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Stem cell-based therapies have shown promising results for the regeneration of the nervous system. However, the survival and integration of the stem cells in the neural circuitry is suboptimal and might compromise the therapeutic outcomes of this approach. The development of functional scaffolds capable of actively interacting with stem cells may overcome the current limitations of stem cell-based therapies. In this study, three-dimensional hydrogels based on graphene derivatives and cerium oxide (CeO2) nanoparticles are presented as prospective supports allowing neural stem cell adhesion, migration and differentiation. The morphological, mechanical and electrical properties of the resulting hydrogels can be finely tuned by controlling several parameters of the self-assembly of graphene oxide sheets, namely the amount of incorporated reducing agent (ascorbic acid) and CeO2 nanoparticles. The intrinsic properties of the hydrogels, as well as the presence of CeO2 nanoparticles, clearly influence the cell fate. Thus, stiffer adhesion substrates promote differentiation to glial cell lineages, while softer substrates enhance mature neuronal differentiation. Remarkably, CeO2 nanoparticle-containing hydrogels support the differentiation of neural stem cells to neuronal, astroglial and oligodendroglial lineage cells, promoting the in vitro generation of nerve tissue grafts that might be employed in neuroregenerative cell therapies.

Thin films of polymeric blends composed of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and polyethylene oxide (PEO) were investigated by varying the concentration of the two components over the entire range of compositions and the molecular weight of PEO. Phase separation and crystallization have been studied at different length scales by combining Atomic Force Microscopy (AFM) and Grazing Incidence Wide Angle X-ray Scattering (GIWAXS) using synchrotron light. Several different arrangements in the thin films of the two polymers constituting the blend were observed and discussed in detail, providing information about their reciprocal influence at the micro- and nano-scale. In addition to that, we were able to estimate quantitative nanomechanical and nanoelectrical properties via AFM and finally revealing the dependence of the thin films' physical properties on their composition and structure. By varying the blend composition, we achieved different coating capability, mechanical properties, and electrical conductivity. Furthermore, depending on the PEO molecular weight, the electrical response of the resulting blends’ thin films shows some differences. In the low range concentration, the blend thin films with high molecular weight PEO present coarser conducting paths than in those with the low molecular weight counterparts. For intermediate concentrations, a more effective phase segregation of PEDOT:PSS and PEO is achieved for high molecular weight PEO. These differences are also translated to different electrical conductivity.

We present the preparation of nanostructured conducting PEDOT:PSS thin films by solvent vapor annealing (SVA), using the low boiling point solvent tetrahydrofuran (THF). An Atomic Force Microscopy (AFM) study allowed the observation of distinct nanostructure development as a function of solvent exposure time. Moreover, the nanostructures’ physical properties were evaluated by nanomechanical, nanoelectrical, and nanoinfrared (nano-FTIR) measurements. In this way, we were able to differentiate the local response of the developed phases and to identify their chemical nature. The combination of these techniques allowed to demonstrate that exposure to THF is a facile method to effectively and selectively modify the surface nanostructure of PEDOT:PSS, and thereafter its final properties. Moreover, our nanoscale studies provided evidence about the molecular rearrangements that PEDOT:PSS suffers during nanostructure fabrication, a fundamental fact in order to expand the potential applications of this polymer in thermoelectric and optoelectronic devices.

Electrically conducting nanospheres of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) with tailored size were prepared using a solvent displacement technique. To fabricate these nanostructures, dried PEDOT:PSS was dissolved in ethylene glycol (EG) and the solution was precipitated in deionized water. The proposed fabrication route allowed obtaining a water-based dispersion of PEDOT:PSS nanospheres with good optical properties. To determine the physical properties of the nanospheres, we followed a nanoscale approach, using atomic force microscopy. Our nanoscale mechanical and electrical investigations showed that the nanospheres retained good physical and conductivity properties, compared to the commercial product. Moreover, the local studies indicated that the reprecipitation process and the spherical shape lead to a different arrangement of the PSS and PEDOT phases.

Acrylic/alkyd hybrid latexes offer the potential to obtain hard films from waterborne polymer dispersions without using coalescing agents. However, despite being widely used commercially, the curing process of the alkyd resin used in such formulations, and its influence on the final film morphology, remain poorly understood. In this work, we explore the curing process and its influence on film morphology in alkyd/acrylic hybrid latexes by nanomechanical mapping of the film during curing. It is shown that, although acrylic domains aid oxygen diffusion and facilitate curing, the rate of curing was substantially lower in the interior. Nevertheless, homogeneous curing was achieved at long times. The role of primary and secondary catalysts in the process is also explored, finding that the variation of the rate of curing of the alkyd plays an influential role in the development of film structure due to phase migration of the two polymers as curing progresses. It is hoped this work goes some way to unraveling the mystery behind the curing process in acrylic/alkyd hybrid latex films.

Dielectric relaxation is used to verify the bidirectional growth of arms in poly(glycidyl phenyl ether) (PGPE) synthesized by ring-opening polymerization with ethylene glycol and a phosphazene base, t-BuP4, in the presence and absence of triisobutylaluminum (i-Bu3Al). The dielectric relaxation is highly sensitive to changes in the dipolar moment orientation along the chain contour, allowing us to precisely identify whether the polymer is composed by “one arm” or “two arms” as well as to verify the arm symmetry. By means of broadband dielectric spectroscopy (BDS), we evaluated the dipolar microstructure of synthesized polymers and observed that in the absence of i-Bu3Al the polymers are certainly composed by two symmetric arms, whereas those obtained in the presence of i-Bu3Al are contaminated with large amounts of “one-arm” byproducts, in agreement with the data obtained by MALDI-ToF MS. Furthermore, BDS allowed us to quantify the relative amounts of one-arm impurities in two-arm PGPE samples, an analysis that cannot be performed by either MALDI-ToF MS or NMR.

In this study, water-based functional polymer inks are prepared using different solvent displacement methods, in particular, polymer functional inks based on semiconducting polymer poly(3-hexylthiophene) and the ferroelectric polymer poly(vinylidene fluoride) and its copolymers with trifluoroethylene. The nanoparticles that are included in the inks are prepared by miniemulsion, as well as flash and dialysis nanoprecipitation techniques and we discuss the properties of the inks obtained by each technique. Finally, an example of the functionality of a semiconducting/ferroelectric polymer coating prepared from water-based inks is presented.

The crystallization and morphology of two linear diblock copolymers based on polymethylene (PM) and poly(vinylidene fluoride) (PVDF) with compositions PM23-b-PVDF77 and PM38-b-PVDF62 (where the subscripts indicate the relative compositions in wt%) were compared with blends of neat components with identical compositions. The samples were studied by SAXS (Small Angle X-ray Scattering), WAXS (Wide Angle X-ray Scattering), PLOM (Polarized Light Optical Microscopy), TEM (Transmission Electron Microscopy), DSC (Differential Scanning Calorimetry), BDS (broadband dielectric spectroscopy), and FTIR (Fourier Transform Infrared Spectroscopy). The results showed that the blends are immiscible, while the diblock copolymers are miscible in the melt state (or very weakly segregated). The PVDF component crystallization was studied in detail. It was found that the polymorphic structure of PVDF was a strong function of its environment. The number of polymorphs and their amount depended on whether it was on its own as a homopolymer, as a block component in the diblock copolymers or as an immiscible phase in the blends. The cooling rate in non-isothermal crystallization or the crystallization temperature in isothermal tests also induced different polymorphic compositions in the PVDF crystals. As a result, we were able to produce samples with exclusive ferroelectric phases at specific preparation conditions, while others with mixtures of paraelectric and ferroelectric phases.

Over the past decades, polymer mechanochemistry has focused on the development and application of advanced force application methods to better understand the mechanochemical response of mechanophores. In this regard, techniques such as ultrasonication and single-molecule force spectroscopy (SMFS) are used to activate and detect up to thousands of chemical events within a polymer single chain, allowing the researchers to probe the mechanochemical reactivity of these stress-responsive motifs. Here, the most recent contributions of the single-molecule force spectroscopy technique to this field are presented, putting emphasis on the fundamental parameters of the technique for triggering specific force responses and on the description of force–extension curves measured for single- and multi-mechanophore polymers. Moreover, new contributions of microscopy-based techniques in the field of polymer mechanochemistry, as well as the potential application of single-chain nanoparticles as mechanoresponsive materials, are highlighted.

We report on the molecular origin of poly(pentamethylene 2,5-furanoate)’s particular physical properties. From the structural point of view, we found that this polymer can develop crystallinity when stored under room conditions for months. On the other hand, we used broadband dielectric spectroscopy measurements to analyze in great detail the local and segmental molecular dynamics of the material subjected to several thermal treatments. In this way, we evidenced that the molecular dynamics are sensitive to thermal history over a broad temperature range. This behavior has been attributed to possible interchain interactions detected via infrared spectroscopy and rheology measurements in the noncrystallized polymer.

Poly(2,5-alkylene furanoate)s are bio-based, smart, and innovative polymers that are considered the most promising materials to replace oil-based plastics. These polymers can be synthesized using ecofriendly approaches, starting from renewable sources, and result into final products with properties comparable and even better than those presented by their terephthalic counterparts. In this work, we present the molecular dynamics of four 100% bio-based poly(alkylene 2,5-furanoate)s, using broadband dielectric spectroscopy measurements that covered a wide temperature and frequency range. We unveiled complex local relaxations, characterized by the simultaneous presence of two components, which were dependent on thermal treatment. The segmental relaxation showed relaxation times and strengths depending on the glycolic subunit length, which were furthermore confirmed by high-frequency experiments in the molten region of the polymers. Our results allowed determining structure–property relations that are able to provide further understanding about the excellent barrier properties of poly(alkylene 2,5-furanoate)s. In addition, we provide results of high industrial interest during polymer processing for possible industrial applications of poly(alkylene furanoate)s.

Poly(alkylene 2,5-furanoate)s are considered as the most attractive and interesting alternatives to replace oil-based terephthalic polymers. These furan-based polyesters can be synthesized using fully bio-based synthetic strategies, allowing to reduce the environmental impact of plastics. At the same time, these polymers have shown outstanding thermal, mechanical and gas-barrier properties. All these results envisage their industrial use in the near future. Now, considering the downscaling of the products' size towards the nanometer scale, we present a study of the morphology and nanomechanical properties of poly(alkylene 2,5-furanoate) thin films. Using Atomic Force Microscopy, we report the development of nanostructures upon crystallization, following different thermal treatments, for thin films with thicknesses below 200 nm. Moreover, we studied the impact of crystal growth in the nanomechanical properties of these materials. We found that the polymer thin films preserve their excellent mechanical response even in the confined geometry, as proved by the Young's moduli values close to the GPa, accompanied by high surface stiffness, and low indentation depths. The poly(alkylene 2,5-furanoate) thin films were found to have nanomechanical properties comparable to those of oil-based terephthalic polymers, a further evidence that in the future they could replace traditional polymers in several applications.

Polymer nanostructures were developed on fully bio-based poly(trimethylene furanoate) (PTF) films, by using the technique of Laser Induced Periodic Surface Structures (LIPSS). We found that irradiation times between 1 and 8 min allowed the formation of periodic and nanometric ripples, when using an UV pulsed laser source at a fluence of 8 mJ/cm2. The wrinkled surfaces were studied by a combined macro- and nanoscale approach. We evaluated possible physicochemical changes taking place on the polymer surface after irradiation by infrared spectroscopy, contact angle measurements and atomic force microscopy. The macroscopic properties of PTF showed almost no changes after nanostructure formation, differently from the results previously found for the terephthalic counterparts, as poly(ethylene terephthalate), PET, and poly(trimethylene terephthalate), PTT. At the nanoscale, the surface mechanical properties of the nanostructured PTF were found to be improved, as evidenced by force spectroscopy measurements. In particular, stiffer surfaces characterized by an increased Young's modulus were measured for the nanostructured sample.

The drying of waterborne acrylic-alkyd hybrids is a complicated process, involving both curing of the alkyd phase and evolution of the overall morphology of the film. Understanding this drying process is of great importance in practical application of these hybrids, where the physical properties of the film are dictated by the film microstructure. Here, a mathematical model for the curing of coatings cast from acrylic-alkyd hybrid waterborne dispersions is developed. The model provides the dynamic development of the crosslinking density through the film. Furthermore, it also provides the evolution of the morphology of the coating in term of the size distribution of alkyd domains. The model is compared with experimental data from literature and used to predict the effect of variables such as primary catalyst concentration and acrylic polymer content on curing.

The effect of humidity on the ionic transport in the amorphous phase of poly(ethylene oxide) thin films has been studied by local dielectric spectroscopy. We explored a controlled humidity range between 15% RH and 50% RH. AFM-based local dielectric imaging allowed the thin film topography and the corresponding dielectric contrast maps to be obtained simultaneously. No humidity effect on the film topography was observed whereas large variation of the dielectric signal could be detected. In addition, we observed a clear dielectric contrast in different locations on the thin film surface. At selected regions with high contrast in the dielectric maps, we performed nanoDielectric Spectroscopy (nDS) measurements covering the frequency range from 5 Hz to 100 kHz. By modeling these spectroscopy results, we quantified the conductivity of the amorphous phase of the semicrystalline poly(ethylene oxide) films. The crystalline fraction of the PEO thin films was extracted and found to be about 36%, independently of humidity. However, the average conductivity increased by a factor of 25 from 2 × 10−10 to 5 × 10−9 S cm−1, by changing environmental humidity in the explored % RH range.

Broadband dielectric spectroscopy (BDS) is a powerful technique that allows studying the molecular dynamics of materials containing polar entities. Among a vast set of different applications, BDS can be used as a complementary tool in polymer synthesis. In this work, we will show how BDS can be used to validate architectural features in Type-A polymers, those having a net dipole moment component along the chain contour. Specifically, we will focus on the evaluation of the dielectric relaxation of poly(glycidyl phenyl ether) (PGPE) samples designed and synthesized with a variety of topologies and regio-orders: linear regio-regular chains synthesized from monofunctional and bifunctional initiators, macrocyclic regio-regular chains, and linear and macrocyclic regio-irregular chains. Our study highlights the impact of using BDS as a complementary characterization technique for providing topological details of polymers, which are otherwise not possible with many traditional techniques (e.g., NMR and mass spectrometry).