AFM cross sectional imaging of perpendicularly oriented nanocylinder structures of microphase

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1 AFM cross sectional imaging of perpendicularly oriented nanocylinder structures of microphase separated block copolymer films by crystal-like cleavage Motonori Komura 1 and Tomokazu Iyoda 1,2* 1 Core Research for Evolutional Science and technology (CREST), Japan Science and Technology Agency (JST), and 2 Division of Integrated Molecular Engineering, Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Japan. Supporting information: Film preparation As reported in the previous paper 1, the amphiphilic block copolymer (PEO-b-PMA(Az)) was synthesized by atom transfer radical polymerization (ATRP) method 2. The PEO 114 -b-pma(az) n (n = 48 and 51) were mainly used in this study. The wt% toluene or chloroform solutions of the block copolymer were spin- or bar-coated on a (100) silicon wafer (Fujimi Fine Technology, Inc., Japan), which was cleaned with acetone by ultrasonication for 10 min and then irradiated with a Xe excimer lamp for 10 min. The films on the substrates were annealed for 24 hr under vacuum at 140 o C, above the isotropic transition temperature. The film thickness was from 100 nm up to 2 µm, too thick to section the film with a microtome. AFM large area observation An AFM phase image of a surface of a PEO 114 -b-pma(az) 48 microphase separated film in a large area of 4 16 µm 2 is shown in Figure S1 crossing the following two pages. The data of 1024 x 4096 points were acquired with the One Scan mode of NanoScope IV (Veeco, USA) and we also used the Fast Scan mode with double-feedback system to reduce scanning time for lessening the effect of scanner drifting. The dot-like structure identical to the (001) plane of the microphase separated structure with hexagonally arranged PEO cylinders were observed in the whole area, which indicated that all cylinders perpendicularly aligned to a surface. We can obtain thus microphase separated films only by once annealing which is conducted at 140 o C for 24 hr under vacuum. 1

2 4 µm Figure S1. An AFM large area phase-shift image PEO114-b-PMA(Az)48 of a microphase separated film (4 x 16 µm2). The film thickness was ca. 1.3 µm. The zoomed images are also shown. A A P P 2

3 P P C C D Some defects were observed around grain boundaries. D 3

4 (a) (b) 400 nm Figure S2. AFM cross sectional topographic (a) and phase shift (b) images of a PEO 114 -b-pma(az) 51 bar-coated film without annealing. AFM cross sectional observation of no annealed film Figure S2 shows AFM cross sectional topographic (a) and phase shift (b) images of a PEO 114 -b-pma(az) 51 bar-coated film without annealing. The cross section of the film in the topographic image has larger roughness than that of Figure 3 in the manuscript, because no annealed film has a lot of small grains in the inside. Spherical nanostructures were observed in the cross section, but disordered. Differential scanning calorimetry measurement Figure S3 shows Differential scanning calorimetry traces of a PEO 114 -b-pma(az) 51. In the first cooling process, PEO 114 -b-pma(az) 51 showed three transitions, isotropic to smectic A, smectic A to smectic C, and smectic C to semi crystalline phases (smectic X), at 118 o C, 104 o C, and 76 o C, respectively. One remaining transition at -18 o C was of PEO crystallization. In the second heating process, there are PEO melting, smectic Heat flow (W/g, Endo down) st cooling 2nd Heating Temperature ( o C) Figure S3. Differential scanning calorimetry traces of a PEO 114 -b-pma(az) 51. X to smectic C, smectic C to smectic A and smectic A to isotropic transitions, at 37 o C, 68 o C, 96 o C and 120 o C, respectively. As the microphase separated films were prepared by cooling from 140 o C to room temperature, the PEO domains were in melting state and the PMA(Az) domains were in semi-crystalline state. Therefore there is elastic 4

5 modulus difference between soft PEO and hard PMA(Az) domains. Small angle x-ray scattering measurement Figure S4 shows a small angle x-ray scattering profile of a PEO 114 -b-pma(az) 51 in bulk. It shows four peaks indicating hexagonally arranged cylinder microphase separation and one azobenzene liquid crystalline layer (100) (110) (200) (120) liquid crystalline layer peak. References: 1. Tian, Y.; Watanabe, K.; Kong, X.; Abe, J.; Iyoda T. Figure S4. A small angle x-ray scattering profile of a PEO 114 -b-pma(az) 51. Macromolecules 2002, 35, Matyjaszewski, K.: Xia, J. H. Chem. Rev. 2001, 101,