Copolymers of Poly(2,5‐benzimidazole) and Poly[2,2′‐(p‐phenylene)‐5,5′‐bibenzimidazole] for High‐Temperature Fuel Cell Applications

Copolymers of poly(2,5‐benzimidazole) (ABPBI) and poly[2,2′‐(p‐phenylene)‐5,5′‐bibenzimidazole] (pPBI) were synthesized for use as fuel cell membranes to take advantage of the properties of both constituents. The composition of the copolymers were controlled by changing the feed ratio of 3,4‐diaminobenzoic acid and terephthalic acid with 3,3′‐diaminobenzidine in the polycondensation reaction. The copolymer membranes showed higher conductivities, better mechanical properties, and larger acid absorbing abilities than commercial poly[2,2′‐(m‐phenylene)‐5,5′‐bibenzimidazole] membranes.

     

1,2‐propanediol–cellulose–acrylamide graft copolymers

1,2‐Propanediol–cellulose–acrylamide graft copolymers (PCACs) were developed for enhanced oil recovery. They were prepared with acrylamide and 1,2‐propanediol (PDO)–cellulose, which was formed through the addition of glycols to cellulose by the Shotten–Baumann reaction between 3‐chloro‐1,2‐propanediol and cellulose. The graft copolymerization was initiated with a redox system between Ce⁴⁺ and glycols in cellulose. The infrared spectrum of PDO–cellulose had some characteristic absorption bands around 2960 (νC? H) and 1050 cm^?1 (νC? O) that also appeared for the PDO group and pyranose ring of cellulose, respectively. The rate of Ce⁴⁺ consumption by PDO–cellulose was investigated through the calculation of the overall kinetic constant from the slopes of ln(D ? D_R) versus time (where D is the absorbance and D_R is the absorbance of the original polysaccharide solution) The results showed that PDO–cellulose had high reactivity and that there were two mechanisms of oxidation by Ce⁴⁺ with PDO–cellulose. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3022–3029, 2004     

Catalyst free synthesis of poly(l‐lactic acid)–poly(propylene glycol) multiblock copolymers and their properties

A simple, green, and economical method for the synthesis of poly(l ‐lactic acid)–poly(propylene glycol) (PLLA–PPG) copolymers is put forward and a series of multiblock PLLA–PPG are synthesized with 1,6‐hexamethylene diisocyanate as chain extender of the melt polymerization. The effect of PPG content on the properties of PLLA–PPG copolymers is also investigated. The elongation at break of the resulting copolymer film with only 5% weight content PPG is 280%, and the tensile strength is 20 MPa. Dynamic mechanical analysis results demonstrated the existence of the shape memory effect for all the copolymers films and the shape recovery ratio of 101% is achieved for PLLA–PPG copolymer film with 5% weight PPG. The process for the synthesis of PLLA–PPG copolymers in the total absence of potentially toxic solvents and catalysts is analyzed, and the films of PLLA–PPG exhibit toughness and shape memory effect. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45299.     

A polythiophene derivative with dioctyloxyltriphenylamine‐vinylene conjugated side chain: Synthesis,hole mobility,and photovoltaic property

A new polythiophene derivative with dioctyloxyl triphenylamine‐vinylene ( DOTPAV ) conjugated side‐chain, DOTPAV‐PT , was synthesized by the Stille coupling method and characterized by ¹H‐NMR, ¹³C‐NMR, elemental analysis, gel permeation chromatography, thermogravimetric analysis, UV–vis absorption spectroscopy, photoluminescence spectroscopy, and cyclic voltammetry. The polymer DOTPAV‐PT is soluble in common organic solvents and possesses good thermal stability with 5% weight loss temperature of 310°C. The weight‐average molecular weight of DOTPAV‐PT is 8.0 K with a polydispersity index of 1.24. The hole mobility of the polymer determined from space‐charge‐limited current model was 1.25 × 10^?4 cm² V^?1 s^?1. The bulk heterojunction polymer solar cell with the configuration of ITO/PEDOT : PSS/polymer : PCBM (1 : 1)/Ca/Al was fabricated, and the power conversion efficiency of the device was 0.16% under the illumination of AM1.5, 100 mW cm^?2. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of alternate copolymers constructed by 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane units with oligo‐dimethylsiloxane segments

1,3‐Dichloro‐1,1,3,3‐tetraphenyldisilazane (DCTPS) with 71.6% yield was synthesized by the reaction of hexaphenylcyclotrisilazane (HPCT) with Ph₂SiCl₂ catalyzed by dibutyltin dilaurate. A ring‐closure reaction of DCTPS was carried out with BuLi in xylene–hexane mixture solvent; 1,3‐bis(chlorodiphenylsilyl)‐2,2,4,4‐tetraphenyl‐cyclodisilazane (BcPTPC) with 73.2% yield was obtained. Hydrolysis of BcPTPC in ether–triethylamine solvent resulted in 71.9% yield of 1,3‐bis(diphenylhydroxysilyl)‐2,2,4,4‐tetraphenylcyclodisilazane (B_HPTPC). By condensation polymerization of B_HPTPC with α,ω‐bis(diethylamino)‐oligo‐dimethylsiloxane, a kind of alternate copolymer constructed by 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane units with oligo‐dimethylsiloxane segments [P(BPTPC‐alt‐ODMS)] was synthesized. BcPTPC, B_HPTPC as well as P(BPTPC‐alt‐ODMS) were characterized by ²⁹Si‐NMR spectra, FT‐IR spectra, and elemental analysis. DGA study shows that P(BPTPC‐alt‐ODMS)s are thermally stable. The thermal decomposition onsets of P(BPTPC‐alt‐ODMS)s are all above 520°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1484–1490, 2005     

Synthesis and properties of new polymerized monomer reactants matrix resins of pyrrolone–benzimidazole copolymers containing pyridine unit

A series of new polymerized monomer reactants (PMR) matrix resins of poly(pyrrolone‐benzimidazole)s containing a pyridine unit (PPBP) were synthesized by polycondensation of monoethyl ester of cis‐5‐norbornene‐endo‐2,3‐dicarboxylic acid, 2,6‐diphenyl ester pyridinedicarboxylic acid or 3,5‐diphenyl ester pyridinedicarboxylic acid, and diethyl ester of 4,4′‐oxydiphthalic acid with 3,3′‐diaminobenzidine in a mixing solution of anhydrous ethyl alcohol and N‐methylpyrrolidone under given temperature and pressure conditions. The resulting resin solutions showed good solubility in polar organic solvents and stability at room temperature. The corresponding PPBP matrix resin, molded powder, and molded plate were prepared by undergoing amidation, imidization, cyclization, and crosslinking reactions when the reaction temperature was increased from 80 to 350°C, successively; the crosslinking structure was formed by the reverse Diels–Alder reaction at 270–290°C under 50 MPa pressure (2.5–3.5 MPa displayed by the pressure meter). The chemical reactions and properties of the resulting PPBP were studied by means of FTIR, TGA, and DMA methods, and the results indicated that the kinds of PPBP materials retain excellent thermal stability and processability; when the initial decomposition temperature was above 620°C the T_g was at 413.5°C for 3,5‐PPBP‐20 molded plate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3981–3990, 2004     

Phosphorus‐containing poly(ester‐imide)–polydimethylsiloxane copolymers

New phosphorus‐containing poly(ester‐imide)‐polydimethylsiloxane copolymers were prepared by solution polycondensation of 1,4‐[2‐(6‐oxido‐6H‐dibenz < c,e > < 1, 2 > oxaphosphorin‐6‐yl)]naphthalene‐bis(trimellitate) dianhydride with a mixture of an aromatic diamine (1,3‐bis(4‐aminophenoxy)benzene) and α,ω‐bis(3‐aminopropyl)oligodimethylsiloxane of controlled molecular weight, in various ratios. Poly(amic acid) intermediates were converted quantitatively to the corresponding polyimide structures using a solution imidization procedure. The polymers are easily soluble in polar organic solvents, such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylformamide, as well as in less polar solvents such as tetrahydrofuran. They show good thermal stability, the decomposition temperature being above 370 °C. The glass transition temperatures are in the range 165–216 °C. Solutions of the polymers in N‐methyl‐2‐pyrrolidone exhibit photoluminescence in the blue region. Copyright © 2010 Society of Chemical Industry     

Validity of poly(1, 6‐bis‐(p‐carboxyphenoxy hexane)‐co‐(sebacic anhydride)) copolymer in biomedical application

To further enhance the performance of biodegradable polymer‐based medical devices, there is an increasing need to obtain independent control of key properties such as mechanical strength, degradation rate, and bioactivity. In this study, biodegradable copolymers of poly(1,6‐bis‐p‐carboxyphenoxyhexane‐co‐sebacic anhydride) (CPH:SA) are synthesized, via melt condensation techniques, at three different molar ratios (7 : 3, 5 : 5, and 3 : 7). Tablets of the copolymers are prepared by mold casting at high temperature. Using an in vitro degradation test, copolymer tablets demonstrate a suitable mechanical strength, a slight decrease in pH value, and a slow degradation rate. High cell viability is observed on the surface of the copolymer tablets. The 3‐(4,5dimethylthiazol‐2‐yl) 2,5‐diphenyltetrazolium bromide (MTT) assay and live/dead staining demonstrate reduced toxicity and high cell survival. In vitro testing with C2C12 cells reveals good cellular attachment and spreading on the tablet surfaces, with the best properties displayed by the 7 : 3 molar ratio copolymer. Materials composed of CPH:SA have the potential to serve as medical implants. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

New low bandgap conjugated polymer derived from 2, 7‐carbazole and 5, 6‐bis(octyloxy)‐4, 7‐di(thiophen‐2‐yl) benzothiadiazole: Synthesis and photovoltaic properties

To develop conjugated polymers with low bandgap, deep HOMO level, and good solubility, a new conjugated alternating copolymer PC‐DODTBT based on N‐9′‐heptadecanyl‐2,7‐carbazole and 5, 6‐bis(octyloxy)‐4,7‐di(thiophen‐2‐yl)benzothiadiazole was synthesized by Suzuki cross‐coupling polymerization reaction. The polymer reveals excellent solubility and thermal stability with the decomposition temperature (5% weight loss) of 327°C. The HOMO level of PC‐DODTBT is ‐5.11 eV, indicating that the polymer has relatively deep HOMO level. The hole mobility of PC‐DODTBT as deduced from SCLC method was found to be 2.03 × 10^?4 cm²/Versus Polymer solar cells (PSCs) based on the blends of PC‐DODTBT and [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM) with a weight ratio of 1:2.5 were fabricated. Under AM 1.5 (AM, air mass), 100 mW/cm^?2 illumination, the devices were found to exhibit an open‐circuit voltage (V_oc) of 0.73 V, short‐circuit current density (J_sc) of 5.63 mA/cm^?2, and a power conversion efficiency (PCE) of 1.44%. This photovoltaic performance indicates that the copolymer is promising for polymer solar cells applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and properties of new photosensitive and chiral poly(amide‐imide)s based on bicyclo[2,2,2]oct‐7‐ene‐2,3,5,6‐tetracarboxylic diimide and dibenzalacetone moieties in the main chain

Aromatic poly(amide‐imide)s (PAIs) are high‐performance materials with a good compromise between thermal stability and processability when compared with polyamides or polyimides of analogous structures. In addition, the incorporation of photosensitive functional groups and chiral segments into the polymer backbone can lead to interesting polymers for various applications. In this work, six new photosensitive and chiral PAIs were synthesized from the direct polycondensation reaction of novel N,N′‐(bicyclo[2,2,2]oct‐7‐ene‐tetracarboxylic)‐bis‐L ‐amino acids with 2,5‐bis(4‐aminobenzylidene)cyclopentanone as dibenzalacetone moiety using two different methods. The polymerization reactions produced a series of photosensitive and optically active PAIs in high yields and with good inherent viscosities. The resulting polymers were characterized using Fourier transform infrared and ¹H NMR spectroscopy, elemental analysis, inherent viscosity, specific rotation, solubility tests and UV‐visible spectroscopy. The thermal properties of the PAIs were investigated using thermogravimetric analysis. Due to the presence of the dibenzalacetone moiety in the polymer chain, the PAIs have photosensitive properties. Also, these PAIs are optically active and soluble in various organic solvents. These resulting new polymers have the potential to be used in column chromatography for the separation of enantiomeric mixtures. Copyright © 2009 Society of Chemical Industry     

Photoresponsive polyurethane–acrylate block copolymers. I. Photochromic effects in copolymers containing 6′‐nitro spiropyranes and 6′‐nitro‐bis‐spiropyranes

The photochromic effect of polyurethane–acrylate block copolymers containing 6′‐nitro spiropyranes and 6′nitro‐bis‐spiropyranes has been investigated. The influence of incorporation of the photochromic agent into the polymeric matrix as a simple solid solution or in a chemically bonded form and the effects of the composition (polyurethane–acrylate) of the block copolymer were studied. In general, it was observed that the photoresponse for the spiropyranes and especially the bis‐spiropyranes obey the combination of several factors, mainly the spatial and electronic differences between the two forms (Sp.–Mer.) in the photoisomerization of these compounds. Such factors are discussed here. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 259–266, 1999     

Synthesis,electroluminescence, and photovoltaic cells of new vinylene‐copolymers with 4‐(anthracene‐10‐yl)‐2,6‐diphenylpyridine segments

Three new soluble vinylene‐copolymers F , C, and P that contain 4‐(anthracene‐10‐yl)‐2,6‐diphenylpyridine as common segment and fluorene, carbazole, or phenylene, respectively, as alternating segment were prepared by Heck coupling. The glass transition temperature was high for F and C (110 and 117°C), whereas was lower than 25°C for P . The polymers were stable up to ～ 300°C. They emitted blue–green light with maximum located at wavelength of 456–550 nm, which was of the order F < C < P . The photoluminescence quantum efficiency in THF solution was ～ 30% for F and P and only 5% for C . All three copolymers were used as active layers for polymer light emitting diodes (PLEDs) and organic photovoltaic cells. The double PLEDs with configuration of indium‐tin oxide (ITO)/poly(ethylenedioxythiophene (PEDOT) : poly(styrenesulfonate)(PSS)/Copolymer F , C , or P /TPBI(1,3,5‐tris(2‐N‐phenylbenzimidazolyl)benzene)/Ca/Al were fabricated. Copolymer P emitted green light with maximum brightness of 28 cd/m² and a current yield of 0.85 cd/A. Organic photovoltaics with the configuration of ITO/PEDOT : PSS/Copolymer and [6,6]‐phenyl‐C61‐butyric acid methyl ester blend (1 : 1) /Ca/Al were also fabricated. Copolymer P showed the highest power conversion efficiency of 0.034%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of poly(1‐vinyl‐3‐propylimidazolium) iodide for quasi‐solid polymer electrolyte in dye‐sensitized solar cells

The synthesis conditions of ionic liquid 1‐vinyl‐3‐propylimidazolium iodide (ViPrIm⁺I⁻) and Poly(1‐vinyl‐3‐propylimidazolium) iodide [P(ViPrIm⁺I⁻)] were studied in this work. P(ViPrIm⁺I⁻) as a single‐ion conductor providing iodine was designed to develop a quasi‐solid polymer electrolyte based on PVDF/PEO film for dye‐sensitized solar cells (DSSCs). The samples were characterized respectively by high‐performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance imaging (NMRI), gel permeation chromatography (GPC), etc. The results showed that the single‐ion conducting quasi‐solid polymer electrolyte (SC‐QPE) exhibited high ionic conductivity of 1.86 × 10⁻³ S cm⁻¹ at room temperature measured by CHI660C Electrochemical Workstation. Moreover, solar cells assembled using the SC‐QPE yielded an open‐circuit voltage of 0.83V, short‐circuit current of 8.01 mA cm⁻² and the conversion efficiency of 2.42%. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and tunable thermoresponsive solution morphologies of 2,2‐bis‐methylolpropionic acid dendron–azobenzene–poly(N‐isopropyl acrylamide) copolymers

Amphiphilic temperature‐ and photoresponsive linear–dendritic block copolymers comprising second‐generation acetonide‐2,2‐bis‐methylolpropionic acid‐based polyester dendron and linear poly(N‐isopropyl acrylamide) (PNIPAM) linked by an azobenzene unit were synthesized using atom transfer radical polymerization (ATRP) followed by click chemistry. Linear PNIPAM precursor was prepared from an azide‐functionalized azobenzene containing ATRP initiator. Two polymers obtained by varying the chain length of the PNIPAM block showed different morphologies and lower critical solution temperature (LCST) values in aqueous solution. Complete change in morphology of the two polymers into large spherical aggregates and nanotubes, respectively, was observed upon heating the micellar solution above LCST. The azobenzene unit was found to undergo trans–cis photoisomerization in the assemblies and caused a change in the microenvironment of an encapsulated hydrophobic dye without any release. Acetonide groups on the dendron were deprotected to afford hydroxylated polymer that showed well‐defined morphologies above the LCST and after heating–cooling cycle while significant dye encapsulation was seen only above the LCST. © 2017 Society of Chemical Industry     

Pyrrole‐based narrow‐band‐gap copolymers for red light‐emitting diodes and bulk heterojunction photovoltaic cells

A series of narrow‐band‐gap conjugated copolymers (PFO‐DPT) derived from pyrrole, benzothiadiazole, and 9,9‐dioctylfluorene (DOF) is prepared by the palladium‐catalyzed Suzuki coupling reaction with the molar feed ratio of 4,7‐bis(N‐methylpyrrol‐2‐yl)‐2,1,3‐benzothiadiazole (DPT) around 1, 5, 15, 30, and 50%. The obtained polymers are readily soluble in common organic solvents. The solutions and the thin solid films of the copolymers absorb light from 300 nm to 600 nm with two absorbance peaks at around 380 nm and 505 nm. The PL emission consists mainly of DPT unit emission at around 624–686 nm depending on the DPT content in solid film. The EL emission peaks are red‐shifted from 630 nm for PFO‐DPT1 to 660 nm for PFO‐DPT50. Bulk heterojunction photovoltaic cells fabricated from composite films of copolymer and [6,6]‐phenyl C₆₁ butyric acid methyl ester (PCBM) as electron donor and electron acceptor, respectively, in device configuration: ITO/PEDOT : PSS/PFO‐DPT : PCBM/Ba/Al shows power conversion efficiencies 0.15% with open‐circuit voltage (V_oc) of 0.60 V and short‐circuit current density (J_sc) of 0.73 mA/cm² under AM1.5 solar simulator (100 mW/cm²). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Investigation of microstructure of 4‐vinyl pyridine–methacylonitrile copolymers by NMR spectroscopy

4‐Vinyl pyridine–methacrylonitrile (V/M) copolymers of different composition were prepared by bulk polymerization using benzoyl peroxide as an initiator. The copolymer composition was determined from quantitative ¹³C{¹H}‐NMR spectra. The reactivity ratios for V/M copolymer obtained from a linear Kelen‐Tudos method (KT) and nonlinear error‐in‐variables method (EVM) are r_V = 0.79 ± 0.12, r_M = 0.38 ± 0.09 and r_V = 0.79 ± 0.13, r_M = 0.38 ± 0.07, respectively. The complete spectral assignment in term of compositional and configurational sequences of these copolymers were done with the help of distortionless enhancement by polarization transfer (DEPT), two‐dimensional heteronuclear single quantum coherence spectroscopy (HSQC). Total correlated spectroscopy (TOCSY) experiment was used to assign the various three‐bond ¹H‐¹H couplings in the V/M copolymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3232–3238, 2003     

Fluorescent microspheres of poly(ethylene glycol)–poly(lactic acid)–fluorescein copolymers synthesized by Ugi four‐component condensation

Microparticles formed by poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) diblock copolymers containing fluorescein grafted to the polymer chain were synthesized by a Ugi four‐component condensation (UFCC) reaction. To synthesize these copolymers, lactide was first polymerized by a ring‐opening polymerization with alcohol initiators containing functional groups to give carboxyl‐ and aldehyde‐end‐functionalized PLA. Two different fluorescent block copolymers (FCPs) of PEG–PLA conjugated to fluorescein (FCP 1 and FCP 2) were then synthesized by UFCC; they gave yields in the range 65–75%. These copolymers were characterized well according their chemical structures and thermal properties, and we prepared fluorescent microspheres (FMSs) from them with the single emulsion–solvent evaporation method (FMS 1 and FMS 2). A new application of UFCC in the preparation of biomasked drug‐delivery systems is proposed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42994.     

Design,synthesis, and characterization of a potential flame retardant poly(lactic acid‐co‐pyrimidine‐2,4,5,6‐tetramine) via direct melt polycondensation

Directly starting from d ,l ‐lactic acid (LA) and pyrimidine‐2,4,5,6‐tetramine (PTA), the copolymer P(LA‐co‐PTA) as a novel potential solid compatible polymeric flame retardant is synthesized as designed via melt polycondensation. When the molar feed ratio LA/PTA is 60/1, the optimal synthetic conditions are discussed. After the prepolymerization at 140°C for 8 h, using 0.5 wt % stannous oxide as the catalyst, the melt copolymerization at 160°C for 4 h gives the copolymer with the biggest intrinsic viscosity 0.88 dL g^?1. The structures and properties of P(LA‐co‐PTA)s at different molar feed ratios are characterized by FT‐IR, ¹H‐NMR, ¹³C‐NMR, GPC, XRD, DSC, and TGA. The decomposition temperatures of P(LA‐co‐PTA)s are higher than these of homopolymer poly(d,l ‐lactic acid) (PDLLA). All copolymers have higher char yield than PDLLA, and the more PTA in the feed content, the higher char yield. What's more, there are some residues at 700–800°C, indicating that P(LA‐co‐PTA)s have good charring ability. When the monomer PTA is introduced into polylactic acid by chemical bonding as purine (PU) unit formed during the condensation, both the PTA's relatively higher nitrogen content and the PU's similar structure with flame retardant benzimidazole are beneficial to improve the thermal stability and charring ability, especially the latter. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40275.     

Design and synthesis of thieno[3,4‐c]pyrrole‐4,6‐dione based conjugated copolymers for organic solar cells

A new series of conjugated copolymers (PBDT‐TPD , PBDT ‐Th‐TPD , PBDT‐TT‐TPD ) containing donor–acceptor (D ? A) structure electron‐rich benzo[1,2‐b :4,5‐b ′]dithiophene (BDT ) units with branched alkyl thiophene side chains and electron‐deficient 5‐(2‐octyl)‐4H ‐thieno[3,4‐c ]pyrrole‐4,6(5H )‐dione (TPD) units was designed and synthesized. To tune the optical and electrochemical properties of the copolymers, the conjugation length of the copolymers was extended by introducing π‐conjugated spacers such as thiophene and thieno[3,2‐b ]thiophene units. It was observed that PBDT‐TPD showed broader absorption spectra in the longer wavelength region and the absorption maximum was red‐shifted compared to that of PBDT‐Th‐TPD, PBDT‐TT‐TPD. Stokes shifts were calculated to be 52 nm for PBDT‐TPD, 153 nm for PBDT‐Th‐TPD and 146 nm for PBDT‐TT‐TPD. Further, PBDT‐TPD exhibited a deeper highest occupied molecular orbital energy level of ?5.53 eV as calculated by cyclic voltammetry. Bulk heterojunction solar cells fabricated using PBDT‐TPD as donor material exhibited a power conversion efficiency of 1.92%. © 2017 Society of Chemical Industry     

Characterization of end‐functionalized styrene–butadiene–styrene copolymers and their application in modified asphalt

End amino, carboxylic acid, and hydroxyl functionalized styrene–butadiene–styrene (SBS) triblock copolymers were prepared with 1,5‐diazabicyclo[3.1.0]hexane, carbon dioxide, and epoxy ethane as capping agents, respectively. The effects of the end polar groups on the morphology and dynamic mechanical properties were investigated. Transmission electron microscopy images suggested that the group at the end of the polystyrene (PS) segment made the morphology of the PS domains disordered and incompact. Dynamic mechanical results showed that the storage and loss modulus increased after SBS was end‐functionalized. End amino and carboxylic acid groups improved the compatibility and storage stability of SBS‐modified asphalt. However, the effect of the end‐hydroxyl group on the improvement of the storage stability of SBS‐modified asphalt was not obvious. The differential scanning calorimetry analysis of SBS‐modified asphalt further showed that the compatibility and storage stability of SBS‐modified asphalt were improved by the attachment of amino or carboxylic acid groups through the anionic polymerization method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 8–16, 2007