A hybrid‐type,chiral π‐conjugated polymer wrapped with polyhedral oligomeric silsesquioxanes

A novel hybrid‐type chiral binaphthyl‐based polyarylene derivative with polyhedral oligomeric silsesquioxanes (POSS) units 2a was prepared by Suzuki–Miyaura coupling polymerization from a chiral (R)‐6,6′‐dibromo‐2,2′‐diPOSS‐substituted 1,1′‐binaphthyl derivative 1a and p‐biphenylene diboronic acid. As a reference, a binaphthyl‐based polyarylene derivative without POSS unit 2b was also prepared. The obtained polymers were studied with thermogravimetric analysis, optical rotations, circular dichroism (CD), ultraviolet‐visible, and photoluminescence (PL) spectra. Gel permeation chromatography measurements of 2a and 2b showed that their number‐average molecular weights were 13,300 and 16,500, respectively. The thermal stability of POSS‐modified polymer 2a (temperature of 10% weight loss; T₁₀ = 380 °C) was extremely high compared with that of polymer without POSS unit 2b (T₁₀ = 335 °C) due to the siliceous bulky POSS segments on the side chains. The specific optical rotation [α]_D was ?66.7° (c 0.06, CHCl₃) for 2a and ?62.3° (c 0.06, CHCl₃) for 2b . The CD spectra showed that these two polymers had very similar and strong Cotton effects. Film polymer 2a showed almost the same PL spectrum as that in dilute CHCl₃ solution, indicating that bulky POSS units strongly suppressed intermolecular aggregation of the π‐conjugated polymer backbone. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6035–6040, 2008     

Thermally Stabilized Blue Luminescent Poly(p‐phenylene)s Covered with Polyhedral Oligomeric Silsesquioxanes

A novel series of poly(p‐phenylene)s (PPPs) with polyhedral oligomeric silsesquioxanes (POSSs) on their side chains was prepared. The obtained POSS‐modified PPPs are as follows: 25POSS‐PPP ( 2b , containing 25 mol‐% of POSS units in all side chains), 50POSS‐PPP ( 2c , containing 50 mol‐% of POSS units in all side chains), 100POSS‐PPP ( 2d , containing 100 mol‐% of POSS units in all side chains), and 0POSS‐PPP ( 2a , as a blank polymer). Films polymer 2d showed the same absorption and photoluminescence (PL) spectra as those in CHCl₃ solution, indicating that bulky POSS units strongly suppressed intermolecular aggregation of the PPP backbone. Polymer 2d showed the same PL spectra even after thermal annealing at 150 °C for 6 h. This enhancement of PL stability is due to the significant effect of the bulky POSS units.

     

Deep‐red emissive conjugated poly(2,6‐BODIPY‐ethynylene)s bearing alkyl side chains

Novel deep‐red emissive poly(2,6‐BODIPY‐ethynylene)s bearing dodecyl side chains (polymers A , B , and C ) have been prepared by palladium‐catalyzed Sonogashira polymerization of 2,6‐diiodo‐functionalized BODIPY monomers with 2,6‐diethynyl‐functionalized BODIPY monomers. These polymers emit in the deep‐red region with emission maxima at up to 690 nm, and exhibit significant red shifts (up to 166 and 179 nm) of both absorption and emission maxima compared with their parent BODIPY dyes due to significant extension of π‐conjugation. These polymers possess good thermal stability with decomposition temperature between 270 and 360 °C. The polymers exhibit a little larger Stokes shifts and shorter lifetime than their corresponding BODIPY dyes. The solid state thin films of polymers A , B , and C emit in near‐infrared region between 723 and 743 nm, and show significantly red shifts (up to 57 nm) in absorption and emission maxima relative to their polymer solution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5354–5366, 2009     

Thermally stable,light‐emitting,triphenylamine‐containing poly(amine hydrazide)s and poly(amine‐1,3,4‐oxadiazole)s bearing pendent carbazolyl groups

A series of new organosoluble poly(amine hydrazide)s were synthesized via the Yamazaki phosphorylation reaction and were solution‐cast into transparent films. Differential scanning calorimetry indicated that the hydrazide polymers could be thermally cyclodehydrated into the corresponding oxadiazole polymers in the range of 300–400 °C. The resulting poly(amine‐1,3,4‐oxadiazole)s exhibited glass‐transition temperatures in the range of 276–297 °C, 10% weight loss temperatures in excess of 520 °C, and char yields at 800 °C in nitrogen higher than 67%. The hole‐transporting and electrochromic properties were examined with electrochemical and spectroelectrochemical methods. Cyclic voltammograms of these polymers prepared by the casting of polymer solutions onto an indium tin oxide coated glass substrate exhibited two reversible oxidative redox couples at 1.10–1.19 and 1.35–1.60 V versus Ag/AgCl in an acetonitrile solution, respectively. The poly(amine hydrazide)s revealed excellent stability of the electrochromic characteristics, changing color from the original pale yellow to green and then to blue. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 48–58, 2007     

Poly(ortho‐phenylene ethynylene)s: Synthetic accessibility and optical properties

Poly(ortho‐phenylene ethynylene)s (PoPEs) have been synthesized via an in situ activation/coupling AB′ polycondensation protocol. The resulting polymers have been characterized by several analytical methods and are shown to have no structural defects. Although the Sonogashira–Hagihara polycondensation reaction is less efficient than for the preparation of the corresponding meta‐ and para‐linked polymers, presumably because of steric hindrance caused by the ortho substituents, the process can be accelerated by the use of microwave irradiation. Optical spectroscopy indicates solvent‐dependent conformational changes between extended transoid and helical cisoid conformations, providing the first experimental evidence for solvophobically driven folding of the PoPE backbone. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1619–1627, 2006     

Study on incomplete fluorescence quenching of cationic poly(p‐phenylenevinylene)s with different contents of cis‐ and trans‐vinylic linkages

Fluorescence properties of a series of cationic poly(p‐phenylenevinylene) (PPV) derivatives with different contents of cis‐ and trans‐vinylic linkages quenched by Fe(CN) were intensively investigated. PPVs with cis‐/trans‐vinylic linkages display downward Stern‐Volmer curves indicating incomplete quenching. The fluorescence quenching mechanism and the effect of many factors possible on the incomplete quenching has been examined, and the difference of the quenching behavior of two isomers was investigated, which further confirmed that the presence of cis‐vinylic linkages would most probably cause inaccessible fluorophores and thus the incomplete quenching. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

New Poly(arylene ethynylene)s Consisting of Electron‐Deficient Aryleneimide Units

Summary: A new class of poly(arylene ethynylene)s (PAEs) containing an electron‐deficient N‐alkylphthalimide unit was prepared by means of a Sonogashira reaction. Complete solubility of the PAEs was observed by utilizing a 2,6‐diisopropylphenyl side chain. The chemical structure of the novel soluble polymer 3c was confirmed by NMR spectra, whereas the insoluble polymers were characterized by elemental analysis and IR spectra. Fluorescence measurements of 3c indicate a rigid structure and high symmetry in the excited state.

     

Synthesis and characterization of eumelanin‐inspired poly(indoylenearylenevinylene)s and poly(indoylenearyleneethynylene)s

Four novel conjugated polymers containing the eumelanin‐inspired indole core have been successfully synthesized using common cross coupling reactions. These polymers differed by the arylene and the carbon–carbon bond linkage. Optoelectronic experiments of these polymers suggest that the ethynylene linkage contributed to the red‐shifted absorption spectra and blue‐shifted emission spectra when compared to the vinylene linkage polymers. Furthermore, the optical bandgaps of the poly(indoylenearyleneethynylene)s (PIAEs) were smaller compared to the poly(indoylenearylenevinylene)s (PIAVs). Surprisingly, the HOMOs of these polymers were less affected by the nature of the carbon–carbon linkage. However, the LUMOs of the PIAEs were lower in comparison to the PIAVs. These eumelanin‐inspired PIAEs and PIAVs are good fluorophores with fluorescence quantum yields ranging from 0.12 to 0.67 and have good thermal stability for applications such as in organic light‐emitting diodes. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 457–463     

Preparation of polypyrrole‐graft‐poly(N‐isopropylacrylamide)/silver nanocomposites from pyrrolyl‐capped macromonomer by AgNO3 and their stimuli responsibility of light emission

Pyrrolyl‐capped poly(N‐isopropylacrylamide) macromonomers (Py‐PNIPAM) were prepared through reversible addition‐fragmentation‐transfer polymerization with benzyl 1‐pyrrolylcarbodithioate as chain‐transfer agent. Polymerizations of Py‐PNIPAM with/without pyrrole using AgNO₃ as oxidizing agent and dimethylforamide as solvent resulted in graft copolymers of polypyrrole‐graft‐poly(N‐isopropylacrylamide) (PPy‐g‐PNIPAM) as well as silver nanoparticles, leading to the formation of PPy‐g‐PNIPAM/silver nanocomposites. The resulting nanocomposites were soluble in water when the content of PPy was low, and when the molar ratio of Py/Py‐PNIPAM increased to 30, the resulting products became insoluble in water. The resulting nanocomposites had special optical properties because of PPy as well as the temperature‐responsible PNIPAM. The chemical structure and composition of nanocomposite were characterized by ¹H nuclear magnetic resonance spectroscopy, gel permeation chromatograms, fourier transform infrared spectroscopy, and X‐ray diffraction. Their optical properties were characterized by UV–vis and fluorescence spectroscopy. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6950–6960, 2008     

Synthesis and properties of low‐dielectric‐constant polyimides with introduced reactive fluorine polyhedral oligomeric silsesquioxanes

A high‐performance, low‐dielectric‐constant polyimide (PI) nanocomposite from poly(amic acid) (PAA) cured with a reactive fluorine polyhedral oligomeric silsesquioxane (POSS) isomer was successfully synthesized. The features of this reactive fluorine POSS isomer [octakis(dimethylsiloxyhexafluoropropylglycidyl ether)silsesquioxane (OFG)] provided two important approaches (containing fluorine or being porous in the polymer matrix) of reducing the dielectric constant of PI. This reactive POSS isomer had an average of four epoxy groups and four fluorine groups on the POSS cage, and the epoxy groups could be cured with PAA to form a network framework of a PI/POSS nanocomposite. The PI/OFG nanocomposite had a high crosslinking density, high porosity (24.3%), high hydrophobicity, and low polarizability. These properties enhanced the thermal (glass‐transition temperature ～ 362 °C) and dielectric (dielectric constant ～2.30) properties of PI more than other POSS derivatives introduced into the PI backbone. A large number of small POSS particles (<10 nm) were embedded inside the PI matrix when the OFG content was low, whereas interconnected POSS aggregation domains were observed when the OFG content was high. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5391–5402, 2006     

Synthesis and characterization of fluorescent poly[fluorene‐co‐phenylene‐1‐(di‐2‐pyridylamine)] copolymer and its Ru(II) complex

2,2′‐dipyridylamine substituted poly(fluorene‐co‐phenylene) copolymers with different concentrations of dipyridylamine have been synthesized by Suzuki polycondensation. These polymers were found to be soluble in organic solvents such as tetrahydrofuran, chloroform, and dimethylformamide. The photoluminescence of the copolymer was slightly blueshifted as the concentration of dipridylamine was increased. The introduction of dipyridylamine and the ruthenium complex into the polymer significantly improved the photoluminescence efficiency. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4838–4846, 2004     

Synthesis of chromo‐ and fluorogenic poly(ortho‐diaminophenylene) chemosensors for fluoride anion

Two new poly(ortho‐diaminophenylene) derivatives containing fluorene and/or quinoxaline moieties per repeat unit in the main chain were synthesized via Suzuki coupling reaction followed by reduction process. The synthesized polymers were characterized and explored as colorimetric and fluorometric anion‐sensing materials. The polymers in dilute tetrahydrofuran (THF) solution emitted green light (about 530 nm) in their precursor benzothiadiazole forms and blue to green light (477–523 nm) in their reduced forms. The color of polymer solution was dramatically altered upon addition of fluoride anion without noticeable absorption change in UV–vis spectrum. The fluorescence was ratiometrically quenched with a linear relationship between fluorescence intensity and fluoride anion concentration implying static quenching mechanism could be applied judging from the maintenance of constant fluorescence lifetime with variable fluoride anion concentration. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1546–1556, 2007     

Photoluminescent energy transfer from poly(phenyleneethynylene)s to near‐infrared emitting fluorophores

Photoluminescent energy transfer was investigated in conjugated polymer‐fluorophore blended thin films. A pentiptycene‐containing poly(phenyleneethynylene) was used as the energy donor, and 13 fluorophores were used as energy acceptors. The efficiency of energy transfer was measured by monitoring both the quenching of the polymer emission and the enhancement of the fluorophore emission. Near‐infrared emitting squaraines and terrylenes were identified as excellent energy acceptors. These results, where a new fluorescent signal occurs in the near‐infrared region on a completely dark background, offer substantial possibilities for designing highly sensitive turn‐on sensors. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3382–3391, 2010     

Single step synthesis of poly(3‐octylthiophene)/multi‐walled carbon nanotube composites and their characterizations

The transport properties of conducting polymers are known to be greatly influenced by the chemical unsaturation surrounding the polymer backbone, besides favorable conformation of the side chains present. Polymeric composites with multi‐walled carbon nanotubes (MWNT) can provide a good conductive path at relatively low carbon contents, as these have high aspect ratio, specific surfaces and are cost effective. Hence their use in various applications such as organic LED, solar cells and supercapacitors are very much anticipated. In this respect poly(3‐octylthiophene)/MWNT composites have been prepared by an “insitu” polymerization process in chloroform medium with FeCl₃ oxidant at room temperature. The composites were characterized by Fourier Transfer Infrared spectroscopy (FT‐IR), Raman, work function and X‐ray diffraction (XRD) measurements. The results indicate only a weak π‐π interaction between the moieties, in the absence of a strong covalent bonding. The ultraviolet–visible (UV–Vis) measurements also support this view. The photoluminescence (PL) quenching indicates the effectiveness of the interface in the formation of the donor–acceptor type composite. The conductivity of the composites is followed by a four probe technique to understand the conduction mechanism. The Hall voltage measurement is followed to monitor carrier concentrations and mobilities. The impressive conductivity and mobility values encourage the utility of the composites as photovoltaic material. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis and characterization of poly(1,4‐bis((E)‐2‐(3‐dodecylthiophen‐2‐yl)vinyl)benzene) derivatives

New amorphous semiconducting copolymers, poly(9,9‐dialkylfluorene)‐alt‐(3‐dodecylthienyl‐divinylbenzene‐3‐dodecylthienyl) derivatives (PEFTVB and POFTVB), were designed, synthesized, and characterized. The structure of copolymers was confirmed by H NMR, IR, and elemental analysis. The copolymers showed very good solubility in organic solvents and high thermal stability with high T_g of 178–185 °C. The weight average molecular weight was found to be 107,900 with polydispersity of 3.14 for PEFTVB and 76,700 with that of 3.31 for POFTVB. UV–vis absorption studies showed the maximum absorption at 428 nm (in solution) and 435 nm (in film) for PEFTVB and at 430 nm (in solution) and 436 nm (in film) for POFTVB. Photoluminescence studies showed the emission at 498 nm (in solution) and 557 nm (in film) for PEFTVB and at 498 nm (in solution) and 536 nm (in film) for POFTVB. The solution‐processed thin‐film transistors showed the carrier mobility of 2 × 10^?4 cm² V^?1 s^?1 for PEFTVB‐based devices and 2 × 10^?5 cm² V^?1 s^?1 for POFTVB‐based devices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3942–3949, 2010     

Synthesis of poly(1‐chloro‐2‐arylacetylene)s with high cis‐content and examination of their absorption/emission properties

A series of 1‐chloro‐2‐arylacetylenes [Cl‐C?C‐Ar, Ar = C₆H₅ ( 1 ), C₆H₄‐p‐i Pr ( 2 ), C₆H₄‐p‐Oi Pr ( 3 ), C₆H₄‐p‐NHC(O)Ot Bu ( 4 ), and C₆H₄‐o‐i Pr ( 5 )] were polymerized using (tBu₃P)PdMeCl/silver trifluoromethanesulfonate (AgOTf) and MoCl₅/SnBu₄ catalysts. The corresponding polymers [poly( 1 )–poly( 5 )] with weight‐average molecular weights of 6,500–690,000 were obtained in 10–91% yields. THF‐insoluble parts, presumably high‐molecular weight polymers, were formed together with THF‐soluble polymers by the Pd‐catalyzed polymerization. The Pd catalyst polymerized nonpolar monomers 1 and 2 to give the polymers in yields lower than the Mo catalyst, while the Pd catalyst polymerized polar monomers 3 and 4 to give the corresponding polymers in higher yields. The ¹H NMR and UV–vis absorption spectra of the polymers indicated that the cis‐contents of the Pd‐based polymers were higher than those of the Mo‐based polymers, and the conjugation length of the Pd‐based polymers was shorter than that of the Mo‐based polymers. Pd‐based poly( 5 ) emitted fluorescence most strongly among poly( 1 )–poly( 5 ). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 382–388     

Synthesis of amphiphilic poly(para‐phenylene)s by Suzuki polycondensation

1,4‐Dibromobenzenes carrying nonpolar hexoxy and polar oligo(ethylene glycol) side chains were subjected to Suzuki polycondensation with a benzene‐1,4‐bisboronic acid ester to produce high‐molar‐mass poly(para‐phenylene)s. The molar masses were determined with size exclusion chromatography with conventional polystyrene and universal calibration. These novel amphiphilically equipped rigid‐rod polymers have the potential to segregate lengthwise into polar and nonpolar domains, a property that has only rarely been described, and promise to exhibit novel interesting supramolecular properties. The oligo(ethylene gylcol) side chains terminate with a silyl‐protected alcohol group, and its deprotection on the polymer was proven to proceed quantitatively. This not only led to a further polarity increase but allows us to attach even more polar (e.g., charged) units in future projects. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2879–2889, 2003     

Synthesis of polymers possessing tetraphenylethylene units by three‐component coupling reactions of poly(p‐phenylene ethynylene) derivative with aryl halides and phenylboronic acid

A derivative of poly(p‐phenylene ethynylene) was subjected to the palladium‐catalyzed three‐component coupling reactions with aryl halides and phenylboronic acid to obtain polymers having tetrasubstituted cis‐vinylene units. For example, 69% of the acetylene units in the prepolymer were converted to cis‐vinylene (i.e., tetrasubstituted cis‐vinylene) units using iodobenzene and phenylboronic acid (5 equiv each with respect to acetylene units). In the UV–vis absorption spectra of the resulting polymers, clear hypsochromic shifts of the absorption maxima were observed, while bathochromic shifts and suppression of the efficiency were observed in their photoluminescence spectra. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 787–791     

Tris[tri(2‐thienyl)phosphine]palladium as the catalyst precursor for thiophene‐based Suzuki‐Miyaura crosscoupling and polycondensation

Zero‐valent palladium complex, Pd(PTh₃)₃, with three tri(2‐thienyl)phosphine ligands was prepared and characterized. Pd(PTh₃)₃ is superior to Pd(PPh₃)₄ in catalyzing Suzuki‐Miyaura coupling and polymerization of thiophene‐based derivatives. The Suzuki polycondensation of 3‐hexyl‐5‐iodothiophene‐2‐boronic pinacol ester with Pd(PTh₃)₃ as the catalyst precursor afforded high‐molecular‐weight P3HT with high regularity and yield. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4556–4563, 2008