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The addition of silver(i) ions to the methylene glycol-sulphite (MGS) clock reaction results in the sudden formation of metallic silver nanoparticles. Stable suspensions are obtained in the presence of poly(vinylpyrrolidone). The time delay before the appearance of the particles, as well as their size, decreases with the initial methylene glycol concentration while their monodispersity increases., Nanoscale Advances, 5 (8), ISSN:2516-0230

The building sector, including building operations and materials, was responsible for the emission of ∼11.9 gigatons of global energy-related CO

The aim of this paper is to demonstrate the efficiency of a low-cost and sustainable timber-based energy dissipation system with recentering ability, which can be used as a seismic isolation system or a tuned mass damper for the seismic protection of structures in developing or developed countries. The system, defined as Dovetail with SPrings (Dove-SP), utilizes the attractive properties of timber to store CO2, thus reducing the carbon footprint of the existing energy dissipation systems: It comprises two timber slabs that are designed to slide against each other in a motion that is restrained by a dovetail sliding joint. Two sliding interfaces that allow this sliding motion at an attractively low friction coefficient are experimentally investigated: A PVC sand-wich (PVC-s) sliding interface, comprising a thin layer of sand that is sand-wiched between two PVC layers and a timber sand-wich sliding interface consisting of a thin layer of sand encapsulated between two beech timber surfaces. A set of low-cost steel springs is designed and installed on both sides of the dovetail joint to recenter the structure back to its original position after the end of an earthquake ground motion excitation. A novel, low-cost and deformable wood material fabricated from delignified balsa wood is used to reduce the pounding effects before the activation of the steel springs. The seismic behavior and the recentering ability of the novel timber-based energy dissipation system subjected to an ensemble of recorded earthquake ground motion excitations was experimentally investigated through a large-scale shaking table investigation at ETH Zurich., Bulletin of Earthquake Engineering, 21 (8), ISSN:1570-761X, ISSN:1573-1456

The autonomous activation of acid-autocatalyzed sulfite-halogenate (iodate, bromate, chlorate) reactions is programmed using slow acid generators (delta-gluconolactone GL, and 1,3-propanesultone PrS). A remarkable correlation is found between the pH- and temperature-time profiles, especially for the chlorate-sulfite-GL system. Further optimization of the latter resulted in a chemical system able to generate sudden temperature and pH changes after a tailorable induction time, that is a "thermochemical clock"., ChemSystemsChem

Buildings are significant end-users of global energy. About 20% of the energy consumption worldwide is used for maintaining a comfortable indoor climate. Therefore, passive systems for indoor temperature and humidity regulation that can respond to environmental changes are very promising to reduce buildings' energy consumption. We developed a process to improve the responsiveness of wood to humidity changes by laser-drilling microscopic holes and incorporating a hygroscopic salt (calcium chloride). The resulting "transpiring wood" displays superior water adsorption capacity and high moisture exchange rate, allowing regulation of humidity and temperature by the exchange of moisture with the surrounding air. We proved that the hygrothermal performance of transpiring wood can be used to regulate indoor climate, with associated energy savings, for various climate types, thus favoring its application in the building sector. The reduction of temperature fluctuations, thanks to the buffering of temperature peaks, can lead to an indirect energy saving of about 10% for cooling and between 4-27% for heating depending on the climate. Furthermore, our transpiring wood meets different sustainability criteria, from raw materials to the fabrication process, resulting in a product with a low overall environmental impact and that is easy to recycle., Materials Horizons, 10 (1), ISSN:2051-6347, ISSN:2051-6355

Wood is a renewable resource with excellent qualities and the potential to become a key element of a future bioeconomy. The increasing environmental awareness and drive to achieve sustainability is leading to a resurgence of research on wood materials. Nevertheless, the global climate changes and associated consequences will soon challenge the wood-value chains in several regions (e.g., central Europe). To cope with these challenges, it is necessary to rethink the current practice of wood sourcing and transformation. The goal of this review is to address the intrinsic natural diversity of wood, from its origin to its technological consequences for the present and future manufacturing of wood products. So far, industrial processes have been optimized to repress the variability of wood properties, enabling more efficient processing and production of reliable products. However, the need to preserve biodiversity and the impact of climate change on forests call for new wood processing techniques and green chemistry protocols for wood modification as enabling factors necessary for managing a more diverse wood provision in the future. This article discusses the past developments that have resulted in the current wood value chains and provides a perspective about how natural variability could be turned into an asset for making truly sustainable wood products. After briefly introducing the chemical and structural complexity of wood, the methods conventionally adopted for industrial homogenization and modification of wood are discussed in relation to their evolution toward increased sustainability. Finally, a perspective is given on technological potentials of machine learning techniques and of novel functional wood materials. Here the main message is that through a combination of sustainable forestry, adherence to green chemistry principles and adapted processes based on machine learning, the wood industry could not only overcome current challenges but also thrive in the near future despite the awaiting challenges.

Wood is a state-of-art, renewable, and sustainable building material with excellent mechanical properties but negligible triboelectric polarizability. Strategies to improve and rationally tune the triboelectric properties of wood are needed to further its application for mechanical energy harvesting in smart buildings. We found that wood becomes more triboelectrically positive when modified by in situ-grown zeolitic imidazolate framework-8 (ZIF-8), a metal-organic framework (MOF), and more triboelectrically negative when coated with poly(dimethylsiloxane) (PDMS). A triboelectric nanogenerator (TENG) made with two radial-cut wood samples (L x R x T: 35 x 20 x 1 mm(3)), respectively functionalized with ZIF-8 and PDMS, can generate an open-circuit voltage (Voc) of 24.3 V and a short-circuit current (Isc) of 0.32 mu A upon 50 N, 80 times higher compared with that of native wood. We demonstrate the applicability of our functionalized wood TENG (FW-TENG) in smart buildings by using it to power household lamps, calculators, and electrochromic windows. ISSN:2590-2385

We report the synthesis and structural characterization of a main-chain liquid crystal polymer constituted by a 1,2,4-oxadiazole-based bent-core repeat unit. For the first time, a liquid crystal polymer made of bent mesogenic units is demonstrated to exhibit cybotactic order in the nematic phase. Coupled with the chain-bond constraints, cybotaxis results in maximized molecular correlations that make this material of great potential in the search for the elusive biaxial and ferroelectric nematic phases. Indeed, repolarization current measurements in the nematic phase hint at a ferroelectric-like switching response (upon application of an electric field of only 1.0 V μm–1) that, albeit to be definitely confirmed by complementary techniques, is strongly supported by the comparative repolarization current measurements in the nematic and isotropic phases. Finally, the weak tendency of this polymer to crystallize makes it possible to supercool the cybotactic nematic phase down to room temperature, thus, paving ...

Iodine clocks are fascinating nonlinear chemical systems with a glorious past and a promising future. The dynamic removal of iodine from these systems by different means can have important consequences for their reaction dynamics, and could be exploited for time-controlled autonomous dissipative self-assembly. Here, the untapped opportunities offered by iodine clocks for materials science, especially for the time-programming of supramolecular assembly and sol-gel transition, are reviewed and discussed with the hope of arousing the interest on the subject and stimulating new research directions., Reaction Kinetics, Mechanisms and Catalysis, 135 (3)

Structural colors are produced by wavelength-dependent scattering of light from nanostructures. While living organisms often exploit phase separation to directly assemble structurally colored materials from macromolecules, synthetic structural colors are typically produced in a two-step process involving the sequential synthesis and assembly of building blocks. Phase separation is attractive for its simplicity, but applications are limited due to a lack of robust methods for its control. A central challenge is to arrest phase separation at the desired length scale. Here, we show that solid-state polymerization-induced phase separation can produce stable structures at optical length scales. In this process, a polymeric solid is swollen and softened with a second monomer. During its polymerization, the two polymers become immiscible and phase separate. As free monomer is depleted, the host matrix resolidifies and arrests coarsening. The resulting polymeric composites have a blue or white appearance. We compare these biomimetic nanostructures to those in structurally-colored feather barbs, and demonstrate the flexibility of this approach by producing structural color in filaments and large sheets., Soft Matter, 17 (23), ISSN:1744-683X, ISSN:1744-6848

The development of controlled processes for continuous hydrogen generation from solid-state storage chemicals such as ammonia borane is central to integrating renewable hydrogen into a clean energy mix. However, to date, most reported platforms operate in batch mode, posing a challenge for controllable hydrogen release, catalyst reusability, and large-scale operation. To address these issues, we developed flow-Through wood-based catalytic microreactors, characterized by inherent natural oriented microchannels. The prepared structured catalysts utilize silver-promoted palladium nanoparticles supported on metal-organic framework (MOF)-coated wood microreactors as the active phase. Catalytic tests demonstrate their highly controllable hydrogen production in continuous mode, and by adjusting the ammonia borane flow and wood species, we reach stable productivities of up to 10.4 cmH23 min-1 cmcat-3. The modular design of the structured catalysts proves readily scalable. Our versatile approach is applicable for other metals and MOF combinations, thus comprising a sustainable and scalable platform for catalytic dehydrogenations and applications in the energy-water nexus., ACS Applied Materials & Interfaces, 14 (6), ISSN:1944-8244, ISSN:1944-8252

Thanks to its optical anisotropy and mechanical properties, luminescent wood is a promising material for indoor lighting applications. However, the state-of-the-art approaches make use of potentially toxic fluorophores and of non-biodegradable polymers to increase the transparency, compromising the otherwise excellent sustainability of wood. Moreover, these procedures require lengthy multistep functionalisation processes and often fail to preserve the natural aesthetics of wood. We took advantage of the intrinsically hierarchical structure of wood coupling it with an efficient fluorophore, europium dibenzoylmethide triethylammonium (EuD3TEA), to achieve uniform illumination via a shine-through effect. A safe, low-power near-UV LED was used to excite the europium complex, and the light emitted was transmitted through the wood scaffold. We explored the effect of different wood cutting directions, as well as of lignin decolourisation. The optical transmission was the highest for cross-section cuts and could be further increased by decolourisation. Our approach is simple, sustainable and fully preserves the aesthetic appearance of natural wood. Moreover, thanks to the pH-responsiveness of EuD3TEA photoluminescence, the resulting luminescent wood could be used as a sensor for acidic or alkaline vapours., Materials Advances, 3 (3), ISSN:2633-5409

Triboelectric nanogenerators (TENG) have great potential to help enhancing the energy efficiency of buildings, and thus to contribute significantly to the reduction of global greenhouse gas emissions. However, there are major barriers against the adoption of such emerging energy technologies. Meeting the need for sustainable large-scale fabrication of high-performance products remains a critical challenge towards real-world TENGs’ building applications. To mitigate this challenge, we enhance the poor polarizability of native wood by a scalable plasma treatment, a facile approach which to the greatest degree preserves wood's warm colors, mechanical robustness while efficiently enhancing the triboelectric output. We demonstrate the enhancement of electric output by assembling wood triboelectric nanogenerators (W-TENGs) in both contact-separation and single-electrode operation modes. We show that when two radial-cut wood samples (L × R × T: 100 × 80 × 1 mm3), one treated with an O2 plasma and the other with a C4F8 + O2 plasma, are subjected to periodic contact and separation with an applied pressure as low as 0.0225 MPa, a maximum voltage of 227 V and a current of 4.8 µA are produced. Eventually, we showcase the real-world applicability of our approach with two prototypes of triboelectric wood floors, opening up new technological pathways towards a ‘net-zero emissions’ future., Nano Energy, 102

Smart membranes that can open and/or close their pores in a controlled manner by external stimuli possess potential in various applications, such as water flow manipulation, indoor climate regulation, and sensing. The design of smart gating membranes with high flux, immediate response, and mechanical robustness is still an open challenge, limiting their versatility and practical applicability. Inspired by the controlled opening and closure of plant stomata, we have developed a smart gating wood membrane, taking advantage of the unique wood scaffold with its hierarchical porous structure to carry thermoresponsive hydrogel gates. Laser drilling was applied to cut channels in the wood scaffold with well-aligned pores to incorporate the smart gating membranes. In situ polymerization of poly(N-isopropylacrylamide) above its lower critical solution temperature inside the channels resulted in a hydrogel with a heterogeneous microstructure acting as a thermoresponsive gate. The wood-based smart gating membranes exhibited reversible and stable pore opening/closing under heating/cooling stimuli. The achieved rapid response and feasibility of scale-up open the venue for various practical applications. In this work, we demonstrated their potential for indoor light regulation and as a water flow manipulator., ACS Sustainable Chemistry & Engineering, 10 (17), ISSN:2168-0485

We demonstrate the autonomous synthesis of iron (hydr)oxide (green rust, magnetite, and lepidocrocite) nanoparticles by precipitating iron(II) ions using hydroxide ions generated in situ with the methylene glycol-sulfite (MGS) reaction, a pH-clock. We show that the nature of the products can be predetermined by tuning the initial iron(II) concentration., Nanomaterials, 12 (21), ISSN:2079-4991

Developing low-cost and biodegradable piezoelectric nanogenerators is of great importance for a variety of applications, from harvesting low-grade mechanical energy to wearable sensors. Many of the most widely used piezoelectric materials, including lead zirconate titanate (PZT), suffer from serious drawbacks such as complicated synthesis, poor mechanical properties (e.g., brittleness), and toxic composition, limiting their development for biomedical applications and posing environmental problems for their disposal. Here, we report a low-cost, biodegradable, biocompatible, and highly compressible piezoelectric nanogenerator based on a wood sponge obtained with a simple delignification process. Thanks to the enhanced compressibility of the wood sponge, our wood nanogenerator (15 × 15 × 14 mm3, longitudinal × radial × tangential) can generate an output voltage of up to 0.69 V, 85 times higher than that generated by native (untreated) wood, and it shows stable performance under repeated cyclic compression (≥600 cycles). Our approach suggests the importance of increased compressibility of bulk materials for improving their piezoelectric output. We demonstrate the versatility of our nanogenerator by showing its application both as a wearable movement monitoring system (made with a single wood sponge) and as a large-scale prototype with increased output (made with 30 wood sponges) able to power simple electronic devices (a LED light, a LCD screen). Moreover, we demonstrate the biodegradability of our wood sponge piezoelectric nanogenerator by studying its decomposition with cellulose-degrading fungi. Our results showcase the potential application of a wood sponge as a sustainable energy source, as a wearable device for monitoring human motions, and its contribution to environmental sustainability by electronic waste reduction.

Easy and visually appealing demonstrations are precious tools for introducing students to the study of enzymes. However, they most often involve purified enzymes and dedicated techniques. Here, we propose a set of demonstrations, which require only fresh horseradish root and consumer chemicals, to help support biochemistry and enzymology courses from high school to the undergraduate level. Horseradish root is a naturally rich source of horseradish peroxidase, an enzyme with many relevant practical applications. Slices of horseradish root are used to demonstrate the characteristic reaction of horseradish peroxidase with hydrogen peroxide, the selective inhibition of this enzyme by dilute hydrochloric acid, its chromogenic reaction with N,N'-diethyl-p-phenylenediamine, and its ability to trigger the chemiluminescent reaction of luminol. © 2019 International Union of Biochemistry and Molecular Biology, 48(1):38-43, 2020.

Non-surfactant-induced synthesis of mesoporous silica nanoparticles (MSNPs) is gaining increasing interest because of their low toxicity and simple purification compared to conventional surfactant-...

High-Z metal oxide nanoparticles hold promise as imaging probes and radio-enhancers. Hafnium dioxide nanoparticles have recently entered clinical evaluation. Despite promising early clinical findings, the potential of HfO2 as a matrix for multimodal theranostics is yet to be developed. Here, we investigate the physicochemical properties and the potential of HfO2-based nanoparticles for multimodal theranostic imaging. Undoped and lanthanide (Eu3+, Tb3+, and Gd3+)-doped HfO2 nanoparticles were synthesized and functionalized with various moieties including poly(vinylpyrrolidone) (PVP), (3-aminopropyl)triethoxysilane (APTES), and folic acid (FA). We show that different synthesis routes, including direct precipitation, microwave-assisted synthesis, and sol-gel chemistry, allow preparation of hafnium dioxide particles with distinct physicochemical properties. Sol-gel based synthesis allows preparation of uniform nanoparticles with dopant incorporation efficiencies superior to the other two methods. Both luminescence and contrast properties can be tweaked by lanthanide doping. We show that MRI contrast can be unified with radio-enhancement by incorporating lanthanide dopants in the HfO2 matrix. Importantly, ion leaching from the HfO2 host matrix in lysosomal-like conditions was minimal. For Gd:HfO2 nanoparticles, leaching was reduced >10× compared to Gd2O3, and no relevant cytotoxic effects have been observed in monocyte-derived macrophages for nanoparticle concentrations up to 250 μg/mL. Chemical surface modification allows further tailoring of the cyto- and hemocompatibility and enables functionalization with molecular targeting entities, which lead to enhanced cellular uptake. Taken together, the present study illustrates the manifold properties of HfO2-based nanomaterials with prospective clinical utility beyond radio-enhancement.

Fungi decay helps wood produce efficient electricity under mechanical stimuli, boosting energy efficiency of future buildings., Producing electricity from renewable sources and reducing its consumption by buildings are necessary to meet energy and climate change challenges. Wood is an excellent “green” building material and, owing to its piezoelectric behavior, could enable direct conversion of mechanical energy into electricity. Although this phenomenon has been discovered decades ago, its exploitation as an energy source has been impaired by the ultralow piezoelectric output of native wood. Here, we demonstrate that, by enhancing the elastic compressibility of balsa wood through a facile, green, and sustainable fungal decay pretreatment, the piezoelectric output is increased over 55 times. A single cube (15 mm by 15 mm by 13.2 mm) of decayed wood is able to produce a maximum voltage of 0.87 V and a current of 13.3 nA under 45-kPa stress. This study is a fundamental step to develop next-generation self-powered green building materials for future energy supply and mitigation of climate change.

Programming supramolecular assembly in the time domain is a fundamental aspect of the design of biomimetic materials. We achieved the time-controlled sol–gel transition of a poly(vinyl alcohol)–iodine supramolecular complex by generating iodine in situ with a clock reaction. We demonstrate that both the gelation time and the mechanical properties of the resulting hydrogel can be tuned by properly selecting the clock parameters or through competitive iodine complexation., Soft Matter, 17 (5), ISSN:1744-683X, ISSN:1744-6848

Autocatalytic pH clocks can be useful to control self-assembly in the time domain. Their applications are, however, limited by the currently available toolbox. We describe here an approach for the design of a dynamic pH switch that generates intense alkali-to-acid changes after a tailorable lagtime (from minutes to hours), and we demonstrate its application for the time-controlled supramolecular self-assembly of nanofibers., Molecular Systems Design & Engineering, 5 (2), ISSN:2058-9689

Self-regulating materials require embedded control systems. Active networks of enzymes fulfill this function in living organisms, and the development of chemical controls for synthetic systems is still in its infancy. While previous work has focused on enzymatic controls, small-molecule networks have unexplored potential. We describe a simple small-molecule network that is able to produce transient pH cycles with tunable lagtimes and lifetimes, based on coupling the acid-to-alkali methylene glycol-sulfite reaction to 1,3-propanesultone, a slow acid generator. Applied to transient pH-driven supramolecular self-assembly of a perylene diimide, our system matches the flexibility of in vitro enzymatic systems, including the ability to perform repeated cycles of assembly and disassembly., Soft Matter, 16 (3), ISSN:1744-683X, ISSN:1744-6848

Lignin is one of the most available biomass products, but its potential for the development of functional materials has yet to be unleashed. Here, the modification of lignin and lignosulfonate with poly(ethylene-alt-maleic anhydride) [P(E-alt-MA)], a functional polymer of wide industrial use, is accomplished by means of a simple esterification reaction. As a result, hybrid adsorbent materials for water purification can be obtained, which were thoroughly characterized. The combination of P(E-alt-MA) with lignin increased hydrophilicity of the latter, making it dispersible in aqueous environments, while with lignosulfonate it gave rise to a water-insoluble, thus easily recoverable, product. The adsorption properties of the resulting products have been tested against a model water pollutant (methylene blue), demonstrating remarkable adsorption speed (in the order of minutes), adsorption efficiency and stability over a wide range of pH (2–12). Moreover, after the incorporation of magnetite nanoparticles by in situ synthesis, adsorbent materials able to be magnetically recovered were developed.

The fluorescent dye 8-hydroxypyrene-1,3,6-trisulfonate (pyranine) combines high photostability with ratiometric pH detection in the physiological range, making it a prime candidate for optical sensors in biomedical applications, such as pH-based chronic wound monitoring. However, pyranine's high water solubility and the difficulty of covalent attachment pose severe limitations in terms of leaching from sensor matrices. Herein, pyranine-modified nanophase-separated amphiphilic polymer conetworks (APCNs) are reported as fluorescent ratiometric pH sensors. The thin, freestanding APCN membranes composed of one hydrophilic and one hydrophobic polymer provide an optically transparent, flexible, and stable ideal matrix that enables contact between dye and aqueous environment. An active ester-based conjugation approach results in a highly homogeneous and stable pyranine modification of the APCN's hydrophilic phase. This concept effectively solves the leaching challenge for pyranine without compromising its functionality, which is demonstrated by ratiometric pH detection in the range of pH 5-9.

Positron annihilation lifetime spectroscopy (PALS) is a valuable technique for assessing the typical sizes of free volume holes in polymers. By coupling the results obtained from the positron annihilation spectra with those supplied by dilatometry, more precise information can be extracted on the free volume fraction and novel insight can be acquired on the shapes of the holes, demonstrating the limitations of the spherical approximation. In the present paper, we apply the combined PALS-dilatometry approach to study an amorphous polyether-polyester polyurethane, a polymer of great technological interest. We find that flattened and elongated holes, rather than spherical ones, better account for the behavior of the free volume fraction as a function of the temperature.

Transient self-assembly is a necessary step towards the development of life-like materials. Our approach allows to program pH-driven supramolecular assembly in the time domain with tailorable lag- and life-times, overcoming the limitations of previously described approaches and setting a new standard for active materials design.

Polymer brushes can be useful as small-scale reactors for the controlled synthesis of nanoparticles, an approach which is gaining increasing interest. In this context, chemical crosslinking of polymer brushes could be considered as a viable approach to control the size and size distribution of the formed nanoparticles. Here we describe the application of Positron Annihilation Spectroscopy (PAS) for the characterization of crosslinked polymer brushes (brush-gels). Poly(hydroxyethyl methacrylate) (PHEMA) brushes were obtained on silicon substrates by means of a surface-initiated atom transfer radical polymerization (SI-ATRP). Crosslinking was achieved during the polymerization by adding different amounts of diethyleneglycol dimethacrylate (DEGDMA) as a difunctional monomer. The resulting brushes, both un- and crosslinked, were then post-modified with carboxylic acid groups, allowing the in situ synthesis of silver nanoparticles after ion exchange with silver nitrate and reduction with sodium borohydride. The detailed characterization of such systems is notoriously challenging and PAS proved to be an effective, non-invasive technique to acquire insight on the structure of the brushes and of their nanoparticle composites.

Flame aerosol technology is a versatile method for scalable synthesis of nanoparticles. Since particles are produced and collected in a dry state, dispersibility and further functionalization could pose hurdles to their biomedical use. We report on a one-pot, scalable and robust procedure for the PEGylation of flame-made yttria and silica nanoparticles. We demonstrate improved colloidal stability, attenuated activation of blood coagulation and decreased uptake into phagocytic cells, all of which pave the way for facilitated biomedical use of flame-made oxide nanoparticles.

The modification of a silicon surface with ultrathin poly(styrene) brushes, obtained by grafting-from, results in a dramatic increase in capacitance as shown by cyclic voltammetry. This difference in the behavior of silicon and poly(styrene) brush-modified silicon electrodes is amplified when the electrochemical measurements are performed under UV light irradiation. The results obtained show that the modification of silicon electrodes with poly(styrene) brushes can improve their capacitive properties even under UV light irradiation.

Pyranine is a non-toxic fluorescent dye, with a broad range of applications in biomedicine where it allows precise ratiometric detection of pH within the physiological pH window. Hereby, the facile synthesis, potentially interesting for commercial applications, of a novel ion pair between pyranine and benzalkonium is described. Benzalkonium, a quaternary ammonium salt with potent antimicrobial properties, makes pyranine sufficiently hydrophobic to allow its incorporation in conventional membranes and commercial wound dressings while maintaining its pH sensing performance unaffected and conferring the resulting ion pair strong antimicrobial properties. In conclusion, this novel fluorescent ion pair could be extremely promising for the non-invasive monitoring of wound pH.

A series of amine-hardened epoxies were prepared by systematically varying the stoichiometric ratio and the relative amounts of diepoxide and monoepoxide resin to chemically control the material composition and macromolecular architecture (chain segments flexibility; cross-link density; amounts of dangling groups). Positron Annihilation Lifetime Spectroscopy was used to investigate the free volume associated to the various epoxy formulations, while dynamic-mechanical analysis was employed to investigate their network density and their primary and secondary mechanical relaxations. The mechanical behavior at small and large strain was studied by means of tensile and compression tests. The results pointed out that deviations from the ideal stoichiometric composition and the addition of monoepoxide resins lead to significant room temperature stiffening, together with a reduction of the cross-link density and glass transition temperature. This behavior, phenomenologically associated to antiplasticization, was interpreted according to the specific macromolecular architecture and ascribed to chain mobility hindrance, as revealed by secondary transitions, whereas no significant contribution from the free volume could be evidenced. Furthermore, it was shown that depending on the strain scale and on the corresponding deformational mechanisms, the mechanical response may be differently influenced either by the presence of dangling groups or by the network density. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers

We demonstrate a convenient and versatile approach based on the photocatalytic lithography to obtain micro- and nanostructures of polymer brushes. Micro-patterns of polymer brushes are obtained through two ways: by the selective photocatalytic degradation of an initiator, self-assembled on the surface (⿿positive⿿ pattern), or by a ⿿negative⿿ pattern obtained, first, degrading an alkylsiloxane monolayer and, then, refilling it with the initiator. In both cases, the patterned initiator monolayer is eventually amplified into polymer brushes with a controlled radical polymerization protocol (ARGET ATRP). The approach described here mimics the conventional photolithography but is free from the disadvantages associated to this technique (i.e. highly energetic light sources, polymeric resists and on purpose-made photomasks). Moreover, the ability to generate nanometer-sized pillars of polymer brushes using remote photocatalysis coupled with nanosphere lithography is demonstrated. Highly monodisperse silica particles with spherical shape (diameter ⿼600 nm) are assembled on the surface to be patterned and used as a mask for remote photocatalysis. Our results confirm the great potentialities of TiO2-photocatalytic lithography for patterning of polymer brushes.

Acid generators, such as cyclic esters, have recently emerged as powerful modulators of clock reactions. Here, we show that a transient pH burst emerges when δ-gluconolactone is coupled to the chlorite-iodide reaction. The timing and strength of the bursts depend on the concentration of the cyclic ester and can be further modulated by sequestration of iodine by tetrabutylammonium cations or α-cyclodextrin. These findings could be useful for the design of new, transient pH- and complexation-driven self-assembly systems, as well as for analytical purposes.