1. Surface Modification of Cellulose Nanocrystals with Glycidyl Methacrylate for UV-crosslinking
COST FP1205
Yuval Nevo
The Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University of Jerusalem

2. Introduction

3. Surface functionalization of CNCs via methacrylation
Chemical modification of CNC surface with methacrylate groups will allow the crosslinking of CNC particles and can lead to the formation of crosslinked films, hydrogels and aerogels. This modification will also allow crosslinking of CNC inside acrylic matrices, resulting in composite materials with improved mechanical properties
Films
Hydrogels
Foams
Stability in water
Improved mechanical properties
Improved physical properties

4. Methacrylation of CNCs
MA-CNCs have available methacrylate groups that can be crosslinked via free radical reactions
Crosslinking can happen between adjacent particles
Crosslinking can be more efficient using a linker (i.e. PEG-diacrylate)
MA-CNCs can also be polymerized inside acrylic polymers OH
C=C
SO3-
Covalent crosslinking

5. Methacrylation of CNCs using Glycidyl methacrylate
Reaction conducted in DMSO
4-Dimethylaminopyridine (DMAP) was used as a catalyst
Butylated hydroxytoluene (BHT) was used as inhibitor (protecting C=C bonds) +
R = H or
(DMAP)
DMSO
CNC
CNC

6. Methacrylation confirmation
FTIR analysis Raman analysis

7. MA-CNC characterization
Atomic force microscopy (AFM)
CNC’s crystal structure was not destroyed by the reaction
0.01% wt.
0.001% wt.

8. MA-CNC characterization
X-ray diffraction (XRD)
Corresponds to cellulose I structure
Modification did not change the native cellulose form of the crystals
MA-CNC
CNC

9. Thermogravimetric analysis
CNC
MA-CNC

10. MA-CNC characterization
Solid-state NMR
New peaks corresponding to GMA appears
Degree of substitution needed to be calculated

11. Hydrogel formation
Irgacure2959 was added to ~1% wt. MA-CNC and 365 nm UV-light was shone
Adjacent CNCs were crosslinked to form a stable gel
Gel was transferred to water

12. Aerogel formation Critical point evaporation was used to form aerogels
The inner architecture is of ~10 µm wide, long pores (“tunnels”)

13. Hydrogel formation with linker
Crosslinking was conducted with the addition of PEGDA
Gels appear to be more stable than those without PEGDA = =
PEGDA

14. MA-CNCs/Acrylamide composites
MA-CNCs were crosslinked together with acrylamide, in DMSO
10% acrylamide, 0.75% bis-acrylamide
Acrylamide
Bis-acrylamide

15. MA-CNCs/Acrylamide hydrogels
Gels with MA-CNCs are much more opaque
Gels with MA-CNCs swell less
Gels with CNCs are less opaque and swell more

16. MA-CNCs/Acrylamide hydrogels properties
Mechanical properties of gels were tested
MA-CNCs mechanically reinforce acrylamide gels
Average curves

17. MA-CNCs/Acrylamide hydrogels
CNC/Acrylamide
MA-CNC/Acrylamide

18. Conclusions
CNC’s surface was successfully modified with GMA, resulting in methacrylated CNC particles
The methacrylation procedure did not change the crystal structure of CNCs
MA-CNCs were crosslinked using UV light to form porous gels
MA-CNCs were crosslinked along with acrylamide to form reinforced polyacrylamide gels with higher crosslinking density

19. Thank you