Vanillin produced by chemical modification of lignin is considered as natural vanillin and is 250 times cheaper than synthetic vanillin. Due to aromatic structure it could be able to replace widely used petro-based aromatic monomers [1]. Photopolymerization engendered high interest both in academia and in industry due to the considerable practical and economic benefits. Advantages of the photopolymerizition are high reaction speed, low energy consumption, high efficiency, low volatile organic compound emission, and the large number of applications in not only conventional areas such as coatings, inks, and adhesives, but also in high-tech domains, such as microelectronics, optoelectronics, laser imaging, stereolithography, and nanotechnology [2].

In this study, cross-linked polymers were obtained by photopolymerization of vanillin diacrylate and vanillin dimethacrylate using ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate as photoinitiator. Chemical structure of the polymers was confirmed by IR spectroscopy. The yield of insoluble fraction of the cross-linked polymers, obtained after Soxhlet extraction in acetone for 24 h, was in the range of (77-96) %. Differential scanning calorimetry (DSC) and thermogravimetrical analysis (TGA) was used to study thermal characteristics of the photocross-linked polymers. The glass transition temperature, obtained from DSC curves, was in the range of (63-87) °C. The temperature of 10 % mass loss, obtained from TGA curves, was in the range of (330-350) °C. Mechanical properties of the resulted polymers were investigated by three point bending test and compression test. Vanillin diacrylate-based polymers demonstrated low deformation during compression, 4.95 % when the force of 5 N was applied. The specimen bend of 30 % was 3.65 N.

Photorheometry was used to monitor the evolution of photocross-linking process. The UV/Vis real-time photorheometry curing tests were performed on a MCR302 rheometer from Anton Paar equipped with the plate/plate measuring system. It was determined that photopolymerization was the fastest when vanillin dimethacrylate was used as monomer. The addition of solvent into the resins slowed down the photocross-linking process and less rigid polymers were obtained. The gel point was reached the fastest when 3 mol.% of ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate was used in all resin series.

The vanillin diacrylate-based polymers without any solvent possessed higher values of cross-linking density, yield of insoluble fraction, and thermal stability in comparison to the vanillin dimethacrylate-based polymers, although the photocross-linking of vanillin dimethacrylate was faster than that of vanillin diacrylate.

Acknowledgements

Financial support from the EU ERDF, through the INTERREG BSR Programme, (ECOLABNET project #R077) is gratefully acknowledged.

References

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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.

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Τhe production of most polymers depends on fossil resources, which are finite raw materials. In a quest towards more sustainable polymers, natural feedstocks have been explored for the production of monomers for the synthesis of bio-based polymers, mainly cellulose, lignin and polysaccharides [1]. After cellulose, lignin is the second most abundant natural polymer and an important source of aromatic monomers and among them vanillin is a versatile building block for polymer synthesis [2]. Vanillic acid or 4-hydroxy-3-methoxybenzoic acid, obtained by vanillin oxidation, is a potentially bio-based building block, which has recently regained attention. Poly(ethylene vanillate) was thus synthesized and studied, exhibiting promising characteristics [3]. Poly(ethylene furanoate) (PEF) is the most prominent member of the family of furandicarboxylate-based polyesters and is considered as a potential substitute of poly(ethylene terephthalate) (PET). In the present work, the preparation of poly(ethylene furanoate-co-ethylene vanillate) copolymers (PEFV) will be presented. PEFV copolymers were obtained by the traditional two-step melt polycondensation method. PEFV copolymers were structurally characterized by nuclear magnetic resonance spectroscopy (NMR), while their thermal behavior and thermal stability was studied by differential scanning calorimetry and thermogravimetric analysis.

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In the last few years several fluorescent poly-e- caprolactones [1-3] were designed, synthesized and subsequently used as nanoparticles [1], nanofibers [2] or scaffolds [3] in various prospective bioapplications. Meanwhile, our interest was directed toward electro - and photoactive moieties - functionalized poly/or oligo-e- caprolactone, that worked as key building blocks (macromonomers) for new grafted conjugated polymers or hybrid systems successfully used as biosensors [4,5] or regenerative medicine [6]. In the same line, the present report is aimed to extend the investigations and to highlight the properties in solution (photophysical, self-assembling) of 3, 4-ethylenedioxythiophene-functionalized poly-e- caprolactone (EDOT-PCL) synthesized by ring-opening polymerization (ROP). The results of the studies in two organic solvents (chloroform and acetonitrile), having different selectivity in relation with the constitutive parts of EDOT-PCL, revealed its propensity for self-assembling, proved by Dynamic Light Scattering (DLS) measurements, while fluorescent emission maxima in the range 310-430 nm, depending on the solvent were evidenced, as well. Moreover, its capability for spontaneous oxidant-free oligomerization, presumably due to and under the action of acidic character of CDCl₃, serendipitously noticed during ¹³C-NMR registration, was subsequently validated by experiments performed in chloroform in the presence of hydrochloric acid. This is an interesting and applications-oriented useful observation which supports that recently demonstration of oxidant-free polymerization of common EDOT in the only presence of some organic acids [7] could also be extended to EDOT-containing more complex structure.

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Chronic obstructive pulmonary disease (COPD) is associated with an enhanced chronic inflammation of the airways caused by tobacco smoking, air pollution or genetic factors. Fluticasone propionate, a corticosteroid with high topi­cal activity and salmeterol xinafoate, a long-acting selective β₂-adrenoceptor agonist, are extensively used in COPD treatment. The main drawbacks of these pharmaceutical compounds are their high degree of crystallinity along with their hydrophobic nature. These problems, can be overcome through the inclusion of these compounds in polymeric microparticles aiming to their amorphization.

In the present study, chitosan was modified through a graft copolymerization with 2-hydroxyethyl acrylate. Microparticles of chitosan derivative were synthesized via ionic gelation technique and fluticasone propionate and salmeterol xinafoate were simultaneously enclosed in their interior in 10, 20 and 30% ratios. FTIR, X-ray diffraction, SEM and DLS measurements were conducted in order to characterize the microparticles while in vitro release studies were performed intending the assessment of the samples’ release behavior.

The successful formation of the microparticles was confirmed by FTIR while the absence of drugs’ crystallinity indicated their amorphization in the interior of the microparticles. SEM images depicted the spherical shaped particles while their actual size, which in any ratio was in micro scale, was measured through DLS. Finally, the enhancement of the in vitro release behavior of both active compounds was accomplished.

In conclusion, our results support the successful formulation of modified chitosan microparticles, the inclusion of both drugs in an amorphous state and the amelioration of their in vitro release behavior.

Acknowledgements:

Τhe author wishes to acknowledge co-funding of this research by European Union-European Regional Development Fund and Greek Ministry of Education, Research and Religions/EYDE-ETAK through program EPANEK 2014-2020/Action “EREVNO-DIMIOURGO-KAINOTOMO” (project Τ1ΕΔΚ-02667).

The widespread use of synthetic polymers has led to the accumulation of their wastes, of which only about 10% is processed, the rest is accumulated in nature, and decomposition in natural conditions occurs for a long time. Therefore, the development of biodegradable plasticates is important. Today, plastics based on plant raw materials do not compete with traditional plastics, since they have unsatisfactory operational properties, and their production technologies consume a significant amount of energy and water and are characterized by emissions of pollutants. The development of composites from traditional plastics with biodegradable additives, which are completely compostable in nature, is relevant. Plasticizers, as the main part of plasticate, are the most convenient way to model the biodegradability of the composite. When developing biodegradable plasticate, it is important to ensure a certain service life. For this purpose, fungicides with a limited duration are used. Zinc compounds are known among them. Therefore, in the presence of catalyst ZnO, a new non-toxic plasticizer, decyl phenoxyethyl adipate, was obtained in 89% yield. Method of its co-production with zinc compound has been developed. For the use of decyl phenoxyethyl adipate in PVC composites by TGA and DSC (Mettler Toledo), thermal stability, crystallization and melting temperatures of the plasticizer, enthalpy values ​ ​ of these processes were studied; PVC compatibility is estimated by the critical dissolution temperature of the polymer in the plasticizer. Effect of zinc compound formed in situ as fungicide on biodegradation of PVC film samples with developed plasticizer is investigated. As a result of the tests, the obtained zinc compound in an amount of 5% in the formulation of the PVC composition provides a fungicidal effect for a certain period of operation of the obtained plasticate, after which the biodegradation process begins.

The growth of the world economy and the rising global population (9 billion by 2050) mean that the Earth’s natural resources are being used up fast. Resources need to be managed more efficiently throughout their life cycle, from extraction, transport, transformation and consumption, to the disposal of waste. Several companies, and research entities have developed biobased polymer resins nevertheless further improvements are needed to provide cost effective solutions with high bio-based content and suitable performances to meet for example the target of the newly enforced laws that requires some disposable items such as tableware to be home compostable from 2017 with a minimum bio-sourced content of 30% (increasing progressively in subsequent years to 60% in 2025). The combined plastic and food sector form an important part of the EU economy, accounting for 15 million jobs (7.6% of total employment). Unlocking the innovation potential in the field of packaging, and cosmetics will significantly contribute to job creation and competitiveness. Sustainable synthesis of polyhydroxyalkanaotes from agro-food by-products as well as synthesis of lactic acid co-polymers constitute a pathway to performing and sustainable polymeric matrices.

Natural fibers as well as polysaccharides (starch, cellulose, chitin, chitosan), cutin and protein rich by-products are abundantly available from the agrofood industry. Running Horizon 2020 EC project target developing eco-efficient ways to convert agro-food wastes into bio-based coating products (ECOFUNCO) or the conversion of food by-products such as bran or coffee silver-skin in biobased sustainable bio-composites (AGRIMAX, PROLIFIC) whose properties may be tuned by lignocellulosic fibres modification. Natural fibres may be modified chemically, with enzymes or treating their surface with natural waxes with a significant improvement in adhesion and impact resistance.

These projects have received funding from the Bio Based Industries Joint Undertaking under the European Union's Horizon2020 research and innovation programme under grant agreement: ECOFUNCO No 837863, AGRIMAX No 720719, Prolific No 790157.

An overview on the availability, collection, treatment and approach to valorization of largely available agro-food waste biomass for both polymers and biocomposites production, is hereby reported with exampled of product developed in our research units, such as sustainable pots, rigid containers, active films, non-woven tissue.

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.

Skin injuries are encountered by millions of patients globally. They are caused by burns, chronic ulcers of different causes, infections, cancer surgery, and other diseases, and require effective treatment to prevent morbidity or mortality. Various patches, with different properties to restore the function of the skin after damage and to facilitate wound healing have been created.

This work concerns the production of a patch with prolonged action based on poly (d-lactic acid) (PDLA) with thioether-containing ω-hydroxyacid (TEHA). PLA is an aliphatic polyester derived from lactic acid, that stands out in a wide range of medical applications, because of its biocompatibility and renewability, and excellent mechanical, thermal and processing properties. It is available at a low cost compared to other common biodegradable polymeric biomaterials. However, the in vivo hydrolysis rate of PLA is very slow. For this reason, block copolymers of TEHA and PDLA (TEHA-co-PDLA) were prepared in various ratios in order to slowly release active substances topically on the skin.

The physicochemical properties of the prepared copolymer were examined with FTIR, DSC and XRD. From 1H NMR and FTIR the successful synthesis of the materials was confirmed. XRD measurements revealed the amorphous form of TEHA-co-PDLA copolymers. DSC was used to be studied the thermal properties of the materials.

Polymers are extensively used advanced materials since plastics meet a wide variety of needs in many applications and sectors. The most commonly used polymers in industry are non-biodegradable and petroleum derived. The increasing demand for these types of polymers brings along the problem of accumulation of plastic waste in the environment and depletion of fossil resources. At this point, biodegradability of polymers gains great importance as well as bio-based polymers produced from renewable resources. In this study, bio-based polyamide 5.6 polymer (PA56) was incorporated with olive stone powder (OSP) in order to manufacture a biodegradable polyamide compound, and its degradability was investigated under environmental conditions for 6 months. Bio-based polyamide 5.6, which is recently introduced to the plastics world, was chosen for this study, since bio-based polymers have many advantages over petroleum derived polymers in respect to environmental concerns. Olive stone powder was used as a biodegradation additive. Utilization of olive stone is important not only for being renewable source for bio-polyols, but also for the valorization of the solid waste from the olive-oil industry. The olive stone powder was incorporated into polyamide 5.6 at 10% (w/w) with a twin screw extruder by extrusion compounding method in order to manufacture the biodegradable polyamide compound, PA56/OSP10. The characterization of the manufactured PA56/OSP10 compound was done using Fourier transform infrared (FTIR) spectroscopy. The biodegradability of the PA56/OSP10 compound was examined through a natural soil burial test which lasted for 180 days. The sign of degradation was assessed by both visual observation and weight loss measurements. At the end of 6 months, 5.24% weight loss and surface deformation were determined for the PA56/OSP10 compound. These results suggest that olive stone powder can be considered as a green alternative to conventional biodegradation additives for polymer compounding.