Nanocomposites, hyperbranched

Keywords Dendrimer Hyperbranched grafts Nanocomposite Polyvalency Surface modification... 

Scheme 6 Formation of hyperbranched thin film nanocomposites using an electrophilic polymeric reagent 14 and a nucleophilic amine-functionalized PAMAM dendrimer 15...

Fig. 11 In situ formation of amine nucleophiles and a,/S-unsaturated carboxamides that react further in thermosetting of hyperbranched dendrimer-polyanhydride nanocomposite thin films...

Maji et al. [136] have examined the effect of 30B loading on the mechanical properties of hyperbranched polyurethane (PU) nanocomposites. The extent of clay loading was varied from 2 to 16 phr. The nanocomposite containing 8 wt% 30B clay shows a 100% increase in the tensile strength as compared to unmodi-fied-clay-filled samples. Above 8 wt% clay loading, the mechanical properties decrease. The efficiency and good dispersion of 30B in the hyperbranched PU40... 

Besides covalent functionalization of carbon nanotubes, non-covalent interaction between CNTs and polyurethane can also help fabricate uniform CNT dispersion nanocomposites. A dominant improvement in the dispersion of MWNTs in hyperbranched polyurethane (HBPU) matrix was found, and good solubility of... 

Zhang RH, Yang YK, Xie XL et al (2010) Dispersion and crystallization studies of hyperbranched poly(urea-urethane)s-grafted carbon nanotubes filled polyamide-6 nanocomposites. Compos A Appl Sci Manuf 41 670-677... 

The pyrolysis of PESs within the channels of the mesoporous silica MCM-41 and the creation of nanostructured magnetic ceramic nanocomposite materials has been achieved. In addition, use of a sacrificial porous alumina yields organometallic and magnetic ceramic nanofibers. Hyperbranched PFSs have also been synthesized and pyrolysis of these interesting materials has been found to lead to superparamagnetic ceramics. Furthermore, pyrolysis of PFSs with pendant Co clusters yields ceramics containing hybrid Fe/Co nanoparticles. ... 

Recently, the authors of this chapter have prepared polymer/clay nanocomposites using a water-soluble hyperbranched aliphatic polyester (Bottom from Perstorp) [Decker et al., 2009]. The nanocomposites were prepared via a solution-intercalation method using deionized water as the solvent medium. The nanocomposite preparation recipe was similar to that used by Plummer et al. [2002]. There are several advantages of this system compared to many other polymer/clay nanocomposite systems. These include the fact that no surfactant is required, the polymer is amorphous, and a broad range of composites from 0 to 95 wt% can be easily prepared. This... 

FIGURE 12.11 o-Ps intensity for nanocomposites of H40 hyperbranched polymer and NaMMT as a function of the volume percent of clay. The straight line indicates trend expected for a two-phase model. 

PEAs, some specific reviews can be taken into account [1-3], The present work is focused to the more recent developments performed with PEAs and highlights current activities on the biomedical field. The review is constituted by six sections the first and the second ones dealing with generic issnes snch as the synthetic methods applied and the derived polymer microstructures, while the third and fourth sections summarize more specific subjects such as preparation of hyperbranched and stiff polymers. The two last sections concern to PEAs prepared from renewable resources, paying special attention to polymers derived from a-amino acids, and specific applications like scaffolds with multiple functionalities, light-responsive materials, or nanocomposites. 

Baek and co-workers grafted hyperbranched poly(ether ketone)s (HPEKs) on to MWCNTs through an in situ polycondensation of A3 (trimesic acid) and B2 (phenyl ether) monomers in the presence of poly(phosphoric acid) and P2O5. Due to the globular molecular architecture of HPs, the morphology of the nanocomposites resembled mushroom-like clusters on MWCNT stalks . The HPEK-g-MWCNT nanocomposites were soluble in polar aprotic... 

As the field of thermosetting layered silicate nanocomposites is still relatively new, the major work to date has focused on the understanding of morphology, processing conditions and properties of less complex binary nanocomposite systems. However, the promising results reported for this new class of material have recently encouraged research in nanocomposites where it is a supplementary additive, used in combination with other phases such as fibres, rubbers or hyperbranched polymers. 

Toughened epoxy resins and epoxy nanocomposite systems were synthesized using DGEBA resin, diethylene famine hardener, octadecylammonium modified montmorillonite and epoxy functional dendritic hyperbranched polymer (Boltorn El, Perstorp Spedahty Chemicals, Sweden) with an epoxy equivalent weight of 875 g/eq and a molecular weight of 10500 g/mol. 

N. Karak, R. Konwarh and B. Voit, Catalytically active vegetable-oil based thermoplastic hyperbranched poiyurethane/siiver nanocomposites , Macromol Mater Eng, 2010, 295,159-69. 

U. Konwar and N. Karak, Hyperbranched poiyether core containing vegetable oil modified polyester and its clay nanocomposites . Polymer I, 2011, 43, 565-76. 

Abstract This chapter describes vegetable oil-based polymer nanocomposites. It deals with the importance, comparison with conventional composites, classification, materials and methods, characterisation, properties and applications of vegetable oil-based polymer nanocomposites. The chapter also includes a short review of polymer nanocomposites of polyester, polyurethanes and epoxies based on different vegetable oils and nanomaterials. The chapter shows that the formation of suitable vegetable oil-based polymer nanocomposite can be considered to be a means of enhancing many of the desirable properties of such polymers or of obtaining materials with an intrinsically new set of properties which will extend their utility in a variety of advanced applications. Vegetable oil-based shape memory hyperbranched polyurethane nanocomposites can be sited as an exampie of such advanced products. 

Information about surface morphology is also obtained from SEM studies. In general, the intercalated clay layers show an intense peak in the range of 1.5° ° (29 value), whereas exfoliated systems have no distinct peak in that range for their loss of structural integrity shown in the XRD pattern of the nanocomposites. XRD studies indicate that there is no infiu-ence of nanomaterial on poly(e-caprolactone)diol PCL crystallinity in sunflower oil-based hyperbranched polyurethane/silver nanocomposite, but that crystallinity is enhanced in castor oil or Mesua ferrea oil-based hyperbranched polyurethane/MWCNT nanocomposites. ... 

Bisphenol-A-based epoxy with a poly(amido amine) hardener system cured Mesuaferrea L. seed oil-based hyperbranched polyurethane (HBPU)/ clay nanocomposites obtained by an ex situ solution technique, was also reported. The partially exfoliated nanocomposites showed a two-fold improvement in adhesive strength and scratch hardness, 10 MPa increments in tensile strength and thermostability at 112°C with little effect on impact resistance, bending and elongation at break compared to a pristine epoxy-modified HBPU system. However, similar epoxy-cured Mesua ferrea L. seed oil-based HBPU/clay nanocomposites exhibited a two-fold increase in tensile strength, a 6°C increase in melting point and thermostability at 111°C after nanocomposite formation using an in situ technique. An excellent shape recovery of about 96-99% was observed for the nanocomposites. The above observations confirm that the performance characteristics of nanocomposites are influenced by their preparation technique. 

Acid modified multi-walled carbon nanotubes and Mesua ferrea L. seed oil-based hyperbranched polyurethane-based nanocomposites have also been reported, exhibiting 300% improvement in tensile strength, enhancement of thermal stability up to 275°C, excellent shape recovery up to 98% (Fig. 11.7), enhanced biodegradabUity and cytocompatibility, confirmed by the inhibition of a RBC haemolysis test at a very low loading of CNT. ... 

Images of different states of shape memory MWNT/ hyperbranched polyurethane nanocomposites. 

Sunflower oil-based hyperbranched and linear thermoplastic polyure-thane/silver nanocomposites have also been prepared by the in situ catalytic reduction of silver salt, using a catalytic amount of organic tin compound. The virgin polymer and its nanocomposites are entirely thermoplastic as... 

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