Search

Water-soluble biopolymers (SBO) were isolated from the alkaline hydrolysate of two materials sampled from an urban waste treatment plant; that is, an anaerobic fermentation digestate and a compost. The digestate biopolymers contained more lipophilic and aliphatic C, and less acidic functional groups than the compost biopolymers. The SBO were blended with poly (vinyl alcohol-co-ethylene), hereinafter EVOH. The blends were extruded and characterized by FTIR spectroscopy, size exclusion chromatography (SEC)– multi angle static light scattering (MALS) analysis, and for their thermal, rheological, and mechanical properties. The blends behavior depended on the type of SBO and its relative content. Evidence was obtained for a condensation reaction occurring between the EVOH and SBO. The best results were obtained with the blends containing up to 10% SBO isolated from the biowaste anaerobic digestate. Compared with the neat EVOH, these blends exhibited lower melt viscosity and no significant or great difference in mechanical properties. The results on the extrudates, compared with those previously obtained on the same blends obtained by solvent casting, indicate that the blends properties depend strongly also on the processing technology.

In order to confer adhesive properties to commercial polypropylene (PP) meshes, a surface plasma-induced deposition of poly-(acrylic acid) (PPAA) is performed. Once biomaterials were functionalized, different postdeposition treatments (i.e. water washing and/or thermal treatments) were investigated with the aim of monitoring the coating degradation (and therefore the loss of adhesion) after 3 months of aging in both humid/oxidant (air) and inert (nitrogen) atmospheres. A wide physicochemical characterization was carried out in order to evaluate the functionalization effectiveness and the adhesive coating homogeneity by means of static water drop shape analysis and several spectroscopies (namely, FTIR, UV–Visible and X-ray Photoemission Spectroscopy). Themodification of the adhesion properties after post-deposition treatments aswell as aging under different storage atmospheres were investigated by means of Atomic Force Microscopy (AFM) used in Force/Distance (F/D) mode. This technique confirms itself as a powerful tool for unveiling the surface adhesion capacity as well as the homogeneity of the functional coatings along the fibers. Results obtained evidenced that post-deposition treatments are mandatory in order to remove all oligomers produced during the plasma-treatment, whereas aging tests evidenced that these devices can be simply stored in presence of air for at least three months without a meaningful degradation of the original properties.

High surface area mesoporous titania has been synthesized using ordinary salts (chlorides) for morphology control during the sol–gel process. Applying Ti-alkoxide (TTIP) as a titania precursor and a highlyconcentrated hypersaline medium, different results have been obtained according to the dispersing medium selected. By working in an acid environment, the hypersaline medium controls the oxide network growth, since different salts (and different salts amount) influence the surface area, porosity, crystallinity and polymorphs rearrangement of the final material, favoring the formation of acicular-like rutile at mild conditions. Nevertheless, it has been verified that, according to the Hofmeister series, salting-in ions induce an increase in the titania surface area, going from 79 (for the reference, without any salts) up to 253 m2 g1 (for the Li-templated titania). By working in alcoholic media, the hypersaline environment favors the gelification process and the formation of amorphous titania aerogels or highlyporous monoliths, according to the drying conditions selected (respectively supercritical CO2 or ambient pressure air drying). Two different alcoholic media (ethanol and 2-propanol) have been compared. Such salt-templated titania aerogels are mesoporous (with BET surface area comprised between 322 and 490 m2 g1). Besides the surface area, even the pore volume and the pore size can be controlled by both the reaction medium and the drying step: in particular, air-dried monoliths are small mesoporous (BET surface area between 419 and 518 m2 g1). Reference materials synthesized in alcoholic media without using any salts do not gelify (thus confirming the importance of the hypersaline medium), whereas titania particles precipitate, inducing aggregation into small mesoporous powders. In general, the hypersaline-mediated titania production seems to be an interesting chemical toolbox, sustainable, highly efficient and also potentially suitable for industrial scaling-up

The use of bio-based substances (BBS) obtained from composted biowaste as stabilizers for the production of silver nanoparticles (AgNPs) in substitution to citrate is investigated herein, evaluating the functionalization of natural fibers for textile antibacterial applications. The results obtained evidenced that BBS can substitute citrate as reducing/stabilizing agent in the synthesis, inducing a geometrical control (in shape and size) of the AgNPs. Two different substrates were selected (wool and cotton) and two dip-coating deposition techniques investigated. The release of AgNPs from the supports in water was evaluated under two different experimental conditions: 1) soaking (static conditions) for 7 and 15 days, simulating the contact with sweat, and 2) centrifugation (dynamic conditions), simulating a washing machine treatment. A wide physicochemical characterization was carried out to evaluate the effects of BBS on the morphology and stability of AgNPs suspensions as well as the functionalization effectiveness.

In this study, a magnetic iron oxide–chitosan composite film is synthesized by one-step method and thoroughly investigated in order to better understand its inorganic/organic properties. A deep physico-chemical characterization of the magnetic films has been performed. In particular, the material composition was evaluated by means of XRD and ATR-FTIR spectroscopy, whereas the thermal stability and the subsequent inorganic phase transitions involving iron oxide species were followed by TGA analyses carried out at different experimental conditions (i.e. inert and oxidative atmosphere). The magnetic properties of the films were tested at the bulk and at the surface level, performing respectively magnetization hysteresis curve and magnetic force microscopy (MFM) surface mapping. Results indicate that the synthesized material can be prepared through a very simple synthetic procedure and suggests that it can be successfully applied for instance to environmental applications, such as the adsorption of contaminants from solid and liquid media thanks to its pronounced magnetic properties, which favourits recover.

Hernia diseases are among the most common and diffuse causes of surgical interventions. Unfortunately, still nowadays there are different phenomena which can cause the hernioplasty failure, for instance post-operative prostheses displacements and proliferation of bacteria in the surgical site. In order to limit these problems, commercial polypropylene (PP) and polypropylene/Teflon (PP/PTFE) bi-material meshes were surface functionalised to confer adhesive properties (and therefore reduce undesired displacements) using polyacrylic acid synthesized by plasma polymerisation (PPAA). A broad physico-chemical and morphological characterisation was carried out and adhesion properties were investigated by means of atomic force microscopy (AFM) used in force/distance (F/D) mode. Once biomedical devices surface was functionalised by PPAA coating, metallic silver nanoparticles (AgNPs) with antimicrobial properties were synthesised and loaded onto the polymeric prostheses. The effect of the PPAA, containing carboxylic functionalities, adhesive coating towards AgNPs loading capacity was verified by means of X-ray photo-electron spectroscopy (XPS). Preliminary measurement of the Ag loaded amount and release in waterwere also investigated via inductively coupled plasma atomic emission spectroscopy (ICP-AES). Promising results were obtained for the functionalised biomaterials, encouraging future in vitro and in vivo tests.

In this study, chitosan, a commercially-available linear polysaccharide mainly used as antibacterial agent, functional coating and drug-delivery system, is investigated to enlighten both water interactions and its thermal stability by using a set of complementary advanced thermal techniques, rarely applied in polysaccharides characterizations. DSC and TGA, here coupled with FTIR and GCMS analysis of the exhausted gas, were used to reveal thermal events and identify degradation products as a function of the temperature: three main steps in chitosan (N-deacetylation degree, DD = 78%) thermal degradation were highlighted and mechanism proposed. In order to make a comparison with other analogous polymeric systems and validate the results obtained, a medical grade chitosan (DD > 93%) and a commercial chitin were investigated too. Moreover, the water adsorption capacity of chitosan (DD = 78%) was followed by using thermo-microgravimetry (TMG) and the distinction between weight losses of both physically and chemically adsorbed water molecules was achieved. The approach followed allows a complete characterization of the thermal behaviors of the chitosan and highlights the need for complementary advanced thermal techniques in the detailed characterization of complex biopolymers.

Highly selective porous films were prepared by spin-coating deposition of colloidal silica nanoparticles on an appropriate macroporous substrate. Silica nanoparticles very homogenous in size were obtained by sol-gel reaction of a metal oxide silica precursor, tetraethyl orthosilicate (TEOS), and using polystyrene-block-poly(ethylene oxide) (PS-b-PEO) copolymers as soft-templating agents. Nanoparticles synthesis was carried out in a mixed solvent system. After spin-coating onto a macroporous silicon nitride support, silica nanoparticles were calcined under controlled conditions. An organized nanoporous layer was obtained characterized by a depth filter-like structure with internal porosity due to interparticle voids. Permeability and size-selectivity were studied by monitoring the diffusion of probe molecules under standard conditions and under the application of an external stimulus (i.e., electric field). Promising results were obtained, suggesting possible applications of these nanoporous films as selective gates for controlled transport of chemical species in solution.

Selective composite membranes with high and controlled porosity have been fabricated using patterned silicon microsieves as support and nanoporous polystyrene-block-poly(ethylene oxide) (PS-b-PEO) membranes as selective layer. The desired morphology of the block copolymer layer is obtained by a supramolecular approach based on the hydrogen bonding of the PEO block with resorcinol. The formation of PS-b-PEO/resorcinol complexes allows to easily control the self-assembly of the block copolymer and to obtain normally oriented PEO/resorcinol nanocylinders by spin coating PS-b-PEO/resorcinol solutions. In a further step resorcinol works as a porogen and by its selective dissolution densely packed, normally oriented nanochannels coated by PEO chains have been obtained. These hydrophilic nanochannels have a diameter of approximately 20 nm and cross the membranes from top to bottom. The nanoporous polymer layer is crack-free and well adheres to the support microsieve. The composite membrane is permeable to methylene blue while blocks larger molecules, such as bovine serum albumin.

Highly selective silica membranes with controlled porosity can be obtained by employing organic/inorganic mixed micellar solutions based on the use of commercial templates. Among others, amphiphilic block copolymers are very attractive materials as structure directing agents [1]: when mixed with organic solvents selective for one of the blocks, they can self-assemble into micelles with the insoluble blocks constituting the micellar core. The morphology and size of self-assembled micelles depend on the size (length) and nature (polarity) of the template blocks, and on solution parameters. Silica porous films described in this contribution were obtained by sol-gel reaction of tetraethyl orthosilicate (TEOS) using polystyrene-block-poly(ethylene-oxide) (PS-b-PEO) copolymers as templates. In order to modulate both pore sizes and alignment in the final material, many different variables were changed: e.g. block copolymer chain length, block copolymer/TEOS ratio, hydrophilic/hydrophobic solvent ratio and use of additives (i.e. polystyrene homopolymer). Moreover, by changing the block copolymer/TEOS ratio, it was possible to obtain reverse micellization and formation of silica nanoparticles. By spin-coating deposition of such nanoparticles onto a macroporous inorganic substrate (followed by calcination) [2] an organized porous layer was obtained, thus generating a depth filter system whose porosity is due to inter-particle voids. Transport measurements involving these porous functionalized devices were realized and promizing results were obtained for applications in the field of microfluidics for separation, detection and dosing of chemicals. [1] R. Nisticò, D. Scalarone. G. Magnacca, Microporous and Mesoporous Materials 190 (2014) 208-214. [2] R.G. Juez, V. Boffa, D.H.A. Blank, J.E. ten Elshof, Journal of Membrane Science 323 (2008) 347-351.

Polypropylene nets are widely used as hernioplasty prostheses. The reproduction of bacteria within the net fibers intersections can occur after the application of the prosthesis causing infections. For this reason, bacteria have to be removed in the very early stage of surgical implantation. Activation of the prosthesis surface was done by an innovative oxidizing plasma treatment (APP-DBD) working under atmospheric conditions in order to favor the deposition of an antibacterial coating of chitosan (biocompatible carbohydrate) and ciprofloxacin (broad spectrum antibiotic). Two different coating mixtures were realised and the antibacterial properties of such functionalised nets were investigated, together with their effectiveness. Physico-chemical characterisations of meshes were carried out before and after functionalisation by SEM-EDS and infrared spectroscopy. The release of both chitosan and ciprofloxacin, under controlled experimental conditions, was followed respectively by colorimetric determination (using UV-Visible spectroscopy) and chromatographic analysis (using HPLC). In vitro tests allow verifying antimicrobial activity (inoculation of specimens in a Staphylococcus aureus suspension).

Through the addition of inorganic salts as porogens during an alcohol-based sol–gel process high surface area silica glasses and aerogels with varying pore sizes are synthesized. In the presence of ZnCl2 and CaCl2 respectively, tetraethyl orthosilicate (TEOS) dissolved in ethanol hydrolyzes also in the absence of any acid or base catalysts, eventually forming high surface area monolithic silica networks. The porosity can be controlled by the gel ageing step as well as the salt nature. Two different gel drying conditions were investigated, i.e., room temperature (RT) air drying at ambient pressure and supercritical (sc) CO2 drying. While a reference solution which only contains ethanol and TEOS does not gel at all, the addition of ZnCl2 leads to mesoporous aerogels with high surface areas of 1400 m2 g−1 after sc CO2 drying. Interestingly, the utilization of CaCl2 however, produces aerogel-like materials of high porosity for both drying methods under preservation of the nano-and macroscopic features. Thereby, it is shown that inorganic salts can influence the structure formation during the sol–gel process where the type of salt controls the framework connectivity/stability and tunes the porosity towards smaller pore sizes than usually obtained. At the same time, the herein presented hypersaline aerogel-synthesis is very simple, fast and in the case of CaCl2 drying can even be performed in air.

Highly selective membranes with controlled porosity can be obtained by growing thin films of mesoporous oxides on an appropriate support. This can be achieved employing organic/inorganic mixed micellar solutions based on metal oxide precursors and commercial templates. In particular amphiphilic block copolymers are very attractive materials as soft-templating agents because they self-assemble into micelles whose morphology and size depend on block composition and solution parameters. Large-mesopore silica films with narrow pore size distribution and high porosity have been obtained by sol–gel reaction of a silicon oxide precursor (TEOS) and using polystyrene-block-poly(ethylene-oxide) (PS-b-PEO) copolymers as templates. In order to modulate size, shape and alignment of the pores, many variables were changed: block copolymer chain length, TEOS/block copolymer ratio, solvent ratio, additives (i.e. polystyrene homopolymer addition). The effect of the different parameters on the porous system was studied by microscopy techniques and gas-volumetric analyses. Final aim of this work is the preparation of silica membranes to be used as selective gates for controlled dosing and transport of chemical species in solution.

Preparation and physico-chemical characterization of ordered large-pore silica films for membranes applications

Nonostante l’ernioplastica sia una procedura chirurgica routinaria pressoché consolidata, esistono a tutt’oggi molte problematiche ancora da risolvere, una su tutte il sopraggiungere di infezioni post-intervento dovute alla proliferazione di batteri. La crescita batterica tra le maglie dei dispositivi biomedicali usati può comportare, infatti, non solo dolori e/o disturbi addominali, ma anche il rigetto della protesi stessa. Come soluzione a tale problema si somministrano cure antibiotiche orali, ma un trattamento antibiotico in situ è comunque da considerare. Anche il posizionamento della protesi può essere causa di problemi dovuti ad eventuali spostamenti nel sito chirurgico: questo attualmente viene evitato utilizzando punti di sutura e/o colle, ma le procedure si semplificherebbero nettamente avendo a disposizione un dispositivo adesivo. In questo lavoro viene presentato uno studio legato alla preparazione di reti protesiche commerciali in polipropilene (PP) funzionalizzate in superficie per conferire proprietà antibatteriche e/o adesive ed alla loro caratterizzazione chimico-fisica. I trattamenti di superficie delle reti sono stati effettuati via plasma, procedura che permette di ottimizzare le proprietà di superficie del PP inducendo nuove funzionalità smart, senza tuttavia perdere le proprietà meccaniche di bulk e strutturali tipiche delle fibre polimeriche. Sono state testate le seguenti procedure: 1) utilizzo del plasma atmosferico per l’attivazione delle fibre in PP e successiva deposizione di un film bioriassorbibile a base di chitosano/ciprofloxacina con cinetica di rilascio controllata e proprietà battericide o batteriostatiche; 2) deposizione di uno strato di poli(acido acrilico) (PAA) direttamente via plasma polymerization in vuoto e successiva funzionalizzazione con nanoparticelle di argento (AgNPs) sintetizzate da citrato, per conferire proprietà adesive ed antibatteriche alla rete garantendo altresì la capacità del dispositivo di eserci

Un approccio supramolecolare per la fabbricazione di membrane polimeriche nano e isoporose a base di copolimeri a blocchi.

Based on recent investigations, the use of inorganic salts is a new powerful route for obtaining high surface area mesoporous materiaIs in a facile one-step approach, also called “salt-templating”. Here, high surface area aerogels were synthesized adding simple inorganic water soluble salts as pore forming agents during the sol-gel process. The model oxide precursor (i.e.,TEOS for silica) hydrolyses in the presence of a salt, e.g. ZnCl2, without using any acid/base catalysts, forming the silica network and producing monoliths with high surface area. The porosity can be controlled by the gel-ageing step (the less the time, the higher the porosity). Two different gel-drying conditions were investigated: room temperature (RT) air drying and CO2 supercritical drying. Supercritically dried silica aerogels reach the impressive BET surface area value of ca. 1400 m2 g-1, but also the simple air-drying procedure produces highly porous monoliths with BET surface areas in the range of 700-800 m2 g-1, thanks to the stabilizing salting-in effect of zinc ions (according to Hofmeister series). Compared to standard sol-gel processes, the herein presented synthesis is extremely simple: it only consists of dissolution of both oxidic precursors and inorganic salts in the selected solvent (i.e. ethanol), gel formation induced by solvent evaporation, salt removal through simple washing with water/ethanol. This way, no organic templates need to be employed and the overall approach is highly efficient and sustainable. In this regard, the salt-templating solution could principally be recovered for following syntheses afterwards, thus reducing by-products. Moreover, the synthesis of highly porous monoliths by RT air drying is of high interest since no special equipment is required, it simplifies the standard procedure and gives access to advanced materials at low cost.

Atmospheric Pressure Plasma-Dielectric Barrier Discharge (APP-DBD, open chamber configuration) was used to functionalize polypropylene (PP) fibers surface in order to generate oxidized-reactive groups such as hydroperoxides, alcohols and carbonyl species (i.e. ketones and others). Such a species increased the surface polarity, without causing material degradation. Three different types of plasma mixture (He, He/O2, He/O2/H2O) under three different values of applied power (750, 1050, 1400 W) were investigated. The formed plasma species (O2+, O single atom and OH radical) and their distribution were monitored via Optical Emission Spectrometry (OES) measurements, and the plasma effects on PP surface species formation were followed by X-ray Photoemission Spectroscopy (XPS). Results allowed to better understand the reaction pathways between plasma phase and PP fibers. In fact, two reaction mechanisms were proposed, the first one concerning the plasma phase reactions and the second one involving material surface modifications.

MICROFLUIDIC DEVICE: DEVELOPMENT AND TESTING OF NANOSTRUCTURED OXIDIC MATERIALS

Polypropylene (PP) fibers can be manufactured to form nets which can find application as prosthesis in hernioplasty. One of the most important problem to deal with when nets are applied in vivo consists in the reproduction of bacteria within the net fibers intersections. This occurs right after the application of the prosthesis, and causes infections, thus it is fundamental to remove bacteria in the very early stage of the nets application. This paper deals with the physico-chemical characterization of such nets, pre-treated by atmospheric pressure plasma dielectric barrier discharge apparatus (APP-DBD) and functionalized with an antibiotic drug such as chitosan. The physico-chemical characterization of sterilized nets, before and after the functionalization with chitosan, was carried out by means of scanning electron microscopy (SEM) coupled with EDS spectroscopy, FTIR spectroscopy, drop shape analysis (DSA), X-ray diffraction and thermal analyses (TGA and DSC). The aim of the work is to individuate a good strategy to characterize this kind of materials, to understand the effects of polypropylene pre-treatment on functionalization efficiency, to follow the materials ageing in order to study the effects of the surface treatment for in vivo applications.

Highly selective membranes with controlled morphology can be obtained by growing thin mesoporous oxide films on an appropriate support. This can be achieved employing organic/inorganic mixed micellar solutions based on the use of proper templates. Amphiphilic block copolymers are very attractive materials for soft-templating. When mixed with organic solvents selective for one of the blocks, they can self-assembly into micelles with the insoluble blocks constituting the micellar core and the soluble ones the corona. The silica porous membranes described in this contribution were obtained by sol-gel reaction of a silicon oxide precursor (TEOS) and using polystyrene-block-poly(ethylene-oxide) (PS-b-PEO) copolymers as templates. Morphology and size of the self-assembled micelles and of the final porous oxide depend both on composition parameters (such as the length and nature of the polymer blocks) and on solution parameters (such as the hydrophilic/hydrophobic balance between solvents and cosolvents). This contribution focuses on the effect of composition parameters, namely the chain length of each polymer block, the stoichiometric ratio of the monomers, and the polymer/silica ratio. By changing these parameters silica structures with narrow pore size distribution and pore shapes ranging from spheres to channels were obtained. The final goal of this research will be the preparation of silica membranes with controlled and high porosity to be applied in the field of microfluidic analyses (e.g. Lab-on-a-chip devices) and as selective gates in microchip-based technologies for separation, detection and dosing of molecular or ionic species, charged nanoparticles and biomolecules.