Poly(benzoxazine-f-chitosan) films: The role of aldehyde neighboring groups on chemical interaction of benzoxazine precursors with chitosan.

This study reports the preparation and characterizations of chitosan-azomethine derivatives containing oxazine ring as new crosslinked polymers. The novel chitosan derivatives have been prepared by functionalization with reactive benzoxazine precursors. Two types of aldehyde-terminated benzoxazine precursors have been synthesized using two different polyetheramines (Jeffamines), 4-hydroxybenzaldehyde, and paraformaldehyde.

Molecular dynamic simulations of self-assembly of amphiphilic comb-like anionic polybenzoxazines.

Fully atomistic molecular dynamic simulations were performed to address the self-assembly of amphiphilic and comb-like polybenzoxazines (iBnXz) in water, with i = 3 (trimer), i = 4 (tetramer); i = 6 (hexamer), i = 8 (octamer), and i = 10 (decamer). Spontaneous aggregation of these comb-like polybenzoxazine molecules into a single micelle occurs in the simulations. The simulations show that molecular size and concentration play important roles in micellar morphology.

Synthesis and evaluation of novel anionic polymeric surfactants based on polybenzoxazines.

A novel platform of anionic polymeric surfactants, poly(4HBA-oca(-)Na(+)), poly(4HBA-dea(-)Na(+)), and poly(4HBA-doa(-)Na(+)), has been synthesized by polymerizing benzoxazine monomers that are synthesized by reacting an aliphatic amine of variable chain length (C8, C10 and C12), with 4-hydroxybenzoic acid and paraformaldehyde. The structures of the monomers and polymeric surfactants are confirmed by NMR and FTIR. The ring-opening polymerization and thermal behavior of the benzoxazine monomers are studied by DSC and TGA.

Biobased chitosan/polybenzoxazine cross-linked films: preparation in aqueous media and synergistic improvements in thermal and mechanical properties.

A novel class of polymer blends has been prepared from main-chain-type benzoxazine polymer (MCBP) and chitosan (CTS), a modified biomacromolecule. A water-soluble, main-chain-type benzoxazine polymer, MCBP(BA-tepa), was synthesized from the reaction of bisphenol A (BA), tetraethylenepentamine (TEPA) and formalin. The structure of the MCBP(BA-tepa) was confirmed by proton nuclear magnetic resonance spectroscopy ((1)H NMR) and Fourier transform infrared spectroscopy (FT-IR).

Graphene arrested in laponite-water colloidal glass.

Graphene production in water from graphite sources is an important technological route toward harvesting the unique properties of this material. Graphene forms thermodynamically unstable dispersions in water, limiting the use of this solvent due to aggregation. We show that graphene-water dispersions can be controlled kinetically to produce graphene by using laponite clay.

Influence of electrolyte and polymer loadings on mechanical properties of clay aerogels.

The effects of electrolyte and polymer loadings on formation, density, and mechanical properties of clay aerogels have been investigated. Coherent aerogels were formed at all tested concentrations except at a combination of low electrolyte (<0.04 M) and polymer (<1% w/v) concentrations because of partial clay flocculation.

Controlled release in transdermal pressure sensitive adhesives using organosilicate nanocomposites.

Polydimethyl siloxane (PDMS) based pressure sensitive adhesives (PSA) incorporating organo-clays at different loadings were fabricated via solution casting. Partially exfoliated nanocomposites were obtained for the hydroxyl terminated PDMS in ethyl acetate solvent as determined by X-ray diffraction and atomic force microscopy. Drug release studies showed that the initial burst release was substantially reduced and the drug release could be controlled by the addition of organo-clay.

Application of mean-field model of polymer melt intercalation in organo-silicates for nanocomposites.

The mean-field, lattice-based model of polymer melt intercalation in organically-modified layered silicates (OLS) originally developed by Vaia and Giannelis was applied for different polymers such as poly(methyl methacrylate) (PMMA), polypropylene (PP), and poly(ethylene oxide) (PEO). The nature of each polymer controls significantly the intercalation of the system. The internal energy change caused by the interaction of polymer, surfactant and clay is the strongest factor in determining the equilibrium structure of the nanocomposite system.

Synthesis of poly(methyl methacrylate) nanocomposites via emulsion polymerization using a zwitterionic surfactant.

The synthesis of nanocomposites via emulsion polymerization was investigated using methyl methacrylate (MMA) monomer, 10 wt % montmorillonite (MMT) clay, and a zwitterionic surfactant octadecyl dimethyl betaine (C18DMB). The particle size of the diluted polymer emulsion was about 550 nm, as determined by light scattering, while the sample without clay had a diameter of about 350 nm. The increase in the droplet size suggests that clay was present in the emulsion droplets.