Sample HTPD Article for RSI

SUPPLEMENTARY MATERIAL

Strongly reduced thermal conductivity in hybrid ZnO/nanocellulose thin films

Hua Jin,1 Giovanni Marin,1 Ashutosh Giri,2 Tommi Tynell,1 Marie Gestranius,3 Benjamin P. Wilson,4 Eero Kontturi,4 Tekla Tammelin,3 Patrick E. Hopkins2 and Maarit Karppinen1*

1Department of Chemistry and Materials Science, Aalto University, 00076 Aalto, Finland

2Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA 22904-4746,

3VTT Technical Research Centre of Finland, 02044 Espoo, Finland

4Department of Bioproducts and Biosystems, Aalto University, 00076 Aalto, Finland

This Supplementary Material section contains:

X-ray reflectivity (XRR) data on the superlattice films (Table S1) Additional experimental descriptions for AFM and XRR

S1 Table S1. Thickness, density and roughness values for the individual layers in N=1-3 ZnO/TOCN superlattice films, obtained from XRR data through simulation of the patterns. Note that the apparent thickness of the TOCN layers is smaller than the thickness of the individual TOCN fibrils (ca. 3-4 nm), and apparent density is larger than that of cellulose (ca. 1.5 g cm-3) because of the submonolayer structure of the TOCN networks as exposed in Figure 2. Nominal mass percentage values for TOCN have also been calculated from the thickness and density values in the table, but it should be noted that these values are also likely to be overestimates due to the reasons detailed above.

ZnO TOCN Layer Thickness Density Roughness Thickness Density Roughness Nominal mass- (nm) (g cm-3) (nm) (nm) (g cm-3) (nm) % Base ZnO 15.8 5.4 1.0 NA NA NA NA N=1 17.0 5.5 1.4 1.0 2.5 0.9 1.4 N=2 17.0 5.6 1.4 1.8 3.1 1.3 2.9 N=3 17.1 5.5 1.7 2.3 3.3 1.6 4.1

Additional Experimental Descriptions

AFM. Morphology of deposited TOCNs on ZnO were characterized by using a MultiMode 8 scanning probe microscope by Bruker AXS Inc. (Madison, WI, USA). Images were collected with an E scanner in intermittent contact mode with NSC15/AIBS silicon cantilevers by Ultrasharp μmasch (Tallinn, Estonia). According to the manufacturer the radius of curvature of the tips used was less than 10 nm with a typical cantilever resonance frequency of 325 kHz. Other than a simple flattening, no image processing was carried out. Inverse grayscale image was obtained with Scanning Probe Image Processor (SPIP) 6.0.6 software (Image Metrology, Lyngby, Denmark).

XRR. X-ray reflectivity (XRR) measurements were performed with a PANalytical X’Pert MPD PRO Alfa 1 (Cu-Kα radiation) instrument in order to determine the thickness and layer structure of the films, and the resulting patterns were analyzed and simulated using X’Pert Reflectivity software.