Polymer Hybrids (polymer + hybrid)

Distribution by Scientific Domains

Selected Abstracts

New Concepts and Applications in the Macromolecular Chemistry of Fullerenes

Francesco Giacalone
Abstract 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 C60 -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 C60 -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 C60 -polymer systems and in the self-assembly of C60 -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. [source]

Preparation and applications of novel fluoroalkyl end-capped sulfonic acid oligomers,silica gel polymer hybrids

Kazuo Sasazawa
Abstract Fluoroalkyl end-capped 2-methacryloxyethanesulfonic acid homo-oligomer [RF,(MES)n,RF] and 2-methacryloxyethanesulfonic acid,N,N -dimethylacrylamide co-oligomers [RF,(MES)x,(DMAA)y,RF] reacted with tetraethoxysilane (TEOS) under acidic conditions to afford RF,(MES)n,RF homo-oligomer,SiO2 polymer hybrid and RF,(MES)x,(DMAA)y,RF co-oligomer,SiO2 polymer hybrid, respectively. Thermogravimetric,mass spectra showed that the thermal stability of RF,(MES)n,RF homo-oligomer,SiO2 polymer hybrid was superior to that of traditionally well-known perfluorinated ion exchange polymers such as Nafion 112 (TR). The sol solutions of the fluorinated co-oligomer,SiO2 polymer hybrid were applied to the surface modification of glass to exhibit not only a strong oleophobicity imparted by fluorine but also a good hydrophilicity on the glass surface. On the other hand, RF,(MES)x,(DMAA)y,RF co-oligomer reacted with TEOS in the presence of a variety of silica nanoparticles (mean diameters: 11,95 nm) under alkaline conditions to afford fluoroalkyl end-capped oligomers,silica nanoparticles (mean diameters: 32,173 nm) with a good dispersibility and stability in methanol. Similarly, a variety of fluorinated oligomers containing sulfo groups,silica nanoparticles were prepared by the homo- and co-oligomerizations of fluoroalkanoyl peroxides with 2-methacryloxyethane sulfonic acid (MES) and comonomers such as N,N -dimethylacrylamide (DMAA) and acryloylmorpholine (ACMO) in the presence of silica nanoparticles. Interestingly, these isolated fluorinated particle powders were found to afford nanometer size-controlled colloidal particles with a good redispersibility and stability in aqueous and organic media such as methanol. These fluorinated nanoparticles containing sulfo groups were also applied to an excellent heterogeneous catalyst for Bronsted acid-catalyzed transformations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 110,117, 2007 [source]

Merging Organic and Polymer Chemistries to Create Glycomaterials for Glycomics Applications

Géraldine Coullerez
Abstract Summary: Oligosaccharides at cell surfaces are known to play a critical role in many biological processes such as biorecognition, interactions between cells and with artificial surfaces, immune response, infection and inflammation. In order to facilitate studies of the role of sugars, an increasing number of novel tools are becoming available. New synthetic strategies now provide much more efficient access to complex carbohydrates or glycoconjugates. Branched carbohydrates and hybrids of carbohydrates conjugated to polymers have been prepared using solution and/or solid-phase synthesis and advanced methods of polymerization. These materials are essential for the development of methodologies to study and map the molecular structure-function relationship at interfaces. This article highlights recent advances in the synthesis of carbohydrates and polymer hybrids mimicking the properties and functionalities of the natural oligosaccharides, as well as selected applications in biology, biotechnology and diagnostics. [source]

Orientation and Dynamics of ZnO Nanorod Liquid Crystals in Electric Fields

Matthias Zorn
Abstract ZnO nanorod polymer hybrids (i.e., ZnO nanorods coated with a block copolymer with a short anchor block (dopamine) and a longer solubilizing block of polystyrene (PS)) form liquid crystalline (LC) phases if they are dispersed at high concentration e.g., in a PS oligomer matrix. Due to the high mobility of the low Tg -matrix the nanorod polymer hybrids show a switching behavior under an applied AC electric field. Hence, the orientation of the nanorod mesogens can be changed from planar (parallel to the substrate) to homeotropic (perpendicular) in full analogy to the switching of low molecular liquid crystals in an electric field. Dielectric measurements show that such a switching is mainly due to the cooperative LC behavior, because the rods themselves exhibit only a very small effective dipole moment. The process can be investigated by polarizing microscopy. SEM images show the orientations of the individual nanorods, which correspond to the Fredericks transition well known for liquid crystals aligned in an electric field. This was the first time such a transition could be visualized by electron microscopy due to the large nanorod mesogens. The observation is interesting to orient nanorods perpendicular to an electrode and can help to improve optoelectronic devices. [source]

Creep and recovery behavior of novel organic-inorganic polymer hybrids

Sunil B. Adalja
A novel class of organic-inorganic polymer hybrids were developed by meltblending up to 50 (v/v) % [about 83 (w/w) %] tin-based polyphosphate glass (Pglass) and low-density polyethylene (LDPE) in conventional plastics processing equipment. The creep and recovery behavior of these polymer hybrids at 30°C were studied to understand the effect of the Pglass on the creep resistance of the LDPE. The results suggest that the Pglass acts as a reinforcement and an increase in the Pglass loading leads to significantly lower creep strains. This creep resistance is further enhanced by pretreating the Pglass with coupling agents prior to incorporating them into the Pglass-LDPE hybrids. The experimental creep compliance of these materials conformed excellently with empirical power-law equation and a modified Burger's model, suggesting that the materials are linearly viscoelastic under the test conditions. [source]

Polyimide nanocomposites: Comparison of their properties with precursor polymer nanocomposites

Jin-Hae Chang
A precursor poly(amic acid) was obtained by solution polymerization of pyromellitic dianhydride and benzidine in N, N-dimethylacetamide. Poly(amic acid)/Organoclay hybrids were prepared by the solution intercalation method with dodecylamine-montmorillonite. A polyimide hybrid was obtained from poly(amic acid) hybrid by heat treatment at various temperatures. The film type polyimide hybrids showed better thermal properties than poly(amic acid) hybrids. Also, the thermal stability of the two polymer hybrids were enhanced linearly with increasing clay content from 0 to 8 wt%. Tensile properties and gas barriers of the hybrids, however, were enhanced remarkably compared to pristine polymers. Intercalations of the polymer chains in clar were examined through wide angle X-ray diffraction (XRD) and electron microscopy (SEM and TEM). Transmission electron microscopy revealed that a partially exfoliated structure had been obtained from polyimide/organo-clay hybrids. [source]