Molecular Mechanism Study on Effect of Biodegradable Amino Acid Ester–Substituted Polyphosphazenes in Stimulating Osteogenic Differentiation

Amino acid ester substituted polyphosphazenes are osteoactive benefiting from their phosphorus‐containing chemical structure, which highlights interests in bone tissue engineering. To correlate their chemical structures with cell activities, in this study, poly[(ethyl alanato)_0.3(ethyl glycinato)_0.7phosphazene] (PAGP) and poly[(ethyl phenylalanato)_0.3(ethyl glycinato)_0.7phosphazene] (PPGP) are synthesized to carry out studies on cell osteogenic differentiation. In the non‐contact culture manner, bone mesenchymal stromal cells (BMSCs) are cultured in transwell chambers containing PAGP or PPGP films, while the cells and the materials do not contact. In the contact culture manner, BMSCs are cultured on the PAGP or PPGP films. In the meantime, solutions containing PAGP or PPGP degradation products (i.e., phosphate, ammonium, and corresponding amino acids) are applied for cell culture using inorganic phosphate (Pi) ion as control. Thus, the influences from substrate surface and degradation products can be identified separately. The results reveal that both the phosphorus‐containing surface of PAGP and PPGP films and their degradation products play significant roles in regulating cell behaviors. In comparison with PAGP, PPGP seems able to provide relatively stable phosphorus‐containing surface to strengthen the cell‐scaffold interaction because of its slower degradation rate and higher Young's modulus, leading to greater promotion in osteogenic differentiation via contact effect.     

Characterization and Distribution of Poly(3‐hexylthiophene) Phases in an Annealed Blend Film

The characteristic absorption spectra of three kinds of phases, the isolated, ordered, and disordered phases, in a solvent‐vapor annealed poly(3‐hexylthiophene)/[6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (P3HT/PCBM) blend film were studied by means of spectroelectrochemistry (SEC) and time‐resolved absorption spectroscopy (TAS). The results reveal that the content of three phases are 12 % isolated, 37 % ordered, and 51 % disordered for the annealed P3HT neat film, and 25 % isolated, 31 % ordered, and 44 % disordered for the annealed P3HT/PCBM blend film. The vertical distribution of the different phases in the blend film was studied by SEC, and the results show that the ordered and isolated phases are mainly distributed in the top and in the bottom of the annealed films, respectively, while the disordered phase is mainly distributed in the middle and the bottom of the films.     

Morphology and Performance of Poly(2-methoxy-5-(20-ethyl-hexyloxy)-p-phenylenevinylene) (MEH-PPV)∶(6,6)-Phenyl-C61-butyric Acid Methyl Ester (PCBM) Based Polymer Solar Cells

Polymer solar cells were fabricated based on composite films of poly(2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenylenevinylene) (MEH‐PPV):fullerene derivative (6,6)‐phenyl‐C₆₁‐butyric acid methyl ester (PCBM) with weight blend ratio of 1:3, 1:4 and 1:5, spin‐coated from chloroform (CF), chlorobenzene (CB), and o‐dichlorobenzene (ODCB) solutions, respectively. Photoinduced current and power conversion efficiency (PCE) of the devices show a dependence on the solvents. The solar cells have the highest PCE at 1:5 blend ratio. Transmission electron microscopy (TEM) morphology reveals that there are some voids in MEH‐PPV:PCBM films. The void number decreases with the solvent from CF to CB and ODCB. We found the voids are located at the bottom of the films through electron tomography technique by TEM and film bottom‐side morphology study by atomic force microscopy. The charge carrier transport efficiency and collection efficiency should decrease greatly due to the voids, and the more voids the film has, the more degree the efficiencies decrease. PCE of the solar cell prepared from CF is lower than that of the solar cells prepared from CB and ODCB. The void phenomenon of MEH‐PPV:PCBM based solar cell and method to investigate the void position provide an experimental evidence and research mentality to fabricate polymer solar cell with high performance.     

PMMA/超支化聚(酯-酰胺)共混物薄膜中柱状相结构的形成

利用相差显微镜、三维形貌测量仪对聚甲基丙烯酸甲酯 超支化聚 (酯 酰胺 ) (PMMA HBP)共混物薄膜在玻璃基板作用下的相分离行为进行了研究 .结果表明 ,不同组分比的共混物薄膜会呈现不同的相形态和相分离过程 .当薄膜厚度在 5 0 0nm左右 ,HBP为低组分时 ,发现了一种特殊的分散相为圆柱状的相形态 ,并对该相形态出现的条件进行了研究 .认为基板与组分之间的相互作用和薄膜厚度决定了圆柱状结构形成 .     

One‐step synthesis of poly(lactic‐co‐glycolic acid)‐g‐poly‐1‐vinylpyrrolidin‐2‐one copolymers

The radical polymerization of 1‐vinylpyrrolidin‐2‐one (NVP) in poly(lactic‐co‐glycolic acid) (PLGA) 50:50 at 100 °C leads to amphiphilic PLGA‐g‐PVP copolymers. Their composition is determined by FT‐IR spectroscopy. Thermogravimetric analyses agree with FT‐IR determinations. Saponification of the PLGA‐g‐PVP polyester portion allows isolating the PVP side chains and measuring their molecular weight, from which the average chain transfer constant (C_T) of the PLGA units is estimated. The MALDI‐TOF spectra of PVP reveal the presence at one chain end of residues of either glycolic acid‐ or lactic acid‐ or lactic/glycolic acid dimers, trimers and one tetramer, the other terminal being hydrogen. This unequivocally demonstrates that grafting occurred. Accordingly, the orthogonal solvent pair ethyl acetate—methanol, while separating the components of PLGA/PVP intimate mixtures, fails to separate pure PVP or PLGA from the reaction products. All PLGA‐g‐PVP and PLGA/PLGA‐g‐PVP blends, but not PLGA/PVP blends, give long‐time stable dispersions in water. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1919–1928     

直链淀粉交联氨基酸酯取代聚膦腈杂化材料的制备

利用直链淀粉与甘/丙氨酸乙酯共取代聚膦腈交联, 制得了一种具有网络结构的新型杂化材料. 实验结果表明, 淀粉衍生物上的羟基转变为醇钠后, 可与聚膦腈分子链上的P-Cl键发生亲核取代反应; 所得聚合物膜无明显相分离, 力学性能优于具有相似组成的直链淀粉/聚膦腈共混膜, 表面亲水性和吸水率与对应的共混膜接近, 且均高于纯聚膦腈膜. 因此, 该聚合物可作为杂化生物材料用于药物控制释放和组织工程方面的研究.     

Synthesis of poly(ethylene‐co‐vinyl alcohol)‐g‐polystyrene graft copolymer and their applications for ordered porous film and compatibilizer

A series of new functional poly(ethylene‐co‐vinyl alcohol)‐g‐polystyrene graft copolymers (EVAL‐g‐PS) with controlled molecular weight (M_n = 38,000–94,000 g mol^?1) and molecular weight distribution (M_w/M_n = 2.31–3.49) were synthesized via a grafting from methodology. The molecular structure and component of EVAL‐g‐PS graft copolymers were confirmed by the analysis of their ¹H NMR spectra and GPC curves. The porous films of such copolymers were fabricated via a static breath‐figure (BF) process. The influencing factors on the morphology of such porous films, such as solvent, temperature, polymer concentration, and molecular weight of polymer were investigated. Ordered porous film and better regularity was fabricated through a static BF process using EVAL‐g‐PS solution in CHCl₃. Scanning electron microscopy observation reveals that the EVAL‐g‐PS graft copolymer is an efficient compatibilizer for the blend system of low‐density polyethylene/polystyrene. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 516–524     

Hyperbranched poly (amine‐ester)‐poly (lactide‐co‐glycolide) copolymer and their nanoparticles as paclitaxel delivery system

A new hyperbranched poly (amine‐ester)‐poly (lactide‐co‐glycolide) copolymer (HPAE‐co‐PLGA) was synthesized by ring‐opening polymerization of D , L ‐lactide (DLLA) glycolid and branched poly (amine‐ester) (HPAE‐OHs) with Sn(Oct)₂ as catalyst. The chemical structures of copolymers were determined by FT‐IR, ¹H‐NMR(¹³C NMR), TGA and their molecular weights were determined by gel permeation chromatography (GPC). Paclitaxel‐loaded copolymer nanoparticles were prepared by the nanoprecipitation method. Their physicochemical characteristics, e.g. morphology and nanoparticles size distribution were then evaluated by means of fluorescence spectroscopy, environmental scanning electron microscopy (ESEM), and dynamic light scattering (DLS). Paclitaxel‐loaded nanoparticles assumed a spherical shape and have unimodal size distribution. It was found that the chemical composition of the nanoparticles was a key factor in controlling nanoparticles size, drug‐loading content, and drug release behavior. As the molar ratio of DL ‐lactide/glycolide to HPAE increased, the nanoparticles size and drug‐loading content increased, and the drug release rate decreased. The antitumor activity of the paclitaxel‐loaded HPAE‐co‐PLGA nanoparticles against human liver cancer H7402 cells was evaluated by 3‐(4, 5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) method. The paclitaxel‐loaded HPAE‐co‐PLGA nanoparticles showed comparable anticancer efficacy with the free drug. Copyright © 2010 John Wiley & Sons, Ltd.     

Poly(alkylthio‐p‐phenylenevinylene): Synthesis and electroluminescent and photovoltaic properties

Two alkylthio‐substituted poly(p‐phenylenevinylene) (AT–PPV) derivatives, poly(2‐octylthio‐p‐phenylenevinylene) (OT–PPV) and poly[5‐methoxy‐2‐(2′‐ethyl‐hexylthio)‐p‐phenylenevinylene] (MEHT–PPV), were synthesized by a Heck coupling reaction for the investigation of the effect of alkylthio groups on the optoelectronic properties of poly(p‐phenylenevinylene) derivatives. The absorption peaks of OT–PPV and MEHT–PPV solutions were located at 431 and 438 nm, respectively. As for solid films, an OT–PPV film showed an absorption maximum wavelength at 444 nm, 13 nm redshifted in comparison with its solution value, whereas an MEHT–PPV film displayed the same absorption peak position as its dilute solution; this indicated that there was no interchain interaction in the MEHT–PPV film. Polymeric light‐emitting diodes (PLEDs) and polymer solar cells (PSCs) based on OT–PPV and MEHT–PPV were fabricated and characterized. Very narrow bandwidths of the electroluminescence (EL) spectra of the two AT–PPVs were found, with the full width at half‐maximum of the emission being 40 and 47 nm for OT–PPV and MEHT–PPV, respectively. The maximum EL efficiency of the single‐layer PLED based on MEHT–PPV with Al as a cathode reached 1.49 cd/A. The PSC based on a blend of OT–PPV and [6,6]‐phenyl‐C₆₁ butyric acid methyl ester (PCBM) showed the power conversion efficiency of 1.4% under the illumination of AM1.5 (80 mW/cm²). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1279–1290, 2006     

Thickness dependence of structural relaxation in spin‐cast polynorbornene films with high glass transition temperatures (>613 K)

The isothermal structural relaxation (densification) of a family of glassy polynorbornene films with high glass transition temperatures (T_g > 613 K) is assessed via spectroscopic ellipsometry. Three polymers were examined: poly(butylnorbornene) (BuNB), poly(hydroxyhexafluoroisopropyl norbornene) (HFANB), and their random copolymer, BuNB‐r‐HFANB. The effective aging rate, β(T), of thick (∼1.2 μm) spun cast films of BuNB‐r‐HFANB is approximately 10⁻³ over a wide temperature window (0.49 < T/T_g < 0.68). At higher temperatures, these polymers undergo reactions that more dramatically decrease the film thickness, which prohibits erasing the process history by annealing above T_g. The aging rate for thick BuNB‐r‐HFANB films is independent of the casting solvent, which infers that rapid aging is not associated with residual solvent. β (at 373 K) decreases for films thinner than ∼500 nm. However, the isothermal structural relaxation of thin films of BuNB‐r‐HFANB exhibits nonmonotonic temporal evolution in thickness for films thinner than 115 nm film. The thickness after 18 h of aging at 373 K can be greater than the initial thickness. The rapid aging of these polynorbornene films is attributed to the unusual rapid local dynamics of this class of polymers and demonstrates the potential for unexpected structural relaxations in membranes and thin films of high‐T_g polymers that could impact their performance. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 53–61     

Solid‐state NMR as a tool to describe and quantify the morphology of photoactive layers used in plastic solar cells

The optimization and control of the nanomorphology of thin films used as active layer in bulk heterojunction (BHJ) plastic solar cells is of key importance for a better understanding of the photovoltaic mechanisms and for increasing the device performances. Hereto, solid‐state NMR relaxation experiments have been evaluated to describe the film morphology of one of the “work‐horse” systems poly(2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylene‐vinylene)/[6, 6]‐phenyl‐C₆₁butyric acid methyl ester (MDMO‐PPV/PCBM) in a quantitative way. Attention is focused on the influence of the processing solvent (toluene vs. chlorobenzene), the blend composition, and the casting technique, that is, spin coating versus doctor blading. It is demonstrated that independently of the solvent and casting technique, part of the PCBM becomes phase separated from the mixed phase. Whereas casting from toluene results in the development of well‐defined PCBM crystallites, casting from chlorobenzene leads to the formation of PCBM‐rich domains that contain substructures of weakly organized PCBM nanoclusters. The amount and physico‐chemical state of the phase separated PCBM is quantified by solid‐state NMR relaxation times experiments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Porous Biodegradable Polyesters, 3. Preparation of Porous Poly(ε‐caprolactone) Films from Blends by Selective Enzymatic Removal of Poly(L‐lactide)

Porous poly(ε‐caprolactone) (PCL) films were prepared by the removal of poly(L ‐lactide) (PLLA) from phase‐separated PLLA/PCL blend films using the selective Proteinase K™‐catalyzed hydrolysis of PLLA and subsequent elution of its water‐soluble oligomers and monomer into the surrounding hydrolysis media. Polarimetry, gravimetry, and differential scanning calorimetry (DSC) confirmed the complete removal of PLLA molecules from the blend films within 5 d of the Proteinase K‐catalyzed hydrolysis and therefore the formation of porous PCL films when the initial PLLA content [X_PLLA(0)(w/w) = PLLA/(PCL + PLLA)] of the blend films was in the range 0.3–0.5. The fragmentation of the blend film with X_PLLA(0) = 0.7 occurred when the Proteinase K‐catalyzed hydrolysis was continued for longer than 5 d. These findings exhibited that both the PLLA‐rich and PCL‐rich phases were continuous in the blend films for X_PLLA(0) ranges of 0.3–0.7 and of 0.3–0.5, respectively, and that the PCL‐rich phase became dispersed when X_PLLA(0) was increased to 0.7. The dependence of enzymatic hydrolysis rate on X_PLLA(0) strongly suggests that the Proteinase K‐catalyzed hydrolysis of the blend films occurs at the interfaces of PLLA‐rich and PCL‐rich phases as well as at the film surfaces.     

Thin films of PS/PS‐b‐pnipam and ps/pnipam polymer blends with tunable wettability

We developed thin films of blends of polystyrene (PS) with the thermoresponsive polymer poly(N‐isopropylacrylamide) (PNIPAM) (PS/PNIPAM) and its diblock copolymer polystyrene‐b‐poly(N‐isopropylacrylamide) (PS/PS‐b‐PNIPAM) in different blend ratios, and we study their surface morphology and thermoresponsive wetting behavior. The blends of PS/PNIPAM and PS/PS‐b‐PNIPAM are spin‐casted on flat silicon surfaces with various drying conditions. The surface morphology of the films depends on the blend ratio and the drying conditions. The PS/PS‐b‐PNIPAM films do not show an increase in their water contact angles with temperature, as it is expected by the presence of the PNIPAM block. All PS/PNIPAM films show an increase in the water contact angle above the lower critical solution temperature of PNIPAM, which depends on the ratio of PNIPAM in the blend and is insensitive to the drying conditions of the films. The difference between the wetting behavior of PS/PS‐b‐PNIPAM and PS/PNIPAM films is due to the arrangement of the PNIPAM chains in the film. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 670–679     

Effect of multiple adduct fullerenes on charge generation and transport in photovoltaic blends with poly(3‐hexylthiophene‐2,5‐diyl)

The effect of replacing [6,6]‐phenyl‐C₆₁ butyric acid methyl ester (PCBM) by its multiadduct analogs (bis‐PCBM and tris‐PCBM) in bulk heterojunction organic solar cells with poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) is studied in terms of blend film microstructure, photophysics, electron transport properties, and device performance. Although the power conversion efficiency of the blend with bis‐PCBM is similar to the blend with PCBM, the performance of the devices with tris‐PCBM is considerably lower as a result of small photocurrent. Despite the lower electron affinity of the fullerene multiadducts, μs‐ms transient absorption measurements show that the charge generation efficiency is similar for all three fullerenes. The annealed blend films with multiadducts show a lower degree of fullerene aggregation and lower P3HT crystallinity than the annealed blend films with PCBM. We conclude that the reduction in performance is due largely to poorer electron transport in the blend films from higher adducts, due to the poorer fullerene network formation as well as the slower electron transport within the fullerene phase, confirmed here by field effect transistor measurements. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

Effects of spin-coating speed on the morphology and photovoltaic performance of the diketopyrrolopyrrole-based terpolymer

Polymer solar cells（PSCs） were fabricated by combining a diketopyrrolopyrrole-based terpolymer（PTBT-HTID-DPP） as the electron donor, and [6,6]-phenyl C₆₁ butyric acid methyl ester(PC₆₁BM) as the electron acceptor, and the power conversion efficiency（PCE） of 4.31% has been achieved under AM 1.5 G(100 m W cm^-2) illumination condition via optimizing the polymer/PC₆₁BM ratio, the variety of solvent and the spin-coating speed. The impact of the spin-coating speed on the photovoltaic performance of the PSCs has been investigated by revealing the effects of the spin-coating speed on the morphology and the absorption spectra of the polymer/PC₆₁BM blend films. When the thickness of the blend films are adjusted by spin-coating a fixed concentration with different spin-coating speeds, the blend film prepared at a lower spin-coating speed shows a stronger absorption per unit thickness, and the correspond device shows higher IPCE value in the longer-wavelength region. Under the conditions of similar thickness, the blend film prepared at a lower spin-coating speed forms a more uniform microphase separation and smaller domain size which leads to a higher absorption intensity per unit thickness of the blend film in long wavenumber band, a larger short-circuit current density(J_sc) and a higher power conversion efficiency（PCE） of the PSC device. Noteworthily, it was found that spin-coating speed is not only a way to control the thickness of active layer but also an influencing factor on morphology and photovoltaic performance for the diketopyrrolopyrrole-based terpolymer.     

Interlocking layer structures formed in spin‐cast polymer blend films by surface segregation and self‐stratification

Surface morphologies formed by the phase segregation of poly(styrene‐b‐ethylene/butylene‐b‐styrene) (SEBS)/poly(methyl methacrylate) (PMMA) blend films prepared via spin coating on mica substrates were studied with atomic force microscopy accompanied by a solvent extraction treatment, X‐ray photoelectron spectroscopy, and contact‐angle measurements. Three kinds of surface structures of films were observed. Besides the ribbonlike morphology and the dispersed domains in a continuous matrix that are common in this field, we found a special interlocking layer structure characterized by a smooth SEBS layer as the cover on the top and a layer composed of hill‐like PMMA dispersed in the SEBS matrix at the bottom when the composition of the film was around 50:50 SEBS and PMMA. A series of blend films with different thicknesses were then prepared to investigate the interfacial structure, and the formation process of the interlocking layer, which could be elucidated by a schematic diagram, was discussed. The interlocking bilayer film with SEBS on the top possessed high thermal stability and the best surface roughness in comparison with other structures. It might find important technical applications in fields such as adhesion, lubrication, and protective coatings. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 532–543, 2007.     

Conducting films of poly(aniline‐co‐1‐amino‐ 2‐naphthol‐4‐sulfonic acid) blended with LDPE for its application as antistatic encapsulation material

The paper presents the electrostatic charge dissipative (ESD) properties of the conducting copolymers of aniline (AN) and 1‐amino‐2‐naphthol‐4‐sulfonic acid (ANSA) blended with low‐density polyethylene (LDPE). The copolymers of aniline and ANSA were synthesized under different reaction conditions. Blending of copolymers with LDPE was carried out in twin screw extruder by melt blending method by loading 0.5 and 1.0 wt% of the conducting copolymer in LDPE matrix. The mechanical properties of the blended films depend on the incorporation of copolymer in the LDPE matrix. The morphology of copolymer–LDPE blend was studied by scanning electron microscopy. The conductivity of the blown film of poly(AN‐co‐ANSA)/LDPE blend was found to be in the range of 10^?6–10^?11 S/cm, showing its potential use as antistatic bag for the encapsulation of electronic equipments. The static decay time of the film was found to be of the order of 0.1–1.9 sec on recording the decay time from 5000 to 500 V. Static charge measurements carried out on the films show that no charge is present on the surface. The level of interaction between the copolymers and the matrix polymer was determined by the FTIR spectra, blend morphology, electrical conductivity, and thermal analysis. The effect of the morphology on electrical and antistatic behavior of copolymers has also been investigated. Copyright © 2009 John Wiley & Sons, Ltd.     

Layer—by—layer Multilaryer Films Self—assembled from a Rare—earth—containing Poly—oxometalate,Na9[Eu（W5O18）2] and Poly （allylamine hydrochloride） and Their Photoluminescent Properties

Ultrathin multilayer films of a rare-earth-containing polyoxometalate Na9[Eu(W5O18)2](EW) and poly (allymamine hydrochloride)(PAH) have been prepared by layer-by-layer self-assembly from dilute aqueous solution.The fabrication process of the EW/PAH multilaryer films was followed by UV-vis spectroscopy and ellipsometry,which show that the deposition process is linear and highly reproducible from layer to layer.An average EW/PAH bilayer thickness of ca.2.1nm was determined by ellipsometry.In addition,the scanning electron microscopy(SEM) image of the EW/PAH film indicates that the film surface is relatively uniform and smooth.The photoluminescent properties of these films were also investigated by fluorescence spectroscopy.     

聚[(双-甘氨酸乙酯)膦腈]/聚酯共混相容性研究

采用溶液混合法制备了聚[(双－甘氨酸乙酯）膦腈]（PGP）与丙交酯均聚物（PLA）或丙交酯／乙交酯共聚物（PLGA）的共混体系，利用示差扫描量热仪、傅里叶红外光谱仪和相差显微镜研究了两体系的共混相容性。实验结果表明，PGP与PLA不相容，但通过氢键相互作用可与PLGA达到部分相容，且PGP／PLGA的共混相容性随着PLGA含量的增加而有所改善。     

Effect of side‐chain positions on morphology and photovoltaic properties of phenazine‐based donor–acceptor copolymers

Two phenazine donor–acceptor‐conjugated copolymers (P1 and P2) with the same polymer backbone but different anchoring positions of alkoxy chain on the phenazine unit were investigated to identify the effect of changing the position of alkoxy chains on their optical, electrochemical, blend film morphology, and photovoltaic properties. Although the optical absorption and frontier orbital energy levels were insensitive to the position of alkoxy chains, the film morphologies and photovoltaic performances changed significantly. P1/PC₇₁BM blend film showed the formation of phase separation with large coarse aggregates, whereas P2/PC₇₁BM blend film was homogeneous and smooth. Accordingly, power conversion efficiency (PCE) of photovoltaic devices increased from 1.50% for P1 to 2.54% for P2. In addition, the PCE of the polymer solar cell based on P2/PC₇₁BM blend film could be further improved to 3.49% by using solvent vapor annealing treatment. These results clearly revealed that tuning the side‐chain position could be an effective way to adjust the morphology of the active layer and the efficiency of the photovoltaic device. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2910–2918