Synthesis and characterization of fullerene grafted poly(ɛ-caprolactone)

synthesis of novel four armed PE-PCL grafted superparamagnetic and biocompatible nanoparticles

Novel biocompatible polymer immobilized superparamagnetic nanoparticles (MNP) are prepared by grafting four armed pentaerythritol poly(ε-polycaprolactone) (PE-PCL) onto silane modified MNP. The MNPs are synthesized by hydrothermal process and its modification using (3-aminopropyl)trimethoxysilane (TMAS) coating is done by the sol-gel technique. The pentaerythritol (PE) initiated ring-opening polymerization (ROP) is carried out to prepare four armed PE-PCL. The reaction is shown to follow first order kinetics. The structure of PE-PCL is confirmed by NMR spectrum and MALDI-TOF analysis. The in situ grafting of PE-PCL onto modified MNP has been carried out by using 4,4'-methylenediphenyl diisocyanate (MDI) as an intermediate linker. The grafting density as determined by TGA analysis has been found to be significantly higher than previously reported linear PCL grafted MNPs in the literature. This leads to uniform dispersion of grafted MNPs which still is a challenging task in contemporary research. The effective dispersion of MNP into PE-PCL matrix is analyzed by HRTEM. The saturation magnetization of the PE-PCL grafted MNPs is significantly high and this can be tailored further by varying the grafting density. The biocompatibility of polymer grafted nanoparticles is confirmed by MTT assay using HeLa cell line. The superparamagnetic and biocompatible novel PE-PCL grafted MNP so prepared would have manifold potential applications including in therapy and targeted drug delivery.

New concepts and applications in the macromolecular chemistry of fullerenes

A new classification on the different types of fullerene-containing polymers is presented according to their different properties and applications they exhibit in a variety of fields. Because of their interest and novelty, water-soluble and biodegradable C(60)-polymers are discussed first, followed by polyfullerene-based membranes where unprecedented supramolecular structures are presented. Next are compounds that involve hybrid materials formed from fullerenes and other components such as silica, DNA, and carbon nanotubes (CNTs) where the most recent advances have been achieved. A most relevant topic is still that of C(60)-based donor-acceptor (D-A) polymers. Since their application in photovoltaics D-A polymers are among the most realistic applications of fullerenes in the so-called molecular electronics. The most relevant aspects in these covalently connected fullerene/polymer hybrids as well as new concepts to improve energy conversion efficiencies are presented.The last topics disccused relate to supramolecular aspects that are in involved in C(60)-polymer systems and in the self-assembly of C(60)-macromolecular structures, which open a new scenario for organizing, by means of non-covalent interactions, new supramolecular structures at the nano- and micrometric scale, in which the combination of the hydrofobicity of fullerenes with the versatility of the noncovalent chemistry afford new and spectacular superstructures.

Insight into the Broad Field of Polymer Nanocomposites: From Carbon Nanotubes to Clay Nanoplatelets, via Metal Nanoparticles

Highly ordered polymer nanocomposites are complex materials that display a rich morphological behavior owing to variations in composition, structure, and properties on a nanometer length scale. Metal-polymer nanocomposite materials are becoming more popular for applications requiring low cost, high metal surface areas. Catalytic systems seem to be the most prevalent application for a wide range of metals used in polymer nanocomposites, particularly for metals like Pt, Ni, Co, and Au, with known catalytic activities. On the other hand, among the most frequently utilized techniques to prepare polymer/CNT and/or polymer/clay nanocomposites are approaches like melt mixing, solution casting, electrospinning and solid-state shear pulverization. Additionally, some of the current and potential applications of polymer/CNT and/or polymer/clay nanocomposites include photovoltaic devices, optical switches, electromagnetic interference (EMI) shielding, aerospace and automotive materials, packaging, adhesives and coatings. This extensive review covers a broad range of articles, typically from high impact-factor journals, on most of the polymer-nanocomposites known to date: polymer/carbon nanotubes, polymer/metal nanospheres, and polymer/clay nanoplatelets composites. The various types of nanocomposites are described form the preparation stages to performance and applications. Comparisons of the various types of nanocomposites are conducted and conclusions are formulated.