期刊
NANO LETTERS
卷 15, 期 10, 页码 6738-6744出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.5b02588
关键词
Cellulose nanocrystals; surface modification; interfacial mechanics; glass transition temperature; nanocomposites
类别
资金
- Army Research Office [W911NF-13-1-0241]
- Center for Hierarchical Materials Design (CHiMaD) - NIST [70NANB14H012]
- Department of Civil and Environmental Engineering at Northwestern University
- Department of Mechanical Engineering at Northwestern University
- Northwestern University High Performance Computing Center
- Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program
Cellulose nanocrystals (CNCs) exhibit impressive interfacial and mechanical properties that make them promising candidates to be used as fillers within nanocomposites. While glass-transition temperature (T-g) is a common metric for describing thermomechanical properties, its prediction is extremely difficult as it depends on filler surface chemistry, volume fraction, and size. Here, taking CNC-reinforced poly(methyl-methacrylate) (PMMA) nanocomposites as a relevant model system, we present a multiscale analysis that combines atomistic molecular dynamics (MD) surface energy calculations with coarse-grained (CG) simulations of relaxation dynamics near filler polymer interfaces to predict composite properties. We discover that increasing the volume fraction of CNCs results in nanoconfinement effects that lead to an appreciation of the composite T-g provided that strong interfacial interactions are achieved, as in the case of TEMPO-mediated surface modifications that promote hydrogen bonding. The upper and lower bounds of shifts in T-g are predicted by fully accounting for nanoconfinement and interfacial properties, providing new insight into tuning these aspects in nanocomposite design. Our multiscale, materials-by-design framework is validated by recent experiments and breaks new ground in predicting, without any empirical parameters, key structure property relationships for nanocomposites.
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