Broadening the coating applications of sustainable materials by reinforcing epoxidized corn oil with single-walled carbon nanotubes.

In the global context of environmental awareness, the present research proposes a sustainable alternative to the widely used petroleum-based epoxy coatings. Epoxidized corn oil (ECO) was tested as potential matrix for advanced nanocomposite coating materials reinforced with 0.25 to 1 wt.% single-walled carbon nanotubes (SW) with carboxyl and amide functionalities. The elemental composition of the epoxy networks was monitored by XPS, showing the increase of O/C ratio to 0.387 when carboxyl-functionalized SW are added. To achieve sustainable composite materials, citric acid was used as curing agent, as a substitute for conventional counterparts. The influence of both surface functional groups and concentration of SW was evaluated through structural and thermo-mechanical analysis. The progressive increase of the DSC enthalpy for SW formulated systems indicates a possible pattern for specific interactions within the bio-based epoxy translated by adjusted activation energy. For 1% neat SW addition, the Ea values decreased to 46 kJ/mol in comparison with 53 kJ/mol calculated for neat epoxy. Furthermore, the -COOH groups from SW nanostructures exerted a strong influence over the mechanical performance of bio-epoxy networks, improving the crosslinking density with ~ 60% and twofold the storage modulus value. Accordingly, by gradual addition of SW-COOH filler within the ECO-based formulations, a very consistent behaviour in seawater was noted, with a 28% decreased value for the absorption degree.

Combined Thermomechanical Effect of Graphene Oxide and Montmorillonite on Biobased Epoxy Network Formation for Coatings.

Epoxy nanocomposites derived from linseed oil, reinforced with graphene oxide (GO) and montmorillonite (MMT) nanostructures, were synthesized. The nanohybrids were developed by enriching the structure of MMT and GO with primary amines through a common and simplified method, which implies physical interactions promoted by ultrasonic processing energy. The influence of the new nanoreinforcing agents along with neat ones on the overall properties of the biobased epoxy materials for coating applications was assessed. Interface formation through surface compatibility was contained by the lower values of activation energy calculated from differential scanning calorimetry (DSC) curves, along with a consistent 70% increase in the cross-linking density when amine-modified MMT was used. Thermomechanical characteristics of the biobased epoxy nanocomposites were explained through the interaction of the functional groups over the curing process of epoxidized linseed oil (ELO), giving a 15 °C higher Tg value increase. Furthermore, the low surface energy values suggested an intrinsic antibacterial activity, as proved by a significant decrease of CFU against Staphylococcus aureus bacterial strains on the 0.25% reinforced coatings.

Tailoring an Effective Interface between Nanocellulose and the Epoxidized Linseed Oil Network through Functionalization.

Sustainable nanocomposite materials based on different functionalized nanocellulose (NC) structures embedded in epoxidized linseed oil (ELO) were developed as foundation toward a greener approach for anticorrosive coating evolution. The work leans on functionalization with (3-aminopropyl) triethoxysilane (APTS), (3-glycidyloxypropyl)trimethoxysilane (GPTS), and vanillin (V) of NC structures isolated from plum seed shells, evaluated as potential reinforcing agents for the increase of thermomechanical properties and water resistance of epoxy nanocomposites from renewable resources. The successful surface modification was confirmed from the deconvolution of X-ray photoelectron spectra for C 1s and correlated with Fourier transform infrared (FTIR) data. The secondary peaks assigned to C-O-Si at 285.9 eV and C-N at 286 eV were observed with the decrease of the C/O atomic ratio. Compatibility and efficient interface formation between the functionalized NC and the biobased epoxy network from linseed oil were translated as decreased values for the surface energy of bio-nanocomposites and better dispersion imaged through scanning electron microscopy (SEM). Thus, the storage modulus of the ELO network reinforced with only 1% APTS-functionalized NC structures reached 5 GPa, an almost 20% increase compared with that of the neat matrix. Mechanical tests were applied to assess an increase of 116% in compressive strength for the addition of 5 wt % NCA to the bioepoxy matrix.

Investigating the Synthesis and Characteristics of UV-Cured Bio-Based Epoxy Vegetable Oil-Lignin Composites Mediated by Structure-Directing Agents.

Bio-based composites were developed from the epoxy derivatives of Lallemantia iberica oil and kraft lignin (ELALO and EpLnK), using UV radiation as a low energy consumption tool for the oxiranes reaction. To avoid the filler sedimentation or its inhomogeneous distribution in the oil matrix, different structure-directing agents (SDA) were employed: 1,3:2,4-dibenzylidene-D-sorbitol (DBS), 12-hydroxystearic acid (HSA) and sorbitan monostearate (Span 60). The SDA and EpLnK effect upon the ELALO-based formulations, their curing reaction and the performance of the resulting materials were investigated. Fourier-transform Infrared Spectrometry (FTIR) indicates different modes of molecular arrangement through H bonds for the initial ELALO-SDA or ELALO-SDA-EpLnK systems, also confirming the epoxy group's reaction through the cationic mechanism for the final composites. Gel fraction measurements validate the significant conversion of the epoxides for those materials containing SDAs or 1% EpLnK; an increased EpLnK amount (5%), with or without SDA addition, conduced to an inefficient polymerization process, with the UV radiation being partially absorbed by the filler. Thermo-gravimetric and dynamic-mechanical analyses (TGA and DMA) revealed good properties for the ELALO-based materials. By loading 1% EpLnK, the thermal stability was improved to with 10 °C (for Td3%) and the addition of each SDA differently influenced the Tg values but also gave differences in the glassy and rubbery states when the storage moduli were interrogated, depending on their chemical structures. Water affinity and morphological studies were also carried out.

Comparative Thermo-Mechanical Properties of Sustainable Epoxy Polymer Networks Derived from Linseed Oil.

Considering its great industrial potential, epoxidized linseed oil (ELO) was crosslinked with different agents, both natural and synthetic: citric acid (CA, in the presence of water-W, or tetrahydrofuran-THF, as activator molecules) and Jeffamine D230, respectively, resulting bio-based polymeric matrices, studied further, comparatively, in terms of their properties, through different methods. Thermal curing parameters were established by means of Differential Scanning Calorimetry (DSC). Fourier transform Infrared Spectroscopy (FTIR) and DSC were used to identify the reactivity of each ELO-based formulation, discussing the influence of the employed curing systems under the conversion of the epoxy rings. Then, the obtained bio-based materials were characterized by different methods, establishing the structure-properties relation. Thermogravimetric analysis revealed higher thermal stability for the ELO_CA material when THF was used as an activator. Moreover, a higher glass transition temperature (Tg) with ~12 °C was registered for this material when compared with the one that resulted through the crosslinking of ELO with D230 conventional amine. Other important features, such as crosslink density, storage modulus, mechanical features, and water affinity, were discussed. Under the loop of a comprehensive approach, a set of remarkable properties were obtained for ELO_CA_THF material when compared with the one resulting from the crosslinking of ELO with the synthetic Jeffamine.

Salicin and Hederacoside C-Based Extracts and UV-Absorbers Co-Loaded into Bioactive Lipid Nanocarriers with Promoted Skin Antiaging and Hydrating Efficacy.

Conventional and herbal active principles can be combined in a beneficial harmony using their best features and compensating for the certain weaknesses of each. The study will answer the question, "how can willow bark extract (Wbe) or ivy leaf extract (Ile) influence the photoprotective, skin permeation and hydration properties of Bioactive Lipid Nanocarriers (BLN) loaded with UV-filters and selected herbals?". BLN-Wbe/Ile-UV-filters were characterized for particle size, zeta potential, thermal behavior, entrapment efficiency and drug loading. The formulated BLN-hydrogels (HG) were subjected to in vitro release and permeation experiments. The in vitro determination of sun protection factors, as well as comparative in vitro photostability tests, rheology behavior and in vivo hydration status have been also considered for hydrogels containing BLN-Ile/Wbe-UV-filters. Photoprotection of BLN-HG against UVA rays was more pronounced as compared with the UVB (UVA-PF reached values of 30, while the maximum SPF value was 13). The in vitro irradiation study demonstrated the photostability of BLN-HG under UV exposure. A noteworthy cosmetic efficacy was detected by in vivo skin test (hydration effect reached 97% for the BLN-Wbe-UV-filters prepared with pomegranate oil). The research novelty, represented by the first-time co-optation of the active herbal extracts (Wbe and Ile) together with two synthetic filters in the same nanostructured delivery system, will provide appropriate scientific support for the cosmetic industry to design novel marketed formulations with improved quality and health benefices.

Composite Materials from Renewable Resources as Sustainable Corrosion Protection Coatings.

Epoxidized linseed oil (ELO) and kraft lignin (LnK) were used to obtain new sustainable composites as corrosion protection layers through a double-curing procedure involving UV radiation and thermal curing to ensure homogeneous distribution of the filler. The crosslinked structures were confirmed by Fourier-transform infrared spectrometry (FTIR), by comparative monitorization of the absorption band at 825 cm-1, attributed to the stretching vibration of epoxy rings. Thermal degradation behavior under N2 gas indicates that the higher LnK content, the better thermal stability of the composites (over 30 °C of Td10% for ELO + 15% LnK), while for the experiment under air-oxidant atmosphere, the lower LnK content (5%) conducted to the more thermo-stable material. Dynamic-mechanic behavior and water affinity of the new materials were also investigated. The increase of the Tg values with the increase of the LnK content (20 °C for the composite with 15% LnK) denote the reinforcement effect of the LnK, while the surface and bulk water affinity were not dramatically affected. All the obtained composites were tested as carbon steel corrosion protection coatings, resulting in significant increase of corrosion inhibition efficiency (IE) of 140-380%, highlighting the great potential of the bio-based ELO-LnK composites as a future perspective for industrial application.

Harnessing a byproduct from wastewater treatment to obtain improved starch/poly(vinyl alcohol) composites.

A rational method to harness a triglyceride-based by-product containing chicken fat traces, extracted from the simulated slaughterhouses wastewater was adopted. Methacrylated linseed oil was used as photo-reactive monomer to "catch" the grease molecules, resulting in a polymeric network (PFrec), further embedded in starch/poly(vinyl alcohol) (St/PVA)-based composites, with or without plasticizer (glycerol-Gly), with enhanced properties. Hydrophobic additive improved the thermal stability of St/PVA blends, an 18 °C increase of Td3 % being registered for PFrec-loaded sample. Mechanical tests revealed that association of PFrec with Gly improved the flexibility and also reinforced the systems, although, no plasticizing effect was observed at PFrec addition. Solubility determinations for the St/PVA-based composite films showed that hydrophobic PFrec increased the water resistance with at least 40 %. According to contact angle measurements a good dispersion of PFrec in the St/PVA network was mediated at the interface by hydrophilic Gly molecules.

Hybrid networks based on epoxidized camelina oil.

Lately, renewable resources received great attention in the macromolecular compounds area, regarding the design of the monomers and polymers with different applications. In this study the capacity of several modified vegetable oil-based monomers to build competitive hybrid networks was investigate, taking into account thermal and mechanical behavior of the designed materials. In order to synthesize such competitive nanocomposites, the selected renewable raw material, camelina oil, was employed due to the non-toxicity and biodegradability behavior. General properties of epoxidized camelina oil-based materials were improved by loading of different types of organic-inorganic hybrid compounds - polyhedral oligomeric silsesquioxane (POSS) bearing one (POSS1Ep) or eight (POSS8Ep) epoxy rings on the cages. In order to identify the chemical changes occurring after the thermal curing reactions, FT-IR spectrometry was employed. The new synthesized nanocomposites based on epoxidized camelina oil (ECO) were characterized by dynamic mechanical analyze and thermogravimetric analyze. The morphology of the ECO-based materials was investigate by scanning electron microscopy and supplementary information regarding the presence of the POSS compounds were establish by energy dispersive X-ray analysis and X-ray photoelectron spectroscopy. The smooth materials without any separation phase indicates a well dispersion of the Si-O-Si cages within the organic matrix and the incorporation of this hybrid compounds into the ECO network demonstrates to be a well strategy to improve the thermal and mechanical properties, simultaneously.

Phenolated Oleic Acid Based Polybenzoxazine Derivatives as Corrosion Protection Layers.

Benzoxazine derivatives were synthesized using phenolated methyl oleate and either aniline, 1,6-diaminohexane, or 4,4'-diaminodiphenylmethane, respectively, as amine components. Polymerization of the benzoxazine derivatives led to the formation of hydrophobic and dense coatings on Zn-Mg-Al alloy coated steel sheets for passive corrosion protection. The polybenzoxazine coatings which are formed by crosslinking during a heat-treatment step invoked a substantial anodic shift of the open-circuit potential as well as the breakthrough potential in potentiodynamic measurements. The proposed polybenzoxazine derivatives pave the way for a new type of passive polymer protection system based on sustainably obtained precursor components.