A free radical assisted strategy for preparing functionalized carbon nanotubes as a highly efficient nucleating agent for poly(L-lactide)

In this work, we synthesized novel functionalized carbon nanotubes (CNTs) by grafting poly(ethylene glycol) methyl ether methacrylate (OEGMA) onto CNTs via free radical polymerization in which the 3-methacryloxypropyltrimethoxysilane (KH570) was used as the silane coupling agent. The resulting OEGMA grafted CNTs (CNT-OEG) were systematically characterized by Fourier transform infrared spectroscopy (FTIR), thermal analysis, transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). Then the obtained CNT-OEG was added to poly(L-lactide) (PLA) as a crystallization nucleation agent. The crystallization behavior of the CNT-OEG/PLA composites was investigated under isothermal and nonisothermal conditions using a differential scanning calorimeter (DSC) and polarized optical microscopy (POM). Interestingly, our results suggested that the addition of CNT-OEG improve the crystallization rate of PLA dramatically. Besides, the decoration of CNTs via free radical polymerization facilitates their distribution in the matrix. This robust method to connect reactive polymers to nanofillers including, but not limited to, graphene, clay and cellulose nanofibrils, may significantly facilitate their utilization in traditional composites or biological engineering materials.