posted on 2021-08-27, 15:41authored byDaniel
A. Osorio, Elina Niinivaara, Nicole C. Jankovic, Eyup C. Demir, Abdelhaq Benkaddour, Victoria Jarvis, Cagri Ayranci, Mark T. McDermott, Charles-François de Lannoy, Emily D. Cranston
Cellulose
nanocrystals (CNCs) are an ideal reinforcing agent for
polymer nanocomposites. CNCs can form hydrogen bonds with polyamide
6 (PA6); however, the direct effects of unmodified CNCs on PA6 morphology
and crystal structure have not been fully elucidated. This work investigated
the influence of CNCs on the mechanical performance and physicochemical
properties of spin-coated CNC–PA6 films through quantitative
analysis using techniques that probe multiple length scales. CNCs
interacted with PA6 to induce the γ (chiral) allomorph over
the α allomorph at low CNC loadings (≤1 wt %) and nucleated
a high density of small uniform spherulites, leading to stiffer nanocomposites.
Higher loadings caused CNC aggregation and crystalline, non-spherulitic
features. Overall, we hypothesize that the reinforcement mechanism
of CNCs in PA6 is dominated by morphological changes in the matrix,
not percolation. Understanding CNC–polymer interactions and
morphology (on films prepared without thermal processing or surface
modification of CNCs) offers “design rules” for how
to incorporate CNCs into nanocomposites for optimized material performance
in various applications, for example, membranes, coatings, and packaging.