Co-reporter:Huina Cui;Xiubao Yang;Juan Peng
Soft Matter (2005-Present) 2017 vol. 13(Issue 31) pp:5261-5268
Publication Date(Web):2017/08/09
DOI:10.1039/C7SM01126A
We report the crystallization and microphase separation behavior of an all-conjugated poly(3-hexylthiophene)-b-poly[3-(6-hydroxy)hexylthiophene] (P3HT-b-P3HHT) block copolymer in mixed solvents and demonstrate how the conformations of P3HT and P3HHT chains influence the photophysical properties of the copolymer. It is shown that the balance among π–π stacking of P3HT, P3HHT and microphase separation of the copolymer can be dynamically shifted by controlling the rod–rod interactions of the copolymer via changing the block ratio and solvent blending. A series of nanostructures such as well-ordered nanofibers, spheres and lamellar structures are formed and their formation mechanisms and kinetics are discussed in detail. The variations in P3HT-b-P3HHT conformations are concomitant with a hybrid photophysical property depending on the competition between intrachain and interchain excitonic coupling, resulting in the transformation between J- and H-aggregation. Overall, this work demonstrates how the P3HT-b-P3HHT conformations crystallize and phase-separate in the solution and solid state, and the correlation between their structures and photophysical properties, which improves our understanding of all-conjugated rod–rod block copolymer systems.
Co-reporter:Cangyi Chen, Tiancai Zhang, Lei Zhu, Bin Zhao, Ping Tang, and Feng Qiu
ACS Macro Letters 2016 Volume 5(Issue 6) pp:718
Publication Date(Web):May 26, 2016
DOI:10.1021/acsmacrolett.6b00176
Hierarchical superstructures assembled by binary mixed homopolymer-grafted nanoparticles are investigated by using a self-consistent field theory (SCFT). Our results demonstrate that grafting mixed homopolymer brushes provides an effective way to program the spatial lattice arrangement of the nanoparticles. For the polymer-grafted nanoparticles with specific interaction parameter and total grafting density, the unusual non-close-packed simple cubic (SC) crystal lattice is obtained at small spherical core/polymer size ratios (R/() < 1). As the size ratio increases to > 1, the nanoparticle arrangement transforms into a body-centered cubic (BCC) crystal lattice. Meanwhile, some unconventional microphases are formed in the polymer matrix, such as the tetragonal cylinder and simple cubic sphere phases. Furthermore, the two-dimensional (2D) model calculations reveal that the binary hairy nanoparticles prefer to arrange into the lattice in a way they can maintain the free energy-minimizing morphology as an isolated particle. Our findings suggest a possible strategy to design hierarchical nanomaterials composed of unique inorganic/organic hybrid superstructures.
Co-reporter:Xiubao Yang, Jing Ge, Ming He, Zhi Ye, Xiaofeng Liu, Juan Peng, and Feng Qiu
Macromolecules 2016 Volume 49(Issue 1) pp:287-297
Publication Date(Web):December 17, 2015
DOI:10.1021/acs.macromol.5b02001
A series of thermal cross-linkable poly(3-hexylthiophene)-b-poly[3-(6-hydroxy)hexylthiophene] (P3HT-b-P3HHT) diblock copolymers (BCPs) with different block ratios were synthesized to explore the effect of cross-linking on crystallization and microphase morphology of polymer films. The obtained BCPs formed microphase separation structure with a lamellar packing due to the different polarity of the two blocks. Though, after thermal annealing at 200 °C, the cross-linking of P3HHT block damaged the microphase separation structure and the roughness of films increased, the crystalline structure still remained “edge on”, and the degree of crystallization greatly improved due to the rearrangement of the un-cross-linked parts. Based on the weight loss of the cross-linking reaction, the degree of cross-linking was calculated, and the ductility of film was characterized by the crack onset strain. Then a quantitative correlation between the ductility of film and the degree of cross-linking was established. It proved that cross-linking during thermal annealing at 200 °C can both improve the ductility of film and the degree of crystallization, which is a promising way to develop flexible electronic devices.
Co-reporter:Cangyi Chen, Ping Tang, Feng Qiu, and An-Chang Shi
The Journal of Physical Chemistry B 2016 Volume 120(Issue 24) pp:5553-5563
Publication Date(Web):May 31, 2016
DOI:10.1021/acs.jpcb.6b03005
The conformation of homodendrimers and amphiphilic dendrimers in various solvents is studied using classical density functional theory (DFT), in which the excluded-volume effects are treated explicitly. For homodendrimers in an athermal solvent, DFT results predict a remarkable fold-back behavior for the outer generation of segments, supporting the dense-core model. A coil-to-globule transition is observed for homodendrimers in a poor solvent. The size of the dendrimers, characterized by the radius of gyration, ⟨Rg⟩, is found to follow the scaling relationship, ⟨Rg⟩ ∼ Nν, where N is the total number of segments of the dendrimers. For amphiphilic dendrimers, DFT results show that chemical modification in the outermost generation is an effective method to drive the ends toward the periphery of the dendrimers. In particular, a conformation with a hollow interior structure could be formed for amphiphilic dendrimers with longer end spacers in a selective solvent. The resulting unimolecular micelles with a hollow core and dense shell could serve as a unique candidate for encapsulation applications, such as sustained-drug-release nanocontainers.
Co-reporter:Zhi Ye, Huina Cui, Xiubao Yang and Feng Qiu
Journal of Materials Chemistry A 2015 vol. 3(Issue 9) pp:1949-1956
Publication Date(Web):31 Dec 2014
DOI:10.1039/C4TC02663B
We investigate the electrohydrodynamic instabilities in poly(3-hexylthiophene) (P3HT) semiconducting polymer films. In the case that a contact is made between the P3HT film and an anode of a doped silicon wafer, the instabilities quickly grow into micro-column arrays in several minutes. The resultant micro-columns in the P3HT film show spherulitic morphology and the polymer chains in the columns are packed with an “edge on” orientation. Charge injection across a small injection barrier is attributed to the promoted electrohydrodynamic instabilities in the thin film.
Co-reporter:Yue Wang, Xiaofeng Liu, Juan Peng and Feng Qiu
RSC Advances 2015 vol. 5(Issue 130) pp:107970-107976
Publication Date(Web):11 Dec 2015
DOI:10.1039/C5RA24266E
Poly(3-hexylselenophene) (P3HS) is much less studied compared with its close analogue poly(3-hexylthiophene) despite its excellent electronic properties. In this work, we report the crystallization behavior of P3HS in aged solution and the effects of aging time, solution concentration, and solvents on the self-assembly of P3HS are explored. A novel bundlelike spherulitic morphology is observed, which is so far scarcely observed in polyselenophenes. These P3HS spherulites consist of nanoribbons in which the polymer chains adopt a flat-on orientation associated with form II crystals. The formation mechanism and kinetics of P3HS spherulites are discussed in detail. Overall, this work offers an effective way to demonstrate how the P3HS crystallize in solution and the correlation between its morphology and crystalline structure, which improves our understanding of P3HS crystallization and facilitates the ongoing exploration of using such spherulites in organic electronics.
Co-reporter:Li Xu, Feng Qiu
Polymer 2015 Volume 64() pp:130-138
Publication Date(Web):1 May 2015
DOI:10.1016/j.polymer.2015.03.043
•The unusual η-CNaSCN curve for PAN/NaSCN aqueous solutions is investigated.•Rheological studies reveal the fluid and gel states exist for PAN aqueous solutions with different CNaSCN.•IR and DSL measurements are employed to elucidate the unusual viscosity behavior.•Three kinds of chain conformations of swelling, collapse and association are tentatively proposed.The rheological behaviors of polyacrylonitrile (PAN) and its copolymers in various NaSCN aqueous solutions are investigated. An unusual shear-viscosity behavior that is unique for PAN/NaSCN aqueous solutions is identified: both in the high and low NaSCN concentration (CNaSCN) regimes, the PAN solution viscosities are higher, with the minimum occurring at CNaSCN = 48–50 wt% for the 11wt% PAN solutions. Infrared spectroscopic and dynamic light scattering measurements are employed to elucidate the solution-structural changes that are responsible for this unusual viscosity behavior. Accordingly, a tentative dissolution mechanism in PAN solutions with high CNaSCN and gelation mechanism with low CNaSCN are proposed.
Co-reporter:Jing Ge, Ming He, Nan Xie, Xiubao Yang, Zhi Ye, and Feng Qiu
Macromolecules 2015 Volume 48(Issue 1) pp:279-286
Publication Date(Web):December 26, 2014
DOI:10.1021/ma502321d
The microphase separation and crystallization of all-conjugated poly(3-butylthiophene)-b-poly(3-dodecylthiophene) (P3BDDT) diblock copolymers were systematically investigated by temperature-resolved wide-angle X-ray diffraction (WAXD), Fourier transform infrared (FTIR), and synchrotron small-angle X-ray scattering (SAXS) in a step-by-step cooling process. The WAXD, FTIR, and SAXS results revealed that the crystallization of poly(3-butylthiophene) (P3BT) blocks with shorter alkyl side-chains in high temperature region led to the formation of microphase-separated lamellar structure consisting of P3BT crystalline domains and P3BT/poly(3-dodecylthiophene) (P3DDT) amorphous domains, followed by a rapid crystallization of P3DDT blocks in relatively low temperature region, which occurred in the amorphous domains between P3BT crystalline domains. Analysis of the one-dimensional (1D) correlation function derived from SAXS data suggested that the previously crystallized P3BT segments could confine the size of P3DDT crystalline subdomains and possibly contribute to the rapid increase in the P3DDT crystallinity.
Co-reporter:Nan Ji, Ping Tang, and Feng Qiu and An-Chang Shi
Macromolecules 2015 Volume 48(Issue 23) pp:8681-8693
Publication Date(Web):November 19, 2015
DOI:10.1021/acs.macromol.5b02023
The kinetic pathways connecting the lamellar and gyroid phases in weakly segregated block copolymers are examined by combining the string method and the self-consistent mean-field theory for polymers. In particular, phase transition from arbitrarily oriented lamellae to gyroid is studied. The results reveal that initially the lamella will evolve into a metastable structure via a nucleation and growth mechanism, and then a secondary nucleation of the gyroid occurs in the metastable phase. The observed metastable structures include the perforated lamellae (PL), the O70 phase, and the tetragonally perforated layers (TPLabc). Nucleation and growth is the dominant mechanism, and prior phase transition passed by HPLabc, which is a long-lived metastable structure, has the minimal energy barrier.
Co-reporter:Zhi Ye, Xiubao Yang, Huina Cui and Feng Qiu
Journal of Materials Chemistry A 2014 vol. 2(Issue 33) pp:6773-6780
Publication Date(Web):13 Jun 2014
DOI:10.1039/C4TC00668B
We promote nanowire formation in a thin film of poly(3-hexylthiophene) (P3HT) by applying a strong electric field. Molecular packing in the formed nanowires is surprisingly different from that usually obtained by thermal annealing or from dilute solutions. In the case of electric-field annealing, the P3HT backbones are parallel to the nanowire axis; while in the former cases of thermal annealing, its backbones are perpendicular to the wire axis. Furthermore, this unusual one-dimensional nanowire exhibits improved crystallinity and electric conductivity compared to the corresponding thermally annealed sample. The growth of unusual nanowires is attributed to the introduction of dipolar interactions at the polymer ends by electric field. This kind of nanowire creates effective charge transport pathways along the intrachain route and contributes to the enhanced conductivity of the P3HT films.
Co-reporter:Hao Xia, Zhi Ye, Xiaofeng Liu, Juan Peng and Feng Qiu
RSC Advances 2014 vol. 4(Issue 38) pp:19646-19653
Publication Date(Web):15 Apr 2014
DOI:10.1039/C4RA01127A
We report on a new class of all-conjugated polyelectrolyte diblock copoly(3-hexylthiophene)s, poly(3-hexylthiophene)-b-poly[3-[6-(N-methylimidazolium)hexyl]thiophene] (P3HT-b-P3MHT). The polyelectrolyte diblock copolymers were prepared by a catalyst-transfer Kumada polycondensation followed by quaternization of the bromohexyl side groups of the poly[3-(6-bromohexyl)thiophene] block with N-methylimidazole. The obtained diblock copolymers have well-defined block ratios, narrow polydispersity indices, and high regioregularity. Their characterization as well as the thermal, crystalline, and optical properties, and self-assembly behavior have been investigated in detail. Transmission electron microscopy (TEM) provided evidence for solvent-induced self-assembly. A series of morphologies including short or long nanowires and nanorings could be obtained depending on the selectivity of solvents toward different blocks and the block ratios.
Co-reporter:Lianhua Long;Yingzi Yang
Chinese Journal of Chemistry 2014 Volume 32( Issue 3) pp:248-256
Publication Date(Web):
DOI:10.1002/cjoc.201300843
Abstract
Glycerol monostearate (GMS) is an additive widely used in plastic industry for its good ability to improve the wettability and antistatic property of polymer surfaces. Based on GMS, we propose five additives of different polarity by attuning the number of oxyethyl groups. All-atom molecular dynamics simulations of these additives in polypropylene (PP) matrix are carried out at temperatures of 300 K, 350 K and 400 K. Detailed molecular conformations are obtained and analyzed. Due to the gauche effect of the dihedral angles, the polar parts of these additives form helix structures. The diffusion coefficient of the additives depends on their molecular conformations and decreases monotonously with increasing polarity. These results are expected to be helpful in rational design of hydrophilic antistatic agents in polymeric materials.
Co-reporter:Cangyi Chen;Ping Tang
Journal of Polymer Science Part B: Polymer Physics 2014 Volume 52( Issue 24) pp:1583-1599
Publication Date(Web):
DOI:10.1002/polb.23528
ABSTRACT
Binary polymer brushes, including mixed homopolymer brushes and diblock copolymer brushes, are an attractive class of environmentally responsive nanostructured materials. Owing to microphase separation of the two chemically distinct components in the brush, multifaceted nanomaterials with functionalized and patterned surfaces can be obtained. This review summarizes recent progress on the theory and simulations related to binary polymer brushes grafted to flat, spherical, and cylindrical substrates, with a focus on patterned morphologies of multifaceted hairy nanoparticles, an intriguing class of hybrid nanostructured particles (e.g., nanospheres and nanorods). In particular, powerful field theory and particle-based simulations suitable for revealing novel structures on these patterned surfaces, including self-consistent field theory and dissipative particle dynamics simulations, are emphasized. The unsolved yet critical issues in this research field, such as dynamic response of binary polymer brushes to environmental stimuli and the hierarchical self-assembly of binary hairy nanoparticles, are briefly discussed. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1583–1599
Co-reporter:Li Xu, Feng Qiu
Polymer 2014 Volume 55(Issue 26) pp:6795-6802
Publication Date(Web):15 December 2014
DOI:10.1016/j.polymer.2014.10.045
We propose an integral procedure to simultaneously obtain the three Flory–Huggins interaction parameters in polymer(3)/solvent(2)/nonsolvent(1) systems by carrying out only viscosity and cloud point measurements. First, the interaction parameter between polymer and solvent, χ23, is obtained by applying the Rudin's model which has been well established for various polymer solutions. Then the solvent/nonsolvent interaction parameter χ12 and polymer/nonsolvent interaction parameter χ13 are calculated by combining the Rudin's model and the modified Flory–Huggins free energy for the ternary system, which leads to a group of candidate values of χ12 and χ13. Finally, these values are selected by the best agreement between the calculated binodal curves and the measured cloud points of the ternary system. This procedure has been successfully applied to PES/NMP/H2O, PAN/DMSO/H2O, and PAN/DMF/H2O systems. All the values obtained are comparable to those reported previously. The procedure is simple and easy to follow, with no requirement of complex equipments.
Co-reporter:Ming He, Jing Ge, Zhiqun Lin, Xuhui Feng, Xinwei Wang, Hongbin Lu, Yuliang Yang and Feng Qiu
Energy & Environmental Science 2012 vol. 5(Issue 8) pp:8351-8358
Publication Date(Web):14 Jun 2012
DOI:10.1039/C2EE21803H
The energy-filtering effect was successfully employed at the organic–inorganic semiconductor interface of poly(3-hexylthiophene) (P3HT) nanocomposites with the addition of Bi2Te3 nanowires, where low-energy carriers were strongly scattered by the appropriately engineered potential barrier of the P3HT–Bi2Te3 interface. The resulting P3HT–Bi2Te3 nanocomposites exhibited a high power factor of 13.6 μW K−2 m−1 compared to that of 3.9 μW K−2 m−1 in P3HT. The transport characteristics of nanocomposites, including the carrier concentration, mobility, and energy-dependent scattering parameter, were revealed by the experimental measurements of electrical conductivity, Seebeck coefficient, and Hall coefficient to quantitatively elucidate the carrier energy scattering at the P3HT–Bi2Te3 interface. The ability to rationally engineer the organic–inorganic semiconductor interfaces of polymer nanocomposites to achieve an improved Seebeck coefficient and power factor provides a potential route to high-performance, large-area, and flexible polymer thermoelectric materials.
Co-reporter:Jing Ge, Ming He, Xiubao Yang, Zhi Ye, Xiaofeng Liu and Feng Qiu
Journal of Materials Chemistry A 2012 vol. 22(Issue 36) pp:19213-19221
Publication Date(Web):06 Aug 2012
DOI:10.1039/C2JM33204C
The crystallinity of all-conjugated diblock copolymer, poly(3-butylthiophene)-b-poly(3-dodecylthiophene) (P3BDDT), with varied block ratios was significantly enhanced by a “two-step” thermal annealing treatment. The resulting P3BDDT exhibited an attractively high crystallinity of ∼35%, which is a 3-fold enhancement over those of its homopolymer counterparts. The space-charge limited current (SCLC) mobility measurement revealed that the carrier mobility of the highly crystalline P3BDDT film was increased to as high as ∼8.4 × 10−3 cm2 V−1 s−1, exceeding the highest SCLC mobility of poly(3-alkylthiophene) homopolymer films reported in previous work (i.e., ∼1.6 × 10−3 cm2 V−1 s−1). DSC, XRD, AFM and SAXS characterizations demonstrated that the interplay of crystallization and microphase separation during the “two-step” thermal annealing treatment plays a key role in the improvement of P3BDDT crystallinity.
Co-reporter:Zhongcheng Pan, Jing Ge, Weihua Li, Juan Peng and Feng Qiu
Soft Matter 2012 vol. 8(Issue 39) pp:9981-9984
Publication Date(Web):28 Aug 2012
DOI:10.1039/C2SM26523K
We report the behavior of one-dimensional polythiophene-based nanofibers in solutions passing through the nanopores under a flow field. Under a strong flow field, a fiber-to-cluster transition can be observed when the nanofiber solution concentration is above a critical value. The Zimm time and the passing time of the nanofibers are compared to explain the way the nanofibers pass through the nanopores under different flow fields.
Co-reporter:Jian Zhu;Ming He
Chinese Journal of Chemistry 2012 Volume 30( Issue 7) pp:1399-1404
Publication Date(Web):
DOI:10.1002/cjoc.201200505
Abstract
The Young's modulus of graphene with various rectangular and circular vacancy defects is investigated by molecular dynamics simulation. By comparing with the results calculated from an effective spring model, it is demonstrated that the Young's modulus of graphene is largely correlated to the size of vacancy defects perpendicular to the stretching direction. And a linear reduction of Young's modulus with the increasing concentration of mono-atomic-vacancy defects (i.e., the slope of −0.03) is also observed. The fracture behavior of graphene, including the fracture strength, crack initiation and propagation are then studied by the molecular dynamics simulation, the effective spring model, and the quantized fracture mechanics. The blunting effect of vacancy edges is demonstrated, and the characterized crack tip radius of 4.44 Å is observed.
Co-reporter:Weihua Li and Feng Qiu and An-Chang Shi
Macromolecules 2012 Volume 45(Issue 1) pp:503-509
Publication Date(Web):December 12, 2011
DOI:10.1021/ma2023952
The emergence and stability of superstructured cylindrical phases in frustrated ABC linear triblock copolymers are investigated by the self-consistent field theory. Our results reveal that the complex single/double/triple helices-on-cylinder phases are formed when the straight cylinders-on-cylinder and rings-on-cylinder phases are frustrated due to packing constraints. A free energy comparison indicates that the double and triple helical phases are stable, whereas the other cylinders-on-cylinder phases are metastable. In addition, the chirality and rotation for the helical supercylinders are considered in our calculations. Our theoretical prediction is consistent with a number of experimental observations.
Co-reporter:Ruobing Wang, Juan Peng, Feng Qiu and Yuliang Yang
Chemical Communications 2011 vol. 47(Issue 10) pp:2787-2789
Publication Date(Web):10 Jan 2011
DOI:10.1039/C0CC04955G
Enhanced white-light emission was achieved by loading green- and red-light-emitting donor–acceptor pairs in the separate micellar cores and blue-light-emitting polymers around their periphery. Fluorescence resonance energy transfer was enabled between a donor and an acceptor in cores, but was suppressed among these three light-emitting species by micellar coronas, which resulted in their enhanced simultaneous emissions.
Co-reporter:Bo Lin, Hongdong Zhang, Ping Tang, Feng Qiu and Yuliang Yang
Soft Matter 2011 vol. 7(Issue 21) pp:10076-10084
Publication Date(Web):13 Sep 2011
DOI:10.1039/C1SM06204B
Microphases and triangle phase diagrams of ABC dendrimers with different chain lengths of the second generation are investigated by a real-space implementation of self-consistent mean field theory in a two-dimensional (2D) space. Seven main stable ordered morphologies have been observed in the intermediate-segregation regime, including “three-color” lamellae phase (LAM3), “three-color” hexagonal honeycomb phase (HEX3), dodecagon-hexagon-tetragon phase (DOHT), octagon-octagon-tetragon phase (OOT), lamellae phase with alternating beads (LAM + AB), decagon-hexagon-tetragon and decagon-hexagon-hexagon phase ([DEHT;DEHH]), and core-shell hexagonal lattice phase (CSH). Simulation experiments reveal that when the volume fractions of three different polymer block species are comparable, the dendritic molecular architecture of the polymer chain has a strong topological constraint on the geometry of microphases. In a particular range of volume fractions fa ≈ fb ≈ fc, the HEX3 phase is found to be the most stable. In addition, near the region of HEX3 in the triangle phase diagrams, another competitive microphase (OOT) has an energy which is close to HEX3 was found to be stable as well. However, when the volume fraction of one block species is big enough, such as fa (or fb, fc) ≥ 0.7, especially in the system of ABC dendrimer with equivalent block chain of the second generation and asymmetric interaction parameters, the influence of dendritic architecture on the morphologies is not so obvious. If the chain topology of the dendrimer does not stretch sufficiently, then it displays a LAM + AB microphase as linear ABC terpolymer.
Co-reporter:Ren Bao, Li Li, Feng Qiu, and Yuliang Yang
The Journal of Physical Chemistry B 2011 Volume 115(Issue 19) pp:5923-5929
Publication Date(Web):April 28, 2011
DOI:10.1021/jp2008122
The effect of monosialoganglioside GM1 (GM1) concentration on the lateral phase separation in the sphingomyelin/1,2-dioleoyl-sn-glycero-3-phosphocholine/cholesterol (SM/DOPC/Chol) bilayers was studied by using atomic force microscopy. The results show that, with the increase of GM1 mol fraction (x), the dominant composition of liquid-ordered (Lo) domains changes from SM to SM/GM1 and finally to GM1. Meanwhile, the decrease of domain area (A) of the Lo phase with the increase of x follows a scaling law of A ∼ x–3/2, for x > 0.005, indicating that the domain growth is pinned with high GM1 concentration. Results of in situ experiments of GM1 insertion into SM/DOPC/cholesterol bilayers further supported our observations.
Co-reporter:Guojie Zhang, Feng Qiu, Hongdong Zhang and Yuliang Yang, An-Chang Shi
Macromolecules 2010 Volume 43(Issue 6) pp:2981-2989
Publication Date(Web):February 19, 2010
DOI:10.1021/ma902735t
Ordered phases of ABC star terpolymer melts are investigated using a generic reciprocal-space implementation of the self-consistent field theory (SCFT) of polymers. The most important feature of ABC star triblock terpolymers is that their three blocks are joined at one junction point. This distinct topology of ABC star terpolymers constraints the junction points in one-dimensional lines in an ordered phase, resulting novel microphase-separated morphologies such as tiling patterns. Two types of star triblock terpolymers, with symmetric and asymmetric interaction parameters, are studied in detail. A variety of tiling patterns in ABC star terpolymers have been predicted from the SCFT calculation and relevant phase diagrams have been constructed. The predicted phase transition sequences from the SCFT calculations are in qualitative agreement with experimental and Monte Carlo simulation results.
Co-reporter:Ming He, Lei Zhao, Jun Wang, Wei Han, Yuliang Yang, Feng Qiu and Zhiqun Lin
ACS Nano 2010 Volume 4(Issue 6) pp:3241
Publication Date(Web):May 14, 2010
DOI:10.1021/nn100543w
The use of mixed selective solvents provides an effective means to control self-assembly of the all-conjugated diblock copolymer poly(3-butylthiophene)-b-poly(3-hexylthiophene) (P3BHT) into nanostructured morphologies. The solvent and temperature effects on the self-assembly of P3BHT during cooling and subsequent crystallization were explored for the first time. Depending on the poor/good solvent ratio (i.e., anisole/chloroform), P3BHT chains experience different kinetic pathways, yielding nanowires at a low anisole/chloroform ratio (≤2:1), and nanorings coexisted with some nanowires at a high anisole/chloroform ratio (≥6:1). The nanowires are formed as a direct consequence of strong interchain π−π stacking, while the formation of nanorings is governed by solvophobic interactions between conjugated blocks and the poor solvent anisole to minimize the unfavorable contacts between the P3BT block (∼50 °C) and later P3HT (below 35 °C) block and anisole.Keywords: all-conjugated diblock copolymer; nanorings; nanowires; polythiophene; self-assembly
Co-reporter:Bo Lin, Hongdong Zhang, Feng Qiu, and Yuliang Yang
Langmuir 2010 Volume 26(Issue 24) pp:19033-19044
Publication Date(Web):November 15, 2010
DOI:10.1021/la102519f
The microphase separation and morphology of a nearly symmetric A0.3B0.3C0.4 star triblock copolymer thin film confined between two parallel, homogeneous hard walls have been investigated by self-consistent mean field theory (SCMFT) with a pseudospectral method. Our simulation experiments reveal that under surface confinement, in addition to the typically parallel, perpendicular, and tilted cylinders, other phases such as lamellae, perforated lamellae, and complex hybrid phases have been found to be stable, which is attributed to block−substrate interactions, especially for those hybrid phases in which A and B blocks disperse as spheres and alternately arrange as cubic CsCl structures, with a network preferred structure of C block. The results show that these hybrid phases are also stable within a broad hybrid region (H region) under a suitable film thickness and a broad field strength of substrates because their free energies are too similar to being distinguished. Phase diagrams have been evaluated by purposefully and systematically varying the film thickness and field strength for three different cases of Flory−Huggins interaction parameters between species in the star polymer. We also compare the phase diagrams for weak and strong preferential substrates, each with a couple of opposite quality, and discuss the influence of confinement, substrate preference, and the nature of the star polymer on the stability of relatively thinner and thick film phases in this work.
Co-reporter:Jing Ge, Ming He, Feng Qiu and Yuliang Yang
Macromolecules 2010 Volume 43(Issue 15) pp:6422-6428
Publication Date(Web):July 16, 2010
DOI:10.1021/ma1010167
A series of all-conjugated diblock copoly(3-alkylthiophene)s with varying alkyl chain length, poly(3-butylthiophene)-b-poly(3-hexylthiophene) (P3BT−P3HT), poly(3-butylthiophene)-b-poly(3-dodecylthiophene) (P3BT−P3DDT), and poly(3-hexylthiophene)-b-poly(3-dodecylthiophene) (P3HT−P3DDT), were synthesized by modified Grignard metathesis polymerization. The obtained diblock copoly(3-alkylthiophene)s have well-controlled block ratios and molecular weights with narrow polydispersity indices. The diblock copoly(3-alkylthiophene)s comprised by the blocks with the alkyl side-chain length different by two carbon atoms (represented by P3BT−P3HT) have the ability of cocrystallizing into an uniform crystal domain, with the mutual interdigitation of the different side chains of the two blocks into a common interchain lamella. Other diblock copoly(3-alkylthiophene)s with the side chains different by more than two carbon atoms prefer to microphase separating into two crystal domains formed by the independent crystallization of each block. The AFM images revealed the characteristics of microphase-separated morphology in P3BT−P3DDT and P3HT−P3DDT diblock copoly(3-alkylthiophene)s.
Co-reporter:Ming He, Jing Ge, Ming Fang, Feng Qiu, Yuliang Yang
Polymer 2010 Volume 51(Issue 10) pp:2236-2243
Publication Date(Web):4 May 2010
DOI:10.1016/j.polymer.2010.02.049
A facile template-free approach to fabricate poly(3-hexylthiophene) (P3HT) into highly aligned microwire film on a large scale via the evaporation of P3HT/Anisole whisker solution has been developed. The microwires in the film typically have the height of 0.8–1.4 μm, width of 2–4 μm and length of 50–1000 μm. X-ray Diffraction and Selected-Area Electron Diffraction results suggest that each microwire is a single crystal with the reduced packing distance of P3HT chains along the π–π stacking direction (d[010] of 6.5 Å) and the interchain direction (d[100] of 15.7 Å). The closer packing of P3HT chains is likely the key factor promoting the formation of the highly aligned microwires. The aligned P3HT microwire films perform enhanced electrical conductivity, and show no substrate dependence, thus can be fabricated into organic electronic devices in situ.
Co-reporter:Ruobing Wang, Juan Peng, Feng Qiu, Yuliang Yang and Zhiyuan Xie
Chemical Communications 2009 (Issue 44) pp:6723-6725
Publication Date(Web):15 Oct 2009
DOI:10.1039/B915378K
White-light emission is achieved from a single layer of diblock copolymer micelles containing green- and red-light-emitting dyes in the separate micellar cores and blue-light-emitting polymer around their periphery, in which fluorescence resonance energy transfer between fluorophores is inhibited due to micelle isolation, resulting in simultaneous emission of these three species.
Co-reporter:Hongdong Zhang;Jiajing Xu;Yuliang Yang
Journal of Polymer Science Part B: Polymer Physics 2006 Volume 44(Issue 19) pp:2811-2820
Publication Date(Web):28 AUG 2006
DOI:10.1002/polb.20884
Using a real space implementation of the self-consistent field theory, we calculated the morphology and interactions of spherical nanoparticles with radius Rp that are grafted by polymer chains of N monomers immersed in a chemically identical polymer melt of polymerization index P. The calculation shows that, for big particles (Rp ≫ N1/2a, with a the segment size), the interactions and density profiles of the grafted layers are that of brushes at flat interface; While for small particles (Rp ≪ N1/2a), the interactions and density profiles are characteristic of star polymers. In the case of intermediate grafted chain lengths, that is, Rp ∼ N1/2a, we found that the grafting density of the polymers and the radius of the spherical nanoparticles are both important in determining the structure and interactions of the grafted layers. Our findings suggest possible ways to tailor the structure and interactions of the nanoparticles to benefit the fabrication of polymeric nanocomposites. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2811–2820, 2006
Co-reporter:Jing Ge, Ming He, Xiubao Yang, Zhi Ye, Xiaofeng Liu and Feng Qiu
Journal of Materials Chemistry A 2012 - vol. 22(Issue 36) pp:NaN19221-19221
Publication Date(Web):2012/08/06
DOI:10.1039/C2JM33204C
The crystallinity of all-conjugated diblock copolymer, poly(3-butylthiophene)-b-poly(3-dodecylthiophene) (P3BDDT), with varied block ratios was significantly enhanced by a “two-step” thermal annealing treatment. The resulting P3BDDT exhibited an attractively high crystallinity of ∼35%, which is a 3-fold enhancement over those of its homopolymer counterparts. The space-charge limited current (SCLC) mobility measurement revealed that the carrier mobility of the highly crystalline P3BDDT film was increased to as high as ∼8.4 × 10−3 cm2 V−1 s−1, exceeding the highest SCLC mobility of poly(3-alkylthiophene) homopolymer films reported in previous work (i.e., ∼1.6 × 10−3 cm2 V−1 s−1). DSC, XRD, AFM and SAXS characterizations demonstrated that the interplay of crystallization and microphase separation during the “two-step” thermal annealing treatment plays a key role in the improvement of P3BDDT crystallinity.
Co-reporter:Zhi Ye, Huina Cui, Xiubao Yang and Feng Qiu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 9) pp:NaN1956-1956
Publication Date(Web):2014/12/31
DOI:10.1039/C4TC02663B
We investigate the electrohydrodynamic instabilities in poly(3-hexylthiophene) (P3HT) semiconducting polymer films. In the case that a contact is made between the P3HT film and an anode of a doped silicon wafer, the instabilities quickly grow into micro-column arrays in several minutes. The resultant micro-columns in the P3HT film show spherulitic morphology and the polymer chains in the columns are packed with an “edge on” orientation. Charge injection across a small injection barrier is attributed to the promoted electrohydrodynamic instabilities in the thin film.
Co-reporter:Ruobing Wang, Juan Peng, Feng Qiu and Yuliang Yang
Chemical Communications 2011 - vol. 47(Issue 10) pp:NaN2789-2789
Publication Date(Web):2011/01/10
DOI:10.1039/C0CC04955G
Enhanced white-light emission was achieved by loading green- and red-light-emitting donor–acceptor pairs in the separate micellar cores and blue-light-emitting polymers around their periphery. Fluorescence resonance energy transfer was enabled between a donor and an acceptor in cores, but was suppressed among these three light-emitting species by micellar coronas, which resulted in their enhanced simultaneous emissions.
Co-reporter:Ruobing Wang, Juan Peng, Feng Qiu, Yuliang Yang and Zhiyuan Xie
Chemical Communications 2009(Issue 44) pp:NaN6725-6725
Publication Date(Web):2009/10/15
DOI:10.1039/B915378K
White-light emission is achieved from a single layer of diblock copolymer micelles containing green- and red-light-emitting dyes in the separate micellar cores and blue-light-emitting polymer around their periphery, in which fluorescence resonance energy transfer between fluorophores is inhibited due to micelle isolation, resulting in simultaneous emission of these three species.
Co-reporter:Zhi Ye, Xiubao Yang, Huina Cui and Feng Qiu
Journal of Materials Chemistry A 2014 - vol. 2(Issue 33) pp:NaN6780-6780
Publication Date(Web):2014/06/13
DOI:10.1039/C4TC00668B
We promote nanowire formation in a thin film of poly(3-hexylthiophene) (P3HT) by applying a strong electric field. Molecular packing in the formed nanowires is surprisingly different from that usually obtained by thermal annealing or from dilute solutions. In the case of electric-field annealing, the P3HT backbones are parallel to the nanowire axis; while in the former cases of thermal annealing, its backbones are perpendicular to the wire axis. Furthermore, this unusual one-dimensional nanowire exhibits improved crystallinity and electric conductivity compared to the corresponding thermally annealed sample. The growth of unusual nanowires is attributed to the introduction of dipolar interactions at the polymer ends by electric field. This kind of nanowire creates effective charge transport pathways along the intrachain route and contributes to the enhanced conductivity of the P3HT films.
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