Poly(ϵ‐caprolactone)‐functionalized carbon nanofibers by surface‐initiated ring‐opening polymerization

Abstract

Carbon nanofibers (CNFs) were covalently functionalized with biodegradable poly(e-caprolactone) (PCL) by in situ ring-opening polymerization (ROP) of e-caprolactone in the presence of stannous octoate. Surface oxidation treatment of the pristine CNFs afforded carboxylic CNFs (CNF-COOH). Reaction of CNF-COOH with excess thionyl chloride (SOCl 2 ) and glycol produced hydroxyl-functionalized CNFs (CNF-OH). Using CNF-OH as macroinitiator, PCL was covalently grafted from the surfaces of CNFs by ROP, in either the presence or absence of sacrificial initiator, butanol. The grafted PCL content was achieved as high as 64.2 wt %, and can be controlled to some extent by adjusting the feed ratio of monomer to CNF-OH. The resulting products were characterized by FTIR, NMR, Raman spectroscopy, TGA, DSC, SEM, TEM, HRTEM, and XRD. Core-shell nanostructures were observed under HRTEM for the PCL-functionalized CNFs because of the thorough grafting. The PCLgrafted CNFs showed different melting and crystallization behaviors from the mechanical mixture of PCL and CNF-OH. This approach to PCL-functionalized CNFs opens an avenue for the synthesis, modification, and application of CNFbased nanomaterials and biomaterials.

Paper‐sheet biocomposites based on wood pulp grafted with poly(ε‐caprolactone)

“…If a cleavable initiator would be used, it would, as well as benzyl alcohol, most likely have a different reactivity than native hydroxyl groups present on the fiber surface . Hence, the assumption that addition of a sacrificial initiator to surface‐initiated graft polymerizations is suitable to control molecular weight of the grafted chains, has been used in studies prior to the present investigation . The polymerizations could have been conducted in the absence of sacrificial initiator, but without it there would be no control of the molecular weight of the grafted PCL .…”

Surface characterization and functionalization of carbon nanofibers

“…23 Extension of the ODA linker molecule with a reactive diluent, butyl glycidyl ether, and incorporation into epoxy resin provided nanofiber/epoxy nanocomposites with enhanced flexural strengths, exemplifying the utility of linker molecules in creating composite materials. Wang et al also employed thionyl chloride with acid oxidized nanofibers to generate hydroxylated nanofiber feedstock, by reaction of the acylchloride functionalized nanofibers with glycol at 120°C for 48 h. 122 Biodegradable poly͑caprolactone͒ ͑PCL͒ was then covalently grafted onto the CNF-OH feedstock using in situ ring opening polymerization ͑ROP͒. Oh et al also utilized a covalent grafting technique to attach polyetherketones to the surfaces of both MWCNTs and CNFs treated with phosphoric acid.…”

Surface modification of single-walled carbon nanotubes and their use in the polymerization of acrylic monomers

“…Even more when the covalent modification on the surface is an ATRP initiator and due to this poor modification, there is a tendency to use a free initiator named 'sacrificial initiator' during the polymerization process. [4][5][6] Here in this work, we develop a method for the sidewall modification of SWCNT based on the diazonium reaction where the aryl diazonium species are formed in situ by reaction of 2-(4-aminophenyl)ethanol and isopentylnitrite (or sodium nitrite) with the SWNTs in organic solvents. Diazonium salts are known to be reactive with different surfaces of carbon; [7,8] in particular, the reaction of CNTs with aryl diazonium salts are mainly focused on reactions electrochemically induced reactions.…”