Premium
Stiffness‐Changing of Polymer Nanocomposites with Cellulose Nanocrystals and Polymeric Dispersant
Author(s) -
Meesorn Worarin,
Zoppe Justin O.,
Weder Christoph
Publication year - 2019
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201800910
Subject(s) - vinyl alcohol , materials science , nanocomposite , polymer , dispersant , ethylene oxide , cellulose , chemical engineering , nanocrystal , composite material , polymer nanocomposite , polyvinyl alcohol , polymer chemistry , dispersion (optics) , nanotechnology , copolymer , physics , optics , engineering
Bio‐inspired, water‐responsive, mechanically adaptive nanocomposites are reported based on cellulose nanocrystals (CNCs), poly(ethylene oxide‐ co ‐epichlorohydrin) (EO‐EPI), and a small amount of poly(vinyl alcohol) (PVA), which is added to aid the dispersion of the CNCs. In the dry state, the CNCs form a reinforcing network within the polymer matrix, and the substantial stiffness increase relative to the neat polymer is thought to be the result of hydrogen‐bonding interactions between the nanocrystals. Exposure to water, however, causes a large stiffness reduction, due to competitive hydrogen bonding of water molecules and the CNCs. It is shown here that the addition of PVA to the EO‐EPI/CNC nanocomposite increases the modulus difference between the dry and the wet state by a factor of up to four compared to the nanocomposites without the PVA. The main reason is that the PVA leads to a substantial increase of the stiffness in the dry state; for example, the storage modulus E ′ increased from 2.7 MPa (neat EO‐EPI) to 50 MPa upon introduction of 10% CNCs, and to 200 MPa when additionally 5% of PVA was added. By contrast, the incorporation of PVA only led to moderate increases of the equilibrium water swelling and the E ′ in the wet state.