Τίτλος:
Surface-initiated titanium-mediated coordination polymerization from catalyst-functionalized single and multiwalled carbon nanotubes
Γλώσσες Τεκμηρίου:
Αγγλικά
Περίληψη:
Single (SWNTs) and multiwalled (MWNTs) carbon nanotubes were functionalized with a titanium alkoxide catalyst through a Diels-Alder cycloaddition reaction. The catalyst-functionalized carbon nanotubes (CNTs) were used for the surface initiated titanium-mediated coordination polymerizations of L-lactide (L-LA), ε-caprolactone (ε-CL) and n-hexyl isocyanate (HIC) employing the "grafting from" technique. 1H NMR, IR and Raman spectra showed that the precursor catalyst was successfully synthesized and covalently attached on the CNTs surface. Thermogravimetric analysis (TGA) revealed that the grafted poly(L-lactide) (PLLA) content could be controlled with time. The final polymer-grafted CNTs were readily dissolved in organic solvents as compared to the insoluble pristine and catalyst-functionalized CNTs. The presence of thick layers of polymers around the CNTs was observed through transmission electron microscopy (TEM). Differential scanning calorimetry (DSC) proved that the glass transition (T g) and melting (T m) temperatures of the PLLA are affected by the presence of the CNTs, while PLLA α-helix conformation remains intact, as revealed by the circular dichroism (CD) spectra. © 2009 American Chemical Society.
Συγγραφείς:
Priftis, D.
Petzetakis, N.
Sakellariou, G.
Pitsikalis, M.
Baskaran, D.
Mays, J.W.
Hadjichristidis, N.
Περιοδικό:
Macromolecules
Λέξεις-κλειδιά:
Caprolactone; Circular dichroism spectra; Coordination polymerization; Diels-Alder cycloaddition; Functionalized; Functionalized carbon nanotubes; Grafting from; Helix conformation; IR and Raman spectra; l-Lactide; Multi-walled; N-hexyl isocyanate; PLLA; Poly-L-lactide; Polymer-grafted; Surface-initiated; TEM; Thick layers; Titanium alkoxide, Catalysis; Catalysts; Coordination reactions; Cycloaddition; Dichroism; Differential scanning calorimetry; Dissolution; Functional polymers; Glass transition; Grafting (chemical); Multiwalled carbon nanotubes (MWCN); Organic solvents; Polymerization; Polymers; Surface analysis; Thermogravimetric analysis; Titanium; Transmission electron microscopy, Carbon nanotubes
