Δημοσιεύσεις

Project Acronym: THIOSIM
Title: Large scale computer simulations for the exploration of the sequence of phase transitions and dynamics of poly- and oligo-thiophenes
Affiliation: university of patras
Pi: Vlasis Mavrantzas
Research Field: chemical sciences and materials

3-Arm Star Pyrene-Functional PMMAs for efficient exfoliation of Graphite in Chloroform: Fabrication of Graphene-Reinforced Fibrous Veils
by Gerboura, Sadra, Papadimitriou, Konstantinia, Skountzos, Emmanuel N., Polyzos, Ioannis, Pastore Carbone, Maria Giovanna, Kotrotsos, Athanasios, Mavrantzas, Vlasis George, Galiotis, Costas and Tsitsilianis, Constantinos
Abstract:
3-arm PMMAs end-functionalized by pyrene were designed as dispersing/stabilizing agents for the liquid-phase exfoliation of graphite in low-boiling point solvents like chloroform. The synthetic procedure comprised ARGET ATRP controlled polymerization, click chemistry and the quaternization reaction of triazole, ensuring tailor-made, well-defined pyrene-functional star PMMAs. Among a series of different pyrene-functional macromolecular topologies, the (PMMA-py2)3 proved the most efficient exfoliation agent giving relatively high graphene concentration (0.36 mg/ml) at exceptionally low polymer/graphite mass ratio (mP/mGF=0.003) and short sonication time (3 hr). A 5-cycle iterative procedure relying on the redispersion of the sediment was developed yielding CG=1.29 mg/ml with 14.8% exfoliation yield, under the favorable conditions of 10.5 hrs total shear mixing/tip sonication time and overall mP/mGF ratio as low as 0.15. In parallel, all-atom molecular dynamics simulations were conducted which helped understand the mechanism by which pyrene-functional macromolecular topologies act as efficient dispersing agents of graphene. Finally the G@(PMMA-Py)3 hybrids were well dispersed into the PMMA matrix by electrospinning to fabricate graphene-based nanocomposite fibrous veils. These graphene/polymer nanocomposites exhibited enhanced stiffness and strength by a factor of 4.4 with 1.5 wt.% graphene hybrids as nanofillers.
Reference:
3-Arm Star Pyrene-Functional PMMAs for efficient exfoliation of Graphite in Chloroform: Fabrication of Graphene-Reinforced Fibrous Veils (Gerboura, Sadra, Papadimitriou, Konstantinia, Skountzos, Emmanuel N., Polyzos, Ioannis, Pastore Carbone, Maria Giovanna, Kotrotsos, Athanasios, Mavrantzas, Vlasis George, Galiotis, Costas and Tsitsilianis, Constantinos), In Nanoscale, The Royal Society of Chemistry, 2018.
Bibtex Entry:
@article{C8NR06888G,
 author = {Gerboura, Sadra and Papadimitriou, Konstantinia and Skountzos, Emmanuel N. and Polyzos, Ioannis and Pastore Carbone, Maria Giovanna and Kotrotsos, Athanasios and Mavrantzas, Vlasis George and Galiotis, Costas and Tsitsilianis, Constantinos},
 title = {3-Arm Star Pyrene-Functional PMMAs for efficient exfoliation of Graphite in Chloroform: Fabrication of Graphene-Reinforced Fibrous Veils},
 journal = {Nanoscale},
 year = {2018},
 bibyear = {2018},
 pages = {-},
 publisher = {The Royal Society of Chemistry},
 doi = {10.1039/C8NR06888G},
 url = {http://dx.doi.org/10.1039/C8NR06888G},
 abstract = {3-arm PMMAs end-functionalized by pyrene were designed as dispersing/stabilizing agents for the liquid-phase exfoliation of graphite in low-boiling point solvents like chloroform. The synthetic procedure comprised ARGET ATRP controlled polymerization{,} click chemistry and the quaternization reaction of triazole{,} ensuring tailor-made{,} well-defined pyrene-functional star PMMAs. Among a series of different pyrene-functional macromolecular topologies{,} the (PMMA-py2)3 proved the most efficient exfoliation agent giving relatively high graphene concentration (0.36 mg/ml) at exceptionally low polymer/graphite mass ratio (mP/mGF=0.003) and short sonication time (3 hr). A 5-cycle iterative procedure relying on the redispersion of the sediment was developed yielding CG=1.29 mg/ml with 14.8% exfoliation yield{,} under the favorable conditions of 10.5 hrs total shear mixing/tip sonication time and overall mP/mGF ratio as low as 0.15. In parallel{,} all-atom molecular dynamics simulations were conducted which helped understand the mechanism by which pyrene-functional macromolecular topologies act as efficient dispersing agents of graphene. Finally the G@(PMMA-Py)3 hybrids were well dispersed into the PMMA matrix by electrospinning to fabricate graphene-based nanocomposite fibrous veils. These graphene/polymer nanocomposites exhibited enhanced stiffness and strength by a factor of 4.4 with 1.5 wt.% graphene hybrids as nanofillers.},
}