Supporting Information Hairy Uniform Permanently-Ligated Hollow Nanoparticles with Precise Dimension Control and Tunable Optical Properties Yihuang Chen, 1,2 Di Yang, 3 Young Jun Yoon, 1 Xinchang Pang, 1 Zewei Wang, 1 Jaehan Jung, 1 Yanjie He, 1 Yeu Wei Harn, 1 Ming He, 1 Shuguang Zhang, 1,2 Guangzhao Zhang,*, 2 and Zhiqun Lin*, 1 1. School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA. 2. Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China. 3. College of Science, Minzu University of China, Beijing 100081, China. S1
Figure S1. 1 H-NMR spectrum of star-like PS in CDCl 3. S2
Figure S2. 1 H-NMR spectrum of star-like PS-b-PtBA in CDCl 3. S3
Figure S3. 1 H-NMR spectrum of star-like PS-b-PtBA-b-PS in CDCl 3. S4
Figure S4. 1 H-NMR spectra of star-like triblock copolymers. Upper spectrum: star-like PS-b-PtBA-b-PS in CDCl 3. Lower spectrum: the resulting amphiphilic star-like PS-b-PAA-b-PS in d 7 -DMF. S5
Figure S5. Schemes of the carboxylic acid (COOH) groups in PAA block associating with (a) HAuCl 4 via direct coordination and (b) AgNO 3 by electrostatic interaction, respectively. S6
Figure S6. TEM images of star-like PS-b-PAA-b-PS triblock copolymers (i.e., Sample B in Table S1) associating with (a) HAuCl4 and (b) AgNO3. S7
Figure S7. AFM height images and the corresponding cross-sectional profiles of uniform (a and c) PS-capped hollow Au NPs (i.e., Hollow Au 2), and (b and d) PS-capped hollow Ag NPs (i.e., Hollow Ag). S8
Figure S8. Nitrogen adsorption-desorption isotherms of PS-capped hollow Au NPs (i.e., Hollow Au 2) and PS-capped solid Au NPs (i.e., Solid Au). Both exhibited a type IV isotherm with a type H3 hysteresis loop. S9
Figure S9. UV-vis spectra of PS-capped hollow Au NPs (i.e., Hollow Au 2) (a) at room temperature (R.T.) and (b) at high temperature (85 C and 105 C) in toluene after desired times. The corresponding maximum peak positions are shown as insets. S10
Figure S10. (a) Schematic of a two-dimensional cross-section of computational geometry for SRP simulation of hollow plasmonic NP. The dimension is truncated by a circular scattering boundary far away from hollow plasmonic NP. On the basis of the experimental condition, the medium surrounding hollow NPs is set to be toluene while the cavity of S11
hollow NPs is filled with PS chains with a refractive index n of 1.59. The incident wave is polarized along z axis, traveling along r axis. E v int and k v are the incident electric field and wavevector, respectively. For SPR simulation of solid plasmonic NPs, solid nanosphere is applied instead of hollow one by utilizing the same computational geometry noted above. (b) The distribution of meshes and simulated electric field. S12
Table S1. Molecular weights of amphiphilic star-like PS-b-PAA-b-PS triblock copolymers and the corresponding dimensions of PS-capped hollow noble metal nanoparticles (NPs). Samples M n, PS1 a M n, PAA b M n, PS2 c PDI d Dimensions of hollow Au NPs (external diameter/shell thickness) e (nm) Dimensions of hollow Ag NPs (external diameter/shell thickness) e (nm) Sample A 1,100 8,700 8,300 1.11 12.0 ± 0.4/4.7 ± 0.3 - Sample B 5,900 5,500 5,600 1.13 12.0 ± 0.5/2.7 ± 0.2 11.6 ± 0.4/2.7 ± 0.3 Sample C 29,800 11,200 13,700 1.18 25.1 ± 1.8/3.1 ± 0.4 - a Number average molecular weight, M n of the inner PS block in each arm can be evaluated based on the calculation of 1 H-NMR spectrum (Figure S1) according to the ratio of the integral area of phenyl protons on the PS chains (A d ) to that of methyl protons at the α-end of grafted PS (A a ): 1,2, = /5 /6 104.15 where M n,ps1 is the M n of the inner PS block in each arm, 104.15 is the molecular weight of St monomer, and the integral area (A a ) is obtained after deconvolution. b M n of the intermediate PAA block in each arm obtained from the molecular weight difference between PtBA block (before hydrolysis) and PAA block (after hydrolysis). M n of the intermediate PtBA block in each arm can be estimated by the following equation:, = /9 /5, 128.17 104.15 where M n,ptba and M n,ps1 are the M n of the intermediate PtBA block and the inner PS block in each arm, A e and A d are the integral areas of methyl protons in tert-butyl group of PtBA chain and the integral area of phenyl protons on PS chain, respectively, in Figure S2, 128.17 and 104.15 are the molecular weights of tba and St monomers, respectively. c M n of outer PS block in each arm can be calculated on the basis of the following equation:, = /5 /9, 104.15 128.17, where M n,ps2, M n,ptba and M n,ps1 are the M n of outer PS block, intermediate PtBA block and inner PS block in each arm, A e and A d are the integral area of methyl protons in tert-butyl group of PtBA chains and the integral area of phenyl protons on the PS chains, respectively, in Figure S3, 128.17 and 104.15 are the molecular weights of tba and St monomers, respectively. d PDI recorded by GPC. e Dimensions determined from TEM image analysis on hollow noble NPs. We note that the PAA blocks may still remain within hollow Au (and Ag) NPs. Similar phenomena have been reported in in-situ growth of inorganic S13
hollow NPs using micelles formed by self-assembly of linear block copolymer 3,4 and other organic molecule/inorganic crystal systems. 5-8 Nonetheless, it merits a detailed study and will be pursued and published in the future. Before performing the third ATRP of styrene monomers, a small amount of star-like PS homopolymers (i.e., ~10 mg) and star-like PS-b-PAA (after hydrolyzed from star-like PS-b-PtBA) diblock copolymers (i.e., ~10 mg) were dissolved in anhydrous DMF (~10 ml), respectively, at a concentration of 1mg/ml at room temperature. The solutions were stirred for 3 days prior to the DLS measurements. The hydrodynamic diameters D h of star-like PS and star-like PS-b-PAA from DLS measurements matched their theoretical sizes (i.e., radius of gyration R g ) and summarized in Table S2. Compared with the inner and external diameters of hollow NPs which are formed in the 9/1 DMF/BA mixed solution, the D h of star-like PS homopolymers and star-like PS-b-PAA diblock copolymers are slightly larger due to the relatively expanded chains in DMF and the minor volume shrinkage of the PAA compartment during the formation of NPs. Table S2. The hydrodynamic diameters from DLS measurements and theoretical radii of gyration of star-like PS homopolymers and star-like PS-b-PAA diblock copolymers. Samples a D h of Star-like PS b D h of Star-like PS-b-PAA b R g of Star-like PS c R g of Star-like PS-b-PAA c Sample A 3.3 ± 0.2 nm 12.9 ± 0.6 nm 1.58 nm 5.58 nm Sample B 7.8 ± 0.5 nm 13.3 ± 0.7 nm 3.66 nm 5.62 nm Sample C 21.9 ± 1.6 nm 28.1 ± 2.3 nm 8.25 nm 10.24 nm a The samples are homopolymers and diblock copolymers before the third ATRP, corresponding to the triblock copolymers in Table S1. b Hydrodynamic diameters D h of star-like PS homopolymers and star-like PS-b-PAA diblock copolymers in DMF measured by DLS. c Radii of gyration R g of star-like PS and star-like PS-b-PAA estimated according to the following equation: 9 S14
< > = 6 3 2/ where N is the degree of polymerization of star-like PS homopolymers or star-like PS-b-PAA diblock copolymers calculated from M n in Table S1, f is the number of arms, and b is the Kuhn length. As the Kuhn length of PAA (~0.69 nm) 10 is similar to that of PS (~0.71 nm) 11, an equivalence (i.e., b = 0.70 nm) of the Kuhn length for both PS and PtBA was used for simplifying the calculation. S15
Table S3. Simulated SPR peak positions of hollow Au NPs (no. 2-11) and their dimensions used in the calculation. Entries External diameter Shell thickness SPR peak position (Shell thickness) -1 (nm) (nm) (nm) (nm -1 ) 1(solid) 12 6.0 528 0.167 2 12 5.0 542 0.200 3 12 4.9 542 0.204 4 12 4.7 543 0.213 5 12 4.4 545 0.227 6 12 4 547 0.250 7 12 3 568 0.333 8 12 2.9 572 0.345 9 12 2.7 583 0.370 10 12 2 613 0.500 11 12 1 732 1.000 S16
Figure S11. Simulated shell thickness dependence of the SPR peak positions of hollow Au NPs summarized in Table S3. S17
Table S4. Simulated SPR peak positions of hollow Ag NPs (no. 2-12) and their dimensions used in the calculation. Entries External diameter Shell thickness SPR peak position (Shell thickness) -1 (nm) (nm) (nm) (nm -1 ) 1(solid) 11.6 5.8 412 0.172 2 11.6 4.8 414 0.208 3 11.6 3.8 423 0.263 4 11.6 3.1 439 0.323 5 11.6 2.8 450 0.357 6 11.6 2.7 454 0.370 7 11.6 2.6 459 0.385 8 11.6 2.5 464 0.400 9 11.6 2.3 475 0.435 10 11.6 2 496 0.500 11 11.6 1.5 553 0.667 12 11.6 1 663 1.000 S18
Figure S12. Simulated shell thickness dependence of the SPR peak positions of hollow Ag NPs summarized in Table S4. S19
Figure S13. (a) TEM image of PS-capped hollow Au NPs (i.e., Hollow Au 3). (b) UV-vis spectra of Hollow Au 2 and Hollow Au 3, in which their shell thicknesses are similar yet the external diameters are substantially different. S20
References (1) Pang, X.; Zhao, L.; Akinc, M.; Kim, J. K.; Lin, Z. Macromolecules 2011, 44, 3746-3752. (2) Chen, Y.; Yoon, Y.; Pang, X.; He, Y.; Jung, J.; Feng, C.; Zhang, G.; Lin, Z. Small 2016, 12, 6714-6723. (3) Koh, H.-D.; Park, S.; Russell, T. P. ACS Nano 2010, 4, 1124-1130. (4) Sasidharan, M.; Senthil, C.; Kumari, V.; Bhaumik, A. Chem. Commun. 2015, 51, 733-736. (5) Penn, R. L.; Banfield, J. F. Science 1998, 281, 969-971. (6) Kahr, B.; Gurney, R. W. Chem. Rev. 2001, 101, 893-952. (7) Rohl, A.; Gay, D.; Davey, R.; Catlow, C. J. Am. Chem. Soc. 1996, 118, 642-648. (8) Bullard, T.; Wustholz, K. L.; Bott, E. D.; Robertson, M.; Reid, P. J.; Kahr, B. Cryst. Growth Des. 2009, 9, 982-990. (9) Xu, Y.; Li, W.; Qiu, F.; Lin, Z. Nanoscale 2014, 6, 6844-6852. (10) Li, H.; Liu, B.; Zhang, X.; Gao, C.; Shen, J.; Zou, G. Langmuir 1999, 15, 2120-2124. (11) Noolandi, J.; Hong, K. M. Macromolecules 1983, 16, 1443-1448. S21