of Poly(3-hexylthiophene)-Based Block

Transcription

1 Supporting Information for: Regioregularity-Driven Morphological Transition of Poly(3-hexylthiophene)-Based Block Copolymers Jin-Seong Kim, Yongjoo Kim, Hyun-Jeong Kim, Hyeong Jun Kim, Hyunseung Yang, Yeon Sik Jung, Gila E. Stein, # and Bumjoon J. Kim *, Department of Chemical and Biomolecular Engineering, KAIST Institute for the Nanocentury and Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea # Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States * bumjoonkim@kaist.ac.kr S1

2 1. Methods General Methods. All commercial chemicals were purchased from Aldrich Co. and used as received without further purification. 2,5-dibromo-3-hexylthiophene, 5 -bromo-3,4 -dihexyl-5- iodo-[2,2 ]-bithiophene, azide-terminated chain transfer agent, 2- dodecylsulfanylthiocarbonylsulfanyl-2-dimethylpropionic acid 2-azido-propyl ester (CTA-N3) were synthesized according to procedures in literatures. 1 P2VP-N3 was synthesized by RAFT (reversible addition fragmentation chain transfer) polymerization according to a literature procedure using 2,2 -azobis(isobutyronitrile) (AIBN) and CTA-N3. 2 All 1 H NMR spectra were recorded at 400 MHz, using CDCl3 as a solvent. The chemical shifts of all 1 H NMR spectra are referenced to the residual signal of CDCl3 (δ 7.26 ppm) using Bruker 400 MHz NMR instrument. For determination of molecular weight and polydispersity index, polymers were dissolved in HPLC grade THF and SEC (Waters 2414) was performed at a flow rate of 1 ml min -1. The DSC curves were obtained from a TA Instruments DSC Q200. The polymer samples (~5 mg) were heated from 25 to 250 C at a heating rate of 10 C min -1 and then cooled down at a rate of 10 C min -1 under an inert atmosphere. The scans were performed twice for each sample. Transmission Electron Microscopy (TEM). To observe the bulk morphology, polymer samples were drop-casted from chloroform solutions on NaCl substrate, followed by thermal annealing at 240 C under argon atmosphere for 72 hours and slowly cooled down for 24 hours to room temperature. Highly pure argon atmosphere was achieved by three times of vacuum and argon purge cycle. Samples were cut to ~50 nm thickness using RMC Powertome-X with S2

3 a diamond knife. To introduce contrast between P3HT and P2VP blocks, the samples were exposed to iodine vapor for 1 hour before TEM observation. All the TEM images of the film were taken on a JEM-3011 HR electron microscope. Grazing-Incidence Small-Angle X-ray Scattering (GI-SAXS). The samples for GI-SAXS measurements were prepared by spin coating of chlorobenzene solution on silicon substrate. The polymer thin films with thickness of ~100 nm were thermally annealed at 240 C under argon atmosphere for 8 hours and slowly cooled down to room temperature. GI-SAXS measurements were performed on beamline 3C and 9A in the Pohang Accelerator Laboratory (South Korea). X-rays with energy of kev were used, and the off-specular scattering was recorded with a MAR-CCD area detector. The incidence angle of the X-ray beam was set in the range of For GI-SAXS, the samples were exposed to iodine vapor for 1 h to enhance the electron density contrast between P3HT and P2VP block. Synthesis of Alkyne-Terminated RR-controlled P3HT (RR X-alkyne). 2,5-dibromo-3- hexylthiophene and 5 -bromo-3,4 -dihexyl-5-iodo-[2,2 ]-bithiophene mixture was prepared with different mole ratio depending on the target RR of P3HT (amount of monomers used for the synthesis is provided below). The mixture was added in a dry flask under nitrogen atmosphere, and, then 20mL of dry THF was added into the flask. The mixture was stirred for 10 min at 0 C, isopropyl magnesium chloride lithium chloride complex solution (1.3 M solution in THF, 0.98 mol% of monomer) was added in one portion and the mixture was stirred for 1.5 h. After the formation of active Grignard monomer, Ni(dppp)Cl2 suspension (2.0 mol% S3

4 of monomer) in dry THF (0.5mL) was added in one portion to the mixture. After stirring for 25 min at room temperature, ethynyl magnesium bromide solution (0.5 M in THF, mol % of monomer) was added via syringe and stirred for 5 min. The reaction mixture was precipitated by pouring cold methanol and filtered. The filtered polymers were dissolved one more time in chloroform, filtrated to remove any impurities and precipitated in methanol followed by drying under the vacuum. 1 H NMR (400 MHz, CDCl3) δ 6.98 (s, 1H), δ 3.52 (s, CH of alkyne end group), δ (m, α-ch2, 2H), δ (m, β-ch2, 2H), δ (m, CH2, 2H), δ (m, CH2CH2, 4H), δ 0.92 (m, CH3, 3H). RR 95-alkyne. 2,5-dibromo-3-hexylthiophene (3.07 mmol, 1.00 g) was used for the synthesis. RR 85-alkyne. 2,5-dibromo-3-hexylthiophene (2.81 mmol, 0.92 g) and 5 -bromo-3,4 -dihexyl- 5-iodo-[2,2 ]-bithiophene (0.16 mmol, 0.08 g) were used for the synthesis. RR 78-alkyne. 2,5-dibromo-3-hexylthiophene (2.60 mmol, 0.85 g) and 5 -bromo-3,4 -dihexyl- 5-iodo-[2,2 ]-bithiophene (0.28 mmol, 0.15 g) were used for the synthesis. RR 73-alkyne. 2,5-dibromo-3-hexylthiophene (2.41 mmol, 0.79 g) and 5 -bromo-3,4 -dihexyl- 5-iodo-[2,2 ]-bithiophene (0.43 mmol, 0.21 g) were used for the synthesis. Synthesis of RR X-b-P2VP. RR-controlled P3HT-alkyne (0.02 g), P2VP-N3 (2.0 equiv), CuBr (5.00 mg, 0.35 mmol) were added into the flask and dissolved in dry THF (2mL) under nitrogen atmosphere. And then, N,N,N,N,N -Pentamethyldiethylenetriamine (PMDETA) (7.5 μl, 0.36 mmol) was added and the reaction mixture was refluxed. After 12 h, the solution was precipitated with hexane. The precipitant was stirred in THF/hexane co-solvent and acetone to remove any unreacted P3HT-alkyne and P2VP-N3 homopolymers, respectively. The resulting S4

5 powder was filtered and dried under the vacuum. Monte Carlo Simulation. In our simulation model, single coarse-grained bead contains three bonds of P3HT. Our GRIM polymerization method only allows either HT-HT-HT or HT-HH- TT (HH: head-to-head bond; HT: head-to-tail bond; TT: tail-to-tail bond) bond types. The P3HT block of P3HT-b-P2VP consists of coarse-grained beads. Nearest-neighbors are connected by harmonic spring. Between two HT-HT-HT beads, revised Lennard-Jones potential is applied and for every HT-HT-HT bead, extra harmonic potential with doubled spring constant between two neighbor beads of HT-HT-HT bead 2 is implemented to induce the crystallization behavior of P3HT block. Between two beads containing at least one HT-HH-TT beads, typical Lennard-Jones potential 4 is applied to induce spatial frustration for non-crystalline properties. The RR is defined as a content of HT bond % We choose random positions of HT-HT-HT beads for each polymer at fixed RR for random polymerization process of RR-controlled P3HT. The P2VP block consists S5

6 of NP2VP beads connected with the same harmonic potential. Between two P2VP beads, typical Lennard-Jones potential 4 is applied for non-crystalline feature of P2VP. Between P3HT and P2VP beads, Weeks-Chandler-Andersen (WCA) potential is applied. Reduced variables are used in this simulation: temperature /, distance 1/, pressure /, and spring constant /. To connect reduced variables to atomistic model, we put the diameter of our coarse-grained bead of P3HT trimer 10 and For the parameters for Lennard-Jones potential and harmonic potential, we set 2.0 and 1000 which gives the glass transition temperature at C and which contains additional three times of pi-pi stacking energy calculated from former coarsegrained model studies of P3HT. 3,4 For P2VP beads, is set up to 2.8 for P2VP to have glass transition temperature at C. NP3HT is set to 12 which corresponds to 36 monomers of P3HT (12.0 kg mol -1 after applying correction factor from SEC results) with four different (7, 8, 9, and 11) to match four RR values (72, 78, 83, and 94). NP2VP is set to either 4 or 12 for relative volume fraction of P2VP to be either 0.25 or RRcontrolled coarse-grained P3HT-b-P2VP polymers are simulated by using Monte-Carlo simulation in a constant pressure and temperature (NPT) ensemble. For each set of condition (RR and NP2VP, we run 10 7 Monte Carlo movement steps to equilibrate the system from random initial configuration of polymers. Each Monte Carlo movement contains 200 accepted moves of monomers with the probability of 0.25 with T * = and P * = to match the annealing condition of 240 C at atmosphere pressure. S6

7 2. Figures and Tables Figure S1. SEC traces of BCPs derived from (a) RR 95-alkyne, (b) RR 85-alkyne, (c) RR78- alkyne, and (d) RR73-alkyne. The SEC was performed with THF at a flow rate of 1mL min -1. The figure shows clear peak shift toward higher molecular weight with a monomodal distribution. S7

8 Figure S2. 1 H NMR spectra for RR 95-alkyne, P2VP-N3 (Mn = 7.5 kg mol -1 ) and RR 95-b- P2VP (0.45). The fp2vp values of all the P3HT-b-P2VP polymer were calculated using the equation described in this Figure. S8

9 Figure S3. 1 H NMR spectra of P3HT-b-P2VP BCPs that have (a) RR 95, (b) RR 85, (c) RR78, and (d) RR73 P3HT segment. S9

10 Figure S4. DSC 2 nd heating curves of the series of P3HT-b-P2VP containing (a) RR 95 (b) RR 85 (c) RR 78 and (d) RR 73 P3HT. S10

11 Table S1. Thermal properties of P3HT-b-P2VP polymers used in this study. Polymer T m, P3HT [ C] T c, P3HT [ C] H m [J/g] D c, P3HT [%] a RR 95-alkyne RR 95-b-P2VP (0.35) RR 95-b-P2VP (0.45) RR 85-alkyne RR 85-b-P2VP (0.27) RR 85-b-P2VP (0.46) RR 78-alkyne RR 78-b-P2VP (0.31) RR 78-b-P2VP (0.44) RR 73-alkyne RR 73-b-P2VP (0.30) RR 73-b-P2VP (0.45) a The D c,p3ht values of BCPs were calculated by comparing their melting enthalpy ( H m ) with the melting enthalpy of an ideal P3HT crystallite (37 J g -1 ), considering only the weight of the P3HT component. S11

12 Figure S5. The GI-SAXS analysis of RR 95-b-P2VP (0.35). (a) In-plane profiles at αf (b) Out-of-plane intensity profile along the first-order peak, qxy = 0.29 nm -1. (c) Out-of-plane intensity profile near qxy 0 (d) GI-SAXS 2D pattern of mixed orientations of fibril-like structures for angle of incidence Analysis: Figure S5a reports the in-plane intensity profile at αf Two peaks are detected at 0.3 nm -1 and 0.6 nm -1 (D 22 nm). This ratio of 1:2 is characteristic of lamellar domains that are vertically-oriented with respect to the substrate, or a HPC phase with cylinders laying down in the plane of the film. Figure S5b reports the out-of-plane intensity profile along the first-order peak, i.e., the crystal truncation rod. The profile exhibits two sharp maximum that are called Yoneda peaks at αf 0.13 and αf 0.15, and then two weak oscillations in the range αf 0.18 to 0.26 that have a period of approximately 0.04, which corresponds with an out-of-plane dimension of ~ 80 nm (the film thickness). We assign this signal to verticallyoriented lamellae or "fibrils" rather than cylindrical layers, because the latter structure would produce Bragg peaks along the crystal truncation rods. (See, for example, Figure 4 in the manuscript.) However, the vertically-oriented fibril-like phase is not well ordered, as the oscillations that indicate an 80 nm length scale rapidly decay. Figure S5c reports the out-ofplane intensity profile near qxy 0. We observe Bragg peaks that come from a layered structure, so we simulate the Bragg peaks for parallel LAM and add them to the experimental pattern in an overlay (Figure S5d). It is consistent with a 22 nm out-of-plane periodicity. Therefore, we conclude that these films have a mixed orientation of fibrils. S12

13 Figure S6. The GI-SAXS in-plane line cuts for the BCPs with fp2vp 0.3. (a) RR 85-b-P2VP (0.27), (b) RR 78-b-P2VP (0.31), (c) RR 73-b-P2VP (0.30). The inset of each figure shows the corresponding 2D images. S13

14 Figure S7. GI-SAXS 2D patterns for (a) RR 95-b-P2VP (0.45) (b) RR 85-b-P2VP (0.46) (c) RR 78-b-P2VP (0.44), and (d) RR 73-b-P2VP (0.45) with incident angle of S14

15 Figure S8. The out-of-plane line cuts from 2D GI-SAXS patterns of (a) RR 95-b-P2VP (0.45), (b) RR 85-b-P2VP (0.46), (c) RR 78-b-P2VP (0.44), (d) RR 73-b-P2VP (0.45). Angle of incidence S15

16 References (1) Erothu, H.; Kolomanska, J.; Johnston, P.; Schumann, S.; Deribew, D.; Toolan, D. T. W.; Gregori, A.; Dagron-Lartigau, C.; Portale, G.; Bras, W.; Arnold, T.; Distler, A.; Hiorns, R. C.; Mokarian-Tabari, P.; Collins, T. W.; Howse, J. R.; Topham, P. D. Synthesis, Thermal Processing, and Thin Film Morphology of Poly(3-hexylthiophene)-Poly(styrenesulfonate) Block Copolymers. Macromolecules 2015, 48, (2) Lim, J.; Yang, H.; Paek, K.; Cho, C. H.; Kim, S.; Bang, J.; Kim, B. J. "Click" Synthesis of Thermally Stable Au Nanoparticles with Highly Grafted Polymer Shell and Control of Their Behavior in Polymer Matrix. J. Polym. Sci. A Polym. Chem. 2011, 49, (3) Schwarz, K. N.; Kee, T. W.; Huang, D. M. Coarse-grained simulations of the solution-phase self-assembly of poly(3-hexylthiophene) nanostructures. Nanoscale 2013, 5, (4) Jankowski, E.; Marsh, H. S.; Jayaraman, A. Computationally Linking Molecular Features of Conjugated Polymers and Fullerene Derivatives to Bulk Heterojunction Morphology. Macromolecules 2013, 46, S16