Supporting Information

Nanocellulose Fibers as Green Dispersant for Two Dimensional Materials

Yuanyuan Li,a,b, § Hongli Zhu,a, § Fei Shen,a Jiayu Wan,a Steven Lacey,a Zhiqiang Fang,a Hongqi Dai,b* Liangbing Hu a*

Y. Y. Li, H. L. Zhu, F. Shen, J. Y. Wan, S. Lacey, Z. Q. Fang, L. B. Hu aDepartment of Materials Science and Engineering, University of Maryland, College Park, MD 20742 USAY. Y. Li, H. Q. DaibCollege of Light Industry Science and Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, P. R. China §These authors contributed equally to this work†Electronic supplementary information (ESI) available

E-mail: binghu@umd.edu , daihq@njfu.com.cn

Figure S1. (a) A digital image of the NFC solution. (b) The crystal structure of BN

represented by B in pink and N in light blue; the inset is a digital image of BN powder. (c)

The molecular structure of MoS2 where S is represented in yellow and Mo in brown; the inset

is a digital image of the MoS2 mineral. (d) Numerous MoS2 water solutions with different

NFC content after sonication for 1 hour. (e-f) Digital images of the BN and MoS2 dispersions

respectively.

Figure S2. (a) SEM cross-section image of the BN composite film where the BN flake

content was 40 wt%; red arrows refer to BN flakes. (b) SEM image of the BN composite film

surface; depicts how NFC glues the BN flakes together. Red arrows refer to BN flakes while

yellow arrows refer to NFC. (c) The BN gel used to prepare the BN fibers. (d) Strong,

flexible BN fibers tied in knots.

Figure S3. SEM image of the MoS2 composite film surface; depicts NFC attaches on the

MoS2 flake. Red arrows refer to MoS2 flakes while yellow arrows refer to NFC.

Concentration Measurement of the Exfoliated 2D Material Solution

The concentration of the exfoliated 2D solution was measured using the oven-dry method.

The exfoliated BN solution will be used as an example. 10 mL of the exfoliated BN solution

was placed into an oven at a temperature of 105oC until the solution was dried completely.

The following equation relates C, the concentration of the exfoliated BN solution (mg/mL) to

W, the dry weight of the exfoliated BN solution (mg):

C=W10

(1)

The weight ratio of the NFC in the exfoliated BN solution was detected by thermogravimetric

analysis (TG) (DTG-60AH) using the following formula:

RNFC=W exfoliated BN−W bulk BN

W NFC−W bulk BN×100 % (2)

where RNFC is the weight ratio of the NFC in the exfoliated BN solution, and Wexfoliated BN, Wbulk

BN, and WNFC are the weight losses for the exfoliated BN, the bulk BN powder, and the freeze

dried NFC respectively. These weight losses were obtained based on the TG curve at 700oC.

The experimental parameters used for the TG analysis included a heating rate of 10 K/min, a

temperature range from room temperature to 700oC, and an N2 purging gas flow rate of 50

mL/min.

The pure BN concentration in the exfoliated solution can be expressed by:

CBN=C × (1−RNFC ) (3)

where CBN is the pure BN concentration in the exfoliated solution (mg/mL), C is the

concentration of the exfoliated BN solution (mg/mL), and RNFC is the weight ratio of the NFC

in the exfoliated BN solution. The TG curve of BN, NFC, and exfoliated BN are shown in

Figure S3. Note that the same method was used to calculate the pure MoS2 concentration.

Figure S4. TG curve of the BN, NFC, and exfoliated BN.