Highly efficient organic solar cells with improved stability enabled by ternary copolymers with antioxidant side chains

The stability of organic solar cells(OSCs)remains a major concern for their ultimate industrialization due to the photo,oxygen,and water susceptibility of organic photoactive materials.Usually,antioxidant additives are blended as radical scavengers into the active layer.However,it will induce the intrinsic morphology instability and adversely affect the efficiency and long-term stability.Herein,the antioxidant dibutylhydroxytoluene(BHT)group has been covalently linked onto the side chain of benzothiadiazole(BT)unit,and a series of ternary copolymers D18-Cl-BTBHTx(x=0,0.05,0.1,0.2)with varied ratio of BHT-containing side chains have been synthesized.It was found that the introduction of BHT side chains would have a negligible effect on the photophysical properties and electronic levels,and the D18-Cl-BTBHT0.05:Y6-based OSC achieved the highest power conversion efficiency(PCE)of 17.6%,which is higher than those based active layer blended with BHT additives.More importantly,the unencapsulated device based on D18-Cl-BTBHTx(x=0.05,0.1,0.2)retained approximately 50%of the initial PCE over 30 hours operation under ambient conditions,significantly outperforming the control device based on D18-Cl(90%degradation in PCE after 30 h).This work provides a new structural design strategy of copolymers for OSCs with simultaneously improved efficiency and stability.

MOLECULAR DESIGN SYNTHESIS AND PROPERTIES OF SIX KINDS OF MULTIPHASE (STYRENE-ETHYLENE OXIDE)COPOLYMERS

Multiphase copolymers of styrene (S) and ethylene oxide (EO) are amphiphilic, because of the hydrophobic and amorphous polystyrene (PS) segments and the hydrophilic and crystalline polyoxyethylene (PEO). They have many uses including polymeric surfactants, electrostatic charge reducers, compatibilizer in polymer

Research on the Marine Antifouling Ability and Mechanism of Acrylate Copolymers and Marine Coatings Based on a Synergistic Effect

Marine biofouling is an urgent global problem in the process of ocean exploitation and utilization.In our work,a series of zinc-based acrylate copolymers(ACZn-x)were designed and synthesized using benzoic acid,zinc oxide(ZnO)and a random quaternion copolymer consisting of ethyl acrylate(EA),butyl acrylate(BA),acrylic acid(AA)and methacrylic acid(MAA)by free radical polymerization and dehydration condensation.The ACZn-x with a zinc benzoate side chain is able to hydrolyze in natural seawater under static conditions,resulting in the formation of a smooth surface.We investigated and confirmed the antifouling(AF)behavior of ACZn-x in the laboratory and revealed that they have better antibacterial(86%for S.aureus and 72%for E.coli)and anti-algal(≥60.1%for N.closterium and≥67.5%for P.subcordiformis)activities.We also assessed the marine AF properties of ACZn-x and corresponding coatings in Qingdao,China;the ACZn-x exhibited ideal AF properties with little silt and biological mucosa adhered to the ACZn-x surface after 6 months,and corresponding coatings exhibited little biofouling after 16 months in the ocean.Importantly,possible AF mechanisms were further proposed at the cellular level.These results could be helpful for the development and application of effective AF coatings.

AMPHIPHILIC STAR-BLOCK COPOLYMERS BY IODIDE-MEDIATED RADICAL POLYMERIZATION

Amphiphilic star-block copolymers composed of polystyrene and poly（acrylic acid） were synthesized by iodide- mediated radical polymerization. Firstly, free radical polymerization of styrene was carried out with AIBN as initiator and 1,1,1-trimethyolpropane tri（2-iodoisobutyrate） as chain transfer agent, giving iodine atom ended star-shaped polystyrene with three arm chains, R（polystyrene）3. Secondly, tert-butyl acrylate was polymerization using polystyrene obtained as macro-chain transfer agent, and star-block copolymer, R（polystyrene-b-poly（tert-butyl acrylate））3 with controlled molecular weight was obtained. Finally, amphiphilic star-block copolymer, R（polystyrene-b-poly（acrylic acid））3 was obtained by hydrolysis of R（polystyrene-b-poly（tert-butyl acrylate））3 under acidic condition.

Self-assembly of block copolymers grafted onto a flat substrate:Recent progress in theory and simulations

Block copolymers are a class of soft matter that self-assemble to form ordered morphologies on the scale of nanome- ters, making them ideal materials for various applications. These applications directly depend on the shape and size of the self-assembled morphologies, and hence, a high degree of control over the self-assembly is desired. Grafting block copolymer chains onto a substrate to form copolymer brushes is a versatile method to fabricate functional surfaces. Such surfaces demonstrate a response to their environment, i.e., they change their surface topography in response to different external conditions. Furthermore, such surfaces may possess nanoscale patterns, which are important for some applica- tions; however, such patterns may not form with spun-cast films under the same condition. In this review, we summarize the recent progress of the self-assembly of block copolymers grafted onto a flat substrate. We mainly concentrate on the self-assembled morphologies of end-grafted AB dibloek eopolymers, junction p0int-grafted AB diblock copolymers （i.e., Y-shaped brushes）, and end-grafted ABA triblock copolymers. Special emphasis is placed on theoretical and simulation progress.

Weavability of β-Hydroxybutyrate and β-Hydroxyvalerate Copolymers( PHBV ) /PLA Used in Artificial Blood Vessels

The β-hydroxybutyrate and β-hydroxyvalerate copolymers( PHBV) /polylactic acid( PLA) is a new biocompatible material,which is developed through bacterial fermentation in vivo systems.The PHBV / PLA material could be used to make continuous filaments.However,features of artificial blood vessels,especially small diameter vascular grafts made of PHVB / PLA materials are not known.This research are to evaluate and improve weavability of the PHBV / PLA material, and to explore feasibility of using it in artificial blood vessels.Preliminary results showed that weavability of PHBV / PLV was not good,but its weavability could be improved by using methods of weak chemical,such as sizing.In this research,scanning electron microscope( SEM) was adopted to evaluate weavability of PHBV / PLV after sizing and observe surfaces of yarns and fabrics.Also,in order to set proper parameters in heat settings,differential scanning calorimetry( DSC) was used to identify glass transition temperature.

Synthesis of polystyrene-styrene/butadiene diblock copolymers via reversible addition-fragmentation chain transfer miniemulsion polymerization

Polystyrene-styrene/butadiene diblock copolymers were synthesized via reversible addition-fragmentation chain transfer （RAFT） miniemulsion polymerization.During the polymerization process,the molecular weight distribution was narrow and the numerical molecular weight of the copolymers increased with increasing conversion of monomers,which was close to the theoretical.FT-IR and ^1H NMR results indicated that the microstructure of the polymer was mainly 1,4-trans-butadiene with small amount of 1,2-units,and composition in the copolymers was obtained.

Synthesis and Characterization of Degraded Gelatin Grafted Poly(ε-caprolactone) Copolymers

Hydrophilic degraded gelatin was modified with hydrophobic poly(ε-caprolactone) (PCL) via a chemical grafting route.Firstly,PCL with one hydroxyl end group was prepared by the ring-opening polymerization of εcaprolactone (ε-CL) with tin (Ⅱ) 2-ethylhexanoate as catalyst and n-butyl alcohol as initiator.Secondly,the PCL reacted with isophorone diisocyanate (IPDI) to prepare PCL with isocyanate functional group (PCL-NCO).Hydroxylamine was used to degrade gelatin by the cleavage between asparagine and glycine residues of gelatin.PCL-NCO reacted with the hydroxyl/amino groups of degraded gelatin in a homogeneous system and yielded the PCL modified gelatin copolymers.The gelatin grafted PCL copolymers were measured by means of XRD,FTIR,DSC and 1 H NMR.The results confirmed the conjugation of PCL onto gelatin chains.The PCL modified gelatin can be used as biomaterials owing to their biocompatibility and biodegradation.

Synthesis and Properties of a New Kind of High Performance Composite Resin Matrix-Poly (Aryl Ether Ketones)/Poly (Ether Sulfone) Block Copolymers

A new kind of high performance composite resin matrix PEEK/PES, PEEKK/PES block copolymers have been prepared from the corresponding oligomers via a nucleophilic aromatic substitution reaction. The different properties of the copolymers are investigated by differential scanning calorimetry (d. s. c), thermogravimetric analysis (t. g. a) and dynamic mechanical analysis (d. m. a). The results show that the relationship between Tg and the compositions of the copolymers approximately follows the formula 1/Tg=W1/Tg1 +W2/Tg2 for PEEKK/PES block copolymers, and Tg=Tg1W1 +Tg2W2 for PEEK/PES block copolymers. The PES content and the segment length of the copolymers have a significant influence on their melting point. The thermal properties and dynamic mechanical behaviour of the copolymers are also studied. The introduction of PES segment into the molecular main chain increases the glass transition temperature of poly aryl ether ketones and decreases their melting temperature, that is to say it decreases their melting processing temperature. The block copolymers keep the high temperature stability and solvent resistance of poly aryl ether ketones. They are expected to be a new kind of high performance composite resin matrix.

NONBRIDGED HALF-TITANOCENES CONTAINING ANIONIC ANCILLARY DONOR LIGANDS:PROMISING NEW CATALYSTS FOR PRECISE SYNTHESIS OF CYCLIC OLEFIN COPOLYMERS(COCs)

Precise,efficient copolymerizations of ethylene with cyclic olefins[norbornene(NBE),cyclopentene(CPE)]using nonbridged half-titanocenes of type,Cp TiCl_2(L)(Cp =cyclopentadienyl group,L=aryloxo,ketimide)-MAO catalyst systems have been summarized.CpTiCl_2(N=C Bu_2)exhibited both remarkable catalytic activity and efficient NBE incorporation for ethylene/NBE copolymerization:the NBE incorporation by Cp TiCl_2(X)(X=N=C Bu_2,O-2,6- Pr_2C_6H_3; Cp =Cp,C_5Me_5,indenyl)was related to the calculated coordination ene...

NUCLEATION AND CRYSTALLIZATION OF H-SHAPED(PS)_2PEG(PS)_2 BLOCK COPOLYMERS

A series of H-shaped （PS）2PEG（PS）2 block copolymers with different PS chain lengths were prepared. The influence of different confinements active on the crystallization and self-nucleation （SN） behavior of the PEG blocks was investigated by differential scanning calorimetry （DSC）. When the content of the crystalline block was high, a classical SN behavior was obtained. The block copolymer with PEG content of 49% （by weight） showed a classical SN behavior with a narrow self-nucleation domain and had bimodal crystallization exotherms. When the PEG dispersed as separated microdomains in the block copolymer, the self-nucleation domain disappeared and only annealing was observed.

Synthesis and properties of polyfluorene copolymers bearing thiophene and porphyrin

To search for more wider absorption and higher charge carriers mobilities materials of polymer solar cell, a series of soluble alternating polyfluorene copolymers were synthesized by palladium-catalyzed Suzuki coupling reaction. Their structures were determined by 1H NMR, IR and UV-vis. And their UV-vis absorption spectra indicated that they had strong absorption over 600 nm spectral range and nearly cover 400-700 nm visible region. The band gaps of copolymers calculated according to cyclic voltammetry （CV） were between 1.96 and 2.03 eV. Polymer：TiO2 bulk-heterojunction films were made from mixtures of polymer and titanium isopropoxide, a precursor for TiO2, via hydrolysis in air overnight. The photoluminescence at 380-800 nm of the blend film of PT-TPP20 （5 mg/mL）：Ti（OC3H7）4 （80 μL/mL） （20% volume fraction） was significantly quenched in the 50% Ti（OC3H7）4 blend film, indicating that rapid and efficient separation of photoinduced electron-hole pairs.

PREPARATION AND SURFACE PROPERTIES OF ACRYLIC COPOLYMERS CONTAINING FLUORINATED MONOMERS

A series of copolymers comprising butylmethacrylate, styrene, butylacrylate, hydroxypropyl acrylate and perfluoroalkyl methacrylate were synthesized by the free radical polymerization using BPO as an initiator. The surface property of the copolymer films was subsequently characterized. The contact angle measurements and energy dispersive analysis of X-ray （EDAX） show that the length and content of perfluoroalkyl side chains in the copolymers are crucial for the preparation of the film with low surface energy. At a given content of fluorinated monomers in the copolymers, the longer the perfluoroalkyl side chain, the larger the water contact angle of the copolymer films will be. On the other hand, the higher the content of fluorinated monomers, the lower the surface energy is. The water contact angle increases with the increase of the fluorinated monomer content and reaches a plateau at 3 wt% of fluorinated monomer content.

Self-assembly of lamella-forming diblock copolymers confined in nanochannels: Effect of confinement geometry

The self-assembly of symmetric diblock copolymers confined in the channels of variously shaped cross sections （regu- lar triangles, squares, and ellipses） is investigated using a simulated annealing technique. In the bulk, the studied symmetric diblock copolymers form a lamellar structure with period LL. The geometry and surface property of the confining channels have a large effect on the self-assembled structures and the orientation of the lamellar structures. Stacked perpendicular lamellae with period LL are observed for neutral surfaces regardless of the channel shape and size, but each lamella is in the shape of the corresponding channel＇s cross section. In the case of triangle-shaped cross sections, stacked parallel lamel- lae are the majority morphologies for weakly selective surfaces, while morphologies including a triangular-prism-shaped B-cylinder and multiple tridentate lamellae are obtained for strongly selective surfaces. In the cases of square-shaped and ellipse-shaped cross sections, concentric lamellae are the signature morphology for strongly selective surfaces, whereas for weakly selective surfaces, stacked parallel lamellae, and several types of folding lamellae are obtained in the case of square-shaped cross sections, and stacked parallel lamellae are the majority morphologies in the case of ellipse-shaped cross sections when the length of the minor axis is commensurate with the bulk lamellar period. The mean-square end- to-end distance, the average contact number between different species and the surface concentration of the A-monomers are computed to elucidate the mechanisms of the formation of the different morphologies. It is found that the resulting morphology is a consequence of competition among the chain stretching, interfacial energy, and surface energy. Our results suggest that the self-assembled morphology and the orientation of lamellae can be manipulated by the shape, the size, and the surface property of the confining channels.

Synthesis and characterization of poly(phthalazinone ether nitrile) (PPEN)-polydimethylsiloxane (PDMS) block copolymers

Block copolymers with different backbone compositions have been prepared by the condensation of dimethylamino terminated poly（dimethylsiloxane） （PDMS） and hydroquinone terminated poly（phthalazinone ether nitrile） （PPEN） in the presence of chlorobenzcne/N-methyl pyrrolidone （NMP） as solvents. The products were characterized by FTIR, ^1H NMR and gel permeation chromatography. Differential scanning calorimetry analysis indicated that the block copolymers showed separated microphase.

SYNTHETIC STUDIES ON BLOOD COMPATIBLE BIOMATERIALS Ⅲ. SYNTHESIS, CHARAC-TERIZATION AND ANTITHROMBOGENICITY OF DIMETHYLDIPHEN YLPOLYSILOXANE/POLY (OXYTETRAM ETHYLENE)-POLYUREA SEGMENTED COPOLYMERS

A novel class of segmented copolymers, dimethyldiphenylpolysiloxane/poly (oxytetramethylene)-polyurea (PSPEU), was synthesized from α , ω-bis (γ-aminopropyl) dimethyldiphenylpolysiloxane (APMPS), which was prepared by means of basic ring-opening copolymerization of octamethylcyclotetrasiloxane, hexaphenylcyclotrisiloxane and 1, 3-bis (γ-aminopropyl) tetramethyl disiloxane. The relationships between the diphenylsiloxy contents and the properties of APMPS, including refractive index, glass transition temperature, solubility parameter as well as thermal stability, were investigated; meanwhile, the thermal stability, dynamic mechanical properties, mechanical properiesas well as the antithrombogenicity in vitro of the PSPEU were also revealed.

Effect of Structural Units on the Adhesion of Acrylic Copolymers to Fibers for Warp Sizing

Radical copolymerization of acrylic acid(AA)with acrylamide(AM)or acrylamide/acrylonitrile(AM/AN)was initiated with ammonium persulfate as initiator to produce acrylic copolymers such as bicopolymer poly(AM-co-AA)and tercopolymer poly(AM-co-AN-co-AA)for revealing the effects of the structural units of the copolymers on the adhesion of the copolymers to polyester or cotton fibers for warp sizing.The adhesion was evaluated in terms of tensile strength and work-to-break of a roving impregnated with the copolymer solution.It was found that the adhesion strongly depended on type and amount of the units incorporated into the copolymeric chains.Whether the fiber is cotton or polyester,the adhesion of the bicopolymer poly(AM-co-AA)is greater than that of polyacrylic acid or polyacyamide.Excessively increasing the amount of AM or AA unit in poly(AM-co-AA)lowers the adhesion.To enhance the adhesion of the bicopolymer,a favorable mole ratio of AM to AA is 70/30.Based on this mole ratio,incorporation of acrylonitrile units into poly(AM-co-AA)to form tercopolymer enhances the adhesion.

Bioengineering functional copolymers. XII. Interaction of boron-containing and PEO branched derivatives of poly(MA-alt-MVE) with HeLa cells

Novel boron-containing bioengineering copoly- mer and its α-hydoxy-ω-methoxy-poly(ethy- lene oxide (PEO) macrobranched derivatives were synthesized by (1) partially amidolysis of poly(maleic anhydride-alt-methyl vinyl ether) w?th ethanolamine ester of diphenylboronic acid and (2) esterification of synthesized B-con- taining copolymers with PEO. They had a com- bination of hydrophilic/hydrophobic linkages, free carboxylic groups, positive charges and an ionized organoboron linkage as antitumor sites, along with an ability to interact with HeLa cells. The structure, composition and properties (cy- totoxicity and antitumor activity) of synthe- sized copolymers were investigated. In vitro cytotoxicity results, obtained by the fluore scence microscopy measurements indicate that unlike the virgin copolymer, boron-containing and PEO macrobranched derivatives exhibit higher antitumor activity. It was found that organoboron copolymer exhibits the most apo- ptotic and necrotic effects against HeLa cells whereas a minor effect relative to cancer cells was observed on L929 Fibroblast cells.

Mechanism for the Self-Assembly of Hollow Micelles from Rod-Coil Block Copolymers

The mechanism for the self-assembly of hollow micelles from rod-coil diblock copolymers is proposed. In a coilselective solvent, the diblock copolymers self-assemble into a layered structure. It is assumed that the rigid rods form an elastic shell whose properties are dictated by a bending energy. For a hollow micelle, the coils outside the micelle form a brush, while the coils inside the micelle can be in two different states, a brush or an adsorption layer, corresponding to symmetric or asymmetric configurations, respectively. The total energy density of a hollow micelle is calculated by combining the interfacial energy, elastic bending energy and the stretching energy of the brushes. For the asymmetric configuration with a polymer brush on one side, the competition between the elastic bending energy and the brush stretching energy leads to a finite spontaneous curvature, stabilizing hollow spherical micelles. Comparison of the free energy density for different geometries demonstrates that transitions for the different geometry micelles are controlled by the degree of polymerization of the coils and the length of the rods. These results are in agreement with the experimental results.

STRUCTURE EVOLUTION OF THE CYLINDRICAL PHASE OF DIBLOCK COPOLYMERS IN FILMS

In the weak segregation limit,the structure evolution of the hexagonal cylindrical phase of diblock copolymers in films was investigated.Employing the Landau-Brazovskii mean field theory,we obtained three amplitude parameters as functions of temperature,surface field strength and film thickness.By controlling confinement size and surface field strength, lamellae and undulated lamellae appear in the cylindrical bulk phase of diblock copolymers.'Phase diagrams'of confinement-induced structures are constructed...