Alireza Kaboorani Bernard Riedl Surface Characterization of Modified Nanocrystalline Cellulose (NCC) Laval University Quebec City Canada SEVENTH INTERNATIONAL SYMPOSIUM ON POLYMER SURFACE MODIFICATION

Introduction Cellulose: abundant, renewable, … Cellulose nanostructure Introduction of different types nanocellulose Nanocrystalline Cellulose (NCC) or nanowhiskers Microfibrillated cellulose (MFC)

Introduction NCC Renewable, abundant, green High modulus and strength Low density Reactive surface NCC is hydrophilic restricts the application of NCC.

Introduction Different methods for modification of NCC : (1) introduce stable negative or positive electrostatic charges on the surface of NCCs to obtain better dispersion (2) tune the surface energy characteristics of NCCs to improve compatibility, especially when used in conjunction with nonpolar or hydrophobic matrices

Introduction Cationic surfactant Hexadecyltrimethylammonium (HDTMA) bromide HDTMA: Used for surface modification zeolite and clay Easily availability and low cost Low negative effects on the environment

Research objective The main objective of this research was to modify the surface of NCC by using a cationic surfactant (Hexadecyltrimethylammonium (HDTMA)bromide).

Materials Nano-material: Nano-cellulose (nanocrystalline cellulose(NCC)), provided by Forest Products Laboratory (PFL) Cationic surfactant: Hexadecyltrimethyl ammonium (HDTMA) bromide, 99% purity: purchased from Sigm-Aldrich

Modification: At room temperature Different variables:  Concentration of HDTMA: 0.35 mmol/g and 1.4 mmol/g  Duration of the reaction: 2 and 4 hours

Surface characterization Fourier transforms infrared spectroscopy(FTIR) X-ray photoelectron spectroscopy(XPS) Atomic force microscopy(AFM) Scanning electron microscope(SEM)

Surface characterisation Fourier transforms infrared spectroscopy (FTIR)  Apparatus: a Perkin-Elmer Spectrum-One spectrometer equipped with a UATR-FTIR accessory  Spectrum resolution: 4 cm -1  Scan range: 4000 to 550 cm -1

Surface characterisation X-ray photoelectron spectroscopy (XPS)  Apparatus: Kratos Axis- Ultra spectrometer (UK)  Pressure :1-5 x 10-8 Torr  Take off angle : 60° with respect to the sample surface  Survey spectra and high- resolution XPS spectra were obatined.

Surface characterisation Atomic force microscopy (AFM)  Determining morphology of NCC including shape and size distributions  Apparatus: Multimode IIIa, Veeco Instruments  Topographic (height), phase and amplitude images were recorded.

Surface characterisation Scanning electron microscope(SEM) Apparatus: JEOL JEM1230 Samples sputter-coated with gold

IR absorbance spectra

XPS survey spectra a)unmodified NCC, b) modified NCC at 0,35 mmol/g HDTMA for 2 hours and c) modified NCC at 1,4 mmol/g HDTMA for 2 hours.

Element composition of NCC in different reaction conditions Samples N 1s C 1s O 1s O/CBr 3d Si 2p S 2p Unmodified NCC NCC mod. 0.35mmol/g- 2h NCC mod mmol/g- 4h NCC mod. 1.4 mmol/g- 2h NCC mod. 1.4 mmol/g- 4h

High-resolution XPS spectra of C a)unmodified NCC, b) modified NCC at 0,35 mmol/g HDTMA for 2 hours and c) modified NCC at 1,4 mmol/g HDTMA for 2 hours.

Element composition of NCC in different reaction conditions Component Unmodified NCC NCC mod mmol/g- 2h NCC mod mmol/g- 4h NCC mod. 1.4 mmol/g- 2h NCC mod. 1.4 mmol/g- 4h C1: C-C, C- H C2: C-O C3: C=O or O-C-O C4: O-C=O

High-resolution XPS spectra of C1s NCC modified at 1,4 mmol/g HDTMA for 4 hours;: a)three C1s compenents and b)four C1s compenents

AFM images (b)(a) a) unmodified NCC, b) modified NCC at 0.35 mmol/g for 2 hours and C) modified NCC at 1.4 mmol/g for 4 hours. The AFM images were taken from NCCs which were redispered in water. The concetration of NCC was 0.025%. (c)

AFM images (c)(b)(a) a) unmodified NCC, b) modified NCC at 0.35 mmol/g for2 hours and c) modified NCC at 1.4 mmol/g for 4 hours. The AFM images for unmodified NCCs were taken from NCCs which wree redispered in water. AFM images for modified NCCs were taken from NCCs which were redispeersed in THF. The concetration of NCC was 0.05%.

Mean diameter and length for NCCs (modified and unmodified) Samples Unmodified NCC NCC mod mmol/g- 2h NCC mod mmol/g- 4h NCC mod. 1.4 mmol/g- 2h NCC mod. 1.4 mmol/g- 4h Diameter (nm) Length (nm)

SEM images (a) (b) (c) (a) unmodified NCC, (b) modified NCC at 0.35 mmol/g for2 hours and (C) modified NCC at 1.4 mmol/g for 4 hours.

Conclusions Capability of HDTMA to change the surface of NCC Changes in chemical structure by the modification Appearance new groups including CH 2, CH 3 and C-N on the surface of NCC Variable degree of hydrophobicity of NCC via changing the concentration of HDTMA in the reaction. XPS: Comprehensive surface characterization of NCC. FT-IR: Fell short in determining the surface compositions of NCC

Conclusions Precise characterization of NCC by AFM We could determine: - Changes in morphology of NCC by the modification - Changes in state of suspension and dispersibility - No negative impact on the dimensions of NCC - Degree of modification SEM : revealed changes in morphology but could not determine the degree of modification and dimensions of NCC.

Acknowledgements

Alireza Kaboorani Research scientist Thank you very much for your attention