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The process of the development of a citizen science platform on Ocean Literacy designed and implemented during the lock down period of 2020 is described. As restrictions due to the COVID-19 health emergency did not allow researchers to organise public events and field data collection activities related to Ocean Literacy, it was decided to take advantage of this situation by building an online platform to bring Ocean Literacy issues directly into citizens' homes. The massive use of digital tools by all civic communities during this time has enabled both the implementation of this idea and rendering it effective. The pandemic control measures then provided a unique opportunity to focus citizen attention on the collection of household data and information and to highlight the more or less direct connections between citizens' lifestyles and the eco-marine system. Short questionnaires were used to ascertain and highlight citizens' household behaviours and daily attitudes during the lockdown towards water use, seafood consumption and plastic material use and disposal. Data and information were also proposed, collected and analyzed in terms of: general environmental awareness of the respondents, perception regarding their purchasing choices during this particular period, as well as any changes in lifestyles and habits during the lockdown with respect to previous periods. The collected data enabled the improvement of our knowledge on some aspects of people's domestic habits as well as their perception vs. real knowledge about the proposed environmental issues. We also realized that it is increasingly crucial for scientists to directly and extensively involve people and schools in educational and outreach activities and events as a good practice of science-society interaction. But to achieve good results there is a need to develop appropriate communication tools and effective involvement strategies to promote their widespread participation in citizen science projects.

Poly(lactide) (PLA) and poly(ethylene glycol) (PEG)-based hydrogels were prepared by mixing phosphate buffer saline (PBS, pH 7.4) solutions of four-arm (PEG-PLA)2-R-(PLA-PEG)2 enantiomerically pure copolymers having the opposite chirality of the poly(lactide) blocks. Dynamic Light Scattering, rheology measurements, and fluorescence spectroscopy suggested that, depending on the nature of the linker R, the gelation process followed rather different mechanisms. In all cases, mixing of equimolar amounts of the enantiomeric copolymers led to micellar aggregates with a stereocomplexed PLA core and a hydrophilic PEG corona. Yet, when R was an aliphatic heptamethylene unit, temperature-dependent reversible gelation was mainly induced by entanglements of PEG chains at concentrations higher than 5 wt.%. When R was a linker containing cationic amine groups, thermo-irreversible hydrogels were promptly generated at concentrations higher than 20 wt.%. In the latter case, stereocomplexation of the PLA blocks randomly distributed in micellar aggregates is proposed as the major determinant of the gelation process.

In this paper, we present two novel experimental setups specifically designed to perform in situ long-term monitoring of the aging behaviour of commercial plastic granules (HDPE, PP, PLA and PBAT). The results of the first six months of a three year monitoring campaign are presented. The two experimental setups consist of: (i) special cages positioned close to the sea floor at a depth of about 10 m, and (ii) a box containing sand exposed to atmospheric agents to simulate the surface of a beach. Starting from March 2020, plastic granules were put into the cages and plunged in seawater and in a sandboxe. Chemical spectroscopic and thermal analyses (GPC, SEM, FTIR-ATR, DSC, TGA) were performed on the granules before and after exposure to natural elements for six months, in order to identify the physical-chemical modifications occurring in marine environmental conditions (both in seawater and in sandy coastal conditions). Changes in colour, surface morphology, chemical composition, thermal properties, molecular weight and polydispersity, showed the different influences of the environmental conditions. Photooxidative reaction pathways were prevalent in the sandbox. Abrasive phenomena acted specially in the sea environment. PLA and PBAT did not show significant degradation after six months, making the possible reduction of marine pollution due to this process negligible.

Emulsion blending as a new method to combine a water-soluble biopolymer, gelatin, with a synthetic biodegradable elastomer, poly(butylene succinate

Pea, lentil, faba bean, chickpea and bean proteins are potentially renewable raw materials for bioplastic production that can be obtained from agricultural waste. Plastics are usually processed under heating, and thus thermal stability is a mandatory requirement for the application. In this study, the thermal behavior of several legume protein isolates at different purity degrees was investigated.; Results: The thermal stability of proteins extracted from legumes was maximum for chickpeas and minimum for beans and decreased with decreasing protein purity in the range 30-88%. A similar dependence on purity was observed for the glass transition temperature. On the contrary, the denaturation temperature was found not to depend on sample purity and origin and was lower than the degradation temperature only in the case of protein samples with purity higher than 60%.; Conclusion: Proteins from legumes are suitable to produce thermoplastic biopolymeric materials if isolated at purity higher than 60%. In fact, under this circumstance, they can be denaturized without degrading and thus are suitable for extrusion processing. © 2018 Society of Chemical Industry.; © 2018 Society of Chemical Industry.

Films made of poly(vinyl butyral) (PVB) and antimony-doped tin oxide (ATO) nanoparticles (NPs), both uncoated and surface-modified with an alkoxysilane, were prepared by solution casting at filler volume fractions ranging from 0.08% to 4.5%. The films were characterized by standard techniques including transmission electron microscopy, thermogravimetric analysis and differential scanning calorimetry (DSC). In the polymeric matrix, the primary NPs (diameter ~10 nm) aggregate exhibiting different morphologies depending on the presence of the surface coating. Coated ATO NPs form spherical particles (with a diameter of 300&ndash, 500 nm), whereas more elongated fractal structures (with a thickness of ~250 nm and length of tens of micrometers) are formed by uncoated NPs. The fraction of the polymer interacting with the NPs is always negligible. In agreement with this finding, DSC data did not reveal any rigid interface and 1H time domain nuclear magnetic resonance (NMR) and fast field-cycling NMR did not show significant differences in polymer dynamics among the different samples. The ultraviolet-visible-near infrared (UV-Vis-NIR) transmittance of the films decreased compared to pure PVB, especially in the NIR range. The solar direct transmittance and the light transmittance were extracted from the spectra according to CEN EN 410/2011 in order to test the performance of our films as plastic layers in laminated glass for glazing.

Polyvinyl butyral (PVB) is an amorphous polymer employed in many technological applications. In order to highlight the relationships between macroscopic properties and dynamics at a microscopic level, motions of the main-chain and of the propyl side-chains were investigated between Tg − 288 °C and Tg + 55 °C, with Tg indicating the glass transition temperature. To this aim, a combination of solid state Nuclear Magnetic Resonance (NMR) methods was applied to two purposely synthesized PVB isotopomers: one fully protonated and the other perdeuterated on the side-chains. 1H time domain NMR and 1H field cycling NMR relaxometry experiments, performed across and above Tg, revealed that the dynamics of the main-chain corresponds to the α-relaxation associated to the glass transition, which was previously characterized by dielectric spectroscopy. A faster secondary relaxation was observed for the first time and ascribed to side-chains. The geometry and rate of motions of the different groups in the side-chains were characterized below Tg by 2H NMR spectroscopy.

Bionancomposites from bioplastics and nanoclays are of great interest for packaging, agricultural and other large-volume and niche applications due to their enhanced physical, thermal, mechanical and processing characteristics compared to the parent polymer. In this study, the biodegradable polyester poly(butylene adipate) (PBA) was synthesized by in situ polycondensation catalysed by titanium tetrabutoxide in the presence of the natural Moroccan clay beidellite (BDT). Optimization of the nanoclay exfoliation in the bionanocomposite was achieved by cation exchange of BDT with cetyltrimethylammonium bromide (CTA) and by selecting the most effective among a range of organically modified xCTA-BDT (x = CTA/BDT equivalent feed ratio). Fourier transform infrared and 1H NMR spectral and size exclusion chromatographic analyses confirmed the effectiveness of the in situ polymerization, yielding structurally regular PBA with narrow molecular weight dispersity and 7750 < M‾n < 30 360 g mol−1, depending on the organoclay load. X-ray diffraction and transmission electron microscopy analyses showed best clay dispersion and homogeneous distribution at 2 wt% 3CTA-BDT. From thermogravimetric analysis and differential scanning calorimetry results the thermal stability of PBA is greatly improved even at 1 wt% 3CTA-BDT, its glass transition temperature is nearly unaffected while crystallinity is increased by the organoclay nucleating action. These results, along with a bionanocomposite hydrophilicity only moderately higher than that of PBA, make this preparation approach particularly promising. © 2017 Society of Chemical Industry

This chapter following the general introduction is devoted to provide the reader with the basic concepts related to the understanding of the fundamental necessary properties of a polymeric material to perform as a plastic material and then to be used in the corresponding applications. The main objective of this chapter is to highlight the structural properties requested to a plastic material and to what extent they can be reached with differentiated molecular structures of the macromolecular chains forming the polymer. Indeed, the plastic behaviour can be found in molecularly different materials, but the precise response requested by many specialized applications in our present style of life is obtained by a well-thought analysis of relationships between detailed molecular structure and ultimate properties. Indeed, the selection of a plastic material among the available products is determined by the requested mechanical response. This last is determined by the type of mechanical stress applied and by the working temperature. Then, the suitability of a plastic polymer to be used for the production of a defined commercial item is based on the determination of its thermal and mechanical features, which allow predicting its behaviour during customer use. Moreover, as the shape of final commercial items is obtained by moulding from the melt, the properties of the molten fully liquid polymer (Rheological properties) must be known before going to an industrial production, including information on how they are modulated by the molecular structure of the polymer. This chapter is consequently devoted to discuss in detail the physical properties, which are presently considered basic for a polymeric material to be classified as a plastic and how they are dependent on macromolecules chemical structure. Thermal, mechanical and rheological features are described separately for sake of clarity even if strictly interrelated. Even if in the commercial use the term plastic is used also for some amorphous polymers, which can be shaped by melt moulding, the real plastic polymer is necessarily consisting of two phases, either physically or chemically different. Then, several commercial plastics are obtained by blending two distinct polymers. Therefore, the mechanical, thermal and rheological properties of blends will be also considered.

Under the pressure of the social requirement for a more natural style of life, many commercial products were rendered more attractive with a more or less valid superficial coverage of bio-related aspect; these products are often mixed without any scientific rule with environmentally friendly products with misleading information of the users. The aim of this chapter is then to provide a survey of information about what we can find under the name of bioplastics and help to identify the really biologically originated properties and how they mix with more technological features often common with those of fossil-originated plastics. Indeed, it must be considered that any commercial product to be available to a large number of people needs an adequate amount of raw material and a suitable production process involving, in general, an appropriate formulation, combination with other compounds, as no one natural product is ready for use in a competitive high-technology world. The involvements of the different industrial production steps of a polymeric material, which can be in some way classified as bioplastics are rather different depending on the level of natural contribution. The raw material for polymers are monomers and any polymer derived through a man-made polymerization process is called bioplastics even if the properties are the same as those of the analogous polymer derived from the same monomer but from fossil origin. Ethylene and the so-called ‘bioethylene’ are identical molecules and the corresponding polyethylenes cannot be distinguished. In other cases, nature supplies directly the macromolecules, so the polymerization reaction was already performed, but purification and formulation remain necessary. In the following sections, various possibilities are presented separately to more clearly evidence the role of the nature and the bio-features of the materials for the production of the commercially classified bioplastics.

The characteristic poor stability and high fluid permeability of Poloxamer®- based gels have severely limited their biomedical application. In this work, Poloxamer 407 was used as building block to synthesize a poly(ether urethane) (PEU), which aqueous solutions formed gels with improved stability and mechanics compared to Poloxamer itself. PEU chains formed micelles in aqueous solution (diameter ~40 nm at 25°C) and systems with PEU content higher than 5±1% w/v underwent a temperature- driven gelation. Gel properties were tuned acting on PEU concentration in the starting solutions, with compositions within the range 8-18% w/v showing high potential for biomedical applications (gelation at 37°C within 3-10 minutes, residence time from few days to many weeks, injectability). Model proteins (bovine serum albumin, horseradish peroxidase) were encapsulated in mild conditions and their release was modulated by gel composition (on day 3, approx. 85, 65 and 55% of encapsulated payload released from gels with 8, 15 and 18% w/v concentration). Released peroxidase retained approx. 30-40% of its activity up to 2 days, a key aspect for biomolecules in the drug delivery field.

Plastics were investigated based on homopolymers, which are polymers consisting of macromolecules characterized by the uniform chemical structure along the main chain, the successive investigation and related discovery demonstrated that the plastics’ behaviour could be reached with more complex systems in terms of molecular structure and composition. Successively copolymers consisting of macromolecules based on two different monomers have offered a possibility for designing plastics with a broader spectrum of properties. Going from molecular differentiation towards structural complexity, the mixing of polymers having different structures and thus different properties has provided a helpful tool to obtain materials with unique ultimate features, which are not characteristic of pristine macromolecules alone. At the same time, the dispersion in a polymer matrix of fillers having different aspect ratios (fibres, particles, lamellae) and dimensions (micro- and nanostructured fillers) can improve the thermo-mechanical properties or/and impart completely new properties, as example the barrier property, depending on the morphologies and dispersion level as well as on the interfacial interactions degrees. In fact, the blending procedure (between polymers or between polymer and filler) is effective only if proper interfacial interactions can be granted through the presence of specific functionalities. These latter can be naturally present onto both man-made and natural-made polymers or have to be inserted/anchored to the polymer backbone by post-reactor modification procedures. Therefore, this chapter summarizes the most important chemical post-modification procedures of polymers to prepare functionalized polymers or grafted copolymers suitable to act as compatibilizers, the main theoretical aspects of blending and the methodologies already get ready to provide composites and nanocomposites by using polymers from fossil, from renewable resources and even natural.

The thermal, mechanical, and rheological properties of biocomposites of poly(lactic acid) (PLA) with potato pulp powder were investigated in order to (1) quantify how the addition of this filler modifies the structure of the polymeric material and (2) to obtain information on the possible miscibility and compatibility between PLA and the potato pulp. The potato pulp powder utilized is a residue of the processing for the production and extraction of starch. The study was conducted by analyzing the effect of the potato pulp concentration on the thermal, mechanical, and rheological properties of the biocomposites. The results showed that the potato pulp powder does not act as reinforcement but as filler for the PLA polymeric matrix. A progressive decrease in elastic modulus, tensile strength, and elongation at break was observed with increasing the potato pulp percentage. This moderate loss of mechanical properties, however, still meets the technical requirements indicated for the production of rigid packaging items. The incorporation of potato pulp powder to PLA offers the possibility to reduce the cost of the final products and promotes a circular economy approach for the valorization of agro-food waste biomass.

This chapter deals with the preparation of products from material based on plastic polymers from fossil origin. The production route of traditional plastic polymers starts from available monomers, followed by reaction for converting them into polymers and successive processing to obtain objects. This synthetic description is considered necessary for the general objective of the book devoted to the comparison between plastics from fossil origin and from renewable sources. Indeed, the alternative use of plastics from renewable source is first of all depending on the evaluation of the real capacity of the bio-related plastics to be produced in adequate amount with sustainable processes. Clearly, this problem arises when monomers with different structures and new polymers are made available from bio-related starting compounds. On the other side, the bio-related monomers and polymers will be clearly submitted to the same production technology as the corresponding fossil products, the problem becoming obvious when the monomer structure is the same as in the case of ethylene from oil or from fermentation. Then, this chapter has the role to resume the state of the art in polymer technology and the scenario of polymerization reactions and material processing encountered by monomers and polymers from renewable sources to be converted in the so-called bioplastics.

Pea, lentil, faba bean, chickpea and bean proteins are potentially renewable raw materials for bioplastic production that can be obtained from agricultural waste. Plastics are usually processed under heating, and thus thermal stability is a mandatory requirement for the application. In this study, the thermal behavior of several legume protein isolates at different purity degrees was investigated.The thermal stability of proteins extracted from legumes was maximum for chickpeas and minimum for beans and decreased with decreasing protein purity in the range 30-88%. A similar dependence on purity was observed for the glass transition temperature. On the contrary, the denaturation temperature was found not to depend on sample purity and origin and was lower than the degradation temperature only in the case of protein samples with purity higher than 60%.Proteins from legumes are suitable to produce thermoplastic biopolymeric materials if isolated at purity higher than 60%. In fact, under this circumstance, they can be denaturized without degrading and thus are suitable for extrusion processing. © 2018 Society of Chemical Industry.

Dielectric Spectroscopy (DS) and

Aiming at the tuning of thermo-mechanical features by chemical cross-linking, a biopolyester commercial blend based on poly(lactic acid) (PLA) with poly(butylene adipate-co-terephthalate)(PBAT) (ecovio®T2280, BASF) was processed in Brabender in the presence of dicumyl peroxide (DCP, 0–0.2 wt.-%). The effect of DCP addition was investigated and rationalized by means of solubility tests and gel content evaluation, as well as rheological, mechanical, and molecular weight analysis of the prepared compounds. Moreover, detailed DSC and TMDSC investigations provided a deep insight into the structural modifications occurred at the macromolecular level. We found that chain branching as well as cross-linking occurred in the samples processed in the presence of DCP, thus returning compounds having increased toughness and modulated crystalline content and thermal behavior. Noteworthy, the presence of specific, undisclosed additives, triggers the occurrence of peculiar behaviors in the ecovio® commercial blend, not previously observed in model PLA/PBAT blends of similar composition. Despite only partially soluble in chloroform, the new ecovio® DCP-modified compounds still remained workable in the melt, thus providing a suitable, simple and economically affordable strategy to finely modulate the thermo-mechanical properties starting from a commercially available, compostable compound.

Dielectric Spectroscopy (DS) and 1H Fast Field-Cycling (FFC) NMR relaxometry were applied for understanding the dynamic behavior of the amorphous ter-polymer poly(vinyl butyral) (PVB) across the glass transition temperature (Tg = 70 °C by Differential Scanning Calorimetry). Above Tg, main chain segmental motions (α relaxation) were detected and characterized using both DS and FFC NMR relaxometry. The correlation times extracted by the analysis of DS and FFC NMR relaxometry data agreed within a factor of three and showed a Vogel-Fulcher-Tammann temperature dependence, with an associated Tg of 69 °C and a fragility of 155 for PVB glass. Below Tg, a secondary process (β relaxation) was revealed by DS, and was ascribed to reorientations of the vinyl alcohol dipoles due to local twisting motions with an associated activation barrier of 11 kcal mol-1. The β process was also found to contribute to 1H NMR relaxation above Tg.

The combined use of Dielectric Spectroscopy (DS) and 1H Fast Field-Cycling (FFC) NMR relaxometry allowed a detailed understanding of the dynamic behavior of the amorphous ter-polymer poly(vinyl butyral) (PVB) to be achieved across the glass transition temperature (Tg=70 °C by Differential Scanning Calorimetry). Above Tg, main chain segmental motions (alpha relaxation) were detected and characterized by both DS and FFC NMR relaxometry. The alpha process showed a Vogel Fulcher Tammann temperature dependence, with an associated Tg of 69 °C and a fragility of 155 for PVB glass. Below Tg, DS revealed a beta relaxation ascribed to reorientations of the vinyl alcohol dipoles due to local twisting motions and allowed an activation barrier of 11 kcal/mol to be determined. NMR relaxometry data supported the occurrence of this motion, although 1H relaxation could also be affected by reorientations of propyl side chains.

Molecularly designed materials based on macromolecules and organic dyes offer unique opportunities in connection with the possibility of preparing optically responsive ‘smart’ materials. Indeed macromolecules are able to transmit and amplify small signals reaching sites at interacting distance through the involvement of the whole chain. The corresponding materials can then acquire stimuli-responsive properties in relation to specific features connected to primary structure and conformation. As a first approach to benefit from the above features for preparing eco-compatible smart materials, bio-related polypeptides, polysaccharides and polyesters can be used as the macromolecular partner in combination with a selected dye following different interaction methodologies. Two distinct routes were used to prepare optically responsive products from the above bio-related polymers, respectively based either on the covalent bonding to the original macromolecules of photochromic molecular species, such as azobenzene and spiropyran, or on the morphology-modulated dispersion of highly conjugated dyes in the polymer bulk. Examples related to the two different routes have been investigated in our laboratory and are presented and discussed also with reference to selected recent cases from the literature. Copyright © 2012 Society of Chemical Industry

Poly(butylene succinate)-hemp composites (PBS-hemp), with hemp content in the range 0–40 wt.%, were prepared in the melt and characterized. This paper focuses on the detailed analysis of the thermal behaviour of the PBS-hemp composites, investigated by differential scanning calorimetry (DSC), to enlighten the polymer/fibre interphase features. The occurrence of specific intermolecular interactions between PBS and hemp was assessed from specific heat capacity data. Different degrees of mobility of the PBS amorphous segments were found at the amorphous/crystal interphases. A broadening of the bulk glass transition was observed, and attributed to the presence of polymer segments slightly constrained. Moreover, a rigid amorphous fraction that devitrifies at temperatures higher than the bulk glass transition, partly before the melting region and partly simultaneously with the fusion, was observed and quantified, and attributed to the presence of major constraints probably occurring in geometrically restricted areas.

Poly(lactic acid) (PLA) and poly(butylene adipate- co -terephthalate) (PBAT) are biodegradable aliphatic polyesters, which being semicrystalline and thermoplastic can be processed by conventional methods. Their blends give interesting materials for industrial packaging applications, due to their increased ductility as PBAT content increases. However, like many aliphatic polyesters, the PLA matrix degrades upon melt processing thus affecting the thermo-mechanical features of the blended material. In this work, we studied the effect of processing at high temperature on the molecular weight distribution, morphology, and thermo-mechanical properties of both homopolymers, as well as the PLA/PBAT 75/25 blend. Notably, different processing conditions were adopted in terms of temperature (range 150–200 °C) and other relevant processing parameters (moisture removal and nitrogen atmosphere). Analysis of PLA/PBAT blends indicated that intermolecular chain reactions took place under strong degradative conditions of PLA, yielding PLA/PBAT mixed chains (copolymers). Increasing amounts of copolymers resulted in improved phase dispersion and increased ductility, as SEM and mechanical tests indicated. Conversely, reduced PLA degradation with less copolymer formation, afforded higher modulus materials, owing to poorer dispersion of the soft phase (PBAT) into the PLA matrix.

Degeneration of intervertebral discs is the most common cause of back pain. The first phase of this degenerative process involves the nucleus pulposus. A rapid recovery of this structure can prevent further degradation of the annulus fibrosus. Guar Gum is an hydrophilic polysaccharide extracted from the seed endosperm of a plant. Through a cross-linking procedure a Guar hydrogel was synthesized. The Guar hydrogel could be injected by a syringe and it is a good candidate as a nucleus pulposus substitute. For the preparation of the artificial fibrosus annulus, commercially available polymer materials are tuned to achieve suitable mechanical properties. To achieve this peculiar behaviour, the main strategy investigated is the dispersion of hollow polymer micro spheres in a thermoplastic polymer matrix. Processing conditions and particle content are finely tuned to get the target mechanical behaviour.

Nanocomposites of polymers and inorganic fillers are materials of great interest for many practical applications. Polyvinylbutyral (PVB) is an amorphous polymer employed as an inter-layer film in laminated safety-glass manufacture industry thanks to its high optical clarity and good adhesion to glass. Additional interesting properties can be obtained by adding a filler to the PVB matrix. Indeed, PVB loaded with Antimony doped Tin Oxide (ATO) nanoparticles is able to filter out the near infrared waves of sunlight, while maintaining transmission in the visible region [1]. Given the worldwide energy saving and environmental preservation policies, this property seems promising for applications in building and vehicle glass construction. In view of the optimization of PVB-ATO nanocomposites for applicative purposes, a thorough characterization of its structural and dynamic microscopic properties is necessary. To this aim, we studied PVB films loaded with 0, 5 and 23 wt% of ATO nanoparticles across the polymer glass transition (Tg = 70 oC) by means of low-field (20 MHz) and fast field-cycling (FFC) 1H NMR relaxometry. Both uncoated and surface modified (with methacryloxypropyltrimethoxysilane) nanoparticles were dispersed in the polymer matrix. Analysis of the FIDs recorded in solid-echo experiments with different echo delays and of the dispersion curves obtained by measuring 1H longitudinal relaxation times by FFC in the 0.01 to 35 MHz frequency range allowed us to investigate the effects of the nanoparticles on the polymer dynamics and to quantitatively determine the fractions of polymer with different mobility. In particular, it was observed that the surface-modified particles do not affect the dynamics of the polymer matrix at any loading level in the whole temperature range investigated. On the contrary, the uncoated particles induce a slowing down of the polymer motions above the glass transition but do not significantly affect them below it. Our data demonstrate the crucial role played by the particle surface in influencing the polymer dynamics. References [1] G. Zhang, W. Yan, T. Jiang J. Wuhan University of Technology-Mater. Sci. Ed. 28, 912-915 (2013)

Industrial processing of materials containing quartz induces physico-chemical modifications that contribute to the variability of quartz hazard in different plants. Here, modifications affecting a quartz-rich sand during cast iron production, have been investigated. Composition, morphology, presence of radicals associated to quartz and reactivity in free radical generation were studied on a raw sand and on a dust recovered after mould dismantling. Additionally, cytotoxicity of the processed dust and ROS and NO generation were evaluated on MH-S macrophages. Particle morphology and size were marginally affected by casting processing, which caused only a slight increase of the amount of respirable fraction. The raw sand was able to catalyze OH and CO2(-) generation in cell-free test, even if in a lesser extent than the reference quartz (Min-U-Sil), and shows hAl radicals, conventionally found in any quartz-bearing raw materials. Enrichment in iron and extensive coverage with amorphous carbon were observed during processing. They likely contributed, respectively, to increasing the ability of processed dust to release CO2- and to suppressing OH generation respect to the raw sand. Carbon coverage and repeated thermal treatments during industrial processing also caused annealing of radiogenic hAl defects. Finally, no cellular responses were observed with the respirable fraction of the processed powder.

Emulsion blending as a new method to combine a water-soluble biopolymer, gelatin, with a synthetic biodegradable elastomer, poly(butylene succinate-co-adipate) (PBSA), was investigated. Blending by wet processing a hydrophilic biopolymer with a hydrophobic synthetic polymer aimed at evaluating the potential for improving the mechanical properties of the biopolymer without affecting its biodegradability. The effect of the variation of blend composition, and of the experimental procedure for the emulsification and the subsequent preparation of cast films from the resulting oil-in-water emulsions was analyzed. In particular, processing temperature, concentration of the precursor solutions (aqueous gelatin and PBSA in dichloromethane, respectively), blending method and post treatment conditions (T, P) affect the quality and stability of the aqueous gelatin emulsion containing PBSA in dichloromethane as the dispersed phase. Control of the aqueous phase viscosity is a key parameter for both the emulsion stability and the morphology of the final heterophasic cast films. In fact, viscosity must be sufficiently low to allow high shear emulsification, but high enough to prevent coalescence among the organic phase droplets. The process conditions optimized for a 80/20 blend were extended to the preparation of blends with 5-30 wt % PBSA. It was found that evaporation of the organic phase must be nearly quantitative before casting to allow the formation of uniform films at any investigated composition of the immiscible polymer blend. In fact, when the films are produced by casting, the presence of residual organic solvent along with too high a viscosity of the aqueous gelatin phase promotes the formation of cavities opening up at the lower film surface as a result of the higher density of CH2Cl2. However, such cavities, internally sheathed with PBSA microbeads precipitated upon evaporation of the organic phase, if smaller than 100 mu m turned out to improve the flexibility of the films.

1,6-Diisocyanatohexane and dimethyl sulfoxide were exploited as crosslinking agent and reaction solvent, respectively, for gelatin modification. Crosslinked samples were fractionated and analyzed by thermogravimetric analysis, infrared spectroscopy, acid and base titrations, and swelling measurements. The yield of crosslinking was found to increase with increasing diisocyanate and gelatin concentrations and the amount of bound crosslinker was evaluated. The chemical analysis of the reaction products allowed the process parameters to be related to the properties of the textile/ gelatin composites. For this purpose poly(propylene)-, poly(ethylene terephthalate)-, and cotton-based textiles were treated to prepare soft and dimensionally stable supported materials with a gel phase composed of gelatin.

A series of cationic palladium complexes of general formula [Pd(CH3)(NCCH3)(N–N)][X] (N–N = phen 1, 3-sec-butyl-1,10-phenanthroline (3-sBu-phen) 2, bpy 3, (−)-(S,S)-3,3′-(1,2-dimethylethylenedioxy)-2,2′-bipyridine (bbpy) 4, (+)-(R)-3,3′-(1-methylethylenedioxy)-2,2′-bipyridine (pbpy) 5, N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediimine (iso-DAB) 6; X = PF 6 - a , OTf (OTf = triflate) b) containing different nitrogen-donor ligands were prepared from the corresponding neutral chloro derivatives [Pd(CH3)(Cl)(N–N)] (1c–6c). They were characterized by 1H NMR spectroscopy and elemental analysis. Single crystals suitable for X-ray determination were obtained for complexes [Pd(CH3)(NCCH3)(bbpy)][PF6] (4a), [Pd(CH3)(NCCH3)(iso-DAB)][PF6] (6a) and [Pd(Cl)2(bbpy)] (4c′). The latter is the result of an exchange reaction of the methyl group, present in complex 4c, with a chloride, that occurred after dissolution of 4c in CDCl3, for 1 week at 0 °C. The catalytic behavior of complexes 1a–5a and 1b–5b in the CO/styrene copolymerization was studied in CH2Cl2 and 2,2,2-trifluoroethanol (TFE) evidencing the positive effect of the fluorinated alcohol both in terms of productivity and molecular weight values of the polymers obtained. Influence of the nitrogen ligand, the anion and the reaction time in both solvents were investigated and is discussed in detail. Encouraging preliminary results were also obtained in the synthesis of polyethylene, in TFE, catalyzed by [Pd(CH3)(NCCH3)(iso-DAB)][PF6] (6a).

Nanocomposites of polymers and inorganic fillers represent a class of materials of great interest for many practical applications. Polyvinylbutyral (PVB) is an amorphous polymer employed in automotive and architectural applications for laminated safety glasses thanks to its high binding efficiency, optical clarity, and good adhesion to several different surfaces. Additional interesting properties for glass construction can be obtained using PVB as a matrix in nanocomposite materials. Indeed, loading PVB with Antimony Tin Oxide (ATO) nanoparticles makes the material capable of filtering out the near infrared (NIR) waves of sunlight while maintaining transmission in the visible region. This property is becoming of relevance in building and vehicle glass construction as a consequence of the worldwide energy saving and environmental preservation policies. In view of the optimization of PVB-ATO nanocomposite formulation for applicative purposes a thorough characterization of structural and dynamic microscopic properties of these materials is necessary. In this study the effects of loading PVB with ATO nanoparticles on the polymer dynamics were investigated combining high resolution solid state 13C NMR spectroscopy and low resolution 1H NMR relaxometry. In particular, 1H longitudinal relaxation times (T1) were measured in the 0.01 to 35 MHz frequency range by Fast Field Cycling NMR relaxometry, whereas 1H transversal relaxation times (T2) were determined by Free Induction Decay (FID) analysis at 20 MHz. All experiments were performed on both PVB and PVB-ATO in the temperature range between 30 and 120 °C, the polymer glass transition occurring at about 70 °C. The analyses of the dispersion curves and FIDs showed that loading with ATO nanoparticles results in an increase in polymer mobility. A comparative study with broadband dielectric relaxation spectroscopy, in a frequency range up to 10 MHz, helped to elucidate peculiar features due to random blocks of polyvinylalcohol and polyvinylbutyral present in the polymer structure. Local dielectric spectroscopy (LDS) experiments were also performed close to the glass transition to highlight changes in the polymer dynamic behavior at the interface with the nanoparticles.

Two pyrene-tagged iminopyridines (NN') were used to synthesize neutral and monocationic, palladium(II) complexes, [Pd(Me)Cl(NN')] and [Pd(Me)(MeCN)(NN')][PF6]. The monocationic complexes generated active catalysts in the CO/vinyl arene copolymerization, leading to polyketones with yields and molecular weight strongly dependent on N-N', with the ketimine catalysts one order of magnitude more productive than the aldimine counterpart. The stereochemistry of polyketones synthesized with the aldimine catalyst was found to be dependent on the vinyl comonomer: prevailingly syndiotactic copolymers were obtained for styrene, prevailingly isotactic copolymers were produced for 4-methyl styrene, and atactic macromolecules were formed for 4-tert-butyl styrene. The statistical analysis demonstrated that the control of the stereochemistry switched from enantioselective site control for 4- methyl styrene to a combination of chain-end and enantioselective site control for styrene.

Polymer nano-composites represent a class of materials of great interest for many practical applications. In particular, polyvinyl butyral (PVB) is used in automotive and architectural applications for laminated safety glasses thanks to its high binding efficiency, optical clarity, and good adhesion to several different surfaces. Furthermore, its use as a polymer matrix in nanocomposite materials allows interesting properties to be obtained depending on the type of embedded inorganic nanoparticles. For example, the use of Antimony Tin Oxide (ATO) nanoparticles provides the nanocomposite material with the capability of filtering out the near infrared (NIR) waves of sunlight while maintaining transmission in the visible region. This property is becoming of relevance in building and vehicle glass construction as a consequence of the worldwide energy saving and environmental preservation policies. In this study the effects of loading PVB with ATO nanoparticles on the polymer dynamics were investigated combining high resolution solid state 13C NMR spectroscopy and low resolution 1H NMR relaxometry. In particular, 1H longitudinal relaxation times (T1) were measured in the 0.01 to 35 MHz frequency range by Fast Field Cycling (FFC) NMR relaxometry, whereas 1H transversal relaxation times (T2) were determined by Free Induction Decay (FID) analysis at 20 MHz. All experiments were performed on both PVB and PVB-ATO in the temperature range between 30 and 120 °C, the polymer glass transition occurring at about 70 °C. The analyses of the dispersion curves and FIDs showed that loading with ATO nanoparticles results in an increase in polymer mobility. A comparative study with broadband dielectric relaxation spectroscopy, in a frequency range up to 10 MHz, helped to elucidate peculiar features due to random blocks of polyvinylalcohol and polyvinylbutyral present in the polymer structure. Local dielectric spectroscopy (LDS) experiments were also performed close to the glass transition to highlight changes in the polymer dynamic behavior at the interface with the nanoinclusions.

International audience; Two pyrene-tagged iminopyridines (N-N′) were used to synthesize neutral and monocationic, palladium(II) complexes, [Pd(Me)Cl(N-N′)] and [Pd(Me)(MeCN)(N-N′)][PF6]. The monocationic complexes generated active catalysts in the CO/vinyl arene copolymerization, leading to polyketones with yields and molecular weight strongly dependent on N-N′, with the ketimine catalysts one order of magnitude more productive than the aldimine counterpart. The stereochemistry of polyketones synthesized with the aldimine catalyst was found to be dependent on the vinyl comonomer: prevailingly syndiotactic copolymers were obtained for styrene, prevailingly isotactic copolymers were produced for 4-methyl styrene, and atactic macromolecules were formed for 4-tert-butyl styrene. The statistical analysis demonstrated that the control of the stereochemistry switched from enantioselective site control for 4-methyl styrene to a combination of chain-end and enantioselective site control for styrene.

In the frame of an ongoing research project dealing with linear optical polarizers produced by dispersing terthiophene derivatives in ultra-high-molecular-weight polyethylene (UHMWPE) and successive orientation by uniaxial stretching of the derived films, the present paper describes the use of linear-low-density polyethylene (LLDPE) or high-density polyethylene (HDPE) as an alternative polymer matrix in relation also to the possibility of taking different preparation routes. The study was performed with the easily prepared 5,5"-bis-thiooctadecyl-2,2':5',2"-terthiophene as the chromophore which was blended in a Brabender mixer at 180degreesC and concentration 0.2-2% w/w with LLDPE or HDPE in the bulk. The morphology and optical properties of the films obtained by compression moulding were compared with those of a similar film in UHMWPE prepared by solution casting. Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) analysis of the unoriented films of the former type were also performed. These data suggest the improved dispersion of the chromophore in case of the films obtained by melt processing. After uniaxial stretching up to 14-30 times the original length, molecular orientation was evaluated in different cases by measuring the dichroic ratio [R = A(parallel to)/A(perpendicular to)] and the order parameter [S = (R - 1)/ R + 2)]. Also the polarizer performance was detected by comparing the dependence of polarizing efficiency on single-piece transmittance of the different samples

Optically active poly(1,4-ketone)s were synthesized by alternating terpolymerization of carbon monoxide with ethene and propene using the dicationic palladium(II) complexes [Pd(PΛP)(H 2 O) 2 ](OSO 2 CF 3 ) 2 1-3 (where PΛP is a chelate diphosphine ligand) modified with the optically pure ligands (R)(S p )-1-[2-(diphenylphosphino)-ferrocenyl]ethyl-dicyclohexylphosphine 1a, (R)-6,6'-(dimethoxybiphenyl-2,2'-diyl)bis(dicyclochexylphosphine) 2a and (S)-6,6'-(dimethoxybiphenyl-2,2'-diyl)bis-(diphenylphosphine) 3a as catalyst precursors. The influence of different ethene to propene ratios in the reaction mixture on the productivity of the catalyst systems as weel as on the composition and structure of the produced terpolymers was investigated. For all catalyst precursors, the distribution of the two olefin comonomers appears to be random. The productivity is more strongly increased by increasing the ethene concentration when the catalyst system is not regiospecific for propene, i.e. when 3 is used. The influence of the growing chain on the enantioface selection for propene appears to be of minor importance with respect to the enantioselectivity caused by the enantiomorphic site of the catalyst.

A cold plasma feed with either oxygen or nitrogen was used to modify thin Low Density Polyethylene films. The treatment improved both the surface wettability and the curing kinetic of a polyurethane based adhesive spread on the surface. The chemical functionalities responsible of the observed behaviours were investigated and monitored over time by high resolution x-ray photoelectron spectroscopy. Atomic force microscopy were used to compare the effects of the two feeding gases on the surface morphology of films exposed (to the plasma) for equal times. The effect on the treated films of the atmosphere exposure and of the aging time were also considered.

After a short comparative analysis of different macromolecular ligands reported in the relevant literature, the presentation will be centered on the results obtained in the authors' laboratory using structurally defined inorganic supports in terms also of their macromolecular structure. Zeolites and mesomorphous silica can link, after proper chemical modification of their surface with MAO, unmodified metallocene complexes through cage entrapment and weak interactions, thus allowing the transfer from the solution to the solid phase. The metallocene complexes in their new phase are characterized by the catalytic behavior in olefin polymerization after activation with MAO. A decrease of productivity is generally observed depending on the type of support. The steric hindrance provided by the support is evidenced by the depression of chain transfer rate with formation of higher molecular weight polymers. Also shape selectivity is observed during copolymerization of ethylene with a-olefins having variable size. These steric effects are released when going from HY zeolite to MCM silica.

Various metallocene complexes of the IV group transition metals supported on HY zeolites were investigated in the polymerization of ethylene and propylene. A comparative study with the-same catalysts operating in solution was also performed. Generally, a decrease in the catalytic activity after support was, observed, whose extent depends on the preliminary treatment of the support with aluminum alkyl. In general, better stability with the time and higher molecular weight of the polymers were obtained, The high isotactic stereospecificity of-chiral metallocene catalysts for propylene polymerization was maintained after support. In the case of the aspecific bis(indenyl) complex, a modest but significant effect on the stereospecific control was observed due to the steric influence of the support.

The thermal degradation of ethylene-carbon monoxide alternating copolymer was studied as a function of the palladium catalyst residue concentration under inert atmosphere and in the presence of oxygen. The copolymer thermal behavior was analyzed by thermogravimetry and accelerated aging monitored through W-Visible and EPR spectroscopies. The traces of palladium do not influence the temperature at which the copolymer starts to degrade in the presence of oxygen, but the combustion temperature increases linearly with the palladium content. A different behavior was observed under inert atmosphere. The above rate increased up to 300 degrees C first, then decreased as the palladium concentration increased. At higher temperatures the loss of weight was independent of the Pd concentration, while the crosslinking increased with the content of catalyst residue. An interpretation of these phenomena is discussed on the basis of different Pd species. (C) 1999 Elsevier Science Ltd. All rights reserved.

PLA-based nanocomposites filled with the commercial organomodified montmorillonite Dellite 43B (D43B) and containing acetyl tri-n-butyl citrate (ATBC) as plasticizer were prepared by extrusion in a pilot-scale twin-screw extruder and melt casted into flexible films. A preliminary investigation was carried out in a laboratory batch mixer by varying blending conditions and addition procedures of the components. Indeed, the method of addition of ATBC and D43B considerably affected thermo-mechanical properties and morphology of the resultant nanocomposites. The simultaneous introduction of both ATBC and D43B during the extrusion process allowed producing clearly exfoliated nanocomposite materials with modulated mechanical and thermal properties. Moreover, rheological results, obtained during melt extrusion, assessed the processability of nanofilled-plasticized PLA, making this simple procedure interesting in view of the industrial production of nanostructured biomaterials based on plasticized PLA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013

Strictly alternating copolymers between olefins and carbon monoxide are synthesized using cationic palladium catalysts modified by phosphorus or nitrogen ligands. Basic chelate diphosphines as the ligand allow the regioregular copolymerization of aliphatic olefins thus affording, e.g. in the case of propene, poly(1-oxo-2-methyltrimethylene). Steric control of the copolymerization process towards the production of overwhelmingly isotactic copolymers is possible particularly when using atropisomeric ligands. In the case of styrene as the substrate and for all ligands employed the copolymerization process is regioregular. Prevailing syndiotactic structure is obtained with 1,10-phenanthroline or 2,2′-bipyridine as the ligand. Chelate thioether ligands allow the preparation of a completely atactic material. For 4-tert-butylstyrene an isotactic structure became accessible by using chiral bisoxazolidines. The prevailing structure of the copolymers of cyclopentene corresponds to a 1,3-enchainment of the olefin units most probably associated with a prevailing diisotactic structure