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Physical properties of urea-formaldehyde microcapsules containing an epoxy resin are presented and discussed. Microcapsules were prepared by in situ polymerization of monomers in an oil-in-water emulsion. Differential scanning calorimetry, thermogravimetric analysis, and scanning electronic microscopy were applied to investigate thermal and morphological microcapsule properties. Microencapsulation was detected by means of FTIR and Raman techniques. It was found that the amount of encapsulated epoxy resin as well as the extent of urea-formaldehyde polymerization depends on the reaction temperature and the stirring speed.

Liquid crystalline elastomers (LCEs) were prepared by reacting rigid-rod mesogenic epoxy monomers with aliphatic diacids of variable length. The influence of acid and nature of epoxy monomer on the mechanism of network growth was investigated through DSC, FT-IR, MALDI, 1H and 13C NMR and rheological experiments. Depending on the nature of epoxy monomer, different mechanisms of network growth occurred, which were responsible for the formation of elastomers with different extent of branching. Clearing temperatures, enthalpies and entropies, and the nature of mesophases were also analyzed through DSC and X-ray diffraction, carried out on unstrained elastomers. It was found that both the rigid-rod mesogens and the aliphatic portions of carboxylic acids contribute to stabilize the mesophase. Moreover, upon stretching, all the LCEs exhibited the polydomain-to-monodomain transition, which is typical of this class of materials.

In this work, mesoporous silica nanoparticles (MSN) hybridized with an organosilane are grafted with hyper-crosslinked poly(vinylbenzyl chloride) (PVBC), which is anchored into the mesopores and onto the external surface of MSN. The obtained nanoparticles are characterized by a MSN-templated hierarchical porosity composed of micropores, mesopores and macropores originated from the hyper-crosslinking of the PVBC phase, with a microporous fraction reaching up to 28% of the total pore volume. Tested for the adsorption of a model dye (Rhodamine 6G, Rh6G), these nanoparticles result much more efficient in Rh6G adsorption with respect to plain MSN, showing a Rh6G uptake of about 125 mg/g in highly concentrated solutions (1000 mg/L) and quite complete removal (about 98%) of the dye in more diluted conditions (30 mg/L) with comparable efficiency in repeated adsorption cycles. Overall results demonstrate the key role of the hierarchical porosity of the hyper-crosslinked PVBC-grafted MSN to tailor their adsorption properties.

Hypothesis Multi-component supramolecular hydrogels are gaining increasing interest as stimuli-responsive materials. To fully understand and possibly exploit the potential of such complex systems, the hierarchical structure of the gel network needs in-depth investigations across multiple length scales. We show that a thorough structural and rheological study represents a crucial pillar for the exploitation of this class of functional materials. Experiments Supramolecular hydrogels are prepared by self-assembly of hexadecyltrimethylammonium bromide (CTAB) and azobenzene-4,4′-dicarboxylic acid (AZO) in alkaline aqueous solution. The CTAB/AZO concentration was varied from ϕ = 0.25 to 4 wt% keeping the CTAB:AZO molar ratio fixed at 2:1. The systems were thoroughly studied through a combination of X-ray scattering, microscopy, rheological and spectroscopic analyses. Findings The CTAB/AZO solutions form a self-supporting gel with nanofibrillar structure below ~30 °C. The critical gelation concentration is ϕc = 0.45 wt%. Above this threshold, the gel elasticity and strength increase with CTAB/AZO content as ~(ϕ-ϕc)1. The hydrogels exhibit self-healing ability when left at rest after a stress-induced damage. Moreover, the light-induced isomerization of the AZO moieties provides the gel with light-responsiveness. Overall, the multi-stimuli responsiveness of the studied CTAB/AZO hydrogels makes them a solid starting point for the development of sensors for mechanical vibrations and UV/visible light exposure.

Biomimetic systems represent one of the most attractive ways to produce artificial complex devices taking the best from nature in a simple and repetitive manner. Some of these systems can imitate trees in some of their functions, in this article, the objective is to imitate trees in their ability to fixate CO 2 and use it to produce organic compounds. As trees do that fixation after the penetration of the gas though the smart pores of the leaves, stomata, we call our pores as artificial stomata. The project aims to end up with compact systems for small size devices that would work with autonomy in the near future in energy systems. Polysulfone based membranes were prepared by a Phase Inversion Precipitation method using different polymeric solutions (N,N-Dimethylformamide or 1-Methyl-2-pyrrolidone). Obtained asymmetric fingerlike, droplike, or spongy morphologies were characterized: by SEM and ESEM equipped with EDX, while their surfaces were investigated by: AFM, dynamic and static contact angle, swelling measurement. Moreover, copper - ferrite nanoparticles, used for preparation of composite membranes was characterized by TEM, and X-ray diffraction. Their influence on material CO 2 solubility, membrane surface morphology and wettability were deeply investigated, and demonstrated influence of membranes roughness on their performance. Furthermore, generated results reveled higher CO 2 assimilation than the natural stomata and shown very high CO 2 absorption flux (67.5 mmol/m 2 *s).

Herein, engineered electrospun core/shell nanofibers containing different percents of Artemisinin (ART) were developed as new systems for drug administration in malaria and prostate cancer fields. In order to preserve drug bioavailability, a hyperbranched poly(butylene adipate) (HB), acting as crystal suppressant of ART, was employed as core material. Poly(vinylpirrolidone) (PVP) was selected as shell material being easy processable, self-standing and effective in facilitating ART release in aqueous medium. The investigation was carried out considering both the technological and biological aspects, by first assessing the release capability of nanofibers, and successively by evaluating the pharmacological activity of encapsulated ART against cancer cell proliferation and malarial parasites ( P. falciparum ) growth through in vitro tests. Inferred results confirmed the formation of nanofibers with an effective drug-loaded capability. Moreover, the different hydrophobic character of the HB and PVP enabled the triggering of the drug release and the control on its solubility in the aqueous medium.

New nanocomposite microporous materials obtained by adding functionalized multi-walled carbon nanotubes (MWCNT) to styrene/vinylbenzyl chloride/divinylbenzene hyper-crosslinked resins were prepared and characterized. In order to promote the embedding of the MWCNT within the gel-type precursor, a suitable surface modi fi cation strategy was set up, based on the grafting of a poly(vinylbenzyl chloride) (PVBC) resin, able to participate in the hyper-crosslinking step, onto the nanotube surface. Characterization of the nanocomposites by FTIR spectroscopy and electron microscopy enabled the assessment of the e ff ect of the nanotubes on the structure and the morphology of the resin. Moreover, gas sorption measurements indicated that by addition of nanotubes it is possible to modulate the pore size distribution, the uptake of CO 2 and H 2 and the CO 2 /N 2 selectivity. Finally, modi fi ed MWCNT are also able to improve the adsorption capacity of phenol from water solutions, suggesting the possible application of the new microporous nanocomposites for water remediatio

Composites based on poly(butylene succinate-co-butylene adipate) (PBSA) containing amorphized and crystalline cellulose reinforcements have been prepared and characterized. In order to improve the polymer/filler interfacial adhesion, an efficient compatibilizing agent has been synthesized by chemical modification of PBSA and characterized by FT-IR, FT-NIR and 1H NMR spectroscopy. Uncompatibilized and compatibilized composites have been tested through morphological, mechanical, calorimetric and thermogravimetric analysis. Moreover, water vapor permeability and biodegradation kinetics of composites have been investigated. The addition to PBSA of cellulose fillers differing from each other by crystallinity degree and morphology, and the use of a compatibilizing agent have allowed modulating tensile and thermal properties, water vapor transmission rate and biodegradation kinetic of the composites.

This work reports on the preparation of UV-light responsive nanocapsules based on cross-linked polyamide, obtained by miniemulsion interfacial polymerization. The photo-triggered E-Z transition of azobenzene moieties of the polymer backbone enabled controlled release of encapsulated molecules. Appropriate selection of emulsion conditions allowed tailoring size distribution of the resulting nanocapsules. The light responsiveness of the nanocapsule systems has been evaluated by monitoring size change and release of a fluorescent probe upon UV irradiation, and an unambiguous relationship between capsule size and release kinetics has been highlighted. In particular, the smaller the capsule size, the faster the achieved release. Therefore, the photoresponsiveness of the nanosized capsule systems can be modulated by a proper selection of emulsion and processing parameters. The significance of the reported results lies in the size control of the encapsulating particles, which in turn enables to tailor their swelling kinetics, and to precisely design light-controlled release systems. (C) 2015 Elsevier Ltd. All rights reserved.

Two oligomers of lactic acid (OLAs), carboxyl (OLA-COOH) or hydroxyl (OLA-OH) end capped, were employed to modulate physical and mechanical properties of poly(lactic acid), PLA. Blends up to 25 wt.% by weight of OLAs were prepared by melt mixing. Mechanical, thermal and transport properties of the materials were tested as a function of OLA functional moieties and blend composition. Moreover, the effect of physical aging on structure and properties of blends was studied by storing the samples in controlled temperature and humidity conditions, up to 8 weeks. OLAs significantly affect mechanical properties of PLA; blends showed an interesting ductility even after aging, suggesting their use as flexible films. Moreover, gas transport and total migration properties of blends are suitable for packaging applications.

The spontaneous oxidative polymerization of 0.01-1% w/w 5,6-dihydroxyindole (DHI) in chicken egg white (CEW) in the absence of added solvents leads to a black, water-soluble, and processable artificial biomelanin (ABM) with robust and 1 order of magnitude stronger broadband light absorption compared to natural and synthetic eumelanin suspensions. Small angle neutron scattering (SANS) and transmission electron microscopy (TEM) analysis indicated the presence in the ABM matrix of isolated eumelanin nanoparticles (=100 nm) differing in shape from pure DHI melanin nanoparticles (SANS evidence). Electron paramagnetic resonance (EPR) spectra showed a slightly asymmetric signal (g similar to 2.0035) similar to that of solid DHI melanin but with a smaller amplitude (Delta B), suggesting hindered spin delocalization in biomatrix. Enhanced light absorption, altered nanoparticle morphology and decreased free radical delocalization in ABM would reflect CEW-induced inhibition of eumelanin aggregation during polymerization accompanied in part by covalent binding of growing polymer to the proteins (SDS-PAGE evidence). The technological potential of eumelanin nanosizing by biomimetic synthesis within a CEW biomatrix is demonstrated by the preparation of an ABM-based black flexible film with characteristics comparable to those of commercially available polymers typically used in electronics and biomedical applications.

Carbon nanoparticles are becoming ubiquitous in many fields of science and technology. However, a grand challenge remains in assembling, patterning, and positioning or even simple manipulation of CNTs for complex functional assemblies. CNTs have in fact enormous perspectives for application in biotechnologies as bactericide agents or as prominent tools for investigating cell mechanisms, or more in general as functionalized nanoparticle-vectors, but their exploitation requires viable technology at the lab-on-a-chip scale. Many approaches have been attempted in developing technologies for manipulating CNTs. One elective approach is based on electric fields driven mechanisms such as DEP forces. A variety of chips have been designed and realized with this aim. Here we report on a novel hybrid microfluidic chip made by assembling a polar-dielectric crystal with polymeric microfluidic channels. One challenging feature of such a hybrid device approach, based on an electrode-free dielectrophoretic (DEP) approach, is that it makes use of surface charge templates for self-assembling and manipulation of CNTs in liquid media directly into a microfluidic channel. Here various examples of self-assembly in microfluidic channels as well as separation and collection of two classes of nano/microparticles are reported. The method can open the way to novel fabrication protocols for the realisation of future flexible devices with new and more complex functionalities, highly desirable in electronics as well as in biotechnology at the lab-on-a-chip scale. 2014 The Royal Society of Chemistry.

In this study, we investigated the influence of ZnO particles obtained by spray pyrolysis with submicron dimensions on the structure, morphology, thermal stability, photodegradation stability, mechanical and antibacterial properties of isotactic polypropylene (iPP)/ZnO composites prepared by melt mixing. The results of the morphological analyses indicate that, despite the surface polarity mismatch between iPP and ZnO, the extrusion process and the unique characteristics of the utilized particles allow a composite with a fair distribution of particles to be obtained, although some agglomeration phenomena can occur, which primarily depends on the composition of the composite. The addition of ZnO particles imparts significant improvements on the photodegradation resistance of iPP to ultraviolet irradiation, which confirms that ZnO particles act as screens for this type of radiation. The thermal stability of the iPP/ZnO composites is improved with respect to that of neat iPP and increases with the content of ZnO. The iPP/ZnO composites exhibit significant antibacterial activity against Escherichia coli. This activity is dependent on exposure time and composition. In the graph, the effect in the antibacterial activity of time and filler content in isotactic polypropylene (iPP)/ZnO composites is reported. Neat iPP has no bactericidal activity. For the composites, a decrease in the E. coli concentration is observed by increasing time. The effect is more evident for iPP/ZnO 95/5.

Poly(3-hydroxybutyrate) (PHB) is a biodegradable polymer, whose applicability is limited by its brittleness and narrow processing window. In this study a pomace extract (EP), from the bio-waste of winery industry, was used as thermal and processing stabilizer for PHB, aimed to engineer a totally bio-based system. The results showed that EP enhanced the thermal stability of PHB, which maintained high molecular weights after processing. This evidence was in agreement with the slower decrease in viscosity over time observed by rheological tests. EP also affected the melt crystallization kinetics and the overall crystallinity extent. Finally, dynamic mechanical and tensile tests showed that EP slightly improved the polymer ductility. The results are intriguing, in view of the development of sustainable alternatives to synthetic polymer additives, thus increasing the applicability of bio-based materials. Moreover, the reported results demonstrated the feasibility of the conversion of an agro-food by-product into a bio-resource in an environmentally friendly and cost-effective way. © 2012 Elsevier B.V.

Uses of flexible poly(vinyl chloride) (PVC) are restricted by plasticizer migration affecting material properties. Moreover, the use of phthalate-based plasticizers is being questioned worldwide because of their potential toxicity to humans and environment. Chemical modification of PVC structure is one of the most effective tools for reduction of plasticizer diffusion. In this work, a flexible dry blend based on cross-linked PVC was obtained using a difunctional amine, namely isophoron diamine (IPDA) as the cross-linking agent. The gel fraction was evaluated from insoluble portions obtained by means of solvent extraction; the efficiency of crosslinking in reducing the plasticizer leaching was evaluated by migration tests. Effects of addition of IPDA on PVC thermal stability were determined by thermogravimetric analysis (TGA). The cross-linking reaction turned out to be responsible for accelerating thermal degradation. Tribological properties of flexible uncross-linked, cross-linked and rigid PVC were determined. Flexible formulations were held in contact for 32 days with rigid PVC sheets. Plasticizer migration towards the interface caused an increase of dynamic friction compared to that of the reference rigid PVC. Vickers microhardness hVickers values of rigid PVC sheets decreased due to plasticizer surface absorption. POLYM. ENG. SCI., 52:211–217, 2012. a 2011 Society of Plastics Engineers

Silica nanoparticles were obtained through the Stober method, from mixtures of tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTS). The nanoparticles were dispersed in tetrahydrofuran (THF) and coupled to bisphenol A epoxy resin (DGEBA) through surface amino groups. After removing THF non-isothermal cure was performed at different heating rates (2–20°C/min), using imidazole (2–4 wt%) as curing agent. For the sake of comparison bare DGEBA epoxy polymers were also prepared with similar schedule A nanocomposite of well-dispersed silica nanoparticles (5 wt%) in a fully cured epoxy matrix was easily obtained. Lower cure kinetics were observed with silica addition. This was attributed to reduction of the imidazole volume concentration. Cure activation energy was not influenced by silica presence, whereas it changed with the imidazole content. Therefore, experimental results suggested that silica had only an indirect effect (the reduction of the imidazole molar concentration) on the epoxy matrix cure kinetics. Glass transformation temperatures, T g, as high as 175°C were recorded. The nanocomposite glass transformation temperature depended on the heating rate of the cure process, the imidazole and silica content. T g changes as high as 40°C were detected as a function of the heating rate. At higher imidazole content no differences in T g values between bare polymer and the nanocomposite were observed. This suggests that a higher imidazole content assures a better interconnection between the compatibilizing epoxy shell around the nanoparticles and the epoxy matrix. The new proposed methodology is an easy route to engineer both nanocomposites structure and interfacial interactions, thus tailoring their properties.

Liquid-crystalline thermosets (LCTs) have received considerable attention since they exhibit many interesting properties. However, some aspects concerning LCTs are still unexplored. In particular, the structure–property relationships, as far as the organization of liquid-crystalline (LC) domains in cured thermosets is concerned, have not been fully elucidated yet. We investigated the effect of the presence of a nematic mesophase on the thermal and dynamic mechanical behaviour of p-(2,3-epoxypropoxy)phenyl-p-(2,3-epoxypropoxy)benzoate cured with 2,4-diaminotoluene. Fourier transform infrared spectral analysis showed that epoxy group conversion was complete in both LC and isotropic (ISO) systems; moreover, a greater amount of intermolecular hydrogen bonding in the LC material was found. Thermogravimetric analysis evidenced similar thermal stability for the two systems, but a kinetic analysis of the data showed that the degradation process is more complex for the LC sample, and is characterized by higher activation energy. Dynamic mechanical thermal analysis (DMTA) showed lower glass transition temperature values for the LC system. Solid-state NMR analysis evidenced lower paramagnetic oxygen absorption for this system. DMTA results show that the ISO material possesses a larger number of physical crosslinks, which act as extra constraints on the molecular motions. In the case of the LCT, the formation of a locally more dense structure is postulated, where the presence of more extended macromolecular segments leads to a smaller number of physical crosslinks, as also confirmed by solid-state NMR analysis. A more compact molecular packing also leads to an increase of the activation energies of the thermal degradation process of the LC system. Copyright © 2010 Society of Chemical Industry

The determinants of the broadband absorption spectrum of eumelanins are still largely unknown. Herein we report a novel approach to investigate eumelanin chromophore which is based on the biomimetic oxidation of the key monomer precursor, 5,6-dihydroxyindole (DHI, 1), with peroxidase/hydrogen peroxide in phosphate buffer, pH 7, containing 1-5% polyvinylalcohol (PVA, 27 000 Da). This approach relies on the discovery that as low as 1% PVA can prevent precipitation of the growing melanin polymer thus allowing investigation of the chromophoric phases accompanying oxidation of DHI without confounding scattering effects. Spectrophotometric monitoring showed the initial development of a band around 530 nm persisting for about 1 h before gradually changing into the typical broadband spectrum of eumelanin. Reductive treatment caused a significant absorbance decrease in the visible region without affecting an absorption band around 320 nm. Initial product analysis indicated an altered formation ratio of 2,4'-biindolyl (2) and 2,7'-biindolyl (3) relative to control experiments. Overall, these results demonstrate for the first time that the development in solution of visible chromophores since the early oligomer stages is independent of strong aggregation/precipitation phenomena.

Cellulose-layered montmorillonite (MMT) nanocomposites were prepared by precipitation from N-methylmorpholine- N-oxide (NMMO)/water solutions. Two hybrid samples were obtained to investigate the influence of the reaction time on the extent of clay dispersion within the matrix. It was observed that longer contact times are needed to yield nanocomposites with a partially exfoliated morphology. The thermal and thermal oxidative properties of the hybrids, which might be of interest for fire-resistant final products, were investigated by thermogravimetry and chemiluminescence (CL). The nanocomposites exhibited increased degradation temperatures compared to plain cellulose, and the partially exfoliated sample showed the maximum stability. This result was explained in terms of hindered transfer of heat, oxygen, and degraded volatiles due to the homogeneously dispersed clay filler. Kinetic analysis of the decomposition process showed that the degradation of regenerated cellulose and cellulose-based hybrids occurred through a multistep mechanism. Moreover, the presence of nanoclay led to drastic changes in the dependence of the activation energy on the degree of degradation. CL analysis showed that longer permanence in NMMO/water solutions brought about the formation of carbonyl compounds on the polymer backbone. Moreover, MMT increased the rate of dehydration and oxidation of cellulose functional moieties. As a consequence, cellulose was found to be less stable at temperatures lower than 100 degrees C. Conversely, at higher temperatures, the hindering of oxygen transfer prevailed, determining an increase in thermo-oxidative stability.

Physical properties of urea-formaldehyde microcapsules containing an epoxy resin are presented and discussed. Microcapsules were prepared by in situ polymerization of monomers in an oil-in-water emulsion. Differential scanning calorimetry, thermogravimetric analysis, and scanning electronic microscopy were applied to investigate thermal and morphological microcapsule properties. Microencapsulation was detected by means of FTIR and Raman techniques. It was found that the amount of encapsulated epoxy resin as well as the extent of urea-formaldehyde polymerization depends on the reaction temperature and the stirring speed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

In this work urea-formaldehyde microcapsules containing an epoxy resin are prepared by in situ polymerization of monomers in an oil-in-water emulsion. Scanning electronic microscopy (SEM) was performed to investigate on microcapsule size and surface morphology. Calorimetric and spectroscopic analyses were carried out with the aim of evaluate the encapsulation yield and the shell features. Factors determining the microencapsulability of the core material were described. In particular, our interest was devoted to a better understanding of the influence of the reaction parameters on the microcapsule properties. It was found that the encapsulation yield as well as the extent of urea-formaldehyde polymerization depends on the reaction temperature and the stirring speed.

The intercalation and exfoliation of liquid crystalline resins (LCRs) in the presence of organophilic montmorillonite were investigated. Their properties were compared with those of pristine resin, as well as with those of nanocomposites based on a commercial epoxy resin containing the same amounts of nanoclays. It was demonstrated that the dispersion of inorganic fillers has a detrimental effect on thermal and mechanical properties if a liquid crystalline (LC) matrix is used. In particular, tensile strength of LC nanocomposites is reduced with the increasing amount of organoclay, which, somehow, disturb the molecular order in the liquid crystalline resin.

As a followup to previous work, experiments with argon and oxygen Radio Frequency plasma treated polyethylene terepthalate (PET) exposed to 100 °C after cold plasma treatment were performed. Tensile tests results in monofilaments treated in oxygen and argon plasma for 5 s, 20 s, 30 s, and 100 s showed a decrease in the average tensile strength compared with the untreated fibers. It was also observed that the reduction in mechanical strength is more significant for argon plasma and very sensitive to the treatment time for oxygen plasma. Experimental data obtained from tensile tests in samples thermal exposed to 100 °C after plasma treatments indicate the same influence of treatment times on mechanical strength, as observed for cold plasma treated fibers. Furthermore, an increase in tensile strength when compared with the samples unexposed to 100 °C was observed. Scanning electron microscopy, used to analyze effects of cold plasma treatment on fibers surfaces, indicates differences in roughness profiles depending on the type of treatment. The distance of roughness interval, Dri, was a parameter introduced to relate the fibers surface condition and average tensile strength. Statistical analysis of experimental data was performed to explain influences of treatment time, and environmental and temperature effects on mechanical properties.

This article reports on a series of experiments with polyethylene terepthalate (PET) treated in a radio frequency plasma reactor using argon and oxygen as a gas fuel, for treatment times equal to 5 s, 20 s, 30 s, and 100 s. The mechanical strength modification of PET fibers, evaluated by tensile tests on monofilaments, showed that oxygen and argon plasma treatment resulted in a decrease in the average tensile strength compared with the untreated fibers. This reduction in tensile strength is more significant for argon plasma and is very sensitive to the treatment time for oxygen plasma. Scanning electron microscopy (SEM) used to analyze the effects of cold plasma treatment of fiber surfaces indicates differences in roughness profiles depending on the type of treatments, which were associated with variations in mechanical strength. Differences in the roughness profile, surveyed through an image analysis method, provided the distance of roughness interval, Dri. This parameter represents the number of peaks contained in a unit length and was introduced to correlate fiber surface condition, before and after cold plasma treatments, and average tensile strength. Statistical analysis of experimental data, using Weibull cumulative distribution and linear representation, was performed to explain influences of treatment time and environmental effects on mechanical properties. The shape parameter, α, and density parameter, β, from the Weibull distribution function were used to indicate the experimental data range and to confirm the mechanical performance obtained experimentally.

The effect of coreacting diglycidyl ether of bisphenol F (DGEBP-F) with diglycidyl ether of 4,4′-dihydroxybiphenol (DGE-DHBP) on mechanical properties is investigated. DGE-DHBP shows a liquid crystal (LC) transition upon curing. Tensile, impact and fracture toughness test results are evaluated. Dynamic mechanical analysis is conducted to determine the effect of the DGE-DHBP component. Scanning electron microscopy of fracture surfaces shows changes in failure mechanisms compared to the pure components. The results indicate that the mechanical properties of these blended samples are significantly improved at 10–20% by weight of DGE-DHBP. This is a consequence of the rigidity of the LC component which thus provides the reinforcement.

Hyper-crosslinked (HCL) polystyrenes show outstanding properties, such as high specific surface area and adsorption capability. Several researches have been recently focused on tailoring their performance for specific applications, such as gas adsorption and separation, energy storage, air and water purification processes, and catalysis. In this review, main strategies for the realization of HCL polystyrene-based materials with advanced properties are reported, including a summary of the synthetic routes that are adopted for their realization and the chemical modification approaches that are used to impart them specific functionalities. Moreover, the most up to date results on the synthesis of HCL polystyrene-based nanocomposites that are realized by embedding these high surface area polymers with metal, metal oxide, and carbon-based nanofillers are discussed in detail, underlining the high potential applicability of these systems in different fields.

Rigid-rod vinyl ester resins represent an interesting family of materials. They can be synthesized starting from the corresponding epoxy resin. Due to their composition, they exhibit outstanding properties, such as heat and chemical resistance, high impact, and corrosion resistance. These features, combined with the ease of curing, make vinyl ester resins good candidates for several industrial applications, such as glass fiber composites, adhesives, corrosion-resistant coatings, electrical encapsulation, and radiation-curable inks. In the first part of this study, a new liquid crystalline methacrylated monomer was prepared and tested as an adhesive. The synthesis was carried out by reacting methacrylic acid with a rigid-rod epoxy monomer derived from the reaction between p-(2,3-epoxypropoxy)-α-methylstilbene (DOMS, diglycidyloxy α-methylstilbene) and aniline in a molar ratio of 3 to 2. The monomer was named md3a2 (methacrylated derivative of DOMS-aniline epoxy compound). Md3a2 is liquid crystalline in a w...

Pristine and surface functionalized multiwalled carbon nanotubes (MWCNT) were melt mixed with a polypropylene (PP) polymer matrix. Rheology, morphology, electrical conductivity and mechanical properties of the nanocomposites were evaluated for different MWCNT loadings. Melt annealing effect on properties was also investigated. It was found that both surface functionalization of MWCNT and thermal annealing were able to favor a better dispersion of the particles, inducing the formation of a percolative network. © 2014 AIP Publishing LLC.

In this work, nanosized capsules based on a lightly cross-linked polyamide containing azobenzene moieties in the main chain were synthesized by miniemulsion interfacial polymerization. The obtained nanocapsules were loaded either with toluene or with the fluorescent probe coumarin-6 as a core. Diameters of the nanocapsules were in the 100-900 nm range, depending on the selected emulsion conditions. The morphology and shape of the samples were observed by TEM and SEM while the emulsion droplets and nanocapsules size was measured by DLS. Under continuous UV irradiation the polymer underwent E-Z photoisomerization allowing the release of the encapsulated material. Variation in diameter of the nanocapsules with the time of UV irradiation was detected through DLS analysis. 10-30% growth was observed, depending on the sample. The kinetics of release of coumarin-6 was followed by spectrofluorimetry in ethanol. In absence of irradiation, the fluorescence intensity appeared to be constant over time, while it increased when the sample was irradiated with 360 nm UV light. © 2014 AIP Publishing LLC.

Two oligomeric esters of lactic acid with carboxyl or hydroxyl terminal groups were employed to plasticize polylactic acid. The miscibility of the blends as well as the mechanical, thermal and gas/vapour transport properties were tested as a function of plasticizer content and of physical ageing. A ductile PLA behavior was obtained with the addition of at least 20 wt% of both esters supplying an increase of elongation at break values higher than 400%. These blends retain their ductile feature also after ageing. Finally migration tests proved the compliance of these materials with the EU regulation for food contact plastics. © 2014 AIP Publishing LLC.

Stable chains of carbon-based nanoparticles were formed directly in polymer matrixes through an electrode-free approach. Spontaneous surface charges were generated pyroelectrically onto functionalized ferroelectric crystals, enabling the formation of electric field gradients that triggered the dipole-dipole interactions responsible for the alignment of the particles, while embedded in the polymer solution. The phenomenon is similar to the dielectrophoretic alignment of carbon nanotubes reported in the literature. However, here the electric fields are generated spontaneously by a simple heat treatment that, simultaneously, aligns the particles and provides the energy necessary for curing the host polymer. The result is a polymer sheet reinforced with well-aligned chains of carbon-based particles, avoiding the invasive implementation of appropriate electrodes and circuits. Because polymers with anisotropic features are of great interest for enhancing the thermal and/or the electrical conductivity, the electrode-free nature of this technique would improve the scaling down and the versatility of those interconnections that find applications in many fields, such as electronics, sensors, and biomedicine. Theoretical simulations of the interactions between the particles and the charge templates were implemented and appear in good agreement with the experimental results. The chain formation was characterized by controlling different parameters, including surface charge configuration, particle concentration, and polymer viscosity, thus demonstrating the reliability of the technique. Moreover, micro-Raman spectroscopy and scanning electron microscopy were used for a thorough inspection of the assembled chains. 2013 American Chemical Society.

This article provides information on the typology, the preparation methods, and the potential applications of microspheres and microcapsules in the field of composites. A wide range of reported protocols for fabrication of these microstructured materials have been presented. The effect of these fillers on the properties of composites has also been discussed. Keywords: microparticles; hollow microspheres; solid microspheres; microcapsules; self-healing composites; phase change materials

A study on the efficiency of bio-based compounds as stabilizers for polypropylene (PP) is reported. A water extract from French maritime pine bark (Pycnogenol (R)), a by-product containing polyphenols obtained from wine production, and a carotenoid-containing oleoresin from processing of tomatoes were used. Their stabilizing activity was compared with that of a commercial phenolic antioxidant. Thermogravimetric analysis and Oxidative Induction Time measurements performed on unaged samples, as well as infrared spectroscopy on samples aged at 70 degrees C, provided evidence for the effectiveness of the natural stabilizers. Mechanical characterization was carried out on aged films and injection moulded samples. Experimental results indicated that particularly grape extract could provide long-term stabilization to PP under conditions of oxidative degradation. Therefore, it could be used as efficient and high value-added additive for polypropylene. Pycnogenol (R) also showed antioxidant activity, however the achievement of a more homogeneous dispersion in the polymer matrix could improve the mechanical performance of aged samples. (C) 2011 Elsevier Ltd. All rights reserved.

A polyphenol-containing extract from winery bio-waste (EP) has been used as an additive for a starch-based polymer (Mater-Bi). EP was used to tailor Mater-Bi properties, thus avoiding the use of synthetic polymer additives. It was found that EP was able to efficiently modulate the processing, mechanical, thermal and biodegradation properties. The observed decrease in melt viscosity showed that EP could improve productivity in polymer processing. Owing to the plasticizing activity of the additive, larger values of elongation at break were found. Moreover, the Mater-Bi crosslinking, which occurs upon thermal aging, was delayed in the presence of EP. Finally, the bio-disintegration rate of doped Mater-Bi decreased, thus suggesting that EP acted as an antimicrobial agent by interfering with the bio-digestion of the polymer films.