Conjugated Polymers Atypically Prepared in Water

Processability remains a fundamental issue for the implementation of conducting polymer technology. A simple synthetic route towards processable precursors to conducting polymers (main chain and side chain) was developed using commercially available materials. These soluble precursor systems were converted to conjugated polymers electrochemically in aqueous media, offering a cheaper and greener method of processing. Oxidative conversion in aqueous and organic media each produced equivalent electrochromics. The precursor method enhances the yield of the electrochromic polymer obtained over that of electrodeposition, and it relies on a less corruptible electrolyte bath. However, electrochemical conversion of the precursor polymers often relies on organic salts and solvents. The ability to achieve oxidative conversion in brine offers a less costly and a more environmentally friendly processing step. It is also beneficial for biological applications. The electrochromics obtained herein were evaluated for electronic, spectral, and morphological properties.     

Synthesis and optical and electrochemical properties of novel copolymers containing alternating 2,3‐divinylquinoxaline and hole‐transporting units

For the enhancement of charge affinity, electron‐affinitive 2,3‐divinylquinoxaline and a series of hole‐transporting chromophores (iminodibenzyl, phenothiazine, dihexyloxybenzene, and didodecyloxydistyrylbenzene) were incorporated alternately into the polymeric main chain. The resulting copolymers ( P1 – P4 ) were basically amorphous materials and were thermally stable below 300 °C. The electronic structures, photoluminescence, and electrochemical properties of these copolymers were mainly determined by the electron‐donating chromophores in the backbone. They showed significant positive solvatochromism in formic acid. An electrochemical study revealed that they exhibited lower band gaps (<2.3 eV) due to alternating donor and acceptor conjugated units (push–pull structure). Single‐layer light‐emitting diodes of aluminum, P1 – P4 , and indium tin oxide glass were fabricated, and preliminary electroluminescence spectra showed that P1 , P3 , and P4 were orange‐emitting materials. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4570–4580, 2002     

Poly(DCAQI): Synthesis and characterization of a new redox‐active polymer

Redox‐active anthraquinone based polymers are synthesized by the introduction of a polymerizable vinyl and ethynyl group, respectively, resulting in redox‐active monomers, which electrochemical behaviors are tailored by the modification of the keto groups to N‐cyanoimine moieties. These monomers can be polymerized by free radical polymerization and Rh‐catalyzed polymerization methods, respectively. The resulting polymers are obtained in molar masses (M_n) of 4,400 to 16,800 g mol^?1 as well as high yields of up to 97%. The monomers and polymers are furthermore electrochemically characterized by cyclic voltammetry. The monomers exhibit two one‐electron redox reactions at about ?0.6 and ?1.0 V versus Fc⁺/Fc. The N‐cyanoimine units are, however, partially hydrolyzed during the polymerization step or during the electrochemical measurements and degenerate to carbonyl groups, resulting in a new reduction signal at ?1.26 V versus Fc⁺/Fc. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1998–2003     

Synthesis,optical and electrochemical properties of arylenevinylene‐based π‐conjugated polymers with imidazolium units in the main chain

Arylenevinylene‐based π‐conjugated polymers containing imidazolium cationic units in the main chain and their model compounds were synthesized and characterized in terms of optical and electrochemical properties. 9,9‐Bisoctylfluorene, 2,5‐bisdodecyloxybenzene, and 3‐dodecylthiophene were introduced as arylene units with different donor characteristics to evaluate the effect on the highest occupied molecular orbital‐lowest unoccupied molecular orbital (HOMO‐LUMO) gap energy. The UV–vis and fluorescence spectra of cationic polymers and model compounds with iodide counter anion exhibited a significant blue shift with respect to the parent neutral molecules. X‐ray single crystal analysis for model compounds revealed that the effective π‐conjugation length of cationic model compounds decreased compared to the neutral model compounds by means of twisted conformation directed by CH‐π interactions between N‐methyl groups of imidazolium and neighboring aryl units. The cyclic voltammetry measurement suggested the negative shift of LUMO levels by the conversion of imidazole to imidazolium, indicating the electron‐accepting characteristics of cationic imidazolium unit. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Facile Synthesis of Chiral Conjugated Polymer Based on BINOL Skeleton

The study of polymer supported chiral catalysts has attracted very extensive attention inrecent years'. The intrinsic advantages of these catalysts in organic synthetic chemistryare that they can be separated with the products by simple filtration. Traditionally,polymer chiral catalysts are prepared by allaching chiral ligand to sterically irregularpolymer backbone2. In this system, the catalytic sites are randomly oriented along thepolymer chain which makes it very difficult to systematically…     

New ladder‐type conjugated polymer containing carbazole and fluorene units in backbone: Synthesis,optical, and electrochemistry properties

This article describes the synthesis and characterization of a new ladder‐type poly (p‐phenylene) (LPFC) containing alkylcarbazole and dialkylfluorene units in backbone, and its optical and electrochemical properties as well as its light‐emitting device performance. LPFC shows the well‐defined structure, high molecular weights, excellent thermal stability, and good solubility in common organic solvents. And it also shows strongly blue emission (λ_max = 465 nm) with quantum efficiency of 70% in solution, while its solid emission (λ_max = 470 nm) is almost the same as its solution. Electrochemical studies show that the highest occupied molecular orbital (HOMO) energy levels of LPFC is up to 5.29 eV, which is significantly higher than that of LPPP without carbazole in backbone, indicating an enhanced ability of hole injection from anodes. Furthermore, the single layer light‐emitting device using LPFC as the active layer shows blue emission (λ_max = 470 nm) with maximum luminescence of ～ 2000 cd/m² and maximum luminance efficiency of 0.43 cd/A. The attractive properties exhibited from new ladder‐type polymer establish LPFC as a good candidate for the potential application as transporting and emitting layer in polymeric light emitting diodes. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3120–3127, 2008     

Synthesis and properties of polythiophene derivatives containing triphenylamine moiety and their photovoltaic applications

A series of novel soluble polythiophene derivatives containing triphenylamine moiety were synthesized by Grignard metathesis (GRIM) method. The structures of the polymers were characterized and their physical properties were investigated. High molecular weight (M_n up to 25,800 g/mol) and thermostable polymers were obtained. The absorption spectra demonstrated that the absorption wavelength of the polymers could be tuned dramatically by introducing thiophene units in the main chain of the polymers. Photoluminescence spectra indicated that there was intramolecular energy transfer from the side chain to the main chain, and the maximum emission was red‐shifted gradually with the increase of thiophene units in the main chain. Cyclic voltammetry displayed that the polymers possessed relatively high oxidation potential, which promised good air stability and high open circuit voltage for photovoltaic cells application. Finally, bulk heterojunction photovoltaic devices were fabricated by using the polymers as donors and (6,6)‐phenyl C₆₁‐butyric acid methyl ester (PCBM) as acceptor. The maximal open circuit voltage of the photovoltaic cells reached 0.71–0.87 V and the power conversion efficiencies of the devices were measured between 0.014% and 0.45% under white light at 100 mW/cm². © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3970–3984, 2008     

Electrochemical fluorescence switching properties of conjugated polymers composed of triphenylamine,fluorene, and cyclic urea moieties

The study of the electrochemical fluorescence switching properties of the conjugated copolymers containing fluorene, triphenylamine, and 1,3‐diphenylimidazolidin‐2‐one moieties is reported. The polymers show high fluorescence quantum yields, excellent thermal stability, and good solubility in polar organic solvents. While the polymer emits blue light under UV irradiation, the fluorescence intensity is quenched upon electrochemical oxidation. The fluorescent behavior can be reversibly switched between nonfluorescent (oxidized) state and strong fluorescence (neutral) state with a high contrast ratio (I_f/I_f0) of 16.3. The role of the electrochemical oxidation of the triphenylamine moieties is to generate the corresponding radical cations that lead to fluorescence quenching in the solid matrix. © 2012 Wiley Periodicals, Inc. J. Polym. Sci. Part A: Polym Chem, 2012     

New Azo Chromophore‐Containing Conjugated Polymers: Facile Synthesis by Using “Click” Chemistry and Enhanced Nonlinear Optical Properties Through the Introduction of Suitable Isolation Groups

A new series of azobenzene‐containing polyfluorenes have been successfully prepared through polymer reactions by the utilization of “click” chemistry. All the polymers were well characterized and soluble in common solvents. By the application of the concept of “suitable isolation group”, the macroscopic nonlinear optical (NLO) properties of the polymers could be boosted to as large as three times that of the polymer without isolation moieties. Also, all the polymers were thermally stable, and demonstrated good procesability, coupled with improved optical transparency. Thus, they are good candidates for the practical applications as new photonic materials.

     

Synthesis and characterization of fluorene and cyclopentadithiophene‐based copolymers exhibiting broad absorption for photovoltaic devices

In this study, two low bandgap copolymers composed of fluorene (Fl), cyclopentadithiophene (CDT), and 4,7‐bis(2‐thienyl)‐2,1,3‐benzothiadiazole (DBT) were synthesized, and their optical, electrochemical, and photovoltaic (PV) characteristics were investigated for applications in PV devices. The feed ratio of the Fl and CDT moieties was modulated to tune the electronic structures and resulting optical properties of the polymers. In the copolymeric structures, the Fl‐CDT unit absorbs the short‐wavelength UV/vis regions, and the CDT‐DBT (or Fl‐DBT) unit with strong intramolecular charge transfer characteristics covers the long‐wavelength visible regions. P1 exhibited a wide UV absorption spectrum covering the UV and entire visible region in the range of 300–800 nm, and P2 showed absorption covering from 300 to 700 nm. UV/vis and electrochemical studies confirmed the desirable highest occupied molecular orbital/lowest unoccupied molecular orbital levels of the copolymers with bandgaps of 1.62–1.86 eV, enabling efficient electron transfer and a high open‐circuit voltage when blending them with fullerene derivatives. When the polymers were blended with [6,6]phenyl‐C₆₁‐butyric acid methyl ester, P1 exhibited the best device performance with an open‐circuit voltage of 0.66 V, short‐circuit current of 4.92 mA cm^?2, and power conversion efficiency of 1.13% under Air Mass 1.5 Global (AM 1.5G, 100 mW cm^?2) illumination. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Alkyne‐Linked Poly(1,8‐carbazole)s: A Novel Class of Conjugated Carbazole Polymers

Novel conjugated carbazole polymers based on the alkyne‐linked 1,8‐carbazole structure are synthesized in high yield by the Sonogashira cross‐coupling reaction and acetylenic oxidative coupling reaction. The polymers are thermally stable and highly soluble in common organic solvents such as CHCl₃, CH₂Cl₂, and THF. As compared to ethynylene‐linked polymer, the butadiynylene‐linked polymer display a bathochromic shift in the absorption maximum and end absorption position. In addition, the fluorescence behaviors in CH₂Cl₂ are almost identical for both polymers. Electrochemical measurements indicate that the ethynylene‐linked polymer possesses a lower first oxidation potential than the butadiynylene‐linked one.

     

New π‐Conjugated Polymers Containing 1,3,5‐Triazine Units in the Main Chain: Synthesis and Optical and Electrochemical Properties of the Polymers

Summary: Three new soluble π‐conjugated polymers containing 1,3,5‐triazine units in the main chain, Pa–Pc, were synthesized. The polymers showed optical properties in solution that were mainly dependant on the properties of the substituting R groups, on the triazine ring. Hence, Pa and Pb (R = H and  OCH₃, respectively) showed blue photoluminescent (PL) emission with high quantum yields (QY) even in polar solvents, whereas Pc (R = N,N‐dimethylamino) gave green‐blue PL emission with very low QY. The PL spectra of the polymers in solution were concentration and polarity dependent, which suggested the formation of an exciplex.

The three new soluble π‐conjugated polymers containing 1,3,5‐triazine units in the main chain synthesized here.     

Electrochromic material containing unsymmetrical substituted N,N,N′,N′‐tetraaryl‐1,4‐phenylenediamine: Synthesis and their optical,electrochemical, and electrochromic properties

A novel dibromo compound containing unsymmetrical substituted bi‐triarylamine was synthesized. A conjugated polymer was prepared via the Suzuki coupling from the newly prepared dibromo compound and 9,9‐dioctylfluorene‐2,7‐bis(trimethyleneboronate). The glass transition temperature (T_g) of the conjugated polymer was 140 °C, 10% weight‐loss temperatures (T_d10) in nitrogen was 458 °C, and char yield at 800 °C in nitrogen higher than 64%. Cyclic voltammogram of the polymer film cast onto an indium‐tin oxide (ITO)‐coated glass substrate exhibited two reversible oxidation redox couples at 0.70 and 1.10 V versus Ag/Ag⁺ in acetonitrile solution. The polymer films revealed excellent stability of electrochromic characteristics, with a color change from yellow green of the neutral form to the dark green and blue of oxidized forms at applied potentials ranging from 0 to 1.3 V. The color switching time and bleaching time were 4.25 and 7.22 s for 860 nm and 5.51 s and 6.48 s for 560 nm. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1469–1476, 2010     

Synthesis and Photovoltaic Properties of Ester Group Functionalized Polythiophene Derivatives

To increase the open circuit voltage (V_OC) of polymer solar cells (PSCs) based on polythiophene, two new ester group functionalized polythiophene derivatives, PCTDT and PCTBDT, were designed and synthesized via alternating copolymerization of thiophene‐3‐carboxylate (CT) with the 2,2′‐bithiophene (DT) and benzodithiophene (BDT) units, respectively. The resulting copolymers exhibited broad and strong absorptions in the visible region, which was similar to that of the commonly used poly(3‐hexylthiophene) (P3HT). Through cyclic voltammetry measurements, it was found that both copolymers showed lower HOMO energy levels (−5.27 eV for PCTDT and −5.36 eV for PCTBDT) than that of P3HT (−5.03 eV), indicating that the HOMO energy level could be efficiently reduced by introducing the ester group into the polymer side chain. Photovoltaic properties of the copolymers blended with [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PCBM) as electron acceptor were investigated. The obtained two devices possessed both relatively large short circuit current (I_SC) and higher V_OC than that of P3HT:PCBM blend. For PCTBDT:PCBM blend, a power conversion efficiency (PCE) up to 2.32%, an I_SC of 6.94 mA · cm⁻², and a V_OC of 0.80 V were observed while PCTDT:PCBM system demonstrated a PCE of 1.75% with a V_OC of 0.68 V.

     

Synthesis and characterization of cyclopentadithiophene‐based low bandgap copolymers containing electron‐deficient benzoselenadiazole derivatives for photovoltaic devices

We have synthesized two cyclopentadithiophene (CDT)‐based low bandgap copolymers, poly[(4,4‐bis(2‐ethyl‐hexyl)‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl)‐alt‐(benzo[c][1,2,5]selenadiazole‐4,7‐diyl)] (PCBSe) and poly[(4,4‐bis(2‐ethyl‐hexyl)‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl)‐alt‐(4,7‐dithiophen‐2‐yl‐benzo[c][1,2,5]selenadiazole‐5,5′‐diyl)] (PCT2BSe), for use in photovoltaic applications. Through the internal charge transfer interaction between the electron‐donating CDT unit and the electron‐accepting benzoselenadiazole, we realized exceedingly low bandgap polymers with bandgaps of 1.37–1.46 eV. The UV–vis absorption maxima of PCT2BSe were subjected to larger hypsochromic shifts than those of PCBSe, because of the distorted electron donor–acceptor (D–A) structures of the PCT2BSe backbone. These results were supported by the calculations of the D–A complex using the ab initio Hartree‐Fock method with a split‐valence 6‐31G* basis set. However, PCT2BSe exhibited a better molar absorption coefficient in the visible region, which can lead to more efficient absorption of sunlight. As a result, PCT2BSe blended with [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM) exhibited a better photovoltaic performance than PCBSe because of the larger spectral overlap integral with respect to the solar spectrum. Furthermore, when the polymers were blended with PC₇₁BM, PCT2BSe showed the best performance, with an open circuit voltage of 0.55 V, a short‐circuit current of 6.63 mA/cm², and a power conversion efficiency of 1.34% under air mass 1.5 global illumination conditions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1423–1432, 2010     

New copolymers with thieno[3,2‐b]thiophene or dithieno[3,2‐b:2′,3′‐d]thiophene units possessing electron‐withdrawing 4‐cyanophenyl groups: Synthesis and photophysical,electrochemical, and electroluminescent properties

New monomers containing 4‐cyanophenyl (–PhCN) groups attached to a thieno[3,2‐b]thiophene (TT) or dithieno[3,2‐b:2′,3′‐d]thiophene (DTT) structure were synthesized and characterized as 4‐(2,5‐dibromothieno[3,2‐b]thiophen‐3‐yl)benzonitrile (Br–TT–PhCN) or 4,4′‐(2,6‐dibromodithieno[3,2‐b:2′,3′‐d]thiophene‐3,5‐diyl)dibenzonitrile (Br–DTT–PhCN). The Suzuki coupling of 9,9‐dioctylfluorene‐2,7‐diboronic acid bis(1,3‐propanediol)ester and the Br–TT–PhCN or Br–DTT–PhCN monomer was utilized for the syntheses of novel copolymers poly{9,9‐dioctylfluorene‐2,7‐diyl‐alt‐3‐(4′‐cyanophenyl)thieno[3,2‐b]thiophene‐2,5‐diyl} (PFTT–PhCN) and poly{9,9‐dioctylfluorene‐2,7‐diyl‐alt‐3,5‐bis(4′‐cyanophenyl)dithieno[3,2‐b:2′,3′‐d]thiophene‐2,6‐diyl} (PFDTT–PhCN), respectively. The photophysical, electrochemical, and electroluminescent (EL) properties of these novel copolymers were studied. Their photoluminescence (PL) exhibited the same emission maximum for both copolymers in solution. Red‐shifted PL emissions were observed in the thin films. The PL emission maximum of PFTT–PhCN was more significantly redshifted than that of PFDTT–PhCN, indicating more pronounced excimer or aggregate formation in PFTT–PhCN. The ionization potential (HOMO level) and electron affinity (LUMO level) values were 5.54 and 2.81 eV, respectively, for PFTT–PhCN and were 5.57 and 2.92 eV, respectively, for PFDTT–PhCN. Polymer light‐emitting diodes (LEDs) with copolymer active layers were fabricated and studied. Anomalous behavior and memory effects were observed from the current–voltage characteristics of the LEDs for both copolymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2629–2638     

水溶性含糖共轭聚合物的制备及应用

水溶性共轭聚合物具有优异的光学稳定性、高亮度、易于修饰和水溶性等特点,广泛应用于离子检测、蛋白检测和生物成像等领域。水溶性共轭聚合物主要通过在共轭聚合物的侧基或端基修饰水溶性的离子基团或水溶性聚合物实现其水溶性,水溶性共轭聚合物还可以通过引入功能性基团或聚合物使其具备不同的功能特性。糖化合物是天然存在的一类生物分子且大部分具有水溶性的特点,因此最近十几年来科研工作者将糖化合物引入共轭聚合物中以赋予共轭聚合物糖化合物的生物功能特性。本文总结了水溶性含糖共轭聚合物的制备方法、化学结构及其在凝集素、细菌检测和细胞荧光成像中的应用。最后总结了此类聚合物的特性、发展方向及目前所需解决的问题。     

Statistical Conjugated Polymers Comprising Optoelectronically Distinct Units

Poly(3‐heptylselenophene)‐stat‐poly(3‐hexylthiophene) is synthesized and characterized in terms of its crystallinity and performance in an organic photovoltaic (OPV) cell. Despite the random distribution of units along the polymer main chain, the material is semi‐crystalline, as demonstrated by differential scanning calorimetry and wide‐angle X‐ray diffraction. Thin‐film absorption suggests an increased compatibility than seen with 3‐hexylselenophene monomer. Optoelectronic properties are an average of the two homopolymers, and OPV performance is enhanced by a broadened absorption profile and a favorable morphology.     

Conformation Control of Conjugated Polymers

In the past few decades, conjugated polymers have aroused extensive interest in organic electronic applications. The electrical performance of conjugated polymers has a close relationship with their backbone conformation. The conformation of the polymer backbone strongly affects the πelectron delocalization along polymer chains, the energy band gap, interchain interactions, and further affects charge transport properties. To realize a rigid coplanar backbone that usually possesses efficient intrachain charge transport properties and enhanced π–π stackings, such conformation control becomes a useful strategy to achieve high-performance (semi)conducting polymers. This minireview summarizes the most important polymer structures through conformation control at the molecular level, and then divides these rigid coplanar conjugated polymers into three categories: 1) noncovalent interactions locked conjugated polymers; 2) double-bond linked conjugated polymers; 3) ladder conjugated polymers. The effect of the conformation control on physical nature, optoelectronic properties, and their device performance is also discussed, as well as the challenges of chemical synthesis and structural characterization.     

A Novel Conjugated Polymer Consists of Benzimidazole and Benzothiadiazole: Synthesis,Photophysics Properties,and Sensing Properties for Pd2+

A conjugated polymer PPBIBTE based on benzimidazole and benzothiadiazole was synthesized through palladium-catalyzed sonogashira cross-coupling reaction. The chemical structures of the monomers and the polymer were indicated by ¹H NMR, and investigation of photophysics properties and sensing optical properties for metal ions were observed by ultraviolet–visible and photoluminescence spectroscopy. PPBIBTE showed remarkable selectivity for Pd²⁺ by “turn-off” fluorescence sensing progress. In addition, the Stern–Volmer and Benesi-Hildebrand plots were used to reveal the interaction between the polymer and Pd²⁺, while job's method was applied to calculate the determination of stoichiometry. The results demonstrate that PPBIBTE can utilize static quenching for Pd²⁺ by forming a 1:1 complex. And it is a potential sensing material as fluorescence chemosensor for Pd²⁺ with high selectivity and sensitivity. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 831-842