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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

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.

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.

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.

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

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.

Graphene oxide (GO) is conveniently prepared from expandable graphite using a simplified Hummers’ method. The product is thoroughly characterized by usual techniques (UV-vis, Fourier-transform infrared (FTIR) and Raman spectroscopies, zeta potential, electron microscopy, X-ray diffraction, nitrogen adsorption) to confirm the success of synthesis. Positron annihilation lifetime spectroscopy (PALS) is then used to extract information on the microenvironment in between the layers of graphene oxide.

Polymer blends are a versatile playground for studying phase separation and its effect on the development of morphology and mechanical properties of the resulting materials. Blends obtained from two immiscible polymers, ethyl cellulose (EC) and poly(vinyl pyrrolidone) (PVP), are especially relevant for their practical applications as coatings for pharmaceutical preparations and controlled drug release. Here, films of EC–PVP blends are studied by means of thermal analysis, dynamic-mechanical analysis as well as positron annihilation lifetime spectroscopy. The morphology of the microstructures generated by phase separation is investigated by means of scanning electron microscopy. The effect of both components’ ratio and of molecular mass of PVP on the final properties of the blends is determined in a systematical way. The results obtained are not only of theoretical interest but will prove useful for the optimization of industrial formulations based on these polymers.

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.

pH-Switchable electrochemical properties are demonstrated for the first time for native oxide-coated silicon wafer electrodes. Ultrathin and ultrathick pH-responsive poly(methacrylic acid) (PMAA) brushes, obtained by surface-initiated atom transfer radical polymerization, were used to achieve redox gating. PMAA brushes are reversibly switched between their protonated and deprotonated states by alternating acidic and basic pH, which corresponds to a swelling/collapsing behavior. As a result, the electrochemical properties of the PMAA brush-modified silicon electrode are switched “ON” and “OFF” simply by changing pH. The electrochemical properties of the modified electrode were examined by means of cyclic voltammetry and electrochemical impedance spectroscopy both in the absence and presence of ruthenium(III) hexamine, a well-known cationic redox probe., Journal of Materials Chemistry C, 4 (26), ISSN:2050-7526, ISSN:2050-7534

Silicon wafer is the material of choice for microfabrication. However, the development of innovative on-chip electrochemical sensors using silicon is hampered by its poor electrochemical properties. In this article we demonstrate how grafted-from micropatterned polymer brushes dramatically enhance the electrochemical response of silicon electrodes. Our results are relevant not only for a deeper understanding of the structure and behavior of polymer brushes, but also for the combination of the versatility of surface-initiated polymerization and an innovative patterning technique (remote photocatalytic lithography) which paves the way for the fabrication of integrated devices.

Chemo-mechanical phenomena, including oscillations and peristaltic motions, are widespread in nature—just think of heartbeats—thanks to the ability of living organisms to convert directly chemical energy into mechanical work. Their imitation with artificial systems is still an open challenge. Chemical clocks and oscillators (such as the popular Belousov–Zhabotinsky (BZ) reaction) are reaction networks characterized by the emergence of peculiar spatiotemporal dynamics. Their application to polymers at interfaces (grafted chains, layer-by-layer assemblies, and polymer brushes) offers great opportunities for developing novel smart biomimetic materials. Despite the wide field of potential applications, limited research has been carried out so far. Here, we aim to showcase the state-of-the-art of this fascinating field of investigation, highlighting the potential for future developments and providing a personal outlook., Materials, 13 (13), ISSN:1996-1944

Clock reactions allow precise control of chemical composition in the time domain. Such nonlinear chemical systems have recently been introduced to mimic the self-assembly pathways common in living organisms. Here, we demonstrate the use of a clock reaction to trigger the formation of polymeric nanoparticles. By adjusting the delay of a formaldehyde clock reaction, we controlled the precipitation of chitosan to form particles with sizes tunable in a wide range (from about 200 to 600 nm diameter). The chemical structure of chitosan was not significantly perturbed by the clock reagents.

Patterning of functional surfaces is one of the cornerstones of nanotechnology as it allows the fabrication of sensors and lab-on-a-chip devices. Here, the patterning of self-assembled monolayers of branched poly(ethyleneimine) (bPEI) on silica was achieved by means of remote photocatalytic lithography. Moreover, when 2-bromoisobutyryl-modified bPEI was used, the resulting pattern could be amplified by grafting polymer brushes by means of surface-initiated atom transfer radical polymerization. In contrast to previous reports for the patterning of bPEI, the present approach can be conducted in minutes instead of hours, reducing the exposure time to UV radiation and enhancing the overall efficiency. Furthermore, our approach is much more user-friendly, allowing a facile fabrication of patterned initiator-modified surfaces and the use of inexpensive instrumentation such as a low-power UV source and a simple photomask. Considering the versatility of bPEI as a scaffold for the development of biosensors, patterning by means of remote photocatalytic lithography will open new opportunities in a broad field of applications.

The controlled shaping of nanoparticles' morphology is one of the pillars of nanotechnology. Here, we demonstrate that photocatalytic lithography, a technique already proved to be useful in materials science, can act as a dry etching technique for noble metal nanoparticles. Triangular silver nanoprisms are self-assembled on titanium dioxide films and photocatalytically shaped into discoidal particles upon irradiation with near-UV light. The obtained patterned surfaces show a dramatically different surface-enhanced Raman scattering response, suggesting the utility of our approach for the development of sensors. The photocatalytic nature of the particle shaping is demonstrated and a plausible mechanism drawn by performing photocatalysis in different configurations (direct and remote) and by irradiating in different solvents.

Grafting-from is the technique of choice to obtain polymer brushes. It is based on the growth of polymer chains directly from an initiator-functionalized surface, and its development gained momentum thanks to recent advances in controlled polymerization techniques. However, despite the great amount of work that has been performed on this subject, the influence exerted by the initiator layer on the characteristics of the resulting brushes has been almost completely overlooked. Our group has already demonstrated that positron annihilation spectroscopy (PAS) is a valuable analytical tool for the study of polymer brushes. Here, we applied this technique to show that differences in the organization of the initiator layer dramatically reflect on the characteristics of polymer brushes. Brushes made by surface-initiated atom transfer radical polymerization (ATRP) of a pH-responsive polymer, poly(dimethylaminoethyl methacrylate) (PDMAEMA), were investigated also in terms of the effects of protonation and of the incorporation of silver nanoparticles inside the brushes, shining a new light on the internal structure of such complex, fascinating systems.

A composite electrode with a sandwich structure combining the properties of silver nanoparticles and a titania photoactive layer was used for the electroanalytical detection, by differential pulse voltammetry, of three neurotransmitters: dopamine, norepinephrine, and serotonin. The three analytes were determined at low detection limits (around 0.03 μM) also in the presence of conventional interferents, such as uric and ascorbic acids. The fouling of the electrode surface was overcome by irradiating the device with UVA light, restoring the initial sensor sensitivity. Dopamine, norepinephrine, and serotonin were determined also in simulated biological matrices: liquor (artificially reproduced cerebrospinal fluid) and serum. Moreover, the contemporaneous detection of dopamine and norepinephrine in simulated human urine solutions was also demonstrated, representing the first step towards clinical applications of the proposed methodology. Graphical abstract The photo-renewable electroanalytical sensor.

Nanoparticle-loaded polymer brushes are powerful tools for the development of innovative devices. However, their characterization is challenging and arrays of different techniques are typically required to gain sufficient insight. Here we demonstrate for the first time the suitability of positron annihilation spectroscopy (PAS) to investigate, with unprecedented detail and without making the least damage to samples, the physico-chemical changes experienced by pH-responsive polymer brushes after protonation and after loading of silver nanoparticles. One of the most important findings is the depth profiling of silver nanoparticles inside the brushes. These results open up a completely new way to understand the structure and behavior of such complex systems.

Widespread access to potable water is still far from being granted to populations of developing countries, especially in rural zones. For this reason, the development of easy-to-make, easy-to-use water purification devices is a topic of great social and economic importance. Poly(ethylene terephthalate) (PET) bottles are available worldwide, even in the remotest and poorest countries, as testified by the increasingly common practice of re-using bottles for solar water disinfection (SODIS). Here, we demonstrate how PET bottles could be re-used as a proof-of-concept water purification system. In this way, virtually the same bottle could be used first for SODIS and then for removing chemical contaminants. In the proposed approach, the bottles are treated with ethylenediamine to introduce amine groups, which are subsequently protonated with dilute acid. These functional groups allow the stable adsorption of a magnetite-activated carbon nanocomposite, which is prepared by a simple coprecipitation protocol. The efficiency of the nanocomposite and of the resulting prototype to remove model inorganic and organic pollutants (hexavalent chromium, industrial dyes) from water has been demonstrated. The proposed purification device is easy, cheap, and effective, all factors which could promote its use in developing and rural countries.

Polymer brushes are dense arrays of macromolecular chains tethered by one end at a surface. They are at the cutting edge of polymer nanotechnology since the dawn of controlled surface-initiated polymerization techniques unlocked new prospects for the synthesis of polymer brushes with tailorable properties. More recently, thanks to the growing interest in the use of brushes for the generation of functional surfaces, the need for advanced patterning and characterization approaches rapidly increased. Meeting these needs requires the contribution of experts from different disciplines: polymer chemistry, surface science, electrochemistry and particle physics. The focus of this review is to highlight recent developments in the field of polymer brushes, specifically the application of photocatalytic lithography as a versatile patterning strategy, the study of grafted-from polymer brushes by electrochemical methods and, most importantly, the introduction of positron annihilation spectroscopy as a powerful technique for the investigation of the structure of polymer brushes and of their composites with nanoparticles.

17th International School on Quantum Electronics - Laser Physics and Applications (ISQE), Nessebar, BULGARIA, SEP 24-28, 2012; International audience; Laser-matter interaction is a unique and simple approach to structure materials or locally modify their properties at the micro and nanoscale level. Playing with the pulse duration and the laser wavelength, a broad range of materials and applications can be addressed. Direct irradiation of surfaces with laser beam through a standard optical beam setup allows an easy and fast structuring of these surfaces in the range of few micrometers. However, the irradiation of materials through an array of dielectric nanospheres provides a unique opportunity to break the diffraction limit and to realize structures in the range of hundred of nanometers. This simple, fast and low-cost near-field nanolithography technique is presented and discussed, as well as its great potential. The theoretical aspects of the near-field enhancement effects underneath the particles have been studied with a simple model based on the Mie theory. A commercial FDTD software has also been used to study the influence of the substrate and the surrounding media, on the energy profile of the photonic jet generated under the sphere. A specific study has been dedicated to the influence of the dispersion of the sphere diameter on the morphology of the ablation craters. This technique has been used for patterning bi-layer substrates. The process leads to the formation of a nanoporous membrane which has been used to realize an array of gold nanodots on silicon. We have also associated the Laser-Induced Forward Transfer (LIFT) process with the near-field nanolithography to print, in a single laser shot, an array of metallic nanobumps.

International audience; Monodisperse silica nanospheres with sizes ranging from 250 to 725 nm were prepared and assembled into monolayers to produce regularly distributed light hot spots at the surface of oxidized silicon substrates when illuminated by a laser. Single UV nanosecond laser pulses were employed with energies above the local ablation threshold for the silicon dioxide layer, resulting in the direct formation of 2D periodically porous membranes on top of the silicon. The periodicity of the array was driven by the size of the self-assembled nanospheres. While the local field enhancement was strongly dependent on the sphere size due to Mie resonances, the size and morphology of the produced features could be maintained for all tested situations by balancing the change in local fields with the laser pulse energy. This work demonstrates the fabrication of 90 nm thick porous membranes with pore size of about 100 nm and periodicity ranging from 250 to 725 nm.