Multichromic benzimidazole‐containing polymers: Comparison of donor and acceptor unit effects

This study reports a comparative study on electrochromic properties of two donor–acceptor–donor (DAD)‐type polymers namely poly(2‐heptyl‐4,7‐di(thiophen‐2‐yl)‐1H‐benzo [d]imidazole) (BImTh) and poly(4,7‐bis(2,3‐dihydrothieno[3,4‐b] [1,4]dioxin‐5‐yl)‐2‐heptyl‐1H‐benzo[d]imidazole) (BImEd). DAD‐type monomers were polymerized electrochemically on indium tin oxide‐coated glass slides to determine the optical properties of the polymers. Electrochemical p‐doping experiments were performed to determine the band gap and absorption band values of the polymer films at different redox states. Polymerization of BImTh and BImEd yields multichromic polymers. Donor and acceptor effects are studied by comparing the PBImEd and PBImTh with corresponding benzotriazole derivatives. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Preparation of novel photoreactive polycarbazole‐based microparticles: Reactivity features

Four types of innovative benzophenone (BPh)‐ or aryl azide (ArAz)‐containing photoreactive polycarbazole (polyCbz)‐based microparticles (MPs) were prepared using an oxidative liquid phase polymerization system. Their photochemical reactivity was evaluated by their reaction with highly inert poly(2‐chloro‐paraxylelene) (Parylene C) films. Possible mechanisms for the photochemical reaction of those MPs with Parylene C were discussed. The highly photoreactive BPh was found to react more inside the particle causing internal cross‐linking of MP polyCbz chains, fusion between adjoining particles and deformation of their spherical structure. In contrast, the less reactive but more selective ArAz‐containing MPs were found to react much more with Parylene C. The strong reactivity of such photoreactive MPs toward Parylene C films emphasizes a general method for the functionalization of stable nonfunctional polymeric coatings. This paves the way to simple and solvent‐free functionalization of nonfunctional coatings and materials by light. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Postfunctionalization of poly(propargyl methacrylate) using copper catalyzed 1,3‐dipolar Huisgen cycloaddition: An easy route to electro‐optic materials

A one‐pot synthetic route based on copper‐catalyzed Huisgen reaction has been developed to functionalize a methacrylate propargylic polymer with azido‐substituted moieties. This procedure was used for the preparation of electro‐optic materials containing well‐known Disperse Red One (DR1) chromophores along with bulky adamantyl moieties (Adam). The postfunctionalization of the propargylic polymer was successfully achieved using different molar ratios of DR1/Adam. These novel polymers exhibit high glass transition temperature owing to the rigid structure of adamantyl units. Moreover, the second harmonic generation measurements demonstrated the effectiveness of adamantyl groups to act as insulating shield limiting thus the electrostatic interactions between chromophores. Indeed, higher optimal chromophore concentration (50 mol %) than in conventional DR1‐containing polymers (30 mol %) allowed us to increase the d₃₃ coefficient up to 92 pm/V. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5652–5660, 2009     

Conjugated polymer‐functionalized graphite oxide sheets thin films for enhanced photovoltaic properties of polymer solar cells

In this study, the maleimide‐thiophene copolymer‐functionalized graphite oxide sheets (PTM21‐GOS) and carbon nanotubes (PTM21‐CNT) were developed for polymer solar cell (PSC) applications. The grafting of PTM21‐OH onto the CNT and GO sheets was confirmed using FTIR spectroscopy. PTM21‐CNT and PTM21‐GOS exhibited excellent dispersal behavior in organic solvents. Better thermal stability was observed for PTM21‐CNT and PTM21‐GOS as compared with that for PTM21‐OH. In addition, the optical band gaps of PTM21‐GOS and PTM21‐CNT were lower than that of PTM21‐OH. We incorporated PTM21‐GOS and PTM21‐CNT individually into poly(3‐hexylthiophene) (P3HT)/[6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PCBM) blends for use as photoconversion layers of PSCs. Good distributional homogeneity was observed for PTM21‐GOS or PTM21‐CNT in the P3HT/PCBM blend film. The UV–vis absorption peaks of the blend films red‐shifted slightly upon increasing the content of PTM21‐GOS or PTM21‐CNT. The band gap energies and LUMO/HOMO energy levels of the P3HT/PTM21‐GOS and P3HT/PTM21‐CNT blend films were slightly lower than those of the P3HT film. The conjugated polymer‐functionalized PTM21‐GOS and PTM21‐CNT behaved as efficient electron acceptors and as charge‐transport assisters when incorporated into the photoactive layers of the PSCs. PV performance of the PSCs was enhanced after incorporating PTM21‐GOS or PTM21‐CNT in the P3HT/PCBM blend. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Influence of molecular weight on the short‐channel effect in polymer‐based field‐effect transistors

In this study, we demonstrate how the intrinsic properties of a polymer can influence the electrical characteristics of organic field‐effect transistors (OFETs). OFETs fabricated with three batches of poly[2‐methoxy,5‐(3′,7′‐dimethyl‐octyloxy)]‐p‐phenylene vinylene (MDMO‐PPV) were investigated. The properties of the polymers were initially investigated using Fourier transform infrared spectroscopy (FTIR), impedance spectroscopy (IS), gel permeation chromotography (GPC), and cyclic voltammetry (CV), respectively. The structure and purity of the polymer batches were found to be very comparable, but the molecular weight (M_n and M_w) and polydispersity (PDI = M_w/M_n), varied between the samples and the HOMO and LUMO levels of the polymers were found to depend on the molecular weight properties. OFETs were then fabricated with the polymers and electrically characterized. It was observed that the channel current and the field‐effect mobility increase with increasing polymer molecular weight. The output characteristics of the transistors, on the other hand, were found to depend on the PDI of the polymer. Saturation of the channel current occurs at higher source–drain voltages and short‐channel behavior was observed to start at longer channel lengths for polymers with a higher PDI. This behavior is observed to be thickness dependent, and the short‐channel behavior was more pronounced for thicker MDMO‐PPV films. These results are explained in terms of influences of chain packing and ordering and high bulk currents on the FET output and transistor parameters. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 50: 117–124, 2012     

Self‐Rolled Polymer Tubes: Novel Tools for Microfluidics,Microbiology, and Drug‐Delivery Systems

Recent work on the fabrication of tubular microstructures via self‐rolling of thin, bilayer polymer films is reviewed. A bending moment in the films arises due to the swelling of one component of the bilayer in a selective solvent. The inner diameters of the tubes vary from hundreds of nanometers to dozens of micrometers. The position of the tubes on the substrate and their length can be preset by photolithographic patterning of the bilayer. Prior to rolling, the bilayers can be exposed to different methods of surface functionalization, providing opportunities for engineering the microtube inner surfaces for use in microfluidic circuits and “microbiological” applications. The self‐rolling approach is promising for the development of novel drug‐ and cell‐delivery systems, as well as for tissue engineering.     

2,3‐bis(5‐Hexylthiophen‐2‐yl)‐6,7‐bis(octyloxy)‐5,8‐di(thiophen‐2‐yl) quinoxaline: A good construction block with adjustable role in the donor‐π‐acceptor system for bulk‐heterojunction solar cells

Three 2,3‐bis(5‐hexylthiophen‐2‐yl)‐6,7‐bis(octyloxy)‐5,8‐di(thiophen‐2‐yl)‐quinoxaline ( BTTQ )‐based conjugated polymers, namely, PF‐BTTQ ( P1 ), PP‐BTTQ ( P2 ), and PDCP‐BTTQ ( P3 ), were successfully synthesized for efficient polymer solar cells (PSCs) with electron‐rich units of fluorene and dialkoxybenzene and electron‐deficient unit dicyanobenzene, respectively. All the polymers exhibited good solubility in common organic solvents and good thermal stability. Their deep‐lying HOMO energy levels enabled them good stability in the air and the relatively low HOMO energy level assured a higher open circuit potential when used in PSCs. Bulk‐heterojunction solar cells were fabricated using these copolymers blended with a fullerene derivative as an acceptor. All of them exhibited promising performance, and the best device performance with power conversion efficiency up to 3.30% was achieved under one sun of AM 1.5 solar simulator illumination (100 mW/cm²). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Construction of hydroxyl‐terminated poly(N‐isopropylacrylamide) brushes on silicon wafer via surface‐initiated atom transfer radical polymerization

Surface‐initiated atom transfer radical polymerization (SI‐ATRP) of N‐isopropylacrylamide (NIPAM) on silicon wafer in the presence of 2‐mercaptoethanol (ME) chain transfer agent was conducted in attempt to create controllable hydroxyl‐terminated brushes. The initiator‐immobilized substrate, was prepared by the esterification of hydroxyl groups on silicon wafer with 2‐bromopropionyl bromide (2‐BPB); followed by the ATRP of NIPAM using a catalyst system, that is, Cu(I)Br/2,2′‐bipyridine (2,2′‐bpy) and a chain transfer agent, that is, ME. The formation of homogeneous tethered poly(N‐isopropylacrylamide) (poly(NIPAM) brushes with hydroxyl end‐group, whose thickness can be tuned by chancing ME concentration, is evidenced by using the combination of grazing angle attenuated total reflectance‐Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, ellipsometry, atomic force microscopy, gel permeation chromatography, and water contact‐angle measurements. The calculation of grafting parameters from experimental measurements indicated the synthesis of densely grafted poly(NIPAM) films with hydroxyl end‐group on silicon wafer and allowed us to predict a ME concentration for forming a “brush” conformation for the chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3880–3887, 2010     

Dithieno[2,3‐d:2',3'‐d']benzo[1,2‐b:4,5‐b']dithiophene (DTBDAT)‐based copolymers for high‐performance organic solar cells

P(BDT‐TCNT) and P(DTBDAT‐TCNT) , which has an extended conjugation length, were designed and synthesized for applications in organic solar cell (OSCs). The solution absorption maxima of P(DTBDAT‐TCNT) with the extended conjugation were red‐shifted by 5–15 nm compared with those of P(BDT‐TCNT) . The optical band gaps and highest occupied molecular orbital (HOMO) energy levels of both P(BDT‐TCNT) and P(DTBDAT‐TCNT) were similar. The structure properties of thin films of these materials were characterized using grazing‐incidence wide‐angle X‐ray scattering and tapping‐mode atomic force microscopy, and charge carrier mobilities were characterized using the space‐charge limited current method. OSCs were formed using [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM) as the electron acceptor and 3% diphenylether as additive suppress aggregation. OSCs with P(BDT‐TCNT) as the electron donor exhibited a power conversion efficiency (PCE) of 4.10% with a short‐circuit current density of J_SC = 9.06 mA/cm², an open‐circuit voltage of V_OC = 0.77 V, and a fill factor of FF = 0.58. OSCs formed using P(DTBDAT‐TCNT) as the electron donor layer exhibited a PCE of 5.83% with J_SC = 12.2 mA/cm², V_OC = 0.77 V, and FF = 0.62. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3182–3192     

Structural characterization and gas‐transport properties of brominated matrimid polyimide

The commercial polyimide Matrimid was modified by bromination for the purpose of improving its membrane‐transport properties as a gas‐separation material and providing functional group reactivity for further modifications. The unmodified and brominated polymers were characterized by elemental analysis and one‐dimensional and two‐dimensional NMR, which revealed that one bromine atom per repeat unit was incorporated regioselectively onto the indane aromatic ring. The thermal and physical properties of the polymers before and after bromination were also investigated. The gas‐transport properties of the unmodified and brominated polymers were compared. © 2002 Government of Canada. Exclusive worldwide publication rights in the article have been transferred to Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4193–4204, 2002     

Synthesis and electrochromic performance of oligoaniline‐containing polyureas capped with various functional groups

Tuning the molecular structure is an effective strategy to modulate the electrochromic behaviors of conducting polymers. In this contribution, a novel oligoaniline‐containing polyurea ended with reactable isocyanate groups is designed and synthesized via nucleophilic polymerization. Then various functional groups such as o‐toluidine, poly(ethylene glycol) (PEG), ethoxysilane, and congo red (CR) are introduced as end groups to modulate the electrochromic performance. Hydrophilic PEG could improve the switching speed due to the rapid electrolyte ions diffusion into polymer film through the hydrophilic region. An enhanced switching stability is afforded by crosslinkable ethoxysilane end groups, ascribed to crosslinked densified surface and great adhesion force between the electrochromic layer and ITO substrate through the hydrolysis reaction. Moreover, an ample color change is achieved by introducing colored CR as end groups. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 412–419     

A facile synthesis of catechol‐functionalized poly(ethylene oxide) block and random copolymers

Herein we develop a facile synthetic strategy for the functionalization of well‐defined polyether copolymers with control over the number and location of catechol groups. Previously, the functionalization of polyethylene oxide (PEO)‐based polymers with catechols has been limited to functionalization of the chain ends only, hampering the synthesis of adhesive and antifouling materials based on this platform. To address this challenge, we describe an efficient and high‐yielding route to catechol‐functionalized polyethers, which could allow the effects of polymer architecture, molecular weight, and catechol incorporation on the adhesive properties of surface‐anchored PEO to be studied. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2685–2692     

Synthesis of medium‐bandgap π‐Conjugated polymers based on isomers of 5‐Alkylphenanthridin‐6(5H)‐one and 6‐Alkoxylphenanthridine

Two novel dibromo monomers consisting of the isomers of 5‐alkylphenanthridin‐6(5H)‐one (PN) and 6‐alkoxylphenanthridine (PO) were synthesized through alkylation of the precursor 3,8‐dibromophenanthrindi‐6(5H)‐one, where the molecular structures were confirmed by NMR spectroscopy. The medium bandgap conjugated polymers PDBTPN and PDBTPO were constructed by utilizing such two isomers PN and PO as the electron‐donating units and dithiophenebenzo[2,1,3]diathiazole as the electron‐accepting unit. The resulting polymers exhibited analogous absorption profiles with optical bandgap of 1.90 eV, while PDBTPO showed slightly higher absorption coefficiency. Cyclic voltammetry measurements revealed that these polymers had relatively deep highest occupied molecular orbital levels of about ?5.70 eV. Polymer solar cells based on such two polymers showed relatively high open‐circuit voltage of about 0.90 V. All devices exhibited moderate performances with the best power conversion efficiency of 3.77% achieved based on PDBTPO. Devices based on PDBTPO showed slightly higher power conversion efficiency than those based on PDBTPN, which can be ascribed to higher hole mobility and more favorable film morphology of the former. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2119–2127     

Effect of different matrices and nanofillers on the rheological behavior of polymer‐clay nanocomposites

In this work, a comprehensive study of the rheological behavior under shear and isothermal and nonisothermal elongational flow of low density polyethylene (LDPE) and ethylene‐vinyl acetate copolymer (EVA) based nanocomposites was reported to evaluate their “filmability”, that is, the ability of these material to be processed for film forming applications. The influence of two different kinds of organoclay – namely Cloisite 15A and Cloisite 30B – and their concentration was evaluated. The presence of filler clearly affects the rheological behavior in oscillatory state of polyolefin‐based nanocomposites but the increase of complex viscosity and the shear thinning are not dramatic. A larger strain‐hardening effect in isothermal elongational flow is shown by the nanocomposites compared to that of the pure matrix, particularly for EVA based nanocomposites. The melt strength measured under nonisothermal elongational flow increases in the presence of the nanofiller, while the drawability is only slightly lower than that measured for the neat matrix. Moreover, the rheological behavior under nonisothermal elongational flow of EVA‐based nanocomposites is similar for both nanoclays used. Differently, LDPE‐based nanocomposites show a strong dependence on the type of organoclay. Finally, the mechanical properties of the materials were measured by tensile tests. They revealed that the presence of the filler provokes, in all the cases, an increase of the rigidity. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 344–355, 2010     

Syntheses of pyrimidine‐based polymers containing electron‐withdrawing substituent with high open circuit voltage and applications for polymer solar cells

Polymers using new electron‐deficient units, 2‐pyriminecarbonitrile and 2‐fluoropyrimidine, were synthesized and utilized for the photovoltaics. Donor‐acceptor (D‐A) types of conjugated polymers ( PBDTCN, PBDTTCN, PBDTF, and PBDTTF ) containing 4,8‐bis(2‐octyldodecyloxy)benzo[1,2‐b;3,4‐b′]dithiophene (BDT) or 4,8‐bis(5‐(2‐octyldodecyloxy)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene (BDTT) as electron rich unit and 2‐pyriminecarbonitrile or 2‐fluoropyrimidine as electron deficient unit were synthesized. We designed pyrimidine derivatives in which strong electron‐withdrawing group (C?N or fluorine) was introduced to the C2 position for the generation of strong electron‐deficient property. By the combination with the electron‐rich unit, the pyrimidines will provide low band gap polymers with low highest occupied molecular orbital (HOMO) energy levels for higher open‐circuit voltages (V_OC). For the syntheses of the polymers, the electron‐rich and the electron‐deficient units were combined by Stille coupling reaction with Pd(0)‐catalyst. Absorption spectra of the thin films of PBDTTCN and PBDTTF with BDTT unit show shift to a longer wavelength region than PBDTCN and PBDTF with BDT unit. Four synthesized polymers provided low electrochemical bandgaps of 1.56 to 1.96 eV and deep HOMO energy levels between ?5.67 and ?5.14 eV. © 2015 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 771–784     

Role of architecture and molecular weight in the formation of tailor‐made ultrathin multilayers using dendritic macromolecules and click chemistry

The high efficiency and mild reaction conditions associated with the Cu(I) catalyzed cycloaddition of azides and alkynes were exploited for the covalent layer‐by‐layer synthesis of dendritic thin films on silicon wafers. The preparation of azide and alkyne‐terminated dendrimers based on bisMPA was accomplished by a divergent strategy; combinations of these monodisperse building blocks from the 2nd to the 5th generation were used for construction of the thin films. The layer‐by‐layer self assembly process proceeds under ambient conditions and was monitored by ellipsometry, XPS, and ATR‐IR, which showed extremely regular growth of the dendritic thin films. Film thickness could be accurately controlled by both the size/generation number of the dendrimers as well as the number of layers. In comparison with linear analogues, the growth of the dendritic films was significantly more controlled and defect‐free with each layer being thinner than the corresponding films prepared from the isomeric linear polymers, demonstrating the well‐defined, three‐dimensional nature of the dendritic architecture. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2835–2846, 2007     

A low bandgap polymer based on isoindigo and bis(dialkylthienyl)benzodithiophene for organic photovoltaic applications

A new conjugated polymer PBDTT‐ID based on N‐alkylated isoindigo (ID) and bis(2,3‐dialkylthienyl)‐substituted benzo[1,2‐b:4,5‐b′]dithiophene (BDTT) as repeating units was synthesized. It had an optical bandgap of 1.56 eV and a highest occupied molecular orbital (HOMO) energy level of ?5.71 eV. The optical, electrochemical, and photovoltaic properties of new polymer were compared with previous reported polymer PBDT‐ID , which was based on bis(alkoxy)‐substituted benzo[1,2‐b:4,5‐b′]dithiophene. The new polymer displayed lower HOMO energy level and better absorption properties than polymer PBDT‐ID . The solar cells fabricated with PBDTT‐ID /PC₆₁BM (1:2, w/w) blends as active layers exhibited photoresponse in the range of 300–800 nm. A power conversion efficiency of 4.02% and an open circuit voltage (V_oc) of 0.94 V were achieved in polymer solar cell device based on the new polymer. This was the highest V_oc realized among the isoindigo‐based polymers. The relatively high performances of new polymer in solar cell devices were interpreted in terms of material properties and morphologies of polymer/PCBM blends. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Vapor‐Based Synthesis of Poly[(4‐formyl‐p‐xylylene)‐co‐(p‐xylylene)] and Its Use for Biomimetic Surface Modifications

Summary: The vapor‐based synthesis and characterization of a reactive polymer, poly[(4‐formyl‐p‐xylylene)‐co‐(p‐xylylene)] ( 1 ), have been reported. The reactive polymer coating enables the immobilization of oligosaccharides via the chemoselective aldehyde‐hydrazide coupling reaction.

     

Synthesis and inhibition performance of a polymer‐supported inhibitor

The synthesis of a polymer‐supported inhibitor (PSI) and its inhibition performance for free‐radical polymerization are reported for the first time. A special method has been devised to synthesize PSI with pure and abundant hydroquinone (HQ) groups anchored onto the polymer surface. A thin HQ/acetone (AC) solution is sandwiched between two polymer films. Under ultraviolet irradiation, AC as an photoinitiator quickly and effectively grafts HQ onto the polymer surface. PSI has been characterized with ultraviolet–visible and attenuated total reflectance/Fourier transform infrared spectroscopy. For potential applications, PSI has been used to inhibit the thermal polymerization of styrene and methyl methacrylate. The corresponding inhibition performance has been investigated through the measurement of the induction period with the dilatometer method. With the same absolute amount, the maximum inhibition ability of PSI approaches half that of a free inhibitor. Increasing the dispersion degree of PSI is favorable for the enhancement of the inhibition ability. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4074–4083, 2004