Supporting information. Activated Ester Middle Block: One-step Synthesis. and Application as Locally Reactive Nanoporous.

Transcription

1 Supporting information Photocleavable Triblock Copolymers Featuring an Activated Ester Middle Block: One-step Synthesis and Application as Locally Reactive Nanoporous Thin Films Hui Zhao, 1 Weiyin Gu, 2 Ryohei Kakuchi, 1 Zhiwei Sun, 2 Elizabeth Sterner, 2 Thomas P. Russell, 2 E. Bryan Coughlin 2* and Patrick Theato 1* 1 Institue for Technical and Macromolecular Chemistry, University of Hamburg, Bundesstr.45, Hamburg, Germany 2 Department of Polymer Science & Engineering, University of Massachusetts, 120 Governors Drive, Amherst MA, Experimental Section Materials and Characterization Pentafluorophenyl 4-maleimidobenzoate (MAIPFP) was synthesized according to reported methods. 1 2,2 -Azobisisobutyronitrile (AIBN) was recrystallized from methanol.

2 Tetrahydrofuran (THF) was distilled from sodium/benzophenone. Monomethyl ether-peo (M n = 5000 g/mol) was purchased from Sigma Aldrich. All other reagents were purchased from commercial sources and used as received unless otherwise noted. 1 H NMR was measured on a Bruker 300 MHz NMR spectrometer using tetramethylsilane (TMS; δ = 0 ppm) as internal standard. The average molecular weights (M w and M n ) and dispersities (Đ) of the polymers were estimated by a Waters Associates GPC system in chloroform against monodisperse linear polystyrene standards covering a molecular weight range of Da. Scanning force microscopy was performed on a Digital Instruments Dimension 3100 operating in tapping mode. XPS analysis was performed in a Physical Electronics apparatus with a nonmonochromatic Mg K α radiation source at a 45 take off angle. The sensitivity factors specified for the spectrometer were used for quantitative analysis. The pressure in the analysis chamber was less than 10-5 Pa. The spectrum collection time was kept under 10 min to minimize X-ray damage. GISAXS measurements were performed on beamline at the Advanced Light Source at the Berkeley National Laboratory. The correct wavelength of X-rays used was 1.24 Å, and the scattered intensity was detected using a 2D charge-coupled device (CCD) camera or a Pilatus 100k fast detector. TEM studies were performed on a JEOL 100CX electron microscope operated at 100 kv. For the TEM measurements, the samples were prepared on silicon substrates with a thick layer of silicon oxide. The polymer film was then floated onto the surface of an aqueous solution containing 5 wt% HF, transferred to a water bath, and then retrieved with a Cu grid for TEM measurement. Macro-CTA Synthesis. PEO-N 3 (M n = 5000, Đ = 1.04, 1 equiv.), compound 1 (1 equiv.), CuBr/PMDETA (0.3 equiv./0.3 equiv.) and dioxane (2 ml) were loaded into a dry Schlenk tube. The reaction mixture was degassed by three freeze-pump-thaw cycles and the flask was refilled

3 with nitrogen. It was then stirred at room temperature for 48 h. The reaction solution was extracted 3 times with DCM from water; then all volatiles were removed under reduced pressure. The pink residue was dissolved in THF and precipitated three times into cold diethyl ether, and dried at 30 C in vacuum. Yield: ~80%, End functionalization degree: ~90%. 1 H NMR (300 MHz, CDCl 3 ), δ (TMS, ppm): 8.21 (d, 1H, ONB), 7.92 (d, 2H, SS-ArH), 7.57 (t, 1H, SS-ArH), 7.39 (t, 2H, SS-ArH), 7.08 (d, 1H, ONB), 7.25 (d, 1H, ONB), 5.58 (s,2h, ONB-CH 2 - O), 5.32 (s, triazole-ch 2 -ONB), 4.55 (t, 2H, triazole-ch 2 -CH 2 -O in PEO), ((broad, CH 2 -CH 2 -O), 3.37 (s, O-CH 3 in PEO), (m, OOC-CH 2 -CH 2 ), 1.98 (s, C(CN)CH 3 ). M n,,gpc = 7000 g/mol, Đ = General Procedure for RAFT Polymerizations. MAIPFP (12 equiv.), Styrene (1250 equiv.), Macro-CTA (1 equiv.) and AIBN (0.125 equiv.) were loaded into a dry Schlenk tube. The reaction mixture was degassed by five freeze-pumpthaw cycles and the flask was refilled with nitrogen. It was then stirred in a preheated oil bath at 80 C for 15 h. The pink product (conversion: 20%) was precipitated three times into cold hexane and dried at 30 C in vacuum. 1 H NMR (300 MHz, CDCl 3 ), δ (TMS, ppm): 8.20 (broad, MAIPFP) 8.12 (d, ONB), 7.85 (broad, SS-ArH), (broad, SS-ArH), (broad, ArH in ONB), 5.47 (s, ONB-CH 2 -O), 5.24 (s, triazole-ch 2 -ONB), 4.48 (t, 2H, triazole-ch 2 - CH 2 -O in PEO), (broad, CH 2 -CH 2 -O), 3.37 (s, O-CH 3 in PEO), (broad, proton in PPFPMA). Table 1, P1, M n,,gpc = g/mol, Đ =1.18. General Procedures for Preparation of the Thin Films. The PEO-b-P(S-co-MAIPFP)-b-PS (P1) BCPs were spin coated from toluene solutions (1wt %) onto silicon substrates and then annealed in a H 2 O/THF (0.1 ml/0.2 ml) atmosphere for 2.5 h at 20 o C. The film thickness was controlled

4 by adjusting the solution concentration and the spinning speed. To cleave the PEO block and functionalize the film simultaneously, the block copolymer films were put in a methanol solution under UV exposure at a wavelength of 365 nm and a dose of 5.6 J cm -2 (Blak-Ray Model B, UVL-56) for 12 h. Iron Nanodots and Nanodouts from Nanoporous Thin Films Template The nanoporous film was immersed into a methanol solution of amine funcational Fc ( Ferrocene, (2-aminoethyl)-, 10 mg/ml) at 35 o C for 12 hours. Nanodots were produced after methanol washing and oxygen plasma treatment. Nanotoroids were produced after acid (HCl, 0.1 M in water) washing and oxygen plasma treatment. P1 after UV P1 before UV Elution time (min) Figure S1. GPC trace for P1 before and after UV in THF.

5 Figure S2. (A) TEM image of the nanoporous thin film from P1 after UV treatment and methanol wash, scale: 70 nm. (B) AFM phase image for iron oxide nanodots. (C) AFM height image for iron oxide nanodots. Scale for B and C: 2 µm x 2 µm. Figure S3. (A) TEM image of nanoporous P1 thin film after UV irradiation, Fc-amine post-modification, and methanol wash, scale: 70 nm. (B) TEM image for sample in Figure S3A after acid wash.

6 Figure S4. High resolution XPS for sample shown in Figure 4. Figure S5. AFM images for P4 thin films after THF-water annealing.

7 Figure S6. AFM image of PS-hv-PEO (27k-5k), annealed at THF/H 2 O solution for 2.5 hours. Figure S7. AFM image of PS-hv-PEO (27k-5k) after UV treatment and washing with MeOH.

8 Figure S8. AFM image of of PS-hv-PEO (27k-5k) after UV treatment, and immersing in a FC-amine solution (2 mg/10 ml methanol) for 1 hour, then wash with 1 M HCl and methanol. Figure S9. AFM image of the film shown in Figure S8 after oxygen plasma treatment. Essentially, only an etched Si-wafer surface can be seen, with some height undulations due to the varying film

9 thickness of the block copolymer. This is confirmed by XPS measurements (see Figure S10), which proofed the absence of Fe 2 O 3 but the presence of SiO 2 due to the etching of the Si-wafer. Similar structures are obtained from nanoporous PS-hv-PEO films without treatment of FC-amine (see Figure S11). Figure S10. XPS spectra of samples shown in Figure S9. Red line was carried out at take-off angle of 15 o, and the blue line was at 75 o which investigated deeper into the wafer compared with the red line. The red line looks at the very surface of the wafer, showed that there was a tiny carbon peak left even after intense oxygen plasma. No trace of Fe atom was detected in both case, indicating that PS-hv-PEO without active ester group cannot trap Fc-amine, so no nanotoroids were observed after oxygen plasma..

10 Figure S11. AFM image of nanoporous pure PS-hv-PEO film without FC-amine treatment after oxygen plasma treatment, indicating that the etching process can result naturally into surface defects. Reference: 1. Kakuchi, R. Zamfir, M.; Lutz, J.F.; Theato, P. Macromolecular Rapid communication 2012, 33, 54.

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