Electric-Field-Assisted Assembly of. Nanopores

Transcription

1 Supporting Information for: Electric-Field-Assisted Assembly of Polymer-Tethered Gold Nanorods in Cylindrical Nanopores Ke Wang, Seon-Mi Jin, Jiangping Xu, Ruijing Liang, Khurram Shezad, Zhigang Xue,*, Xiaolin Xie, Eunji Lee,*, and Jintao Zhu*, Key Laboratory of Materials Chemistry for Energy Conversion and Storage (HUST) of Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan , China Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon , Republic of Korea *Corresponding authors. (Z. X.); (E. L.); (J. Z.) Characterization Transmission Electron Microscope (TEM). TEM investigation was performed on a JEOL 2100 LaB 6 or FEG TEM operated at an acceleration voltage of 200 kv. TEM samples were prepared on 300 mesh copper grids covered with carbon film. 1

2 Thermogravimetric Analysis (TGA). Dry PS-tethered AuNRs powders were placed in ceramic crucible and analyzed over the temperature ranged from room temperature to 800 o C at the rate of 10 o C min -1 under dry flow of N 2 at a rate of 30 ml min -1, performed on Diamond TG/DTA (PerkinElmer Instruments, Waltham, USA). UV-vis Spectroscopy. The hybrid assemblies in ethanol were placed in quartz sample cell with a 0.7 cm cell path length. Absorption spectra (ranged from 400 nm to 850 nm) were recorded by using UV 1801 spectrophotometer (Beijing Rayleigh Analytical Instrument Corporation) at 25 o C with reference spectrum of anhydrous ethanol. 3D reconstruction by TEM tomography. 3D reconstruction obtained from a series of 2D TEM image projections of the samples at different viewing angles. For TEM tomography, images were obtained by using a JEM-1400 (JEOL, Japan), operating at 120 kv. The current density of electron beam remained constantly at 13.5 pa/cm 2. The tilt series of TEM images were recorded with a 1 s exposure time using a pixel charge-coupled device (CCD) camera (JEOL, Japan). Tilting, refocusing, and repositioning were carried out after every individual tilt increase. Alignment and reconstruction of tilt series were performed in IMOD software. UCSF chimera software was used for visualization. - Electron tomography acquisition conditions: 1) For figure S3: AuNRs@PS 20K when D C = 61.2 nm under parallel electric field Angular sampling: -60 to 60 at 1 increments Magnification: 40,000 Pixel size: 0.64 nm for images 2) For figure 3: AuNRs@PS 50K when D C = 61.2 nm under perpendicular electric field Angular sampling: -70 to 64 at 2 increments Magnification: 50,000 2

3 Pixel size: 0.51 nm for images 3) For figure 4: 5K when D C = 96.3 nm under perpendicular electric field Angular sampling: -60 to 60 at 1 increments Magnification: 60,000 Pixel size: 0.43 nm for images 4) For figure S4: AuNRs@PS 50K when D C = 96.3 nm under perpendicular electric field Angular sampling: -70 to 66 at 2 increments Magnification: 40,000 Pixel size: 0.64 nm for images Calculation of relational expression between electric field force (F) and electric field intensity (E) When AuNR was put in an electric field, due to the dipolarization of AuNRs, the positive and negative charges were created and around the end of the NRs. The charges will be attracted with electrode and give a driving force to rotate AuNRs, and make the AuNRs along the electric field line (Scheme S2). Electric field intensity (E) can be defined as: 2 E = kq /( ε m r ) (1) Where k is the Coulomb's constant, Q is the quantity of inducing charge, ε m is the permittivity of medium, and r is the distance between the inducing charge and induced charge. The electric field force (F) for the induced charge showed as: Where q is the quantity of induced charge. F = qe (2) 3

4 Moreover, expression of the Coulomb force ( f ) between the positive and negative charges can be give by: f = ( kq 2 2 ) /( ε PSl ) (3) Where is the permittivity of AuNRs@PS, and l is the length of AuNRs@PS. Au PS When the system gets to electrostatic equilibrium, the electric field force (F) will be equal to the Coulomb force ( f ). And after inserting equation (1) into equation (2), we can obtain the following equation: q = 2 2 Q( ε Au PSl ) /( εmr ) From equation (1) we can also get: 2 Q = E( εm r ) / k (5) Inserting equation (4) and (5) into equation (2), then we can obtain the relational expression between the electric field force and the electric field intensity as: F = 2 2 E ( ε PSl ) / k (6) Since and l of AuNRs@PS are invariant, and k is constant, implying an Au PS exponential relation between the electric field force and electric field intensity. 4

5 SUPPORTING FIGURES: Scheme S1. Rotation of spherical AuNPs and cylindrical AuNRs in 2D cylindrical confinement. Where r is the radius of gyration, and broken circle shows the rotational path. Clearly, due to the anisotropy structures, AuNRs are blocked by each other and walls when rotating, while the isotropy AuNPs are not affected. This phenomenon indicates the enhanced steric hindrance for the movement of AuNRs under strong 2D confinement than AuNPs. 5

6 Scheme S2. Schematic illustrations of inducing AuNRs along the electric field line. Where Q is the quantity of inducing charges, q is the quantity of induced charges, r is the distance between the inducing charges and induced charges, F is the electric field force, and f is the Coulomb force. Scheme S3. Schematic illustrations of D NR-S, D NR-L and D Pro. 6

7 Figure S1. TEM images of 12k assemblies formed in AAO channel (pore size: 61.2 nm). (a) Confined assembly of 12k in the absence of electric field. (b-f) Confined assembly under parallel electric field with different electric field intensity (E): (b) E= V/m; (c) E= V/m; (d) E= V/m; (e) E= V/m; (f) E= V/m. 7

8 Figure S2. TEM images of hybrid assemblies in the absence of electric field while adjusting AAO membrane pore size (D C ) and molecular weight of PS brush (M w-ps ). The images display AuNRs@PS 5k, AuNRs@PS 12k, AuNRs@PS 20k, and AuNRs@PS 50k in AAO channel with pore size of 24.6 nm in (a-d), 61.2 nm in (e-h) and 96.3 nm in (i-l), respectively. 8

9 Figure S3. 3D reconstruction obtained by tomography of 20k assembly when D C = 61.2 nm. The 3D volume rendering shows the entire structure, in which the reconstructed density is color coded, that is, the AuNRs appear golden (high density) while the ligand PS appears grey (low density). From the tomogram, some of the AuNRs are segmented to visualize their arrangements along the longitudinal axis of cylindrical channel. The xz slice shows the hexagonal packing of AuNRs. 9

10 Figure S4. 3D reconstruction obtained by tomography of unique assembly from 50k, when D C = 96.3 nm. The 3D volume rendering shows the entire structure, in which the reconstructed density is color coded, that is, the AuNRs appear golden (high density) and the ligand PS appears grey (low density). Inner (red) and perpheral (green) AuNRs are arranged in parallel and perpendicular to the direction of cylindrical axis, respectively. The slices show sections through the center of the 3D volume in the three directions in space. 10

11 Figure S5. TEM images of AuNRs hybrid assemblies in AAO channel with pore size of nm under parallel electric field line (a-d) or perpendicular electric field line (e-h) with M w-ps of (a, e) 5 kg/mol, (b, f) 12 kg/mol, (c, g) 20 kg/mol, and (d, h) 50 kg/mol. 11

12 Figure S6. (a, b) Plots show the length of AuNRs hybrid assemblies as a function of M w of tethered PS, and (c, d) plots show correlation length of ordering structures as a function of M w of tethered PS: (a, c) assemblies formed under parallel E-field in different AAO channel (pore size: 24.3 nm, 61.2 nm, 96.3 nm); (b, d) assemblies formed under perpendicular E-field in different AAO channel (pore size: 24.3 nm, 61.2 nm, 96.3 nm). 12

13 Figure S7. (a-d) Representative TEM images of AuNRs hybrid assemblies in AAO channel (pore size: 61.2 nm) with M w-ps of (a) 5 kg/mol, (b) 12 kg/mol, (c) 20 kg/mol, and (d) 50 kg/mol. (e) The dependency of end-to-end distance between AuNRs and tilt angle to the long axis of AuNRs in hybrid assemblies on the M w of tethered PS. (f) UV-Vis spectra of different assemblies organized from different kinds of AuNRs@PS confined in 61.8 nm AAO membranes, respectively. 13

14 Figure S8. SEM images and histograms of AAO membrane with different pore size: (a) 24.6 ± 1.7 nm, (b) 61.2 ± 3.1 nm, (c) 96.3 ± 1.7 nm and (d) ± 6.2 nm, respectively. 14

15 Figure S9. Cross-sectional SEM images AAO membrane with different pore size: (a) 24.6 ± 1.7 nm, (b) 61.2 ± 3.1 nm, (c) 96.3 ± 1.7 nm and (d) ± 6.2 nm, respectively. 15

16 Figure S10. TEM images of monolayer packing film of organized from (a) 5k, (b) 12k, (c) 20k and (d) 50k, respectively; and histograms of D NR-L and D NR-S of different AuNRs@PS have been shown respectively. D NR-L and D NR-S contained the AuNRs core and the polymer PS shell which measured from end-to-end distance and side-by-side distance between the center of AuNRs, respectively. 16