Ruoli Sun

Recent progress in the preparation of polyaniline nanostructures and their applications in anticorrosive coatings

Research on composites/blends containing polyaniline (PANI) has attracted numerous scientists and engineers due to their excellent adhesion and anticorrosive properties. Nano-structured PANI composites and matrix resins play a key role in physical and anticorrosive performance. This paper reviews the synthesis, growth mechanisms and corrosion application with different resin coatings of PANI-based nano-composites. It also highlights the failures of corrosion protection and methods and suggestions to improve it.

Ferrocene-based polyethyleneimines for burning rate catalysts

Ferrocene-based polymers and their derivatives have the ability to catalyze the burning process of composite solid propellants efficiently. However, the simple and volatile ferrocene migrates to the surface of the solid propellant on prolonged storage, which alters the designed burning parameters and more seriously causes unexpected explosions. To retard migration problems, six novel ferrocene-based polyethyleneimines (PEI-Fcs) were synthesized by the condensation reaction of branched polyethyleneimine (PEI) with ferrocenecarbonyl chloride. The structures of the synthesized PEI-Fcs were characterized using 1H NMR, FT-IR and UV-Vis spectroscopy. The redox properties of the polymers are very important for burning rate catalysts (BRCs). Cyclic voltammetry (CV) revealed that all the PEI-Fcs showed redox properties due to the presence of ferrocene moieties. Migration studies confirmed that the migration of these PEI-Fcs was much slower than that of 2,2-bis(ethylferrocenyl)propane (catocene) and ferrocene. The catalytic effect of PEI-Fcs on the thermal decomposition of ammonium perchlorate (AP) was investigated using thermogravimetry (TG) and differential thermogravimetry (DTG). It was found that in the presence of PEI-Fcs (1–6), the peak decomposition temperature of AP was shifted towards the left (decreased) significantly. The results from the TG and DTG analysis indicated that the novel PEI-Fcs had good catalytic effects of lowering the thermal decomposition temperature of AP and were almost stable up to 220 °C. We expect that these novel PEI-Fcs would have great value as high BRCs for composite solid propellants.

Synthesis of Ferrocene-Based Hyperbranched Polyether and Its Catalytic Performance for Thermal Decomposition of Ammonium Perchlorate

A series of ferrocene-based hyperbranched polyethers (HBPE-Fc) with different ferrocene content were synthesized by esterification of ferrocenecarbonyl chloride and hyperbranched polyether (HBPE). 1H NMR and FT-IR were used to confirm the structure of HBPE and HBPE-Fc. GPC was used to calculate the molecular weights. The catalytic performance of the synthesized HBPE-Fc for thermal decomposition of ammonium perchlorate (AP) was investigated by TG and DTG techniques. The results showed that HBPE-Fc exhibited good catalytic activity on the thermal decomposition of AP. The influence factors on catalytic performances, such as substitution degree of ferrocene and mass ratio of AP/HBPE-Fc were discussed as well.

Synthesis of reductive responsive polyphosphazenes and their fabrication of nanocarriers for drug delivery application

ABSTRACT Reductive responsive nanovehicles have the ability to deliver the anticancer drugs to intracellular compartments. The purpose of this study was to develop reductive sensitive nanocarriers based on polyphosphazenes. Amphiphilic polyphosphazenes with hydrophilic reductive sensitive side group and different molecular weights were synthesized and characterized. The synthesized copolymers show solvent dependent self-aggregation and form spherical micelles by using THF as co-organic solvent in dialysis method with critical micelle concentration value ranging from 5.73 µg/mL to 11.24 µg/mL. Micelles can encapsulate the hydrophobic drugs such as camptothecin (CPT) and indomethacin. In in vitro release experiments, CPT-loaded micelles release 70–80% of the loaded CPT in the presence of reducing agent dithiothreitol within 15 h. The results indicate that these reductive sensitive amphiphilic polyphosphazenes may find an application as anticancer drug carriers for safe drug delivery. GRAPHICAL ABSTRACT

Synthesis of Soluble Ferrocene-Based Polythiophenes and Their Properties

Ferrocene-based polythiophenes are the promising class of the functional materials, but mostly the polythiophenes are insoluble in common solvents except some derivatives of polythiophenes like poly(3-hexylthiophene) (P3HT). Herein, two new ferrocene-based thiophene monomers, 2-(thiophen-3-yl) ethyl ferrocenoate and 2-(thiophen-3-yl) methyl ferrocenoate were synthesized and copolymerized with 3-hexylthiophene (3HT) respectively. The resulting polymers were soluble (in common organic solvents) and processable. The synthesis and the molecular weights were confirmed by the 1H-NMR and GPC studies respectively. Poly (TEF-co-3HT) was subjected to study the electrochemical properties in comparison of respective monomers and ferrocene. It was found that the resulting copolymer had the combined redox properties of its monomers. Also, very interestingly, the copolymer showed improved reversible redox properties which were not only better than its parent monomers but even better than the pure ferrocene. Photoemission spectra of P3HT and Poly (TEF-co-3HT) were also rerecorded and compared with each other.Graphical Abstract

Stimuli-responsive HBPS-g-PDMAEMA and its application as nanocarrier in loading hydrophobic molecules

Summary The topic of stimuli-responsive nanocarriers for loading guest molecules is dynamic. It has been widely studied in applications including drug controlled release, smart sensing, catalysis, and modeling. In this paper, a graft copolymer (hyperbranched polystyrene)-g-poly[2-(dimethylamino)ethyl methacrylate] (HBPS-g-PDMAEMA) was synthesized and characterized by 1H NMR and GPC. It was observed that the star-like HBPS-g-PDMAEMA formed aggregates in aqueous solution. The influence of polymer concentration, ionic strength and pH value on the aggregates in aqueous solution was investigated by using UV–vis spectroscopy and DLS analysis. The results showed that size of aggregates was affected by a corresponding stimulus. In addition, the loading ability of HBPS-g-PDMAEMA aggregates was investigated by using pyrene or Nile red as the model guest molecules by using UV–vis and fluorescence spectroscopy. The results showed that HBPS-g-PDMAEMA aggregates were capable to encapsulate small hydrophobic molecules. These newly prepared HBPS-g-PDMAEMA nanocarriers might be used in, e.g., medicine or catalysis.