Polymer/layered silicate nanocomposites: a review from preparation to processing

Progress in preparation, processing and applications of polyaniline

Direct polymerization of sulfonated poly(arylene ether sulfone) random (statistical) copolymers: candidates for new proton exchange membranes

10. Patented Literature 2616 10.1. Esterification 2616 10.2. Ether Formation 2619 10.2.1. Etherification without Cyclization 2619 10.2.2. Etherification with Cyclization 2624 10.3. N-Alkylation 2625 10.4. Other Reactions 2627 11. Summary and Outlook 2628 12. Note Added in Proof 2628 13. Abbreviations Used in This Review 2629 14. Acknowledgments 2629 15. Supporting Information Available 2630 16. References 2630

Mitsunobu and Related Reactions: Advances and Applications

The design of advanced functional materials with nanometer- and micrometer-scale control over their properties is of considerable interest for both fundamental and applied studies because of the many potential applications for these materials in the fields of biomedical materials, tissue engineering, and regenerative medicine. The layer-by-layer deposition technique introduced in the early 1990s by Decher, Moehwald, and Lvov is a versatile technique, which has attracted an increasing number of researchers in recent years due to its wide range of advantages for biomedical applications: ease of preparation under "mild" conditions compatible with physiological media, capability of incorporating bioactive molecules, extra-cellular matrix components and biopolymers in the films, tunable mechanical properties, and spatio-temporal control over film organization. The last few years have seen a significant increase in reports exploring the possibilities offered by diffusing molecules into films to control their internal structures or design "reservoirs," as well as control their mechanical properties. Such properties, associated with the chemical properties of films, are particularly important for designing biomedical devices that contain bioactive molecules. In this review, we highlight recent work on designing and controlling film properties at the nanometer and micrometer scales with a view to developing new biomaterial coatings, tissue engineered constructs that could mimic in vivo cellular microenvironments, and stem cell "niches."

Multiple Functionalities of Polyelectrolyte Multilayer Films: New Biomedical Applications

It was recently reported that water soluble conducting polyaniline may be prepared using a new template-guided enzymatic approach. To address the mechanistic role of the template in this reaction, various macromolecular and surfactant templates were investigated. It was found that the template provides a necessary type of “local” environment where the pH and charge density near the template molecule is different from that of the bulk solution. 13C and 1H NMR studies showed that this “local” environment serves as a type of nano-reactor that is critical in anchoring, aligning, and reacting the aniline monomers and ultimately controls what form of polyaniline (conducting or insulating) is obtained during reaction. Strong acid polyelectrolytes, such as sulfonated polystyrene (SPS), are the most favorable because they provide a lower, local pH environment that serves to both charge and preferentially align the aniline monomers through electrostatic and hydrophobic interactions to promote the desired head-to-ta...

The Role of Template in the Enzymatic Synthesis of Conducting Polyaniline

A novel template guided enzymatic approach has been developed to synthesize optically active conducting polyaniline (PANI) nanocomposites in the presence of H2O2 as an oxidant, using (+) and (-) 10-camphorsulfonic acid (CSA) as a dopant and chiral inductor. The formation of chiral polyaniline in the nanocomposites was confirmed by circular dichroism (CD). Interestingly, the CD spectra of nanocomposites formed either with (+) or with (-) CSA show the enzyme itself plays a critical role in controlling the stereospecificity of the polyaniline (PANI) in the nanocomposite. The enzyme used for the polymerization of aniline in the nanocomposite was horseradish peroxidase (HRP). It was shown that this enzyme prefers a specific helical conformation, regardless of whether induced chirality in the complex CSA-aniline is from (+) or (-) CSA. UV-vis spectra show that the polyaniline is in the conducting form, and transmission electron micrographs (TEM) show that the nanocomposites are dispersed nicely with particle size dimensions in the range of 20-50 nm. Electron diffraction patterns of these chiral polymer nanocomposites suggest that these nanocomposites are in both crystalline and amorphous states.

Ashok L. Cholli

Papers

The Role of Template in the Enzymatic Synthesis of Conducting Polyaniline

Helical Conformational Specificity of Enzymatically Synthesized Water-Soluble Conducting Polyaniline Nanocomposites

Nature of the water-epoxy interaction

Aromatic ring flips in a semicrystalline polymer

Molecular basis of the β-transition in poly(arylene ether sulfones)