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Poly(lactide) (PLA) and poly(ethylene glycol) (PEG)-based hydrogels were prepared by mixing phosphate buffer saline (PBS, pH 7.4) solutions of four-arm (PEG-PLA)2-R-(PLA-PEG)2 enantiomerically pure copolymers having the opposite chirality of the poly(lactide) blocks. Dynamic Light Scattering, rheology measurements, and fluorescence spectroscopy suggested that, depending on the nature of the linker R, the gelation process followed rather different mechanisms. In all cases, mixing of equimolar amounts of the enantiomeric copolymers led to micellar aggregates with a stereocomplexed PLA core and a hydrophilic PEG corona. Yet, when R was an aliphatic heptamethylene unit, temperature-dependent reversible gelation was mainly induced by entanglements of PEG chains at concentrations higher than 5 wt.%. When R was a linker containing cationic amine groups, thermo-irreversible hydrogels were promptly generated at concentrations higher than 20 wt.%. In the latter case, stereocomplexation of the PLA blocks randomly distributed in micellar aggregates is proposed as the major determinant of the gelation process. [ABSTRACT FROM AUTHOR]

Aiming at the tuning of thermo-mechanical features by chemical cross-linking, a biopolyester commercial blend based on poly(lactic acid) (PLA) with poly(butylene adipate-co-terephthalate)(PBAT) (ecovio®T2280, BASF) was processed in Brabender in the presence of dicumyl peroxide (DCP, 0-0.2 wt.-%). The effect of DCP addition was investigated and rationalized by means of solubility tests and gel content evaluation, as well as rheological, mechanical, and molecular weight analysis of the prepared compounds. Moreover, detailed DSC and TMDSC investigations provided a deep insight into the structural modifications occurred at the macromolecular level. We found that chain branching as well as cross-linking occurred in the samples processed in the presence of DCP, thus returning compounds having increased toughness and modulated crystalline content and thermal behavior. Noteworthy, the presence of specific, undisclosed additives, triggers the occurrence of peculiar behaviors in the ecovio® commercial blend, not previously observed in model PLA/PBAT blends of similar composition. Despite only partially soluble in chloroform, the new ecovio® DCP-modified compounds still remained workable in the melt, thus providing a suitable, simple and economically affordable strategy to finely modulate the thermo-mechanical properties starting from a commercially available, compostable compound. [ABSTRACT FROM AUTHOR]

Abstract: Poly(butylene succinate)-hemp composites (PBS-hemp), with hemp content in the range 0–40 wt.%, were prepared in the melt and characterized. This paper focuses on the detailed analysis of the thermal behaviour of the PBS-hemp composites, investigated by differential scanning calorimetry (DSC), to enlighten the polymer/fibre interphase features. The occurrence of specific intermolecular interactions between PBS and hemp was assessed from specific heat capacity data. Different degrees of mobility of the PBS amorphous segments were found at the amorphous/crystal interphases. A broadening of the bulk glass transition was observed, and attributed to the presence of polymer segments slightly constrained. Moreover, a rigid amorphous fraction that devitrifies at temperatures higher than the bulk glass transition, partly before the melting region and partly simultaneously with the fusion, was observed and quantified, and attributed to the presence of major constraints probably occurring in geometrically restricted areas. [Copyright &y& Elsevier]

Abstract: Maleic anhydride (MAH), trans cinnamic acid (AcCin) and ethyl cinnamate (EtCin) were radically graft onto poly(butylene succinate-co-adipate) (PBSA). Samples were prepared in Brabender at 175 °C by addition of increasing amounts of MAH, AcCin, EtCin and their combinations, i.e. MAH/AcCin and MAH/EtCin, setting DCP content in the 0.2–0.6 wt% range. Monomer grafting was quantitatively determined by FT-IR. MAH grafting degrees (FDM) resulted up to 1 mol%. Conversely, AcCin grafting degrees (FDA) were found almost negligible in all cases. EtCin was found grafted in the 0.3–1.0 mol% range when the binary system MAH/EtCin was applied. Same MAH feeds returned almost doubled MAH grafting degrees (FDM) when AcCin was the stoichiometric co-agent, and even three times higher FDM when EtCin was the stoichiometric co-agent. On accounts of all the collected results, a kinetic model of the investigated systems is proposed. [Copyright &y& Elsevier]

Abstract: Poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) are biodegradable aliphatic polyesters, which being semicrystalline and thermoplastic can be processed by conventional methods. Their blends give interesting materials for industrial packaging applications, due to their increased ductility as PBAT content increases. However, like many aliphatic polyesters, the PLA matrix degrades upon melt processing thus affecting the thermo-mechanical features of the blended material. In this work, we studied the effect of processing at high temperature on the molecular weight distribution, morphology, and thermo-mechanical properties of both homopolymers, as well as the PLA/PBAT 75/25 blend. Notably, different processing conditions were adopted in terms of temperature (range 150–200°C) and other relevant processing parameters (moisture removal and nitrogen atmosphere). Analysis of PLA/PBAT blends indicated that intermolecular chain reactions took place under strong degradative conditions of PLA, yielding PLA/PBAT mixed chains (copolymers). Increasing amounts of copolymers resulted in improved phase dispersion and increased ductility, as SEM and mechanical tests indicated. Conversely, reduced PLA degradation with less copolymer formation, afforded higher modulus materials, owing to poorer dispersion of the soft phase (PBAT) into the PLA matrix. [Copyright &y& Elsevier]

Abstract: New biodegradable–biocompatible amphiphilic block copolymers were prepared in good yields by SnOct2 catalyzed ring opening polymerization of ε-caprolactone initiated by monomethoxy-terminated poly(ethylene glycol) (MPEG). Coupling of the AB copolymers with hexamethylene diisocyanate afforded ABA (formally ABBA) block copolymers. Both AB and ABA copolymers were thoroughly characterized by IR and NMR spectroscopy, size exclusion chromatography, TGA and DSC thermal analysis. In particular, DSC measurements evidenced that the copolymer hydrophilic–lipophilic balance appreciably affected the state of adsorbed water. Polarized optical microscopy of bulk materials and pyrene fluorescence emission of polymer water solutions highlighted the copolymer tendency to phase separation and self-organization, respectively. Most of the prepared materials formed micelles in water and the copolymer structure appreciably affected their critical micellar concentration. In vitro cytocompatibility tests confirmed the low toxicity of the prepared polymeric materials which enhances their potential for biomedical applications. [Copyright &y& Elsevier]

Front Cover: Processing of PLA/PBAT compostable blends with dicumyl peroxide gives chain‐branching and crosslinking, thus providing a simple and economically affordable strategy to finely modulate the thermo‐mechanical properties of the commercial material. Further details can be found in the article by F. Signori,* A. Boggioni, M. C. Righetti, C. E. Rondán, S. Bronco, and F. Ciardelli on page 153. [ABSTRACT FROM AUTHOR]

Immobilizing natural antioxidant and biologically active molecules in layered double hydroxides (LDHs) is an excellent method to retain and release these substances in a controlled manner, as well as protect them from thermal and photochemical degradation. Herein, we describe the preparation of host–guest systems based on LDHs and rosmarinic and glycyrrhetinic acids, two molecules obtained from the extraction of herbs and licorice root, respectively, with antioxidant, antimicrobial, and anti-inflammatory properties. Intercalation between the lamellae of the mono-deprotonated anions of rosmarinic and glycyrrhetinic acid (RA and GA), alone or in the presence of an alkyl surfactant, allows for readily dispersible systems in biobased polymer matrices such as poly(lactic acid) (PLA), poly(butylene succinate) (PBS), and a 60/40 wt./wt. PLA/PBS blend. The composites based on the PLA/PBS blend showed better interphase compatibility than the neat blend, correlated with increased adhesion at the interface and a decreased dispersed phase size. In addition, we proved that the active species migrate slowly from thin films of the composite materials in a hydroalcoholic solvent, confirming the optimization of the release process. Finally, both host–guest systems and polymeric composites showed antioxidant capacity and, in the case of the PLA composite containing LDH-RA, excellent inhibitory capacity against E. coli and S. aureus. [ABSTRACT FROM AUTHOR]

Abstract: Molecular optical brighteners incorporated into filmable polymers to a very low extent from 0.05 to 0.5wt.% by melt-processing, provide materials which show a well-defined excimer emission by increasing dye concentration flanked by a characteristic change of the luminescent properties of the films. Then, the original colour of the film, provided by the radiative transitions of the isolated dye molecules, may be restored after polymer stretching that promotes the aggregates break-up and the alignment of the single chromophore molecules along the stretching direction thus providing an easy detectable colour change. The approach can be extended to polymer blends allowing to obtain a wide range of films with different structure and performances in colour changes determined by external stimuli. Also, nanostructured polymer films with unusual and anisotropic optical properties can be obtained through the dispersion of gold and silver nanoparticles. The metal nanoparticles can be produced directly inside the polymer matrix by a photo-reduction process. Both organic chromophores and metal particles nanostructured systems can be used to prepare “smart” coating materials with a broad type of structural characteristics and capable to detect and stores external stimuli of different origin and under different conditions. [Copyright &y& Elsevier]

A series of task-specific ionic liquids (TSILs) based on glycerylimidazolium cations have been prepared by reaction of 1-chloropropanediol, a compound obtainable from glycerol (a widely available and in-expensive waste product), with the appropriate base (1-H-imidazole, 1,2-dimethylimidazole and 1-methyl-1-H-imidazole). The reaction of 3-(1H-imidazol-1-yl)propane-1,2-diol with chloroalkanes, bromoalkanes and alkyl mesylates gave the corresponding salts which were characterized. The possibility to use these ILs in palladium catalyzed reactions was evaluated, evidencing good catalyst stability and a high recyclability. [ABSTRACT FROM AUTHOR]

In the perspective of producing a rigid renewable and environmentally friendly rigid packaging material, two comb-like copolymers of cellulose acetate (AC) and oligo(lactic acid) OLA, feeding different percentages of oligo(lactic acid) segments, were prepared by chemical synthesis in solvent or reactive extrusion in the melt, using a diepoxide as the coupling agent and were used as compatibilizers for poly(lactic acid)/plasticized cellulose acetate PLA/pAC blends. The blends were extruded at 230 °C or 197 °C and a similar compatibilizing behavior was observed for the different compatibilizers. The compatibilizer C1 containing 80 wt% of AC and 14 wt% of OLA resulted effective in compatibilization and it was easily obtained by reactive extrusion. Considering these results, different PLAX/pAC(100-X) compounds containing C1 as the compatibilizer were prepared by extrusion at 197 °C and tested in terms of their tensile and impact properties. Reference materials were the uncompatibilized corresponding blend (PLAX/pAC(100-X)) and the blend of PLA, at the same wt%, with C1. Significant increase in Young's modulus and tensile strength were observed in the compatibilized blends, in dependence of their morphologic features, suggesting the achievement of an improved interfacial adhesion thanks to the occurred compatibilization. [ABSTRACT FROM AUTHOR]

The world is confronted with the depletion of natural resources due to their unsustainable use and the increasing size of populations. In this context, the efficient use of by-products, residues and wastes generated from agro-industrial and food processing opens the perspective for a wide range of benefits. In particular, legume residues are produced yearly in very large amounts and may represent an interesting source of plant proteins that contribute to satisfying the steadily increasing global protein demand. Innovative biorefinery extraction cascades may also enable the recovery of further bioactive molecules and fibers from these insufficiently tapped biomass streams. This review article gives a summary of the potential for the valorization of legume residual streams resulting from agro-industrial processing and more particularly for pea, green bean and chickpea by-products/wastes. Valuable information on the annual production volumes, geographical origin and state-of-the-art technologies for the extraction of proteins, fibers and other bioactive molecules from this source of biomass, is exhaustively listed and discussed. Finally, promising applications, already using the recovered fractions from pea, bean and chickpea residues for the formulation of feed, food, cosmetic and packaging products, are listed and discussed. [ABSTRACT FROM AUTHOR]