along the polymer backbone. Poly(?‐caprolactone) prepolymers were prepared using either 1,4‐butanediol or 4‐(hydroxymethyl)benzoic acid as initiators, yielding hydroxyl‐terminated intermediates that were then converted to carboxylic acid‐terminated prepolymers by reaction with succinic anhydride. Prepolymers were then allowed to react with an excess of acetic anhydride, followed by subsequent polycondensation to resulting high molecular weight poly(ester‐anhydride)s. Upon coupling of prepolymers, size exclusion chromatography analyses showed an increase from 3600 to 70,000 g/mol in number‐average molecular weight (M_n) for the 1,4‐butanediol initiated polymer, and an increase from 7200 to 68,000 g/mol for the 4‐(hydroxymethyl)benzoic acid‐initiated polymer. 4‐Hydroxybenzoic acid and adipic acid were also used as initiators in the preparation of poly(?‐caprolactone) prepolymers. However, with these initiators, the results were not satisfactory. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 176–185, 2001     

Determination of the physicochemical characteristics and electrical performance of postsulfonated and grafted sulfonated derivatives of poly(para‐phenylene) as new proton‐conducting membranes for direct methanol fuel cell

Poly(para‐phenylene)s (PPPs) are an interesting class of rigid‐rod polymers that have excellent thermal and mechanical properties. Because of their high degree of crystallinity and lower permeability to methanol, PPPs are insoluble and infusible. A number of methods have been developed to synthesize substituted sulfonated PPPs bearing lateral chains to improve their solubility. In this work, a comparison of the physicochemical properties of three PPP‐based polymers is made with respect to Nafion membranes. One of these polymers was prepared with the postsulfonation method, and the other two were made with a new method of grafting developed in the Commissariat à l'Energie Atomique laboratory (a grafted sulfonated PPP polymer and a grafted perfluorinated sulfonated polymer). The sulfonated PPP polymers were examined for their mechanical properties, small‐angle X‐ray scattering, water absorption, proton conductivity, and methanol permeability. Relations between structures and properties were also investigated. Performances in fuel‐cell tests were also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 944–952, 2006     

Part 7. Effects of poly(L‐lactide‐co‐ϵ‐caprolactone) on morphology,structure, crystallization,and physical properties of blends of poly(L‐lactide) and poly(ϵ‐caprolactone)

Blended films of poly(L ‐lactide) [ie poly(L ‐lactic acid)] (PLLA) and poly(?‐caprolactone) (PCL) without or mixed with 10 wt% poly(L ‐lactide‐co‐?‐caprolactone) (PLLA‐CL) were prepared by solution‐casting. The effects of PLLA‐CL on the morphology, phase structure, crystallization, and mechanical properties of films have been investigated using polarization optical microscopy, scanning electron microscopy, differential scanning calorimetry and tensile testing. Addition of PLLA‐CL decreased number densities of spherulites in PLLA and PCL films, and improved the observability of spherulites and the smoothness of cross‐section of the PLLA/PCL blend film. The melting temperatures (T_m) of PLLA and PCL in the films remained unchanged upon addition of PLLA‐CL, while the crystallinities of PLLA and PCL increased at PLLA contents [X_PLLA = weight of PLLA/(weight of PLLA and PCL)] of 0.4–0.7 and at most of the X_PLLA values, respectively. The addition of PLLA‐CL improved the tensile strength and the Young modulus of the films at X_PLLA of 0.5–0.8 and of 0–0.1 and 0.5–0.8, respectively, and the elongation at break of the films at all the X_PLLA values. These findings strongly suggest that PLLA‐CL was miscible with PLLA and PCL, and that the dissolved PLLA‐CL in PLLA‐rich and PCL‐rich phases increased the compatibility between these two phases. © 2003 Society of Chemical Industry     

Preparation and characterization of modified poly(m‐phenylene terephthalamide) and its fiber

Modified poly(m ‐phenylene terephthalamide) (co ‐PMTA₃ ) was prepared by polycondensation of m ‐phenylenediamine, 4,4′‐diaminodiphenylsulfone and terephthaloyl dichloride with an initial feed mole ratio of 3:1:4 in N ,N ′‐dimethylacetamide (DMAc ). The co ‐PMTA₃ was dissolved in DMAc and then spun into fiber via wet spinning. The properties of co ‐PMTA₃ pulp and fiber were investigated using ¹H NMR spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy, X‐ray diffraction, sonic velocity meter measurements and thermomechanical analysis. The results indicate that co ‐PMTA₃ has excellent heat resistance with a softening temperature of 323.6 °C. The co ‐PMTA₃ fiber has high strength with a breaking strength of 4.7 cN dtex^?1 and a knot tenacity of 2.2 cN dtex^?1. © 2017 Society of Chemical Industry     

Synthesis and properties of poly(amide–imide)s based on N,N′‐bis(4‐carboxyphenyl)‐4,4′‐oxydiphthalimide,p‐aminobenzoic acid and various aromatic diamines

A new diimide–diacid monomer, N,N′‐bis(4‐carboxyphenyl)‐4,4′‐oxydiphthalimide (I), was prepared by azeotropic condensation of 4,4′‐oxydiphthalic anhydride (ODPA) and p‐aminobenzoic acid (p‐ABA) at a 1:2 molar ratio in a polar solvent mixed with toluene. A series of poly(amide–imide)s (PAI, III_a–m) was synthesized from the diimide–diacid I (or I′, diacid chloride of I) and various aromatic diamines by direct polycondensation (or low temperature polycondensation) using triphenyl phosphite and pyridine as condensing agents. It was found that only III_k–m having a meta‐structure at two terminals of the diamine could afford good quality, creasable films by solution‐casting; other PAIs III using diamine with para‐linkage at terminals were insoluble and crystalline; though III_g–i contained the soluble group of the diamine moieties, their solvent‐cast films were brittle. In order to improve their to solubility and film quality, copoly(amide–imide)s (Co‐PAIs) based on I and mixtures of p‐ABA and aromatic diamines were synthesized. When on equimolar of p‐ABA (m = 1) was mixed, most of Co‐PAIs IV had improved solubility and high inherent viscosities in the range 0.9–1.5 dl g^?1; however, their films were still brittle. With m = 3, series V was obtained, and all members exhibited high toughness. The solubility, film‐forming ability, crystallinity, and thermal properties of the resultant poly(amide–imide)s were investigated. © 2002 Society of Chemical Industry