Antonino Pollicino

New fluorinated acrylic monomers for the surface modification of UV-curable systems

New fluorinated acrylates were synthesized and used as modifying additives for acrylic UV-curable systems. Their chemical structure is: CnF2n+1 R—OCO—CHCH2, where the linear perfluorinated chain contains from 4 to 10 carbon atoms, while R is a linear alkyl group containing or not a thioether group. Notwithstanding their very low concentration, the fluorinated monomers caused a dramatic change of the surface properties of the films, without changing their curing conditions and their bulk properties. X-ray photoelectron spectroscopy measurements showed that the monomers were able to concentrate selectively on the surfaces of the films, depending on their chemical structure and on the kind of substrate employed. The synthesis of the fluorinated monomers and the relationship between their chemical structure and the final surface properties of the UV-cured films will be discussed.

Perfluoropolyether structures as surface modifying agents of UV-curable systems

New functionalised macromers containing perfluoropolyether (PFPE) structures and methacrylic end groups were synthesised and used as modifying additives for acrylic UV-curable systems. Their chemical structure is Rh-Rf-Rh, where Rh= -CH 2 O-CONH-CH 2 CH 2 OCOC(CH 3 )=CH 2 and Rf=-CF 2 O-(CF 2 CF 2 O) p (CF 2 O) q -CF 2 - with p ≃ q. Notwithstanding their very low concentration, below 0.5 wt.-%, the fluorinated macromers cause a dramatic change of the surface properties of the films, without changing their curing conditions and their bulk properties. X-ray photoelectron spectroscopy (XPS) measurements showed that the macromers are able to concentrate selectively at the surfaces of the films, depending on their chemical structure and on the kind of substrate employed.

Synthesis, characterization and study of the thermal properties of new polyarylene ethers

Abstract In order to investigate the contrasting propensities for crystallization between aryl sulphone and aryl ketone polymers, new aromatic monomers containing sulphone, ketone and ehter linkages were synthesized and reacted to prepare new polyarylene ethers. The polymers obtained were characterized by solution viscosity, thermal gravimetric analysis and differential scanning calorimetry (d.s.c.). The effect of the presence of ketone and/or sulphone linkages in the polyarylene ethers during synthesis and on the final properties is discussed.

New aromatic polyamide materials containing sulfone, ether and ketone linkages

Abstract Several aromatic polyamides were prepared from 4,4′-[sulfonyl bis( p -benzoyl)( p -phenyleneoxy)]dibenzoic acid with various diamines by the phosphorylation route. The polymers were characterized by elemental analysis, thermogravimetric analysis, differential scanning calorimetry and infra-red analysis. The polyamides, obtained in quantitative yield, possessed inherent viscosities in the range 0.3–1 dl g −1 and 10% weight loss in nitrogen and air were above 460 and 440°C, respectively. Most of the polymers were soluble in aprotic solvents. The effect of the structure on properties such as solubility and thermal behaviour were also studied.

Evaluation of the influence of various (ether, ketone and sulfone) groups on the apparent activation energy values of polymer degradation

Abstract The kinetics of degradation of four model polymers containing ether, carbonyl and sulfone groups was studied in both N 2 flow and static air atmosphere, with the aim of evaluating the influence of various groups on the apparent activation energy values ( E a ) of degradation. The initial temperatures of decomposition ( T i ) and the temperatures of half decomposition ( T 1/2 ), were also determined. The degradation of all polymers was carried out in the scanning mode and the Kissinger equation used to evaluate the E a values of the first degradation stage. The results allowed us to make a kinetic stability classification among various groups (sulfone>ketone>ether) which could be explained on the basis of the double-bond character of the polymer chain links. The E a values showed a trend analogous to the glass transition temperatures ( T g ), in agreement with literature reports. By contrast, the characteristic temperatures of decomposition showed a different trend which could not be interpreted on the basis of the experiments until now performed.

A Kinetic Study of the Thermal and Oxidative Degradations of a New Poly(arylene)ether Copolymer

The degradation of a new thermoplastic poly(arylene)ether copolymer was carried out in both dynamic and isothermal heating conditions, under nitrogen flow and in a static air atmosphere. The measurements showed that the copolymer degraded through two stages in both investigated environments with the formation of a stable residue in N2 and complete mass loss in air. The apparent activation energy values associated with the degradation processes were evaluated. The obtained results suggested different degradation mechanisms between N2and air. Results were discussed and compared with those obtained for several polymers previously investigated.

Advantages of Surface-Initiated ATRP (SI-ATRP) for the Functionalization of Electrospun Materials

Surface-initiated atom transfer radical polymerization (SI-ATRP) is successfully applied to electrospun constructs of poly(L-lactide). ATRP macroinitiators are adsorbed through polyelectrolyte complexation following the introduction of negative charges on the polyester surface through its blending with a six-armed carboxy-terminated oligolactide. SI-ATRP of glycerol monomethacrylate (GMMA) or 2-(N,N-diethylamino)ethyl methacrylate (DEAEMA) allows then to grow surface films with controllable thickness, and in this way also to control the wetting and interactions of the construct.

Surface properties and adhesion of maleinized polyethylene films

The wettability and the adhesion of polyethylene films were improved by introducing polar groups in the polymer chains. The surface properties of films grafted with maleic anhydride (MA) were investigated. The wettability was found to be dependent on the MA content, on the film preparation conditions and on the hydrolytic process of the anhydride groups. The kinetics of the hydrolysis indicated a restructuring of the polymeric surface due to the movement of the polar groups towards the surface; it did not influence the adhesion properties. The behaviour of the maleinized films was compared with oxygen plasma treated materials, which showed a better wettability, but a worse adhesion on polar substrates than the maleinized polyethylene. These results were explained on the basis of X-ray photoelectron spectroscopic analyses, by which the main functional groups present at the surface were identified and quantitatively determined.

Determination of degradation apparent activation energy values of polymers

The isothermal degradation of three aromatic polyetherketones was studied in an inert environment at various temperatures in the range 683-803 K. In the first degradation stage (mass loss D£20%) a linear increase of D as a function of heating time (t) was observed and the corresponding kinetic D=Do+bt equations at various temperatures were directly drawn by smoothing the experimental TG data. The b values, which represent the mass loss rates during degradation, increased as a function of temperature according to Arrhenius-type equations, from which degradation Ea values were determined, which appear in agreement with those from literature methods. Some differences observed were discussed and interpreted.

Kinetic study of the thermal degradation of some poly(arylenether)s containing naphthalene units

Abstract The degradations of five aromatic thermoplastics, containing carbonyl, ether and sulfone linkages and in whose repeating units the –ArCONaphCOAr– moiety (where Ar=1,4 substituted phenylene; Naph=2,6 substituted naphthalene) was present, were performed under N 2 flow in dynamic heating conditions. The obtained results suggested that degradations occurred through random chain scission followed by branching and crosslinking, which partially superimposed with the initial process. The Kissinger method was used to determine the apparent activation energy ( E a ) associated with the first degradation stage, and double linear relationships, attributable to slow diffusion of degradation products in the melt, were found in some cases. A thermal stability classification among the studied polymers was made on the basis of the obtained E a values. This classification was compared with those previously obtained for two analogous groups of thermoplastics and some correlations between thermal stability and polymer chain structure were drawn.