Supporting Information: Random Photografting
of Polymers to Nanoparticles for WellDispersed Nanocomposites
Adam W. Hauser and Ryan C. Hayward*
Department of Polymer Science and Engineering, University of Massachusetts Amherst,
Amherst, Massachusetts 01003, United States
Table S1 – Summary of copolymers used
Abbreviation
PMMA
PpMS
PS
Mol% AABP
(1H NMR)
2.8
5.4
4.8
Mn (kg/mol, THF GPC,
PMMA or PS stds)
24
25
17
Đ
1.7
2.1
1.9
Supporting Figures:
S1. Selected FTIR spectra of PMMA composites at 0 and 90 min UV exposure.
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S2. FTIR spectra of BMPE ligand and AuNPs.
S3. 1H NMR spectra (CDCl3, 400 MHz, normalized to TMS) of (top to bottom) benzyl 3bromopropyl
ether,
1-{[3-(benzyloxy)propyl]sulfanyl}ethan-1-one,
and
benzyl
mercaptopropyl ether. The integrations are for benzyl mercaptopropyl ether. Small peak
at ~5.2 ppm is methylene chloride, and small peaks at ~2.8 and ~2.9 in the middle
spectrum are DMF.
S4. TEM of un-exposed PMMA homopolymer (left) and PMMA-BP (right) composites,
showing that BP provides some improvement in dispersion of BMPE-functionalized
AuNPs without any UV exposure. Scale bars are 100 nm.
2
S5. TEM of PS nanocomposite films at (left to right) 0, 10 and 90 min exposures. Scale
bars are 20 nm.
S6. UV-Vis spectra of PpMS (left) and PS (right) NC films at various UV exposure times.
All spectra are normalized to 1 at the maximum of the SPR absorption.
S7. Normalized n-π* absorbance of BP (340 nm) for solutions with the indicated small
molecule analogs, with initial concentrations of 10 mM BP and 100 mM of the analog in
benzene. Exponential fits, 𝑓(𝑡) = 𝐴exp(−𝑘𝑡) are shown as solid lines, with the best-fit
decay constants k (min-1 x 10-3) indicated, where t = 0 was chosen where each fit
intersects 1 to account for the observed lag-time prior to the decrease in BP
absorbance, the origin of which is not fully understood. The ‘neat’ sample corresponds
to 10 mM of BP alone in benzene, showing that reaction with the solvent or impurities
over this time-scale is negligible.
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S8. SEM micrograph of a portion of the photo-patterned PMMA composite from Figure
4. The patterned feature size was 24.0 µm, while the measured width (grayscale
intensity profile (right)) was 28.1 ± 0.5 µm from three images, corresponding to a
broadening by 4.1 ± 0.5 µm (averaged profiles for each image are found with ImageJ
software; dotted box represents the analyzed area). The observed broadening is
reasonable in light of the size of the pixels in the micro-mirror array (1.4 m/pixel at the
sample plane) and the resolution of the objective lens (0.4 m).
S9. Left: DLS measurements of the PMMA composites used in Figure 3. 0 and 90 min
and 6 h samples were analyzed at a total concentration of 0.5 mg/mL, and the pure
PMMA at ~40 mg/mL in benzene. Right: van der Waals interaction potential calculated
following an approach described previously,1,2 using a NP radius of 2.5 nm and a shell
radius of 1.5 nm (ligand) and 3.5 nm (ligand plus grafted polymer layer, based on
dimensions determined by DLS) for the 0 and 6 h curves, respectively; Hamaker
constants of 3.5 x 10-21 and 1 x 10-19 J were used for PMMA/ligand and gold,
respectively.
Supporting Information References
1
Li, Y.; Tao, P.; Viswanath, A.; Benicewicz, B. C.; Schadler, L. S. Bimodal Surface
Ligand Engineering: The Key to Tunable Nanocomposites. Langmuir 2013, 29, 1211–
1220.
2
Jouault, N.; Lee, D.; Zhao, D.; Kumar, S. K. Block-Copolymer-Mediated
Nanoparticle Dispersion and Assembly in Polymer Nanocomposites. Adv. Mater. 2014,
26, 4031–4036.
4