During the past few years, the production of biodegradable polymeric materials from renewable sources has gained extended attention in both academic and industrial fields. It is a promising approach to solve a number of problems connected with increasing pollution and energy shortage caused by the petroleum consumption. Focusing on this eco-friendly approach, aliphatic polyesters are of great interest due to their wide spectrum of potential applications and sustainability. Among this group segmented block copolymers exhibit a broad range of advantageous features as they can be produced using monomers from biomass feedstock. These copolymers consist of different types of sequences with different properties and distinct transition temperatures, thus being capable of forming hard and soft segments. Hard segments are responsible for the dimensional, thermal and mechanical stability of the polymer while the soft segments are designed to impart the elasticity to the polymer. Herein, biodegradable poly(butylene succinate-co-dilinoleic succinate) (PBS-DLS) copolymers with 70:30 (wt%) ratio of hard to soft segments were successfully synthesized using Candida antarctica lipase B (CAL-B) as a biocatalyst. During two-step synthesis in diphenyl ether, biobased succinate was polymerized with renewable 1,4 – butanediol and dimer linoleic diol to obtain “green” copolyesters as sustainable alternative to petroleum-based materials. Structure-properties relationships were discussed by investigating the number average molecular weight, chemical structure, crystalline behavior and thermal transition temperatures. Moreover, cytotoxicity test using mouse fibroblast cells L929 were performed on extracts of obtained PBS-DLS materials indicating excellent biocompatibility in vitro.

The depletion of petroleum resources and the environmental concerns during the last decade, led both academia and industry to look for a new class of ecofriendly materials with improved functional properties. In this regard, the biodegradable composites, also called "green composites" have been paid increasing attention by researchers worldwide. Among all the biodegradable polymers, polyhydroxyalcanoates (PHA) are considered as the potential candidates to replace the petroleum-based polymers. On the other hand, cellulose-based fibers which have many advantages including low cost, good biodegradability and thermal insulation can be used as reinforcement in polymer composites. However, to ensure good adhesion between lignocellulosic fibers and the matrix, the fibersurface is modified using chemical (alkaline, silane, acetylation, benzoylation, acrylation, permanganate, peroxide or isocyanate treatment) or physical treatments (corona or plasma treatment) prior to processing. Therefore, the objective of the paper was to investigate the effect of various surface treatments of Aloe Vera fibers (AVF) used as reinforcement in poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) biocomposites. Indeed, various fiber treatments were carried out involving alkaline, organosilanes and combined alkaline/organosilanes. PHBHHx/AVF biocomposites samples were prepared by melt compounding at loading ratio of 20 wt% selected as an optimal composition. The results showed that the biocomposite PHBHHx/ combined alkaline/organosilanes treated AVF exhibits a finer and homogeneous surface morphology indicating a good fiber/matrix interfacial adhesion. Accordingly, the rheological properties (complex viscosity and storage modulus) were increased and the water uptake was reduced. This study highlights the effectiveness of combined alkaline/organo-silanes treatment of AVF over alkaline and organo-silanes and their applications in PHBHHx biocomposites as an interesting source of cellulosic reinforcing materials.

The development of biofunctionalized polymer interfaces through the deposition of bio-derived polymeric layers to flat surfaces has attracted great attention in recent years due to the wide range of potentially relevant applications. Examples are the production of coatings for protection against corrosion, novel adhesive materials, protein resistant bio-surfaces, chemical lubricants and polymer-carriers for the controlled release of active compounds, which are derived from the highly efficient adaptation of the physicochemical properties of these surfaces. Mostly these polymeric layers are produced by a grafting-from synthesis strategy wherein polymer chains are produced in situ from suitable polymerization initiator molecules previously attached to the surface, resulting in a surface with a high grafting density of initiating sites. This synthesis strategy can be accomplished by implementing different surface-initiated polymerization mechanisms, including living cationic and anionic polymerization, as well as surface-initiated reversible deactivation radical polymerization that enables the production of "green" biopolymeric materials from environmentally friendly chemical sources.

One of the most important challenges to face during the preparation of the polymer layer is to perform a thorough characterization based on the molar mass and dispersity on the individual chain level, as well as the variation of its thickness as a function of the polymerization time and the grafting density, which define the mushroom/brush character of the biofunctionalized polymer interface. Such characterization is although a cumbersome task to perform solely based on experimental studies. These limitations can be circumvented from the implementation of advance computational modeling tools that make possible the extensive in silico characterization of the desired polymerization products. In this context, a generic matrix-based kinetic Monte platform has been developed by our group [1, 2], capable of evaluating the three-dimensional growth pattern of the individual polymer chains within the (biofunctionalized) polymer interface. It allows for a detailed study of the conformation of the polymer chains and other relevant molecular properties, enabling the optimization of the synthesis conditions and control strategies for the production of well-defined polymer interfaces.

1. Arraez, F. J.; Van Steenberge, P. H. M.; D’hooge, D. R. Conformational Distributions near and on the Substrate during Surface-Initiated Living Polymerization: A Lattice-Based Kinetic Monte Carlo Approach. Macromolecules 2020, DOI: 10.1021/acs.macromol.0c00585.
2. Arraez, F. J.; Van Steenberge, P. H. M.; D'Hooge D, R. The Competition of Termination and Shielding to Evaluate the Success of Surface-Initiated Reversible Deactivation Radical Polymerization. Polymers) 2020, 12 (6), DOI: 10.3390/polym12061409.

The population growth and the limited reservoir of fossil resources have ignited the attention of scientific communities and entrepreneurs to produce alternative products with raw-materials from renewable sources. In this work, proteins derived from the recycling of waste textiles were studied as raw-material in the synthesis of thermosetting polymers of phenolic type (phenol-formaldehyde resins) suitable for use as adhesives in the production of wood-based panels. The physical, thermal, and morphological properties of the thermosetting polymers were investigated. For comparison reasons, a typical phenol-formaldehyde (PF) resin was also presented in this study. In detail, the chemical bonds between raw-materials and PF resins were verified with Fourier Transform Infrared spectroscopy (FTIR). The curing performance and thermal stability of the thermosetting PF resins were studied with Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA), respectively. Wood-based panels were prepared and tested at a lab scale following a simulation of the industrial practice. Optical Microscope and Scanning Electron Microscopy (SEM) were applied for the study of the interaction between PF resins and woodchips at the lab scale. It was found that the resins were successfully prepared. The maximum curing temperature of the experimental resins was shifted to higher values than the control PF. According to the TGA results, the protein-based resins seem to lose mass with a lower rate, which denotes that they are more thermally stable than a typical PF resin. It can be concluded that protein from waste textiles can effectively replace part of the petrochemical phenol in the PF resin synthesis, thereby increasing the bio-content of the PF resin and making them more friendly to the environment.

The European food sector generates about 250 million tons/yr of by-products and waste, of which around 10% from fruit and vegetable processing, with a heavy environmental burden.

The agri-food residues (AFR) contain a significant fraction of cellulose and bioactive compounds (mainly antioxidants), which, if recovered, are high added-value material components. The reduction of cellulose down to nano-sized crystalline structures (nanocellulose, NC) provides versatile building blocks, which self-assemble into new materials with superior performances. Despite wood-derived NC is generally considered a green material, its production process is environmentally unfriendly and its large scale utilization would contribute to deforestation. Therefore, more sustainable sources, such as AFR, are desired.

The PANACEA project, within the frame of PRIN 2017 call supported by the Italian Ministry of University and Research, proposes an approach based on the recovery of cellulose and bioactive compounds from AFR, with high yield, at various degrees of hierarchical organization, by cascading different physical and chemical processes of increasing complexity. More specifically, physical processes and microbial digestion are exploited to obtain micro-sized cellulose structures while preserving their bioactivity. Chemical and enzymatic processes are used to isolate, purify and functionalize NC at different levels of hierarchical organization, and to design advanced functional materials such as food ingredients, edible coatings, functional colloids, biocides and flame retardants.

The sustainable integrated valorization of AFR is addressed through (i) ad hoc pre-treatment of different AFR (Tomato peels, Wheat straw, Coffee residues, Rice bran, Grape marcs, Orange peels), available all year round and with different composition, (ii) application of proprietary high-pressure homogenization (HPH) techniques to micronize the residues in water and completely disintegrate the vegetable cells, with integrated physical fractionation to recover insoluble fibers, (iii) combination with chemical fractionation or high P/T autohydrolysis, or enzymatic treatments.

The fabrication of NC structures with tunable size, crystallinity, and surface properties is important to bridge the gap between the production of cellulose and cellulose hybrids and the final applications and is pursued through (i) the size-reduction of NC, or enzymatic lysis, (ii) functionalization via amination or phosphorylation, or (iii) via physical immobilization or covalent bonding with limonene.

The characterization of NC in terms of (i) yields, purity, physicochemical, structural, and functional properties, using a multi-technique approach, is associated to the evaluation of (ii) bio-accessibility (through the simulated digestive process) of bioactive compounds and fibers, (iii) film-forming capacity, (iv) gas-barrier properties, (v) rheological behavior, as well as (vi) energy, water, and reagents consumptions.

Finally, the PANACEA project also addresses the exploitation of NC-based colloids for novel materials and applications, such as (i) edible coatings, antimicrobial varnishes, and oil structuring materials, (ii) packaging films with gas-barrier properties, and (iii) fabrics and foams with flame-retardant properties (iv) advanced nanocomposite films, (v) Pickering emulsions, and (vi) antimicrobial films and coatings.

The main contribution of the PANACEA project to the advancement of the knowledge is expected in (i) the deployment of greener and sustainable, cascading processes exploiting raw AFR functionalities, (ii) the tailored valorization of different AFR by developing physical, chemical, and biological procedures for sculpting the nanostructures, and (iii) the development of sustainable, high performing advanced materials such as edible coatings and gas barrier packages for the food industry, foams, and textiles with flame retardant properties, biocides for organic pest control in agriculture.