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The spontaneously self-organizing multilayered graphite-like carbon (denoted as GLC) /TiC films with various bilayer periods in the range of 13.3–17.5 nm were deposited on silicon and 1Cr18Mn8Ni5N stainless steel substrates using closed field magnetron sputtering deposition facility. The microstructures and chemical compositions of the prepared multilayered films were characterized by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy respectively. The self-organizing multilayered structures in all of the films consisted of titanium carbide layers and sp2-rich carbon layers periodically alternate arrangement. The TiC contents and bilayer periods of the multilayered films can be controlled by means of adjusting of sputtering current of graphite target. Furthermore, the mechanical and tribological performances of the prepared films were appraised by nano-indentor, scratch measures, and ball-on-plate tribometer respectively. The results indicated that multilayer structure endowed the as-deposited TiC/GLC films outstanding mechanical and tribological properties, especially the multilayer film with 15.9 nm bilayer period deposited at 10 A sputtering current showed the excellent adhesion strength and hardness, Simultaneously it also exhibited the lowest average friction coefficient in the humid environment owing to its high content of sp2 hybrid carbon.

Introduction. An incomplete list of graphene properties includes high electric conductivity, thermal conductivity, strength, large surface area, high light transmittance. Graphene is a very promising material from the point of view of its application in micro- and nanoelectronics. In addition, graphene advantage is a possibility of its obtaining by various ways. It allows creating materials with desired physicochemical properties by using appropriate technological methods. Objective. The investigation of a thermal reduction temperature influence on physicochemical properties of graphene oxide (GO) films. Materials and methods. In the present work, GO films are obtained on a slide surface by its immersing and removing from a graphene oxide water dispersion (dip coating). Obtained samples are studied by methods of scanning electron microscopy, Raman spectroscopy, and elemental CHN analysis. A sheet resistance is measured by a four-point probes method. Results. A content difference of elements (C, H, N) in studied samples, and both graphene structure defectiveness and sheet resistance decrease, are found to be proportional to a reduction temperature increase. A GO films thickness decrease during a heat treatment is also observed, which is presumably associated with a functional GO groups loss while thermal reduction. Conclusion. Research results demonstrate a possibility of a carbon films with desired physicochemical properties obtaining from a reduced graphene oxide (RGO), which can be used in thin-film technologies. Presented materials can also be useful in issues related to GO and RGO obtaining and applying.

High dielectric constant ceramics fillers are widely used as fillers in polymer matrix to prepare high performance dielectric composites. Homogeneous filler distribution in these composites films is found to be quite difficult to achieve balance between high dielectric constant and high breakdown strength. Herein, multilayer structured composites films containing nickelous hydroxide (Ni(OH)2) as fillers, with different multilayered structures were designed and prepared, including 2–5 layers structure with various filler distribution. The effects of multilayer structure on the dielectric performance are explored by keeping the overall filler content constant. Combined with computer simulation, it is suggested that the variation in filler distribution in these films can effectively redistribute electric field intensity. Meanwhile, the dielectric constant and breakdown strength of the overall composites can be adjusted by changing the volume ratio between high filler content layer and low filler content layer. It is noted that at least 1/3 of the overall film volume should be occupied by a high breakdown strength layer to keep rather high overall breakdown strength. Moreover, high dielectric constant layer should be the outer layers to achieve overall high dielectric constant. Among all the layered structures investigated, the maximum energy density of 6.03 J/cm3 is obtained for film with a 3-layer nonsequential arrangement structure, which is 68% higher than single layer film with identical composition. This study provides some reference value for the preparation of multilayered dielectric polymer composites films for energy storage applications.

Multilayer thin films polymer have been commonly used in a wide range of electronics applications, such as solar cells, photoconductors, semiconductors, and light-emitting diodes, in which failure due to delamination can occur. For evaluating and improving the quality of a multilayer thin-film product, the interfacial strength between its layers must be measured correctly and accurately. In this work, the interfacial strength of a multilayer thin-film polymer was quantified by measuring the interfacial energy release rate (interfacial fracture toughness), Gi , using the nanoindentation test technique. Three specimens of four-layer thin films were fabricated on a glass substrate. The top layer of each specimen was prepared with different thicknesses. The unloading curve technique introduced by Kozuki and Kishimoto (2010) was implemented to quantify the Gi of each specimen. Then, cross-sectional observation of the specimens was performed to confirm the layer thicknesses and to identify the delamination condition after the test. The measured Gi tended to increase as the range between the two unloading curves used to calculate the delamination energy widened. This phenomenon is believed to be caused by the plastic energy of the deformed films during the indentation process. Finally, an empirical method for eliminating the effect of the plastic energy on the measured Gi was proposed. Using this method, a pure Gi value can be effectively extracted; thus, the interfacial strength of multilayer thin-film polymers can be measured correctly and accurately.

In the increasingly pressing context of improving recycling, optical technologies present a broad potential to support the adequate sorting of plastics. Nevertheless, the commercially available solutions (for example, employing near-infrared spectroscopy) generally focus on identifying mono-materials of a few selected types which currently have a market-interest as secondary materials. Current progress in photonic sciences together with advanced data analysis, such as artificial intelligence, enable bridging practical challenges previously not feasible, for example in terms of classifying more complex materials. In the present paper, the different techniques are initially reviewed based on their main characteristics. Then, based on academic literature, their suitability for monitoring the composition of multi-materials, such as different types of multi-layered packaging and fibre-reinforced polymer composites as well as black plastics used in the motor vehicle industry, is discussed. Finally, some commercial systems with applications in those sectors are also presented. This review mainly focuses on the materials identification step (taking place after waste collection and before sorting and reprocessing) but in outlook, further insights on sorting are given as well as future prospects which can contribute to increasing the circularity of the plastic composites’ value chains.

In this study, we report the isolation of cellulose nanocrystals (CNCs) from Isora plant fibers by sulfuric acid hydrolysis and their assembly on hydrophilic cellulose and silicon-di-oxide (SiO2) surfaces via a layer-by-layer (LBL) deposition method. The isolated CNCs were monodis-persed and exhibited a length of 200-300 nm and a diameter of 10-20 nm, a negative zetapotential (34-39 mV) over a wide pH range, and high stability in water at various concentrations. The multi-layered structure, adsorbed mass, conformational changes, and anticoagulant activity of sequen-tially deposited anionic (sulfated) CNCs and cationic polyethyleneimine (PEI) on the surfaces of cellulose and SiO2 by LBL deposition were investigated using a quartz crystal microbalance tech-nique. The organization and surface features (i.e., morphology, thickness, wettability) of CNCs ad-sorbed on the surfaces of PEI deposited at different ionic strengths (50-300 mM) of sodium chloride were analysed in detail by profilometry layer-thickness, atomic force microscopy and contact angle measurements. Compared to cellulose (control sample), the total coagulation time and plasma deposition were increased and decreased, respectively, for multilayers of PEI/CNCs. This study should provide new possibilities to fabricate and tailor the physicochemical properties of multilayer films from polysaccharide-based nanocrystals for various biomedical applications. Acknowledgments: The authors acknowledge Volker Ribitsch (retired) from the University of Graz/Austria for his support and valuable discussion for this manuscript. The authors also acknowledge the financial support from the Slovenian National Research Agency ARRS (Grant No. J4-1764). Scopus

Xingfang Yu,1,* Xin Liao,2,* Hongwei Chen1 1Department of Orthopedics, The Affiliated Yiwu Hospital of Wenzhou Medical University, Yiwu, Zhejiang, 322000, People’s Republic of China; 2Department of Orthopedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, People’s Republic of China*These authors contributed equally to this workCorrespondence: Hongwei ChenDepartment of Orthopedics, The Affiliated Yiwu Hospital of Wenzhou Medical University, Yiwu, Zhejiang, 322000, People’s Republic of ChinaTel +86-13506896988Email sssaaa18@163.comBackground: Bone infections remain one of the most common and serious complications of orthopedic surgery, posing a tremendous economic burden to society and patients. This is because bacteria colonize and multiply on the surface of the implant. The (MMT/PLL)8 multilayer films have been shown to effectively release antibiotics depending on the changes in the microenvironment. Here, vancomycin was loaded into the (MMT/PLL)8 multilayer films, which were prepared to be used as a local delivery system for the treatment of bone infections.Methods: We used the layer-by-layer self-assembly method to prepare VA-loaded coatings (MMT/PLL-VA)8 consisting of montmorillonite (MMT), poly-L-lysine (PLL), and VA. The thickness and surface morphology of coatings were characterized using spectroscopic ellipsometry and scanning electron microscopy (SEM). In order to evaluate the drug release behavior from coatings in different media, we measured the size of the zone of inhibition. Additionally, in vitro antibacterial activity was assessed using the shake-flask culture method and SEM images, while that of in vivo was evaluated by establishing an animal model of bone infection.Results: Our findings revealed that small-molecule antibiotics were successfully loaded into the (MMT/PLL-VA)8 multilayer film structure during the hierarchical self-assembly process and subsequently the multilayer film structure depicted linear growth behavior. The PLL in the multilayer films was progressively degraded which triggered the VA release when contacted with CMS or bacterial infections. The release of VA from multilayer film structure depends on the concentration changes of CMS. Notably, the multilayer films presented great in vitro cell compatibility. Moreover, the prepared antibacterial multilayer films showed excellent antibacterial property by killing more than 99.99% of S. aureus in 24 h. More importantly, we found that multilayer film exhibits good sterilization effect and biocompatibility under the stimulation of bacterial liquid both in vitro and in vivo antibacterial ability tests.Conclusion: Altogether, this study shows that (MMT/PLL-VA)8 multilayer films containing CMS and bacteria-responsive drug release properties posess high bactericidal activity and good biocompatibility. This finding provides a novel strategy for the treatment of bone infections.Keywords: bone infections, multilayer films, microenvironment, layer-by-layer, antibacterial

Adjusting the inter-particle distances in ordered nanoparticle arrays can create new nano-devices and is of increasing importance to a number of applications such as nanoelectronics and optical devices. The assembly of negatively charged polystyrene (PS) nanoparticles (NPs) on Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes, quaternized PDMAEMA brushes and Si/PEI/(PSS/PAH)2, was studied using dip- and spin-coating techniques. By dip-coating, two dimensional (2-D), randomly distributed non-close packed particle arrays were assembled on Si/PEI/(PSS/PAH)2 and PDMAEMA brushes. The inter-particle repulsion leads to lateral mobility of the particles on these surfaces. The 200 nm diameter PS NPs tended to an inter-particle distance of 350 to 400 nm (center to center). On quaternized PDMAEMA brushes, the strong attractive interaction between the NPs and the brush dominated, leading to clustering of the particles on the brush surface. Particle deposition using spin-coating at low spin rates resulted in hexagonal close-packed multilayer structures on Si/PEI/(PSS/PAH)2. Close-packed assemblies with more pronounced defects are also observed on PDMAEMA brushes and QPDMAEMA brushes. In contrast, randomly distributed monolayer NP arrays were achieved at higher spin rates on all polyelectrolyte architectures. The area fraction of the particles decreased with increasing spin rate.

Ferroelectric multilayer films attract great attention for a wide variation of applications. The synergistic effect by combining different functional layers induces distinctive electrical properties. In this study, ferroelectric BaZr0.2Ti0.8O3/PbZr0.52Ti0.48O3/BaZr0.2Ti0.8O3 (BZT/PZT/BZT) multilayer thin films are designed and fabricated by using the magnetron sputtering method, and a LaNiO3 (LNO) seed layer is introduced. The microstructures and electrical properties of the BZT/PZT/BZT films with and without the LNO seed layer are systematically studied. The results show that the BZT/PZT/BZT/LNO thin film exhibits much lower surface roughness and a preferred (100)-orientation growth, with the growth template and tensile stress provided by the LNO layer. Moreover, an enhanced dielectric constant, decreased dielectric loss, and improved ferroelectric properties are achieved in BZT/PZT/BZT/LNO thin films. This work reveals that the seed layer can play an important role in improving the microstructure and properties of ferroelectric multilayer films. Published version The authors gratefully acknowledge support from the Outstanding Youth Fund of Heilongjiang Province (No. YQ2020E031). China Postdoctoral Science Foundation (No.2021T140166)

Orientadores: Marisa Masumi Beppu, Bradley David Olsen Tese (doutorado)- Universidade Estadual de Campinas, Faculdade de Engenharia Química Resumo: A funcionalização de superfícies com recobrimentos nanoestruturados tem sido explorada para superar desafios biotecnológicos, da entrega direcionada de fármacos à captura seletiva de analitos para diagnóstico. Proteínas recombinantes tem um papel de destaque no desenvolvimento de superfícies bioativas, permitindo o desenvolvimento de macromoléculas com as funcionalidades desejadas. A técnica layer-by-layer (LbL) tem se popularizado como uma estratégia simples e versátil para a funcionalização de superfícies com mínimas restrições quanto à superfície e aos materiais depositados. Ambas as estratégias, no entanto, requerem esforços significativos para determinar as condições adequadas produzir novos materiais. Esta tese teve como objetivo facilitar a produção de materiais à base de biopolímeros e proteínas recombinantes, a partir de métodos automatizados de alta produtividade (high-throughput). Inicialmente, a técnica LbL foi adaptada para a deposição de filmes multicamadas em placas de 96 de poços, permitindo a investigação de diferentes condições de deposição dos recobrimentos na mesma batelada. Este método mostrou-se efetivo para a produção de recobrimentos de polissacarídeos, indicando que a quantidade de grupos amino e carboxílicos livres dos recobrimentos varia de acordo com o pH de deposição. Filmes híbridos à base de polipeptídios do tipo elastina (ELPs) e polissacarídeos, formados a partir de interações eletrostáticas, demostraram que condições de pH que promoveram baixos graus de ionização dos polieletrólitos e a presença de aminoácidos com resíduos hidrofóbicos nas ELPs favoreceram o crescimento dos recobrimentos. Esta tese também explorou a versatilidade no design de ELPs para investigar uma biblioteca de interações complementares para a formação de recobrimentos multicamadas. Interações do tipo Spy-Tag/Spy-Catcher e ZE/ZR (ou zíperes de leucina), dentre outras, mostraram-se capazes de direcionar a deposição auto-organizada dos recobrimentos. Recobrimentos formados por interações Spy-Tag/Spy-Catcher também apresentaram significativa estabilidade em diversas condições de pH (3.0 - 12.0) e força iônica (5.0 mol/L NaCl) que dissociaram filmes formados por interações eletrostáticas. O método high-throughput-LbL também foi usado para investigar o efeito das condições de deposição na incorporação e liberação de uma molécula modelo (calceína) em recobrimentos de poli(ácido acrílico)/poli(alilamina). Neste caso, maiores valores de pH (> 8.5) e a presença de sais como NaCl ou MgCl2 (ambos a 0.05 mol/L) nas soluções polieletrolíticas favoreceram a incorporação de calceína nos recobrimentos. O método de incorporação também alterou a morfologia dos recobrimentos e os mecanismos de liberação de calceína, resultando em taxas de liberação mais lentas para incorporação durante a deposição das multicamadas. Por fim, esta tese também explorou estratégias high-throughput para testar a síntese de proteínas recombinantes. Protocolos de biologia molecular, da transformação à biossíntese das proteínas, foram automatizados, permitindo testar dezenas de combinações de linhagem celular-vetor em cada experimento. Foram desenvolvidos ainda protocolos automatizados para a quantificação de proteína total (Bradford) e específica (6×His-tag immunoassay), auxiliando na triagem das condições adequadas para a biossíntese de mCherry (proteína modelo). De modo geral, esta tese destacou o uso de métodos high-throughput para facilitar o desenvolvimento de materiais à base de biopolímeros e proteínas que demandem inúmeras etapas de testagem e otimização, contribuindo para acelerar os ciclos de inovação na área de biotecnologia Abstract: Surface functionalization has been explored to overcome biotechnologically relevant challenges, from the targeted drug delivery to the selective capture of bioactive agents for diagnosis. Recombinant protein plays an important role in designing bioactive surfaces by designing macromolecules with the desired functionalities. The layer-by-layer (LbL) technique became a popular strategy for surface functionalization with minimal restrictions regarding the coated surface and the materials deposited. Nevertheless, both strategies demand substantial efforts to determine the appropriate conditions to prepare the newly designed materials. This thesis aimed to streamline the production of biopolymer- and recombinant protein-based materials through high-throughput methods. At first, the LbL method was adapted to deposit multilayer films on 96-well plates, enabling one to investigate different assembly conditions into the same batch. This method effectively produced polysaccharide-based films, indicating the dependence of free amino and carboxylate groups on multilayers to the assembly pH conditions. Hybrid polysaccharide/recombinant elastin-like polypeptides (ELPs) were also assembled based on electrostatic interactions. ELP variants containing a higher number of hydrophobic residues and assembly pH conditions that promoted lower ionization degrees of both polyelectrolytes led to higher film growth. This thesis also explored protein engineering's versatility for designing a library ELPs fused with complementary isopeptide binding domains for self-assembly LbL films. Spy-Tag/Spy-Catcher and leucine zipper ZE/ZR interactions, among others, were effective to drive the self-assembly deposition of multilayer films. Spy-Tag/Spy-Catcher also led to resistant multilayers over a wide range of pH (3.0 – 12.0) and ionic strength (5.0 mol/L NaCl), which may disassemble traditional polyelectrolyte-based multilayers. The high-throughput-LbL method was also used to investigate the role of film assembly conditions on the loading and release of a model drug molecule (calcein) on poly(acrylic acid)/poly(allylamine hydrochloride) multilayer films. Higher values of pH (> 8.5) and the presence of NaCl or MgCl2 salts (both at 0.05 mol/L) in the polyelectrolyte solutions favored the model drug loading in multilayer films. The drug loading method also affected the film morphology and drug transport mechanisms, leading to slower drug release rates for films loaded during polyelectrolyte multilayer deposition. Finally, this thesis explored the use of the high-throughput approach for recombinant protein test expression. Molecular biology protocols, from cell transformation to protein biosynthesis, were automated to screen tens of different cell strain-vector combinations per batch. The study also focused on automating analytical total (Bradford) and histidine-tagged (immunoassay) protein quantification to determine the most favorable condition for mCherry biosynthesis (model protein). Overall, this thesis sheds light on using high-throughput methods to facilitate the development of biopolymer- or protein-based materials that demand intense testing and optimization, contributing to accelerating the innovation cycles in the biotechnology arena Doutorado Engenharia Química Doutor em Engenharia Química FAPESP 2016/10193-9 CAPES 33003017034P8

An understanding of the structural evolution in micro-/nano-layer co-extrusion process is essential to fabricate high-performance multilayered products. Therefore, in this work, we reveal systematically the multiscale structural development, involving both the layer architecture and microstructure within layers of micro-/nano-layer coextruded polymer films, as well as its relationship to dielectric properties, based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/polycarbonate (PC) system. Interestingly, layer architecture and morphology show strong dependences on the nominal layer thicknesses. Particularly, with layer thickness reduced to nanometer scale, interfacial instabilities triggered by viscoelastic differences between components emerge with the creation of micro-droplets and micro-sheets. Films show an enhanced crystallization with the formation of two-dimensional (2D) spherulites in microlayer coextruded systems and the oriented in-plane lamellae in nanolayer coextruded counterparts, where layer breakup in the thinner layers further changes the crystallization behaviors. These macro- and microscopic structures, developed from the co-extrusion process, substantially influence the dielectric properties of coextruded films. Mechanism responsible for dielectric performance is further proposed by considering these effects of multiscale structure on the dipole switching and charge hopping in the multilayered structures. This work clearly demonstrates how the multiscale structural evolution during the micro-/nano-layer coextrusion process can control the dielectric properties of multilayered products.

Poster presentation at CIS 2019 - Salerno (Italy)

In this work, we prepared TiO2 and Co multilayer thin films via DC magnetron sputtering method on (100) GaAs and (100) Si substrates. The power for each target (TiO2 and Co), deposition time of the layers, and pressure during deposition were kept constant. From XRD, Raman, and IR measurements, the formation of the rutile and triclinic Co phases were identified in the multilayer thin films. An annealing process was carried in situ on all samples and subsequent to the deposition stage during 2 h. The substrate used was GaAs and Si wafer, favoring the formation and growth of the found phases. The diffusion and interdiffusion of the layers in the thin films were determined from Rutherford Backscattering Spectroscopy (RBS). In particular, Co and Ga were observed to associate after the annealing process according to the depth profiles. Due to the interdiffusion layers, the parallel magnetic contribution is not significant in the bilayer. Curves I-V of the Co/TiO2 bilayer showed the presence of resistive switching, according to the bipolar resistive. A correlation between synthesis parameters and the physical properties of the multilayers is presented, The Universidad Nacional de Colombia, COLCIENCIAS Conv. 727- 2015 and Universidad del Rosario supported this work. Heiddy Paola Quiroz is scholarship PhD of Doctorados COLCIENCIAS. Acknowledgments to the Universidad del Rosario for the EDI 2017 scholarship to professor Fredy Mesa

O uso de polímeros tem crescido rapidamente nas últimas décadas, sendo este fenômeno atribuído tanto ao aumento da população global quanto à mudança na forma de consumo da mesma. Apesar de inúmeras características desejáveis que estes materiais apresentam, inúmeras são as embalagens poliméricas comercializadas que carecem de meios econômica e/ou tecnologicamente viáveis de reciclagem, seja devido à sua composição, forma ou quantidade presente nos resíduos. O objetivo deste trabalho foi desenvolver materiais reciclados de filmes multicamadas pós-consumo a partir de sua estabilização à degradação termomecânica e fotooxidativa, e tenacificação, tendo em vista a sua valorização econômica, bem como a busca por alternativas à sua destinação final. Resíduos de filmes multicamadas pós-consumo metalizados e laminados foram coletados em uma cooperativa de reciclagem de Porto Alegre, e após beneficiados a partir de sua lavagem, secagem e moagem em aglutinador de filmes. Os resíduos foram aditivados com antioxidantes primário, secundário e absorvedor de UV. Melhores propriedades mecânicas foram buscadas a partir da incorporação tanto de compatibilizantes como polietileno graftizado com anidrido maléico (PE-gAM) e polipropileno graftizado com anidrido maléico (PP-gAM) quanto de copolímero de propileno-etileno (EPR) como tenacificante. A partir de análise de calorimetria diferencial por varredura, verificou-se a composição polimérica aproximada de polipropileno (44,61%), polietilenos de baixa densidade e linear de baixa densidade (21,17%) e poli(tereftalato de etileno) (19,31%) do material reciclado obtido. Análises térmicas, físicas e morfológicas indicaram o efeito compatibilizante tanto dos compostos grafitizados, quanto do co-polímero EPR no resíduo, resultando em morfologias mais homogêneas e suaves, e propriedades mecânicas melhoradas. A adição de 5/5 %m de PE-gAM/PP-gAM resultou em um aumento de até 70% na resistência ao impacto do material (26,13 kJ/m²), enquanto que a incorporação de 30% de EPR aumentou em até 172% esta propriedade (41,93 kJ/m²). Em termos gerais, a adição em conjunto de compatibilizantes e copolímero nas proporções de 3/3 %m e 20%, respectivamente, apresentou a melhor performance. The use of polymers has grown rapidly in recent decades due to the increase in the global population and the change in the form of consumption thereof. Despite of numerous desirable characteristics these materials present, countless commercial polymeric packages lacks of economical and/or technologically viable means of recycling, either due to their composition, shape or quantity present in the waste. The aim of this work was to develop recycled materials from post-consumer multilayer films with stabilization to thermomechanical and photooxidative degradation, and tenacification, in view of their economic valorization, as well as the search for alternatives to their final destination. Metallized and laminated post-consumer multilayer film residues were collected at a recycling cooperative in Porto Alegre, and then washed, dried and grinded in a film agglutinator. Primary and secondary antioxidants and UV-absorbing additive were added to the residues. Better mechanical properties were sought through the incorporation of both compatibilizers and polyethylene graftized with maleic anhydride (PE-gAM) and polypropylene graftized with maleic anhydride (PP-gAM) as well as propylene-ethylene copolymer (EPR) as tenacifier. From differential scanning calorimetry analysis, the approximate polymeric composition of the recycled material was identified of polypropylene (44.61%), low density linear and low density polyethylene (21.17%) and poly (ethylene terephthalate) (19%). Thermal, physical and morphological analyzes indicated the compatibilizing effect of both graphitized compounds and EPR copolymer in the residue, resulting in more homogeneous and smooth morphologies, and improved mechanical properties. The addition of 5/5% m PE-gAM / PP-gAM resulted in an increase of up to 70% in the material's impact resistance (26.13 kJ / m²), while the incorporation of 30% EPR increased by up to 172% this property (41.93 kJ / m²). In general terms, the addition of compatibilizers and copolymer in the proportions of 3/3% m and 20%, respectively, presented the best performance.

Thermoplastic foams nowadays are widely used in a variety of applications, such as packaging, construction, and the automotive industry because of their wide range of properties such as lightweight, excellent strength/weight ratio, insulation properties, energy absorption performance, and material cost. However, there are still issues on the gas barrier and mechanical properties in use because of the cellular structure. This work targeted to unveil the processing-structure-property relationships of three film/foam multilayer polymeric systems with diverse transport properties. The first part of the thesis (Chapter 2) focuses on the understanding of the effect of the number of layers and composition on mechanical properties and barrier properties of multilayer film/foam material with alternating ethylene-vinyl alcohol copolymer (EVOH) film layers and low-density polyethylene (LDPE) foam layers. Tensile properties of the film/foams at elevated temperatures were used to optimize thermoforming conditions. Uniaxial orientation was discovered as an efficient approach to evaluate the potential for thermoforming. Oxygen transmission showed a strong correlation with the thickness reduction which could be used as an indicator for barrier properties of the packaging materials. Film/foam materials with 32 layers demonstrated optimum performance with low oxygen transmission along with high drawing capability. In the third chapter, the previous system (Chapter 2) was innovated with high-density polyethylene (HDPE) skin layer. High oxygen and water vapor barrier film/foam system had been developed using multilayer co-extrusion technology. The film/foams contained alternating low-density polyethylene (LDPE) foam layers and ethylene–vinyl alcohol (EVOH) copolymer film layers with HDPE skin layer. The lightweight film/foams showed oxygen and water vapor transmission rate are correlated with the EVOH film layer and HDPE skin layer composition. The layered film/foam was successfully thermoformed at 80 °C with low oxygen transmission along with high drawing capability. The fourth chapter introduces a novel approach, to produce PLA/PLA multilayer film/foams structures having 16, 32, and 64 alternating layers. The lightweight multilayered PLA/PLA film/foam has a unique solid/porous alternating horizontal architecture, in which the film layers can effectively control the growth of the cells and suppress the premature rupture of cells during coextrusion process. Tensile properties at elevated temperatures of the PLA film were used to optimize thermoforming conditions. The effects of annealing temperature and time on the crystallinity and oxygen permeability of PLA/PLA multilayer film/foams were investigated. Oxygen transmission showed a strong correlation with the crystallinity of PLA/PLA multilayer film/foam. The material demonstrated high performance with low oxygen transmission which could be used as high barrier material.

We report a study of the magnetization reversals and skyrmion configurations in two systems - Pt/Co/MgO and Ir/Fe/Co/Pt multilayers, where magnetic skyrmions are stabilized by a combination of dipolar and Dzyaloshinskii-Moriya interactions (DMI). First Order Reversal Curve (FORC) diagrams of low-DMI Pt/Co/MgO and high-DMI Ir/Fe/Co/Pt exhibit stark differences, which are identified by micromagnetic simulations to be indicative of hybrid and pure N\'eel skyrmions, respectively. Tracking the evolution of FORC features in multilayers with dipolar interactions and DMI, we find that the negative FORC valley, typically accompanying the positive FORC peak near saturation, disappears under both reduced dipolar interactions and enhanced DMI. As these conditions favor the formation of pure Neel skyrmions, we propose that the resultant FORC feature - a single positive FORC peak near saturation - can act as a fingerprint for pure N\'eel skyrmions in multilayers. Our study thus expands on the utility of FORC analysis as a tool for characterizing spin topology in multilayer thin films., Comment: 11 pages, 4 figures

Electromagnetic interference (EMI), an unwanted phenomenon, often affects the reliability of precise electronic circuitry. To prevent this, an effective shielding is prerequisite to protect the electronic devices. In this study, an attempt was made to understand how processing of polymeric blend nanocomposites involving multiwalled carbon nanotubes (MWCNTs) affects the evolving interconnected network structure of MWCNTs and eventually their EMI shielding properties. Thereby, the overall blend morphology and especially the connectivity of the polycarbonate (PC) component, in which the MWCNTs tend to migrate, as well as the perfectness of their migration, and the state of nanotube dispersion are considered. For this purpose, blends of varying composition of PC and poly(methyl methacrylate) were chosen as a model system as they show a phase diagram with lower critical solution temperature type of characteristic. Such blends were processed in two different ways: solution mixing (from the homogeneous state) and melt mixing (in the biphasic state). In both the processes, MWCNTs (3 wt %) were mixed into the blends, and the evolved structures (after phase separation induced by annealing in solution-mixed blends) and the quenched structures (as the blends exit the extruder) were systematically studied using transmission electron microscopy (TEM). Both the set of blends were subjected to the same thermal history, however, under different conditions such as under quiescent conditions (in the case of solution mixing) and under shear (in the case of melt mixing). The electrical volume conductivity and the evolved morphologies of these blend nanocomposites were evaluated and correlated with the measured EMI shielding behavior. The results indicated that irrespective of the type of processing, the MWCNTs localized in the PC component; driven by thermodynamic factors and depending on the blend composition, sea-island, cocontinuous, and phase-inverted structures evolved. Interestingly, the better interconnected network structures of MWCNTs observed using TEM in the solution-mixed samples together with larger nanotube lengths resulted in higher EMI shielding properties (-27 dB at 18 GHz) even if slightly higher electrical volume conductivities were observed in melt-mixed samples. Moreover, the shielding was absorption-driven, facilitated by the dense network of MWCNTs in the PC component of the blends, at any given concentration of nanotubes. Taken together, this study highlights the effects of different blend nanocomposite preparation methods (solution and melt) and the developed morphology and nanotube network structure in MWCNT filled blend nanocomposites on the EMI shielding behavior.

Encapsulation of cells has been an active area of research. Among various methods for encapsulation, Layer-by-Layer (LbL) offers extensive flexibility in the design of surfaces and their interfacial nanoarchitectonics. A diverse range of functionalities have been recently demonstrated for cell encapsulation including protection and improved circulation. Here, we present a new strategy of cell encapsulation in a hybrid coating containing LbL assembly functionalized with gold nanoparticle aggregates. The effect of this hybrid coating on cell viability was assessed. Subsequently, upon laser illumination the encapsulated cells undergo immediate necrosis caused by the localized heat generated by the laser beam on gold nanoparticle aggregates. Similarly to affecting polyelectrolyte multilayer capsules, one envisions controlling surface properties of cells remotely by a laser beam. Further applications of the proposed approach are expected to be in biomedicine.