Hansen Solubility Parameters Determination And Application Of Nanodiamonds And Nanofibrillated Cellulose

Nanodiamonds（NDs）and nanofibrillated cellulose（NFC）have been widely used in many fields due to their excellent properties,and preparing high-performance composites as nanofillers mixed with different media（various solvents or polymers）is one of the important research work.For the composite system,the dispersion of the filler in the matrix has a key impact on its comprehensive performance.Hansen solubility parameters（HSPs）,as the important parameters to measure the degree of interaction between substances,can effectively predict and evaluate the dispersibility of nanofillers in different media,thereby guiding the preparation of composite systems.Although many HSPs of nanomaterials have been reported,there is still a large gap in the related research on NDs and NFC.Based on the HSPs theory,this paper studies the dispersion state of NDs and NFC in various solvents before and after modification,then using the results to optimize and fit their HSPs with MATLAB software.On this basis,with the help of HSPs theory,the dispersibility of NDs and NFC before and after modification in polyethylene oxide（PEO）matrix was evaluated,and the rationality of the theoretical evaluation results was verified.The research in this paper not only supplements the database of nanomaterial HSPs,but also provides theoretical support and guidance for the in-depth research and application of NDs and NFC.The main research contents and conclusions of this paper are as follows:（1）The dispersion state of NDs in different solvents was studied by dynamic light scattering（DLS）and ultraviolet-visible（UV-vis）spectroscopy,and the results showed that the dispersibility of NDs was affected by the polar component（δ_P）and the hydrogen bond component（δ_H）of the solvents HSPs,while the dispersion component（δ_D）had no significant effect on it.The HSPs of NDs obtained by fitting and calculation wereδ_D=17.5 MPa^1/2,δ_P=14.2 MPa^1/2,δ_H=10.5 MPa^1/2.Based on the HSPs theory,the dispersion of NDs in PEO/NDs composites prepared by casting with different solvents was further evaluated and verified.（2）The NDs were subjected to amination and alkylation modification using ammonium bicarbonate and octadecylamine（ODA）,respectively.Their dispersion in different solvents was investigated by UV-vis.The HSPs of aminated modified NDs（NDs-NH₂）obtained by fitting wereδ_D=19.9 MPa^1/2,δ_P=16.1 MPa^1/2,δ_H=14.7 MPa^1/2.And the HSPs of alkylated modified NDs（NDs-ODA）wereδ_D=24.8 MPa^1/2,δ_P=7.5MPa^1/2,δ_H=6.0 MPa^1/2.The dispersibility of NDs before and after modification in PEO was predicted according to HSPs theory,and the reasonable feasibility of the prediction was verified by morphology observation and performance test.（3）Using microcrystalline cellulose（MCC）as the main raw material,8 kinds of NFC with different sizes and surface carboxyl group contents were prepared using TEMPO oxidation method by changing the concentration of oxidant Na Cl O and the times of high-pressure homogenization.The turbidity method was used to investigate their respective dispersions in different solvents,then obtaining the corresponding HSPs by fitting.Among them,the HSPs of 5-30 NFC with the smallest diameter and the highest carboxyl group content wereδ_D=19.9 MPa^1/2,δ_P=14.2 MPa^1/2,δ_H=13.6MPa^1/2.After analyzing the effect of morphology and surface structure on their HSPs,it was concluded thatδ_D of different NFC had a trend of decreasing with the increase of particle size,δ_H had a trend of increasing with the increase of carboxyl functional group content,whileδ_P had no clear relationship with the topographic structure of NFC.（4）The 5-30 NFC was surface modified with silane coupling agent KH550 and ODA,respectively,then investigating their turbidity and dispersion state in different solvents.The HSPs of NFC-KH550 obtained by fitting wereδ_D=18.6 MPa^1/2,δ_P=12.5 MPa^1/2,δ_H=17.5 MPa^1/2.And the HSPs of NFC-ODA wereδ_D=24.9 MPa^1/2,δ_P=7.7 MPa^1/2,δ_H=10.8 MPa^1/2.The dispersion of NFC before and after modification in PEO was predicted based on HSPs theory,and was verified by morphology observation and performance test,which proved the guiding role of HSPs theory on the preparation and performance of composite materials.