Polystyrene‐Clay Nanocomposites Prepared with Polymerizable Imidazolium Surfactants

Polystyrene/montmorillonite nanocomposites were prepared via in situ bulk polymerization. New imidazolium salts were used to modify montmorillonite obtaining an improvement in thermal stability in comparison with a montmorillonite modified with a standard alkylammonium cation. The synthesized cations facilitate the formation of partially exfoliated structures because of the presence in their structure of a polymerizable group. The polystyrene/montmorillonite nanocomposites were characterized by X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

The new thermally stable, reactive surfactant imidazolium salts (C₁₂, C₁₆ and C₁₈) used to organically modify montmorillonite in this study.     

Natural and Synthetic Polyampholytes, 2

The ability of natural and synthetic polyampholytes to exist in globular, coil, helix, stretched, and ordered conformations is reviewed and transformations and transitions between the respective states upon variation of conditions are highlighted. The properties of polyampholytes in solution, condensed, and gel state as well as at various interfaces are discussed in order to clarify the principles of the structural organization of proteins, model the function of biomembranes, and study the biocompatibility of modified materials. Application aspects of polyampholytes in protein separation, desalination, catalysis, the oil industry, biotechnology, nanotechnology, and medicine are given.

     

Direct Assembly of BaTiO3‐Poly(methyl methacrylate) Nanocomposite Films

Summary: This study examines the use of a PMMA‐mediated assembly of BaTiO₃ nanoparticles directly onto Cu electrodes under an electric field. The compatibility of the interface between BaTiO₃ nanoparticles and PMMA in a mixed organic solvent system enables the homogeneous dispersion of nanoparticles in a solid polymer matrix. This results in the effective packing of particles, which is desirable from the point of view of achieving a high dielectric constant in the composite. In this study, three‐phase Al/BaTiO₃/PMMA nanocomposite films from stable colloidal suspensions containing aluminium nitrate salts were also designed using an electrodeposition process. The simultaneous formation of Al metallic inclusions in the BaTiO₃ nanoparticles in the PMMA matrix significantly improved the dielectric constant of nanocomposite films.

HRTEM micrographs of BaTiO₃ (240 nm)/PMMA and magnified view of BaTiO₃ (50 nm)/PMMA/Al(NO₃)₃ · 9H₂O composite particles in each suspension, and FESEM micrograph of electrodeposited three‐phase nanocomposite film.     

One‐Component Bimolecular Photoinitiating Systems, 2

The compounds 2‐thioxanthone‐thioacetic acid and 2‐(carboxymethoxy)thioxanthone, bimolecular photoinitiators for free radical polymerization, are synthesized and characterized. Their capability to act as initiators for the polymerization of methyl methacrylate was examined. The postulated mechanism is based on the intermolecular electron‐transfer reaction of the excited photoinitiator with the sulfur or oxygen atom of the ground state of the respective photoinitiator followed by decarboxylation. The resulting alkyl radicals initiate the polymerization.

Structures of the photoinitiators.     

Chain Transfer and Efficiency of End‐Group Introduction in Free Radical Polymerization of Methyl Methacrylate in the Presence of Poly(methyl methacrylate) Macromonomer

Summary: Experimental and modeling studies of addition–fragmentation chain transfer (AFCT) during radical polymerization of methyl methacrylate in the presence of poly(methyl methacrylate) macromonomer with 2‐carbomethoxy‐2‐propenyl ω‐ends (PMMA‐CO₂Me) at 60 °C are reported. The results revealed that AFCT involving PMMA‐CO₂Me formed in situ during methyl methacrylate polymerization has a negligible effect on the molecular weight distribution.

     

Electrostatically Dissipative Polystyrene Nanocomposites containing Copper Nanowires

Summary: A scalable synthesis of copper nanowires by alternating current electrodeposition into porous aluminium oxide was used to produce multigram quantities of 16 nm diameter by >2 µm long nanowires. Polystyrene nanocomposites were prepared by solution processing. The composites containing unpassivated nanowires were non‐uniformly dispersed and showed electrical percolation at ≈2 vol.‐% Cu loading, while the composites containing HSC₁₈H₃₇‐passivated nanowires were uniformly dispersed, but remained resistive up to at least 10 vol.‐% Cu loading.

Copper nanowires prepared by alternating current electrodeposition into porous aluminium oxide templates.     

Strategy for Better Ordering in Diblock Copolymer Based Nanocomposites

A simple approach to improve the structural ordering in block copolymer/nanoparticle nanocomposites is presented. It is to blend a small molecular weight homopolymer with the composites, which can uniformly swell the preferred domain where the nanoparticles locate and increase the conformational entropy of the domain. Consequently, the interfaces between the block copolymer domains become smooth that improves the long range order in the nanocomposites. Furthermore, the uniform swelling of the preferred domain by the homopolymer will allow higher loading of nanoparticles without adversely affecting the long range order.

     

A Composite Polymer Film with both Superhydrophobicity and Superoleophilicity

Summary: A composite film composed of porous polyurethane (PU) and polystyrene (PS) microspheres with both superhydrophobicity and superoleophilicity has been prepared. In this film, the dual‐scale structure enhances both the hydrophobicity and oleophilicity of the surface material. The composite film with such an ‘intelligent’ wettability property can be utilized to separate oil and water systems efficiently.

The composite film can be used to separate diesel oil and water.     

A Novel Route for Fabricating Metal‐Polymer Composite Nanoparticles with Phase‐Separated Structures

Au nanoparticles (NPs) and polymer composite particles with phase‐separation structures were prepared based on phase separation structures. Au NPs were successfully synthesized in amphiphilic block‐copolymer micelles, and then composite particles were formed by a simple solvent evaporation process from Au NPs and polymer solution. The phase separated structures (Janus and Core‐shell) were controlled by changing the combination of polymers having differing hydrophobicity.

     

A Convenient A2 + B3 Approach to Hyperbranched Poly(arylene oxindole)s

Summary: We developed a facile approach to hyperbranched polymers by applying a superelectrophilic reaction within an A₂ + B₃ strategy. A significant reactivity difference between the intermediate and the starting material was utilized to avoid gelation in the A₂ + B₃ polymerization. A number of hyperbranched poly(arylene oxindole)s were achieved in a one‐step polymerization and characterized by NMR spectroscopy and gel permeation chromatography. Moreover, further modifications at the interior and exterior of the resulting polymers were explored as well.

Structure of the hyperbranched polymers produced using the A₂ + B₃ approach.     

Polymorphism Control of Poly(vinylidene fluoride) through Electrospinning

Polymorphism control of PVDF has been realized through electrospinning. PVDF fibrous membranes with fiber diameter in the range of 100 nm to several micrometers were produced by electrospinning and the crystal phase of electrospun PVDF fibers can be adjusted at the same time. Through the control of electrospinning parameters such as the solvent, electrospinning temperature, feeding rate, and tip‐to‐collector distance, PVDF fibrous membranes containing mainly α‐ or β‐ or γ‐phase could be fabricated successfully.

     

Noble Metal Decoration and Alignment of Carbon Nanotubes in Carboxymethyl Cellulose

A facile microwave method (MW) is described that accomplishes alignment and decoration of noble metals on carbon nanotubes (CNT) wrapped with carboxymethyl cellulose (CMC). Carbon nanotubes such as single‐ and multi‐walled, and Buckminsterfullerene (C‐60) are well dispersed using the sodium salt of CMC under sonication. Addition of respective noble metal salts then generates noble metal‐decorated CNT composites at room temperature. However, aligned nanocomposites of CNTs could only be generated by exposing the above nanocomposites to MW irradiation. The CNT composites are characterized using scanning electron microscopy, energy dispersive X‐ray analysis, X‐ray mapping, transmission electron microscopy, and UV‐visible spectroscopy. The general preparative procedure is versatile and provides a simple route to manufacturing useful metal‐coated CNT nanocomposites.

     

A New Route for the Preparation of Brain‐Like Nanostructured Polyaniline

A novel approach has been explored to prepare brain‐like polyaniline (PANI) nanostructures with many convolutions (140–170 nm in average diameter) using aniline/citric acid (CA) salt as the template and chlorine gas as the oxidant by a gas/solid reaction for the first time. The method provided here differs significantly from the traditional one in which the polymerization of PANI is usually carried out in acidic solution.

     

Protonatable Ionenes for Nucleic Acid Complexation

Novel tboc‐protected ionenes with exceeding 30 kDa were prepared from the step‐growth polymerization of tert‐butyl bis[3‐(dimethylamino)propyl]carbamate and 1,12‐dibromododecane. The protected ionenes yielded pH‐sensitive, protonatable ionenes with pK_a ≈ 6.6 for the conjugate acid of the protonated secondary amine. Polyplexes of the protected and deprotected ionenes, whose cytotoxicity for endothelial cells was analyzed using the MTT assay, efficiently complex plasmid DNA. Polyplexes destabilized cellular membranes as revealed using the lactate dehydrogenase assay at high concentrations. The polyplexes were successfully transfected into HBMECs at mass ratios 2, 4, 8, 12, and 16 (polymer/DNA) at polyplex concentrations less than 10 µg · mL^?1.

     

Plasma‐Initiated Controlled/Living Radical Polymerization of Methyl Methacrylate in the Presence of 2‐Cyanoprop‐2‐yl 1‐dithionaphthalate (CPDN)

Summary: Plasma‐initiated controlled/living radical polymerization of methyl methacrylate (MMA) was carried out in the presence of 2‐cyanoprop‐2‐yl 1‐dithionaphthalate. Well‐defined poly(methyl methacrylate) (PMMA), with a narrow polydispersity, could be synthesized. The polymerization is proposed to occur via a RAFT mechanism. Chain‐extension reactions were also successfully carried out to obtain higher molecular weight PMMA and PMMA‐block‐PSt copolymer.

Dependence of ln([M]₀/[M]) on post‐polymerization time (above), and \overline M _{\rm n} and PDI against conversion (below) for plasma initiated RAFT polymerization of MMA at 25 °C.     

Plasma Functionalization of Multiwalled Carbon Nanotube Bucky Papers and the Effect on Properties of Melt‐Mixed Composites with Polycarbonate

Multiwalled carbon nanotubes in the form of bucky papers were modified using Ar/O₂ plasma and thereafter melt‐mixed into polycarbonate. The effect of plasma modification on the nanotubes was followed by XPS, indicating the formation of carboxylic or ester groups at the nanotube surfaces. In the melt‐mixed nanocomposites, the modified nanotubes exhibited a better macrodispersion and better phase adhesion to the matrix as evidenced by morphological investigations. The electrical percolation threshold was not altered and occurred below 0.5 wt.‐% nanotubes. The mechanical properties were improved by having higher values of stress at yield, stress beyond the yield point, and strain at break illustrating the effect of both better dispersion and enhanced phase adhesion.