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In this investigation, two novel multifunctional initiators for ring-opening polymerization were synthesized in three steps starting from cholic acid. Thus, cholic acid (1a) and its methyl ester (1b) were quantitatively transformed, via solvent-free reaction with succinic anhydride, to the corresponding 3, 7, 12-tri-hemisuccinate derivatives (3a-b). The polyacidic compounds (3a-b) were treated with thionyl chloride affording the corresponding acyl chlorides 4a-b which, in turn, were reacted with ethylene glycol to give the derivatives 2a-b having three and four primary alcohol end groups. These compounds, fully characterized by H, C NMR and mass spectrometry, have been assessed as initiators in the ring-opening polymerization of L-lactide using stannous octanoate as catalyst. The resulting three- and four-armed star-shaped poly(L-lactide)s, which were characterized by H NMR, SEC, DSC and TGA analysis, were amorphous, and their glass transition temperatures ranged from 13.7 to 36.5 °C. Additionally, some cholic acid-based star-shaped polylactic structures recently published have been critically reconsidered showing that these molecules, described as star polymers, were actually linear polymers.

New polymeric photoinitiators bearing the side-chain camphorquinone moiety spaced from the backbone by a long and flexible connection have been prepared and tested in the photocuring of acrylic monomers upon irradation with visible light in the presence of tertiary amine coinitiator. The results indicate that the photoinitiating activity of the polymeric initiators may be comparable to the related combination of low molecular weight derivatives when the camphorquinone component has a polymeric structure, and depends on the chemical structure of both the components of the initiator/coinitiator pair. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5879–5888, 2005

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.

The physical and dynamic-mechanical behaviour during the photo-oxidation under accelerated conditons of three poly(ethylene-co-propene-co-5-ethylidene-2-norbornene) (EPDM) rubbers with different contents of 5-ethylidene-2-norbornene1 (ENB) are reported. These results show the dependence of the glass transition temperature both on the ENB content and on the photo-oxidation time in accordance with network formation in the rubber matrix under accelerated conditions. The tensile experiments also show an increase of the elastic modulus as function both of ENB content and of photo-oxidation time. The Murayama and Mooney-Rivlin equations are applied to estimate the average molecular weight between two crosslinking nodes occurring in the rubber matrix during photo-oxidation with tensile and dynamic-mechanical experiments, respectively. Some correlations of physical and dynamic-mechanical changes with the proposed mechanism of photo-oxidation, due to the formation and reactivity of unsaturated groups, show that the crosslinking processes prevail over chain scissions.

In this work the reexamination of the photo-oxidation mechanism of three poly(ethylene-co-propene-co-5-ethylidene-2-norbornene) (EPDM) terpolymers containing different amounts of 5-ethylidene-2-norbornene (ENB)1 (2-8 wt.-%) is discussed. The photo-oxidation depends on the initial content of ENB units in the chains. The formation of a band at 923 cm−1 is attributed to the CH out-of-plane deformation of a new double bond in terminal position in the ethylidene moieties. The presence of double bond migration suggests the formation of stable tertiary hydroperoxides which show a new band at 870 cm−1. The kinetic behaviour of a band with similar spectral pattern in the UV at 235 nm has been correlated with double bond migration. The identification of photoproducts both by 2,4-dinitrophenylhydrazin and SO2 confirms the proposed spectroscopic assignments. The gel measurements of the studied terpolymers, and some comparisons with a poly(ethylene-co-propene) (EPR) copolymer having a similar ethylene to propene ratio, suggest that the presence of ENB can strongly influence both the photo-oxidation and the crosslinking yields of these rubbers.

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.

We present the first type of tetraazide-functionalized calix[4]arene TiO(2) nanoparticles and their coupling to propargyl glycosides under Cu(I)-catalysis (click reaction), resulting in the immobilization of calix[4]arene-based glycoclusters on the TiO(2) surface.

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.

This paper presents results on the photo-induced grafting of poly(methyl methacrylate) onto poly[bis(4-isopropylphenoxy)phosphazene], using benzophenone as photoinitiator. The formation of polyphosphazene-g-poly(methyl methacrylate) copolymers was followed by FTIR-ATR spectroscopy, and the products were characterized by contact angle and DSC measurements. Among the parameters affecting the photografting, irradiation time and the ratio methanol/unsaturated monomer used in the grafting experiments are of particular importance.

Four different types of montmorillonites have been dispersed by sonication at 50 °C into a propoxylated aromatic epoxy diacrylate oligomer to achieve interlayered or exfoliated nanocomposites. A thermally-induced crosslinking reaction, forming a polyurethane network in the presence of 7 wt.-% of a montmorillonite, has been promoted by addition of an allophanate modified polyisocyanurate based on hexamethylene diisocyanate. The kinetic behavior of the network formation has been studied at 25, 40 and 60 °C by following the disappearance of the isocyanate vibrational band found at 2 270 cm -1 . A tight crosslinked polyurethane acrylate network has been achieved by a subsequent dual UV curing promoted by a photoinitiator mixture (0.6 wt.-%) added to the reactive mixture because of further reactions occur to the acrylate double bonds. The photopolymerization kinetic has been investigated on the different thermally treated polyurethane nanocomposite networks by Real Time FTIR spectroscopy monitoring the changes of the IR band at 810 cm -1 assigned to the acrylate double bond vibrations. The influence of the different montmorillonite clays on the final nanocomposite morphology has been investigated by using XRD and SEM. Finally, the use of these mixtures as internal layer between two modified surface PET films has been also studied for the laminate production. The based-PET laminate films have been characterized by determining the bending resistance and optical properties as a function of different nanofillers.

Copolyethers and polyurethanes containing lower and upper rim calix[4]arene units in the fixed cone conformation were prepared in good yield by polycondensation reactions of distal calix[4]arene diols with bisphenol-A/dibromomethane and 2,4-tolylendiisocyanate (TDI), respectively. In a similar way were prepared calix[4]arene-crown-5 and -crown-6 polyurethanes in the fixed 1,3-alternate conformation by condensation of TDI with lower rim calixcrown-5 and calixcrown-6 diols. However, the poor solubility in common organic solvents of the copolyether derivatives (M w ¼ 11; 100 - 11; 600 g/mol) hampered further studies on their ionophoric properties. Aiming to obtain model compounds for the investigation of both extraction abilities and ionophoric properties of the polyurethane materials, several bis-urethanes were also synthesized by reaction of the calix[4]arene diols with p-tolylisocyanate (TI). The extraction ability measurements of monomeric and polymeric calix[4]arene urethanes (M w ¼ 12,300 - 83,500 g/mol) towards alkali metal cations (Li þ ,Naþ ,K þ ,Rbþ ,Cs þ ) and Ag þ showed a remarkable efficiency and selectivity of calixcrown-6 polyurethane toward Rbþ ,Csþ and Agþ .

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.

The synthesis of 1,3-dimethyl calix[4]arene–bisphenol-A copolyethers and copolyesters with variable amounts of the macrocycle in the chain is described; the receptor ability of the copolyethers 4 toward silver(I) ions was one hundred-fold that of calix[4]arene tetrapropyl ether 3.