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The diffusion of a thermal stabiliser, Irganox 1010, has been studied both in a commercially available polypropylene homopolymer (HomoQ) and in a poly(propylene-co-ethylene) copolymer (RacoS). The diffusion experiments were carried out by using the Roe method formed by a stack of several polymer films having 60–70 μm as thickness under nitrogen atmosphere. The concentration profile of stabiliser in every film has been monitored by the absorbance at 282 nm in UV spectra recorded for every film forming the stack assembly. Under our experimental conditions, the diffusion of Irganox 1010 in each film stack for both polymer materials can be correctly interpreted by using the Fick's second law. The best fit of the experimental data with this equation allows calculation of the diffusion coefficients, D, for these polymer materials at 40, 70 and 80 °C. By applying an Arrhenius equation to the calculated D coefficients, an estimation of activation energies of the diffusion process has been also achieved.

In this paper we report the light-induced grafting copolymerization of N , N ′-dimethylacrylamide onto four poly(organophosphazene) films i.e. poly[bis(4-isopropylphenoxy)phosphazene], poly[bis(4-s-butylphenoxy)phosphazene], poly[bis(4-benzylphenoxy)phosphazene] and poly[bis(2,2′,2″-trifluoroethoxy)phosphazene]. The process was carried out in N , N ′-dimethylacrylamide/methanol mixtures in presence of benzophenone as sensitizer. The yield of the grafting process was evaluated as a function of the phosphazene structure, of the relative amounts of N , N ′-dimethylacrylamide and methanol in the reaction mixtures, and of the swelling capability of the polymer films. The obtained polyphosphazene-g-poly- N , N ′-dimethylacrylamide copolymers were characterized by i.r. spectroscopy, both ATR and transmission, and by contact angle measurements.

Photodegradable polyolefins based on ketone carbonyl and carbon monoxide copolymers are discussed. The proposed photo-oxidation mechanisms for these copolymers show efficient chain scission processes photoinduced by Norrish I and II reaction in polymer matrix. Other polyolefins copolymers containing unsaturation have been suggested as new innovative and photodegradable materials. In the photo-oxidative conditions, the formation of α,β-unsaturated ketone impart high yields of chains scissions leading to a rapid embrittlement and fragmentation of these copolymers.

In this paper we present results on the photolysis of poly[bis(4-benzylphenoxy)-phosphazene] in solution and in film, both in the presence and in the absence of molecular oxygen. Light irradiation of the polymer in oxygen-saturated CH2Cl2 solutions results in a remarkable degradation of the polyphosphazene, while in argon-purged solutions no appreciable variations of the polymer structure could be detected. The photolysis of poly[bis(4-benzylphenoxy)phosphazene] in films induces the cross-linking of the polymer regardless of the presence or the absence of molecular oxygen. The main process observed during the photochemistry both in solution and in the solid state of the polymer is the oxidation of the 4-benzylphenoxy group on the polyphosphazene, without involvement of the inorganic -P=N- backbone. The effect of temperature on the photolysis of the polyphosphazene substrate in film is also reported.

Optical recording and luminescence readout of novel covalently linked photochrome/luminophore supramolecular complexes has been demonstrated by near-field scanning optical microscopy (NSOM). Localized UV irradiation of these complexes dispersed in polymeric matrices resulted in photoinduced state switching and a concomitant increase in emission intensity. Subsequent luminescence imaging showed well- resolved luminescent data bit arrays with good signal-to-noise ratios. Spatially resolved emission spectra of the luminescent data bits confirmed the switching mechanism.

Innovative polymeric films based on blends of nylon 6 and ethylene-co-vinyl alcohol, previously tested by contact with the simulating fat-containing foods, were further tested as packaging for fresh minced meat. As quality attributes for the shelf-life evaluation, the microbiological parameters and some chemical–physical parameters were chosen. The changes that occurred during the evaluation period of 6 days were monitored by several means on both the polymer films and the fresh meat. The results suggest that the barrier properties of the polymeric films were shown to play a determinant role in the lipid oxidation, thus confirming the previous evaluation of the simulating foods. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 23–29, 2004

The polymerization of (+)-catechin with various aldehydes has been performed in the presence of an acid catalyst to produce catechin-aldehyde polycondensates in high yields. NMR analysis of the product showed that the polymerization regioselectively proceeded to form the polymer linked by an ethyl bridge through C-6 and C-8 positions of catechin A ring. Specific rotation and CD measurements of the polymer showed the change of chemical bonding and confromation at near chiral center. The direction of specific rotation was changes from dextrorotatory (+) to levorotatory (-) and a new chiral center was formed on the bridge moiety between the catechin units. Computer simulation suggests the coiled interactions in the polymer by hydrogen bonds between hydroxyl groups and pyranic oxygens.

The syntheses of methacrylate- and styrene-based monomers containing substituted pyridine ligands are reported. The preparation of the corresponding homopolymers has been performed by free radical polymerization by using 2,2'-azoisobutyronitrile (AIBN) at 60°C. The high molecular weights, up to 119 000 g. mol -1 , and low glass transition (T g ) values (< -43°C) have been obtained by the copolymerization reaction with butyl acrylate. The free metal homopolymer and copolymer were subsequently metalated by reaction with Re[phen(CO) 3 (acetone)]+. All polymer materials have been characterized by conventional experimental techniques, such as gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). UV-Vis and fluorescence spectroscopy have been used to investigate the optical and photophysical properties of the polymers in solid-state films and in solution. 1H NMR spectra confirmed the structure of the synthesized polymers and contributed to the estimate of the monomer sequences in the copolymer chains. Time-resolved and emission-quenching experiments in diluted solutions and on the solid films suggest application of the polymeric materials as oxygen sensors. The morphological aspects of some polymers containing a low amount of rhenium metal complexes have been investigated by scanning electron microscopy (SEM).

A modified interfacial polycondensation between bisphenol-A and 1,3-dimethoxy lower-rim substituted calix[4]arene derivatives with dibromomethane in the presence of tetrabutylammonium hydrogen sulfate as phase transfer catalyst (PTC) leads to copolyethers with variable M w values depending on the reaction temperature and the amount of PTC. The calix[4]arene content in the polymer chains depends on the phenolic monomer ratios. The polycondensation reaction of the same comonomers with terephthaloyl chloride but in the absence of the above PTC affords the corresponding copolyester. The soluble fraction of this polymeric material in CHCl 3 showed M w of ca. 21000 and a variable calix[4]arene content depending on the phenolic monomer ratio as well. The binding properties of the copolyethers toward silver ions are ten-fold higher than those of a model tetraalkoxy calix[4]arene derivative. It is suggested that this increased receptor ability is due to the change of the original cone conformation of the macrocyclic monomer into the partial-cone conformation by incorporation in the polymer.

Spectroscopic methods, ultraviolet (UV) and Fourier transform infrared (FTIR) were used to determine the concentrations of the two components of hindered amine light stabilisers (HALS) in low density polyethylene (LDPE) films exposed to natural weathering up to 650 days. The used HALS is a Ciba-Geigy commercial mixture of Chimassorb 944 and Tinuvin 622 with same percentage in weight (50/50% (wt/wt)). The spectroscopic measurements were carried out on the LDPE films having some different HALS contents of 0.1, 0.2, 0.4, and 0.6% (wt/wt). The Chimassorb 944 concentration was determined by means of the absorption band area centred at 225 nm in UV spectra for the absorption of 1,3,5-triazine group, while Tinuvin 622 concentration was measured by the absorption band area at 1734 cm−1 in FTIR spectra corresponding to the ester group absorption. The plots describing the loss of the concentration of each component versus time exhibited similar profiles. The results suggest that the two HALS components are involved at the same time in the polymer stabilisation processes. The effect of the HALS concentration on LDPE stabilisation was interpreted applying the well-known operative mechanisms involving piperidinoxyl radicals for natural and accelerated photo-oxidative conditions. Finally electron spin resonance spectroscopy performed on 0.6 and 0.2% under natural exposure formulations are in good agreement with the spectroscopic determination of the HALS contents in the different formulations.