Controlled Functionalization of Multiwalled Carbon Nanotubes with Various Molecular-Weight Poly(l-lactic acid)

Abstract

Multiwalled carbon nanotubes (MWNT) were functionalized with poly(L-lactic acid) (PLLA) with different molecular weights using a "grafting to" technique. The oxidized MWNT (MWNT-COOH) were converted to the acyl-chloride-functionalized MWNT (MWNT-COCl) by treating them with thionyl chloride (SOCl2) and reacting them with PLLA to prepare the MWNT-g-PLLA. FTIR and Raman spectroscopy revealed that the PLLA was covalently attached to the MWNT, and the weight gain due to the functionalization was determined by thermogravimetric analyses (TGA). The Raman signals of the MWNT were greatly weakened as a result of the PLLA grafting. The morphology of the grafted PLLA was examined by using SEM and TEM. The amount of grafted PLLA depended on the molecular weight of the PLLA. The PLLA coated on the MWNT became thicker and more uniform with increasing PLLA molecular weight from 1000 to 3000. However, the amount of grafted PLLA became lower when the molecular weight of PLLA was further increased to 11,000 and 15,000, and the PLLA attached to the MWNT showed a squid leglike morphology forming blobs and leaving much of the MWNT surface bare.

Polylactic Acid (PLA) Carbon Nanotube Nanocomposites

“…Chen et al converted the oxidized MWCNT (MWCNT-COOH) to the acylchloride-functionalized MWCNT (MWCNT-COCl) by treatment with thionyl chloride (SOCl 2 ) and then reacting with PLLA to prepare the MWCNT-g-PLLA [40]. It was apparently demonstrated from the experimental results that the amount of grafted PLLA and its squid leglike morphology depended strongly on the molecular weight of the PLLA.…”

Study of low weight percentage filler on dielectric properties of MCWNT-epoxy nanocomposites

“…21 Some researchers studied the surface coating of CNTs to improve the dielectric constant of the prepared composite samples. [22][23][24][25][26][27][28] Zhang et al prepared unique cyanate ester composites with high dielectric constant based on multifunctional CNTs coated with phosphaphenanthrene terminated hyperbranched polysiloxane. Qiang et al 29 prepared new high dielectric constant composites based on unique multibranched polyaniline and CNT hybrids, in which the multibranched structure, large polyaniline concentration and flexible Si-O chains make the multibranched polyaniline coated on surfaces of CNTs through -interaction and the CNT hybrids have good dispersion in epoxy matrix.…”

Microwave-Assisted Modification of Carbon Nanotubes with Biocompatible Polylactic Acid

“…Several researchers have prepared PLAfunctionalized CNTs via "grafting from" and/or "grafting to" methods. Chen et al [26,27] synthesized PLA functionalized CNTs by reacting functional group COCl on the surface of CNTs with different weight molecular PLA or using the surface initiating ring-open polymerization of L-lactide. Song et al have prepared CNT-gPLAs by polycondensation of L-lactic acid with carboxylic acid-functionalized CNT in xylene solution.…”