Semi-synthetic hydrogels made of carboxymethyl hyaluronic acid (CMHA) and polyacrylic acid (PAA) were synthesized using electron beam irradiation. The CMHA, with a degree of substitution of 0.87 and molecular weight of 141 kDa, was mixed with linear PAA and slightly crosslinked PAA(Carbopol). The gel properties of CMHA-PAA blends containing low amount of linear PAA (i.e. 35% CMHA: 5% PAA) irradiated at 40 kGy seemed to have similar gel properties to those of pure 40% CMHA hydrogels in our previous study. Equimolar ratio of CMHA-Carbopol blends (i.e. 10% CMHA: 10% Carbopol) were successfully crosslinked even at low irradiation dose (20 kGy) producing hydrogel with 60% gel fraction and 430 g/g degree of swelling. Furthermore, the FT-IR spectra of the 10% CMHA- 10% Carbopol blends revealed new peak at 875 cm-1 and increase of peak intensity at 1405 cm-1 due to neutralization reaction between the COOH and COO- groups of PAA and CMHA polymers. Interaction effects between the concentration of CMHA and PAA (small molar ratios) and varying irradiation doses in the gel properties in CMHA-PAA hydrogels will be explored in the future study. Radiation-crosslinking of biocompatible CMHA to other synthetic polymers, including PAA, provides a cleaner method of producing biomaterials with tunable properties that are ideal for pharmaceutical, medical, and cosmetic applications.

The interaction of polyelectrolyte-surfactant with interfaces plays a very important role in many technological fields, including cosmetics, food science or drug delivery. This has stimulated the research trying to shed light on the most fundamental aspects governing the adsorption processes and the equilibration of the interfacial layers. The current knowledge of the physico-chemistry of polyelectrolyte-surfactant systems has evidenced that in most of the cases, the association process of polyelectrolyte and surfactant molecules in the bulk is guided by non-equilibrium effects, even though the control of the mixing protocol allows obtaining reproducible aggregates (kinetically trapped-aggregates), with these non-equilibrium effects impacting decisively on their interfacial properties of polyelelectrolyte-surfactant systems. Therefore, the understanding of the interfacial processes involving polyelectrolyte-surfactant mixtures makes necessary the analysis of the association phenomena occurring in the bulk, i.e. the formation of the so-called polyelectrolyte-surfactant complexes, and their impact on the equilibration of the interface.

This work addresses the main physico-chemical aspects related to the formation of polyelectrolyte-surfactant layers at fluid interfaces, combining a careful examination of the equilibrium and rheological properties of the interfacial films with the structural and compositional information obtained using neutron reflectometry. Furthermore, the assembly of the mixtures will be correlated to the bulk association processes trying to provide a comprehensive picture describing the interfacial behavior of polyelectrolyte-surfactant mixtures at fluid interface. This requires the study of combinations of different polycations (poly(diallyldimethylammonium chloride) and chitosan) with surfactant bearing different charge (neutral, anionic and zwitterionic). Thus, it will be possible to obtain a whole perspective of the role of the association processes on the structure and properties of the interfacial layers.

Hydrogels (HG) are 3D network of hydrophilic macromolecules linked by different "cross-linking points", which have as main advantage their capacity for the adsorption of large amounts of water without any apparent dissolution due to cross-linking. Thus, the hydrogels can undergo reversible swelling-shrinking process upon the modification of the environmental conditions (pH, ionic strength or temperature). This stimuli-responsiveness and their ability to entrap in their interior different types of molecules makes of them suitable platforms for drug delivery applications. Furthermore, HGs exhibit certain similarities to the extracellular tissue matrix and can be used as a support for cell proliferation and migration.
The interest of the interaction between biological systems and hydrogels in different applications has stimulated the interest for designing hydrogels with a homogeneous nanometric size that can be distributed within different organ and tissue, and used for drug delivery or biosensing. This work proposes to take advantage of the inner cavity of liposomes for fabricating hyaluronic acid hydrogel nanoparticles with a well-controlled size. For this purpose, liposomes obtained using the reverse phase [1,2] technique where loaded with hyaluronic acid molecules which then undergo a cross-linking to
form a hydrogel matrix with a well-controlled size define by the dimensions of the inner core of the template liposome (Figure 1). This makes possible to fabricate either liposomes-coated or nude hydrogel nanoparticles which may be exploited in different technological fields including cosmetic,
ophthalmology (dry eye disease treatment) or food science.

Due to the wide-ranging of preservative surfaces applications, there is a need for a fundamental understanding of not only how to produce such exceptional surfaces but also to know how specific surface properties affect coatings pore wettability, for example, morphology and chemical comprehending. Silica-based hybrid coatings as advanced hybrid polymers have been shown to exhibit excellent chemical stability with a chance to functionalize combined with reducing the corrosion of metal substrates. However, researches show that sol-gel only has some limitations in terms of the period of anti-corrosive properties due to the high porosity. Therefore, this work will report the preliminary performance of the diffusion prevention in a silica-based hybrid sol-gel coating that has been enhanced by adding Oleic acid (OA) to the sol-gel formula. The evaluation of the effect of the adsorption mechanism of OA on aluminium alloys surface was studied based upon using infrared analysis (FTIR) as a non-destructive test separately. The chemical confirmation of adding OA to Sol-gel was done by infrared spectroscopy (ATR-FTIR) and supported by analyzing the morphology of the surface by using scanning electron microscopy (SEM) and water contact angle test (WCA). Furthermore, the coatings' corrosion performances were studied using electrochemical impedance spectroscopy (EIS) and Potential-dynamic polarization scanning (PDPS). As a result, the Oleic acid - silica-based hybrid coating exhibited exceptional functionalized pore-blocking, hydrophobic and anti-corrosion properties, providing mimicked active protection on the aluminium alloy 2024-T3 samples compared to sol-gel-only and non-coated samples.

There are a variety of hydrogels commonly used in 3D bioprinting. Hydrogels are synthetic matrices made up of a network of hydrophilic polymers that absorb water and/or biological fluids. They can be created from a large number of water-soluble materials including synthetic polymers, proteins, and polysaccharides. The 3D structure of these hydrogels is due to crosslinking which forms a structure which is insoluble in environmental fluid. The resemblance to different biological tissues, due to the elasticity and the presence of a large amount of water, allows the use of hydrogels in the regeneration of several types of damaged tissues (e.g., fibrin hydrogel is seeded with neural cells to regenerate brain tissue, keratinocytes are seeded in collagen hydrogel to regenerate skin tissue)

This work in the form of patent landscape analysis englobes information which could be used as a reference by researchers in the fields of 3D bioprinting, biomaterials, tissue engineering and biomedical engineering, as well as those interested especially in formulation of hydrogels. The state of the art has been reviewed by introducing what has been patented in relation to hydrogel-based bioinks. Furthermore, a detailed analysis of the patentability of the used hydrogels, their preparation methods and their formulations, as well as the 3D bioprinting process using hydrogels, have been provided by determining publication years, classifications, inventors, applicants, owners, and jurisdictions. The patent classification codes reveal that most inventions intended for hydrogels used as materials for prostheses or for coating prostheses characterized by their function or properties. Knowledge clusters and expert driving factors indicate that the research based on biomaterials, tissue engineering and biofabrication is concentrated in the most patents. Finally, this work which gives an analysis of the past, present and future trends lead to various recommendations that could help one to plan and innovate research strategy.

Silica-based coatings prepared by sol-gel polymerizing technology have been shown to exhibit excellent chemical stability combined with reducing the corrosion of metal substrates, showing promising use in aerospace and marine applications to protect light alloys. Moreover, this technology is an eco-friendly technique route for producing surface coatings, showing high potential for replacing toxic pre-treatment coatings of traditional conversation chromate coatings. This study aims to investigate the enhancement in corrosion protection of a hybrid-organic-inorganic silica-based coating cured at (80°C) by increasing the hydrophobicity to work on the aluminium 2024-T3 alloy. This approach involving a novel silica-based hybrid coating was prepared by introducing a 1H,1H,2H,2Hperfluorodecyltriethoxysilane (PFDTES) into the base hybrid formula created from tetraethylorthosilicatesilane (TEOS) and triethoxymethylsilane (MTMS) precursors; this formula was enhanced by introducing Polydimethylsiloxane polymer (PDMS). The corrosion protection properties of these coatings were examined by immersed in 3.5% NaCl with electrochemical impedance testing (EIS) and Potentiodynamic polarization scanning (PDPS). The chemical elements confirmation was done by infrared spectroscopy (ATR-FTIR); all this was supported by analyzing the surface morphology before and after the immersion by using scanning electron microscopy (SEM). The results of Electrochemical impedance testing analyses reveal the new open finite-length diffusion circuit element due to electrolyte media diffusion preventive by fluorinated groups. Also, it shows increases in corrosion protection arising from the increasing the hydrophobicity of the fluorinated coating compared to other formulas cured under similar conditions and bare Substrate. Additionally, the modified sol-gel exhibited improved resistance to cracking, while the increased hydrophobicity may also promote self-cleaning.

Poly(3-hexylthiophene) (P3HT) is a p-type organic semiconductor and is intrinsically a donor material. It is one of the most attractive polymers because of its high electrical conductivity and solubility in various solvents. However, its carrier mobility is considered low when compared to that of inorganic semiconductors. In the current study, it will be shown how the addition of different graphene (G) contents tailors the principal optical parameters of P3HT such as the bandgap, the hole collection, the carrier mobility, and the refractive index and the extinction coefficient. In particular, the hole collection and the carrier mobility are enhanced, and the bandgap reduced with increasing graphene content. The optical constants n (refractive index) and κ (absorption coefficient) of the nanocomposite with 1 wt% G have been fitted to different analitical functions with good agreement between the experimental an the theoretical values. The application of these nanocomposites in a specific organic solar cell (OSC) will be assessed. Finally, the simulation of the photocurrent in this OSC and the comparison with the OSC comprising only pristine P3HT is detailed.

Filler and fiber material loading and surface modification are some of the factors that significantly influences the tensile properties of the natural fiber-reinforced plastic composites. It is therefore pertinent that they are suitably selected in order to yield the optimum tensile properties. In this work, Box-Behnken Design was selected as experimental design approach. Fiber-reinforced PLA composites were prepared using compression molding. Rice husks and clay were utilized as fiber and filler materials respectively. The factors, namely clay filler loading (1-5 wt.%), rice husk fiber loading (10-30 wt.%), alkali concentration (0-4 wt.%), rice husk variety (K85, K98) and alkali type (NaOH, Mg(OH)₂) were varied with a total of 68 individual experiments. ANOVA was used to determine the significance of the factors affecting composites’ tensile strength. Results from ANOVA also revealed that the reduced cubic model best fits the tensile strength response. Derringer’s desirability function revealed that the variable values leading to optimum tensile strength (33.67 MPa) were 4.99 wt.%, 12.17 wt.% and 3.97 wt.% for filler loading, fiber loading and alkali concentration, respectively.

Using aqueous emulsion as the medium in radiation-induced graft polymerization (RIGP) offers an environment-friendly shift from organic solvents while increasing polymerization efficiency through known water radiolysis-based graft initiation. It has been successfully applied to a variety of hydrophobic vinyl monomers conventionally grafted in bulk or solution. Here, we further extend the applicability of RIGP in emulsion under the influence of reversible addition-fragmentation chain transfer (RAFT) polymerization mechanisms. Emulsions consisting of glycidyl methacrylate, 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid, and Tween-20 showed good colloidal stability for several hours. These emulsions were then used to graft abaca fibers through simultaneous gamma irradiation up to 6 kGy. Emulsions with smaller monomer micelles seemed to enhance the degree of grafting as a function of diffusion coefficient and surface area coverage. The degree of grafting also increased linearly with irradiation time before plateauing, at which point conversion indicated complete consumption of monomers. Indirect molecular weight analysis – using the free polymers generated during RIGP – showed good agreement with theoretical calculations and displayed relatively low polydispersity. Successful grafting was further supported by IR, SEM, and TG analysis. RAFT-mediated RIGP in aqueous emulsion shows good potential as a versatile and green surface modification technique for natural fibers for various functional and industrial applications.

The development of the automotive sector and increasing amount of vehicles all over the world poses multiple threats to the environment. One of them, probably not so emphasized as others, is the enormous amount of post-consumer car tires. Due to the potential fire threat, waste tires are considered as dangerous waste, which should not be landfilled, so it is essential to develop efficient methods of their utilization. One of the possibilities is their shredding and application of resulting ground tire rubber (GTR) as filler for polymer composites, which could take advantage of the excellent mechanical performance of car tires. Nevertheless, due to the poor compatibility with majority of polymer matrices, prior to the application, surface of GTR particles should be modified and activated. In the presented work, the introduction of thermo-mechanically modified GTR into flexible foamed polyurethane matrix was analyzed. Among the compounds applied during manufacturing of polyurethane foams can be found isocyanates, which are able to react and generate covalent bonds with the functional groups present on the surface of modified GTR. Such an effect can noticeably enhance the interfacial interactions and boost up the mechanical performance. Nevertheless, it requires the adjustment of formulations used during manufacturing of foams. Therefore, for better understanding of the process foams with varying isocyanate index (from 0.9 to 1.1) were prepared with and without taking into account the possible interactions with functional groups of GTR. For comparison, unfilled matrix and composite containing deactivated GTR were also prepared.