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Polymers of natural polyphenols have so far received little attention as bioavailable, biocompatible antioxidants for different applications e.g. in packaging and related technologies. Expected advantages with respect to the monomers would include lower volatility (with reduced adverse effects), greater chemical stability under processing conditions and lower tendency to be released from the polymer into the contact medium (food, water, etc.). Herein we report data on the synthesis, structural characterization and antioxidant properties of two novel bioinspired phenolic polymers prepared by horseradish/H2O2 oxidation of tyrosol (polyTYR) and caffeic acid methyl ester (polyCAME). The materials, obtained in 80-85% yields, were subjected to structural characterization by solid state CPMAS NMR, mass spectrometry and gel permeation chromatography (GPC). ESI(-)/MS and NMR analysis indicated that polyTYR was a mixture of regular oligomers up to the undecamer with heptamer as the most abundant, all featuring units linked through C-C bonds. GPC showed an average molecular weight of 1862 Da with a polydispersity index of 1.64. ESI(-)/MS of polyCAME showed oligomers up to at least the decamer stage, peaking at the tetramer. Analysis of the clusters of the pseudomolecular ion peaks and the presence of CH carbons due to O-substituted benzylic positions in NMR spectra suggested a structure including dihydrobenzofuran units. Both PolyTYR and polyCAME exhibited antioxidant properties in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays and proved to be efficient hydroxyl radical scavengers in a Fenton reaction assay. The potential of PolyCAME as stabilizer toward polyethylene (PE) thermal and photo-oxidative degradation was also evaluated. PolyCAME exhibited high stability toward decarboxylation and oxidative degradation during the thermal processes associated with PE film preparation. Characterization of PE films by thermal methods, photo-oxidative treatments combined with chemiluminescence and FTIR spectroscopy and mechanical tests indicated a significant effect of polyCAME on PE durability as shown for example by the increase of the Oxidative Induction Time (OIT).1The synthesized phenolic biopolymers are thus proposed as novel easily accessible, eco-friendly and biocompatible materials for a sustainable approach in packaging and other applications. 1) Ambrogi, V.; Panzella, L.; Persico, P.; Cerruti, P.; Lonz, C. A.; Carfagna, C.; Verotta, L.; Caneva, E.; Napolitano, A.; d'Ischia, M. Biomacromolecules 2014, 15, 302-310.

A study was carried out on the effect of a hybrid linear-hyperbranched poly(butylene adipate) copolymer on the properties of a commercial epoxy resin. First, the synthesis of the hyperbranched systems was optimized. These systems were obtained by reacting linear oligomers with 1,1,1-tris(hydroxymethyl)propane used as branching agent and varying the reaction times from 16 to 44 h. The synthesized samples were characterized through matrix-assisted laser desorption ionization time-of-flight mass spectrometry, differential scanning calorimetry and thermogravimetric analysis. Results showed that for reaction times of 30 h a highly branched system, namely 5HB30, was obtained. This system was chosen as toughening agent for a commercial high-performance epoxy resin. A kinetics analysis of epoxy/5HB30 blends indicated that the hyperbranched system had no accelerator or catalytic effect on the crosslinking reaction in the resin. Furthermore, it was demonstrated that 5HB30 acted as an excellent toughening agent, increasing significantly impact resistance up to 90% with respect to neat epoxy resin. The toughness behaviours of epoxy-based blends were explained by investigating the fracture surface after impact tests through scanning electron microscopy before and after solvent etching. It was observed that the globular-like hyperbranch-rich domains, dispersed throughout the continuous epoxy resin, were able to absorb the impact energy without affecting thermal stability.

The curing process of a commercial vinyl ester (VE) resin was characterized by calorimetric and spectroscopic techniques. A phenomenological kinetic model, experienced in previous studies, was employed to describe the proceeding of curing reactions. The model is able to describe the behavior of the processing variables, i.e. rate and degree of the reaction, during the curing of the resin under different conditions (heating rates). The effect of diffusion control phenomena on the reaction kinetics, associated with the evolution of the glass transition temperature as a function of the degree of polymerization and cross-linking, was taken into account in the formulation of the kinetic model. A simpler model was proposed and verified for a liquid crystalline vinyl ester resin, synthesized by the authors. The model, in particular, did not take into account the effects of vitrification. The kinetic parameters were again evaluated by processing the calorimetric data. The kinetic study of the liquid crystalline monomer is performed after isotropization and therefore, the acceleration effect, associated with the cure in liquid crystalline phase is not taken into account for the kinetic analysis. Also in this case, the comparison between theoretical and experimental data was very satisfying.

Di-(2-ethylhexyl) phthalate (DEHP) is an ester of phthalic acid, which is mainly used as plasticizer in polyvinyl chloride (PVC) to increase its flexibility, elongation and processability. The main drawback, related to its low molecular weight, is the leaching out from flexible PVC (pPVC), which affects the polymer properties limiting its employ. Moreover, the use of phthalate-based plasticizers is being questioned worldwide because of their potential toxicity to humans and environment. Migration of such harmful substances from PVC can be avoided by substituting the unsafe plasticizer or by preventing its mass transfer from polymer matrix. In this communication, promising alternatives to reduce phthalate mass transfer are discussed in detail: the chemical cross-linking of flexible PVC and the use of chlorinated polyethylene (CPE) as physical barrier against DEHP leaching. Cross-linked flexible PVC samples were obtained using a difunctional amine, namely isophoron diamine (IPDA), as cross-linking agent while two different CPE resins were employed for the preparation of new CPE/pPVC compounds. The effect of cross-linking and the efficiency of CPE in preventing plasticizer leaching were evaluated through migration tests and supported by tribological analysis. Thermal, mechanical and dynamic-mechanical properties were also studied.