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The development of effective thermally conductive rubber nanocomposites for heat management represents a tricky point for several modern technologies, ranging from electronic devices to the tire industry. Since rubber materials generally exhibit poor thermal transfer, the addition of high loadings of different carbon-based or inorganic thermally conductive fillers is mandatory to achieve satisfactory heat dissipation performance. However, this dramatically alters the mechanical behavior of the final materials, representing a real limitation to their application. Moreover, upon fillers’ incorporation into the polymer matrix, interfacial thermal resistance arises due to differences between the phonon spectra and scattering at the hybrid interface between the phases. Thus, a suitable filler functionalization is required to avoid discontinuities in the thermal transfer. In this challenging scenario, the present review aims at summarizing the most recent efforts to improve the thermal conductivity of rubber nanocomposites by exploiting, in particular, inorganic and hybrid filler systems, focusing on those that may guarantee a viable transfer of lab-scale formulations to technological applicable solutions. The intrinsic relationship among the filler’s loading, structure, morphology, and interfacial features and the heat transfer in the rubber matrix will be explored in depth, with the ambition of providing some methodological tools for a more profitable design of thermally conductive rubber nanocomposites, especially those for the formulation of tires.

The present study provides a comprehensive investigation at the micro and nanoscale of the interface between hybrid SiO2@POSS nanofiller, where silica nanoparticles (NPs) and POSS nanocages are intimately interconnected, and Styrene Butadiene Rubber (SBR). SEM and AFM inspection and, more in depth, solid state 1H NMR revealed a remarkable fraction of rigid rubber close to the SiO2@POSS surfaces, which increases with the curing temperature. Instead, a reduced amount of immobilized rubber was detected for SBR/SiO2+POSS nanocomposites, obtained by simply mixing SBR, SiO2 and POSS. The results allowed us to propose a model for the network formation in C-SBR/SiO2@POSS. This is based on the progressive activation by dicumylperoxide (DCP) of the methacryl functionalities of POSS nanounits which, being closely connected to SiO2 NPs in SiO2@POSS, promote crosslinking in proximity of the filler surfaces, and lead to the generation of a tight network strongly bonded to the rubber chains.

An efficient method for the preparation of stable microcapsules with an industrially relevant core material was investigated for future use in self-repairing coatings. Microcapsules filled with isophorone diisocyanate (IPDI) were synthesized with different polymeric shells: polyurethane PU, poly(urea-formaldehyde) PUF and bi-layer polyurethane/poly(urea-formaldehyde) PU/PUF. Changing the encapsulation process by adding more shell wall monomers and pre-polymers allows the modulation of physical and mechanical properties of microcapsules. The thickness of microcapsules shell walls can be tuned for coating thicknesses and chemical environments. The effect of diverse process parameters and ingredients on the morphology of the microcapsules was observed by scanning electron microscopy (SEM) and optical microscopy (OM). Different techniques for the characterization of the chemical structure and the core content were considered such as Fourier transform infrared spectroscopy (FT-IR) as well as the characterization of thermal properties by differential scanning calorimetry (DSC). High yields of free flowing powder of spherical microcapsules were produced. The application of a liquid phase IPDI in self-healing polymer composite is studied. Diisocyanates, being reactive with water, introduce the possibility of achieving a really autonomous self-healing system in an aqueous or moisture-sensitive environment. © 2013 Elsevier Ltd. All rights reserved.

The synthesis of new 4-carboxy oxazoles, thiazoles and thiazolidines by condensation of serine or cysteine with aldehydes or acids is described. Due to the optimization of a mild and selective procedure, which takes advantage of the positive effect of microwave irradiation on the MnO2 mediated oxidation step, the 2-substituted-4-carboxy derivatives can be obtained in multi-gram scale. Examples of coordination chemistry to Ni(II) and Co(II) are described.

Silica/styrene butadiene rubber (SBR) nanocomposites were prepared by blending method using shape-controlled spherical and rod-like nanoparticles with different aspect ratios as filler for the rubber reinforcement. The differently shaped silica particles were synthesized by sol-gel method using tetraethoxysilane (TEOS) and (3-mercaptopropyl) trimethoxysilane (MPTSM) as silica precursors, and cetyltrimethylammonium bromide (CTAB) as structure directing agent. This strategy allowed to study the influence of the particle morphology on the reinforcing effect independently of the silica surface chemistry and considering the aspect ratio as the only geometrical variance. Spherical and anisotropic rod-like particles, dispersed in the nanocomposites, formed a network of particles bridged by thin rubber layers throughout the SBR matrix. Moreover, differently oriented domains of aligned rods are observed when the aspect ratio of particles increases and is >=2. Dynamic-mechanical properties demonstrated that the rod-like particles with the higher aspect ratio provided stronger reinforcement of the rubber. This was related to the self-alignment of the anisotropic particles and to the consequent larger filler/polymer interface, compared to that of spherical ones. © 2014 Elsevier Ltd. All rights reserved.

A mild and selective procedure for the synthesis of 4-carboxy thiazoles and thiazolidines starting from naturally occurring cysteine by condensation with aldehydes is described. The optimized procedure, taking advantage of the positive effect of microwave irradiation on the MnO2-mediated oxidation step, is suitable for multigram scale. Coordination of these ligands towards a variety of transition metal ions gave new interesting metallorganic supramolecular architectures in which an extensive 3D network is created through hydrogen bonding. Copyright © Taylor and Francis Group, LLC.

New enantiomerically enriched 1,4,5-piperazines and 1,4,5-dihydro-2H-pyrazines have been prepared by reduction of the corresponding 2-oxo-piperazines. Selective reduction can be achieved by careful control of the reaction conditions using LiAlH4. Notably the two nitrogen atoms of the final compounds are orthogonally protected. © 2010 Elsevier Ltd. All rights reserved

The reaction of [CpRuCl(PPh(3))(2)] (Cp = cyclopentadienyl) and [CpRuCl(dppe)] (dppe = Ph(2)PCH(2)CH(2)PPh(2)) with bis- and tris-phosphine ligands 1,4-(Ph(2)PC[triple bond]C)(2)C(6)H(4) (1) and 1,3,5-(Ph(2)PC[triple bond]C)(3)C(6)H(3) (2), prepared by Ni-catalysed cross-coupling reactions between terminal alkynes and diphenylchlorophosphine, has been investigated. Using metal-directed self-assembly methodologies, two linear bimetallic complexes, [{CpRuCl(PPh(3))}(2)(mu-dppab)] (3) and [{CpRu(dppe)}(2)(mu-dppab)](PF(6))(2) (4), and the mononuclear complex [CpRuCl(PPh(3))(eta(1)-dppab)] (6), which contains a "dangling arm" ligand, were prepared (dppab =1,4-bis[(diphenylphosphino)ethynyl]benzene). Moreover, by using the triphosphine 1,3,5-tris[(diphenylphosphino)ethynyl]benzene (tppab), the trimetallic [{CpRuCl(PPh(3))}(3)(mu(3)-tppab)] (5) species was synthesised, which is the first example of a chiral-at-ruthenium complex containing three different stereogenic centres. Besides these open-chain complexes, the neutral cyclic species [{CpRuCl(mu-dppab)}(2)] (7) was also obtained under different experimental conditions. The coordination chemistry of such systems towards supramolecular assemblies was tested by reaction of the bimetallic precursor 3 with additional equivalents of ligand 2. Two rigid macrocycles based on cis coordination of dppab to [CpRu(PPh(3))] were obtained, that is, the dinuclear complex [{CpRu(PPh(3))(mu-dppab)}(2)](PF(6))(2) (8) and the tetranuclear square [{CpRu(PPh(3))(mu-dppab)}(4)](PF(6))(4) (9). The solid-state structures of 7 and 8 have been determined by X-ray diffraction analysis and show a different arrangement of the two parallel dppab ligands. All compounds were characterised by various methods including ESIMS, electrochemistry and by X-band ESR spectroscopy in the case of the electrogenerated paramagnetic species.

A highly stereoselective approach to 1,3,4,5- and 1,3,3′,4,5-polysubstituted 2-oxopiperazines is reported. The method is based on the synthetic elaboration of naturally occurring amino acids to obtain enantiomerically enriched C-5 substituted oxopiperazines, which are further functionalized at C-3 via enolate formation and reaction with electrophiles. Notably, the two nitrogens of the ring can be orthogonally protected. © 2007 Elsevier Ltd. All rights reserved

This work describes the stereochemistry and the relative rates of epoxidation reactions of the title compounds with sulfur ylides (methylenedimethylsulfurane and methylenedimethyloxysulfurane) in DMSO and C6H6. The electronic perturbative effect of substituent X depends on the solvent and on the reactant. It is transmitted in opposite way in solvents of different polarity depending on the reactant. The electronegativity of the substituent scarcely affects the percentages of axial/equatorial attack. The percentage of equatorial attack with methylenedimethyloxysulfurane is markedly lower for 5-X-adamantan-2-ones than for 4-X-cyclohexanones. © 2005 The Japan Institute of Heterocyclic Chemistry All rights reserved