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Polymer brush layers are responsive materials that swell in contact with good solvents and their vapors. We deposit drops of an almost completely wetting volatile oil onto an oleophilic polymer brush layer and follow the response of the system upon simultaneous exposure to both liquid and vapor. Interferometric imaging shows that a halo of partly swollen polymer brush layer forms ahead of the moving contact line. The swelling dynamics of this halo is controlled by a subtle balance of direct imbibition from the drop into the brush layer and vapor phase transport and can lead to very long-lived transient swelling profiles as well as nonequilibrium configurations involving thickness gradients in a stationary state. A gradient dynamics model based on a free energy functional with three coupled fields is developed and numerically solved. It describes experimental observations and reveals how local evaporation and condensation conspire to stabilize the inhomogeneous nonequilibrium stationary swelling profiles. A quantitative comparison of experiments and calculations provides access to the solvent diffusion coefficient within the brush layer. Overall, the results highlight the—presumably generally applicable—crucial role of vapor phase transport in dynamic wetting phenomena involving volatile liquids on swelling functional surfaces.

Crotonic acid (CA) and trans-2-pentenoic acid (2-PA) can be obtained from renewable resources by pyrolysis of the bio-based poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymer. In this study, direct pyrolysis of the PHBV-enriched biomass into CA and 2-PA was studied under an inert atmosphere and N2 carrier gas flow, aiming at obtaining high acid yields from mixed microbial cultures (MMCs). The highest yields of 80 ± 2% for CA and 67 ± 1% for 2-PA were obtained at conditions of 240 °C, 1 h, and 0.15 L/min nitrogen flow rate, corresponding to a mean hot vapor residence time of 20 s. A similar acid yield was achieved when the pyrolysis was performed under reduced pressure (150 mbar) instead of using nitrogen gas. The combined pyrolysis of extracted PHBV at 220 °C and 90 min with vapor fractionation by distillation resulted in yields of 81 and 92% for CA and 2-PA, respectively.

Polymer brushes, coatings of polymers covalently end-grafted to a surface, have been proposed as a more stable alternative to traditional physisorbed coatings. However, when such coatings are applied in settings such as vapor sensing and gas separation technologies, their responsiveness to solvent vapors becomes an important consideration. It can be anticipated that the end-anchoring in polymer brushes reduces the translational entropy of the polymers and instead introduces an entropic penalty against stretching when vapor is absorbed. Therefore, swelling can be expected to be diminished in brushes compared to nongrafted films. Here, we study the effect of the anchoring-constraint on vapor sorption in polymer coatings using coarse-grained molecular dynamics simulations as well as humidity-controlled ellipsometry on chemically identical polymer brushes and nongrafted films. We find a qualitative agreement between simulations and experiments, with both indicating that brushes certainly swell less than physisorbed films, although this effect is minor for common grafting densities. Our results imply that polymer brushes indeed hold great potential for the intended applications.

Lignin sulfonate (LS), a waste material from the paper pulping, was modified with benzoic anhydride to obtain benzoylated lignin sulfonates of adjustable hydrophilicity (BLS). When BLS was combined with difenoconazole (Di), a broad-spectrum fungicide, lignin-based, non-crosslinked nanoparticles were obtained either by solvent exchange or solvent evaporation. When a mass ratio of 1:5 LS: benzoic anhydride was used, the Di release from Di@BLS5 after 1248 h was ca. 74 %, while a commercial difenoconazole microemulsion (Di ME) reached 100 % already after 96 h, proving the sustained release from the lignin nanocarriers. The formulation of Di in lignin-based nanocarriers also improved the UV stability and the foliar retention of Di compared to the commercial formulation of the fungicide. Bioactivity assay showed that Di@BLS5 exhibited high activities and duration against strawberry anthracnose (Colletotrichum gloeosporioides). Overall, the construction of fungicide delivery nano-platform using BLS via a simple non-crosslinked approach is a novel and promising way to develop new formulations for nanopesticide and the development of sustainable agriculture.

Imidazolium cations enhance the performance of several electrodes in converting CO2 to CO in non-aqueous media. In this publication, we elucidate the origin of the function of imidazolium cations when exposed to Au electrodes in anhydrous acetonitrile in CO2 atmosphere. We demonstrate that imidazolium cations lead to unprecedentedly low overpotentials for CO2 reduction to CO on Au, with ∼100% Faradaic efficiency. By modification of the N1 and N3 functionality of the imidazolium cation, we show a direct correlation between the performance in CO2 reduction and the C2-H acidity of the cation. Based on NMR analyses, DFT calculations, and isotopic labeling, showing an inverse kinetic isotope effect, we demonstrate that the mechanism involves a concerted proton-electron transfer to the electrode-adsorbed CO2 intermediate. The demonstrated mechanism provides guidelines for improvement in the energy efficiency of non-aqueous electrochemical CO2 reduction, by a tailored design of electrolyte cations.

Advanced high-performance structural applications require the right materials in the right place and suitable interface engineering. However, poor adhesion in harsh environmental conditions frequently challenge material interfaces. An example is the moisture sensitivity of titanium-poly ether ketone ketone (PEKK) interfaces. Here, this work offers a high-performance composite adhesive system, which combines strong adhesion and high interfacial toughness, particularly when used in metal-polymer bonding. This system includes aminopropyl triethoxy silane (APTES)–polydopamine (SiPDA) layers, which can be formed on the titanium surface before the joining process with carbon fiber-reinforced PEKK (C/PEKK). Adhesion between PEKK and titanium is evaluated before and after hot/wet conditioning using mandrel peel tests. This work discovers that applying thin SiPDA layers not only results in a remarkable rise in the interfacial fracture toughness but also provides durable bond stability after hot/wet conditioning. These findings indicate that polydopamine-based coatings show great potential to achieve stable interfaces for the next generation of high-performance metal-polymer hybrid materials.

Poly(ferrocenylsilane)s (PFSs) as redox-responsive organometallic polymers have been used in redox reactions in noble metal ion-containing electrolyte solutions and in hydrogels swollen by electrolytes for successful preparation of metal nanoparticles (NPs) by in situ direct reduction. We report a surprising imbalance of stoichiometric ratios in redox reactions with transition metals between metal cations and PFS observed in hydrogels. Due to the redox-active ferrocene center in PFS backbones, well-dispersed noble metal NPs are directly formed in situ in the hydrogel matrix depending on their redox potential. By careful analysis, an extra-stoichiometric amount of gold NPs was found in the reaction when following the principle of exergonic electron transfer from ferrocene to gold(III) with the reduction of AuIII to Au0, and the iron center's oxidation state increases from II to III. This surprising result is targeted to account for a stoichiometric balance of the electrons in the redox reaction, that is, we tackle the question "where do the electrons come from?"First, HAuCl4 was allowed to react with an oxidized PFS hydrogel to determine the source of the unaccounted electrons. Surprisingly, essentially regardless of the redox state of PFS, similar amounts of gold NPs were formed. The formation of H+ ions in the reaction indicates that H2O could be a possible electron source. A comparison with the stoichiometric relations in PtNP formation further confirms this hypothesis.

Emulsification is one of the important processes in chemical flooding to mobilize the residual oil in wells following secondary recovery. Oil displacement efficiency is enhanced and volumetric sweep efficiency is increased by engineering the interactions of the supporting chemicals used with the geological formations present in the wells. Polymers and surfactants are often applied to enhanced oil recovery (EOR) as emulsification displacement. However, polymers are limited by poor temperature and salt tolerance, while surfactants have a high cost. In this contribution, we report on the use of lignin nanoparticles (LNPs) as Pickering emulsifiers obtained from enzymatic hydrolysis of lignin powders to apply in EOR. The interfacial activity of LNPs prepared this way is greatly improved, which substantially promotes its emulsification ability. We show that kerosene emulsified with different concentrations of LNPs can form stable Pickering emulsions, and the emulsions can be stored for up to 6 months. In addition, due to the pH responsive character of lignin, rapid oil-water separation can be achieved by alkali demulsification. This enables the reuse of lignin suspension under pH control, which provides a new platform for the application of green and low-cost flooding, employing LNPs in EOR.

Polyphosphoesters (PPEs) are a class of versatile degradable polymers. Despite the high potential of this class of polymers in biomedical applications, little is known about their blood interaction and compatibility. We evaluated the hemocompatibility of water-soluble PPEs (with different hydrophilicities and molar masses) and PPE-coated model nanocarriers. Overall, we identified high hemocompatibility of PPEs, comparable to poly(ethylene glycol) (PEG), currently used for many applications in nanomedicine. Hydrophilic PPEs caused no significant changes in blood coagulation, negligible platelet activation, the absence of red blood cells lysis, or aggregation. However, when a more hydrophobic copolymer was studied, some changes in the whole blood clot strength at the highest concentration were detected, but only concentrations above that are typically used for biomedical applications. Also, the PPE-coated model nanocarriers showed high hemocompatibility. These results contribute to defining hydrophilic PPEs as a promising platform for degradable and biocompatible materials in the biomedical field.

Bio-based and biodegradable polymers are essential for a sustainable society. Cellulose is the most abundant biopolymer on earth; however, derivatization is necessary for its processing, which slows down its biodegradability dramatically, e.g. used cigarette filters made from cellulose acetate are barely biodegradable. We developed the first reversible modification of cellulose, which allows processing and guarantees full biodegradation even at high degrees of substitution as the linkers, acetals, can be cleaved first during the degradation process releasing native cellulose that biodegrades in a second step. Acetalization is a versatile platform approach to bio-based and fully degradable cellulose-derivatives, which are characterized by solubility in common organic solvents (alcohols, aromatic and chlorinated solvents), adjustable glass transition temperatures (-48 °C < Tg < 80 °C), young's modulus (1.9 MPa < E < 58 MPa) and contact angle (86°< θ < 124°). In contrast to previously known cellulose modifications, cellulose acetals remain fully degradable as the acetal bond is reversible and undergoes an acidic cleavage under desired conditions, for instance in compost, followed by enzymatic degradation of the remaining cellulose backbone. With climate change and plastic pollution, these new and versatile cellulose acetals provide bio-based and biodegradable alternatives to fossil-based and non-degradable polyolefin plastics, leading to a more sustainable future for our planet.

In this work, we unravel the role of surface properties of colloidal particles on the formation of supraparticles (clusters of colloidal particles) in a colloidal Ouzo droplet. Self-lubricating colloidal Ouzo droplets are an efficient and simple approach to form supraparticles, overcoming the challenge of the coffee stain effect in situ. Supraparticles are an efficient route to high-performance materials in various fields, from catalysis to carriers for therapeutics. Yet, the role of the surface of colloidal particles in the formation of supraparticles using Ouzo droplets remains unknown. Therefore, we used silica particles as a model system and compared sterically stabilized versus electrostatically stabilized silica particles - positively and negatively charged. Additionally, we studied the effect of hydration. Hydrated negatively charged silica particles and sterically stabilized silica particles form supraparticles. Conversely, dehydrated negatively charged silica particles and positively charged amine-coated particles form flat film-like deposits. Notably, the assembly process is different for all the four types of particles. The surface modifications alter (a) the contact line motion of the Ouzo droplet and (b) the particle-oil and particle-substrate interactions. These alterations modify the particle accumulation at the various interfaces, which ultimately determines the shape of the final deposit. Thus, by modulating the surface properties of the colloidal particles, we can tune the shape of the final deposit, from a spheroidal supraparticle to a flat deposit. In the future, this approach can be used to tailor the supraparticles for applications such as optics and catalysis, where the shape affects the functionality., 38 pages, 9 figures

Polylactic acid (PLA)/cellulose nanocrystal (CNC) composite foams have attracted much attention due to their biodegradability and potential to replace petroleum-based foams. However, the dispersion of (unmodified) CNCs in PLA remains challenging. Here, we used the Pickering emulsion templating method of unmodified CNCs to stabilize PLA microspheres and prepare a concentrated masterbatch. This masterbatch was used in conventional melt blending of pristine PLA to obtain well-dispersed CNCs in PLA with a CNC loading of up to 5 wt %. In comparison, PLA/CNC composites prepared by direct melt blending of CNCs in PLA showed visual agglomerates of CNCs. PLA/CNC composites were batch foamed with CO2 as a physical blowing agent. We demonstrate that the good CNC dispersion obtained by the Pickering emulsion route is favorable for preparing PLA foams with smaller and more uniform cell sizes and with a higher cell density. These results demonstrate that the Pickering emulsion approach to prepare CNC masterbatches for subsequent dispersion in thermoplastics by conventional processing seems promising for numerous industrial applications.

We describe an in situ facile synthetic approach to prepare carbon quantum dot (CQD) fluorescent markers (FMs) for polyethylene (PE) in the presence of agglomerated silica nanoparticles (SiO2 NPs) under mild reaction conditions. First SiO2 NPs, prepared by the Stöber method, were dispersed in toluene. This dispersion was added to a PE solution in toluene. After heating (either in air or under Ar) a fluorescent mixture was obtained. After drying, PE films were obtained by compression molding, which showed strong blue fluorescence, attributed to CQDs. SiO2 NPs loading values varied between 0.5 and 4 wt %. Subsequent to isolation, the fluorescent CQDs were characterized by TEM, UV-vis, and fluorescence spectroscopy. TEM imaging unveiled a lattice spacing value of 0.21 nm of the isolated fluorescent particles which is typical for (100) graphite plane lattice spacing in CQDs. UV spectroscopy and fluorescence measurements show characteristic absorption and excitation spectra for the aromatic core and oxidized surface defects typically observed for CQDs. The emission maximum for PE/CQD samples increased from 394 to 408 nm when the reaction temperature was decreased from 110 to 90 °C, which is attributed to increasing oxygen content in the reaction mixture upon decreasing the reaction temperature. When the reaction was performed under Ar, the PE/CQD samples emitted in the ultraviolet region (286 nm). Finally, we demonstrated that PE samples marked with CQDs can be easily visually identified upon irradiating with 367 nm light. Thus, the marked PE can be used, for example, as a labeling ingredient in master batches for component identification and in recycling.

Transitional composition between two thin-film morphologies of the block copolymer, polystyrene-block-poly(tert-butyl acrylate) (PS-b-PtBuA), was investigated using near-field infrared spectroscopy and atomic force microscopy mechanical measurements. These techniques allowed block identification with nanoscale spatial resolution and elucidated the material's sub-surface composition. PS was found to form coronae around the PtBuA block in spherical valleys on flat areas of the film, and coronae of PtBuA surrounding the PS lamellae were observed at the edge of the polymer film, where parallel lamellae are formed. Furthermore, we found that the peak position and width varied by location, which may be a result of block composition, chain tension, or substrate interaction.

Marine plastic pollution caused by non-biodegradable polymers is a major worldwide concern. So-called “biodegradable” polymers should reduce plastic pollution in the environment by the safeguard of biodegradation. However, many polyesters degrade very slowly in seawater. We therefore designed a systematic library of “breaking points” that are installed into a polylactide backbone and simulated their degradation mechanisms, including internal and external SN2 mechanisms, Addition-Elimination (AE) mechanisms, and RNA-inspired mechanisms. The breaking points are composed of phosphoesters with pendant nucleophiles directly at the P-atom, or structurally similar silicones, or side-chain functional polyesters. All P-containing breaking points react via the RNA-inspired mechanism, while Si-containing linkers undergo decomposition via the A-E mechanism. For C-containing linkers, only when a long pendant chain (4 carbon atoms) is present can the reaction proceed via the RNA-inspired mechanism. In cases of shorter pendants, the Addition-Elimination (AE) mechanism is energetically favorable. We believe that these calculations will pave the way for the synthesis of exceptionally seawater-degradable polyesters in the future that can act as a safeguard to prevent microplastic formation after eventual littering.

Polymer brushes in gaseous environments absorb and adsorb vapors of favorable solvents, which makes them potentially relevant for sensing applications and separation technologies. Though significant amounts of vapor are sorbed in homopolymer brushes at high vapor pressures, at low vapor pressures sorption remains limited. In this work, we vary the structure of two-component polymer brushes and investigate the enhancement in vapor sorption at different relative vapor pressures compared to homopolymer brushes. We perform molecular dynamics simulations on two-component block and random copolymer brushes and investigate the influence of monomer miscibility and formation of high-energy interfaces between immiscible monomers on vapor sorption. Additionally, we present absorption isotherms of pure homopolymer, mixed binary brush and 2-block, 4-block, and random copolymer brushes. Based on these isotherms, we finally show that random copolymer brushes absorb more vapor than any other architecture investigated thus far. Random brushes display enhanced sorption at both high and low vapor pressures, with the largest enhancement in sorption at low vapor pressures.

Protein-polymer conjugates are a promising class of biohybrids. In this work, the dynamics of a set of biodegradable conjugates myoglobin-poly(ethyl ethylene phosphate) (My-PEEP) with variations in the number of attached polymers and their molar mass in the dry-state, have been investigated to understand the role of polymer on protein dynamics. We performed Differential Scanning Calorimetry measurements between 190 and 300 K, observing the large-scale dynamics arising from reorganization of conformational states, i.e. within the 100 s timescale. The application of an annealing time during the cooling scans was used to investigate the non-equilibrium glassy-state of the samples, observing the relaxation enthalpy at different annealing temperatures. This procedure permitted to extensively describe the transition broadness and the system relaxation kinetics in the glassy state. The samples show an experimental behaviour different from the theoretical predictions, suggesting the establishment of interactions among the protein and the polymer chains. The different behaviour of the conjugates and the physical mixture (composed of the protein and the polymer physically mixed) highlighted the importance of the covalent bond in defining the system dynamics. Graphical abstract

Reversible addition–fragmentation chain transfer (RAFT) polymerization has become a straightforward approach to block copolymers using a wide variety of functional vinyl monomers. Polyphosphoester (PPE) macroinitiators from ring-opening polymerization (ROP) of their corresponding cyclic phosphoesters have been previously prepared for atom transfer radical polymerization; however, to date, these biodegradable macroinitiators for RAFT polymerization have not been reported. Herein, a macromolecular RAFT-chain transfer agent (CTA) based on poly(ethyl ethylene phosphonate) was prepared by the organocatalytic ROP of 2-ethyl-2-oxo-1,3,2-dioxaphospholane using 2-cyano-5-hydroxypentan-2-yl dodecyl trithiocarbonate as the initiator and 1,8-diazabycyclo[5.4.0]undec-7-ene as the catalyst. Precise macro-CTAs of degrees of polymerization (DPn) from 34 to 70 with Đ ≤ 1.10 were prepared and used in the dioxane solution RAFT polymerization of acrylamide, acrylates, methacrylates, and 2-vinylpyridine to yield a library of well-defined block copolymers. Additionally, the PPE-based macro RAFT-CTA was used as a nonionic surfactant in a typical aqueous emulsion polymerization of styrene to produce well-defined nanoparticles with the hydrophilic PPEs on their surface as the stabilizing agent. This general protocol allowed the combination of polyphosphoesters with RAFT polymerization.

Poly(N-vinylpyrrolidone) (PVP) is a well-known biocompatible polymer widely used in cosmetics, pharmaceuticals, and many other applications and is usually synthesized via radical polymerization. High molar mass PVP lacks biodegradability according to the OECD 301 F standard and can lead to permanent accumulation within the body or in the environment. Nowadays, lower molar mass PVP is produced via xanthate-mediated reversible addition-fragmentation chain-transfer (RAFT) polymerization. However, this type of polymerization also leads to a large amount of undesired dimer formation. Herein, various homotelechelic PVP oligomers were prepared via a trithiocarbonate-mediated RAFT polymerization with the production of a minimal amount of unsaturated dimer. These PVP oligomers showed similar surfactant properties as the well-known Lutensol AT50 surfactant, and they were used as a nonionic surfactant in a typical radical aqueous miniemulsion polymerization of methyl methacrylate (MMA) to produce well-defined PMMA nanoparticles. Additionally, PVP oligomers showed no toxicity to the bacterial strain Escherichia coli and to the water fleas Daphnia pulex, which is promising for safe release in wastewater systems.

Adv. Sci. 2021, 9, 2104884 DOI: 10.1002/advs.202104884 In the subpart “2.5. Enzymatic-Photocatalytic Heterogeneous Cascade Reactions of Enzyme-Photocatalyst in Suprastructures” of the original published article, the citation of the Equation are wrongly displayed. The corrected part is shown below: Then, the produced proton helps the oxidization of iodide into iodine in the presence of hydrogen peroxide, as described in Equation (2).[52]2 (Formula presented.) In addition, the iodide ion acts as a scavenger of the hydroxyl radical and becomes an iodine ion that also induces the formation of iodine, as described in Equations (3) and (4).[55,56]3 (Formula presented.) 4 (Formula presented.) The authors apologize for any inconvenience caused.

Initial retention of the bacterium Escherichia coli on model poly(dimethylsiloxane) (PDMS) surfaces was studied as a function of substrate bulk and surface mechanical stiffness values. Our reference PDMS system was designed such that out of the parameters that govern bacterial adhesion only the mechanical stiffness was systematically varied. This was achieved by varying the crosslinking density of PDMS. Following crosslinking, we performed Soxhlet extraction of non-crosslinked, free chains to rule out their effect on bacterial response. Bulk moduli were assessed by dynamic mechanical analysis at 1 rad sec−1 frequency and the values obtained ranged between 0.03 and 1.8 MPa. The increase in crosslink density resulted in increasing surface modulus, as measured by atomic force microscopy, with values ranging between 0.7 and 9 MPa. The number of bacteria retained was then assessed. We observed a decreasing trend with the increase of both bulk and surface mechanical stiffnesses down to a limit corresponding to the Young's modulus of the bacterial cell surface. For higher values than this threshold, the number of retained bacteria remained constant. We tentatively explain this observation by considering conformal overlay of bacterial and material surfaces.

Encapsulation of multiple adjuvants along with antigens into nanocarriers allows a co-delivery to antigen-presenting cells for the synergistic induction of robust immune responses. However, loading cargoes of different molar masses, polarities, and solubilities in high efficiencies remains a challenge. Therefore, we developed a strategy to encapsulate a triple combination of the so-called adjuvants, i.e. with Resiquimod (R848), muramyl dipeptide (MDP) and polyinosinic-polycytidylic acid (Poly(I : C)) into human serum albumin (HSA) nanocarriers. The loading is conducted in situ while the nanocarrier is formed by an orthogonal and metal-free click reaction at the interface of an inverse miniemulsion. By this unique approach, high encapsulation efficiency without harming the cargo during the nanocarrier formation process and regardless of their physical properties is achieved, thus keeping their bioactivity. Furthermore, we demonstrated high control over the encapsulation efficiency and varying the amount of each cargo did not influence the efficiency of multicomponent encapsulation. Azide-modified HSA was crosslinked with hexanediol dipropiolate (HDDP) at the interface of a water-in-oil miniemulsion. Varying the crosslinker amount allowed us to tailor the density and degradation rates of the protein shell. Additional installation of disulfide bonds into the crosslinker created redox-responsive nanocarriers, which degraded both by protease and under reducing conditions with dithiothreitol. The prepared HSA nanocarriers were efficiently taken up by dendritic cells and exhibited an additive cell activation and maturation, exceeding the nanocarriers loaded with only a single drug. This general protocol allows the orthogonal and metal-free encapsulation of various drugs or adjuvants at defined concentrations into the protein nanocarriers.

Molecular interactions in polymer/metal oxide interfaces are of paramount interest in polymer composite applications, including comolding of polymer-metal joints, additive manufacturing, and mold release. This study shows the potential of biomimetic polydopamine (PDA) layers to control polymer-metal adhesion covering a range from strong bonding to release for poly(lactic acid) (PLA) adhering to two metals of significant commercial importance, i.e., titanium (Ti) and stainless steel (SS). The results show that even though PLA bonds significantly weaker to Ti than to SS surfaces, both metals exhibit considerably higher and similar adhesion values following deposition of a PDA layer. In addition, a simple thermal annealing of the PDA-coated wires before the comolding process results in a sharp increase of the bonding strength at low annealing temperatures, followed by a gradual drop at higher annealing temperatures. This observation opens the possibility to provide control of adhesion in polymer-metal interfaces. As PDA forms strongly bound adhesive layers on a wide range of materials, this study proposes that the phenomenon described here can be successfully applied to surfaces other than metals, raising high expectations for future polymer composite applications.

The aerobic composting of biodegradable plastics can be a promising solution to the growing issue of waste accumulation. Therefore, this article offers a review of papers investigating the biodegradability of polyesters (PLA, PHB, PBS and PCL) in home- and industrial composting. Not only the thermal and biodegradation properties are discussed, but also a comparison is made between the different polyesters under the same composting conditions. From this review, it becomes clear that composting shows promise for polyester waste management. However, although several methods for assessing the composting properties of polyester have been developed, the fact that they rarely follow the same standards does not allow for a comparative analysis that would clearly define composting as the most viable solution.

Applications operating at high temperatures may suffer from oxidative lubricant degradation. The current test methods to evaluate thermoxidative stability and performance are resource intensive and they often provide results that are difficult to extrapolate to application conditions where the temperatures are lower than the test temperature. In this paper, we present a method to evaluate the thermoxidative performance of lubricants via non-isothermal thermogravimetric experiments under conditions closer to application conditions. We can provide effective kinetic parameters for the oxidation process. Based on these parameters, we can simulate mass-loss in experiments at a constant temperature, and estimates of induction times of oils with different antioxidant concentrations agree well with experimental values. Additionally, the kinetic parameters may be used in grease life models.

Polymer brushes are highly responsive materials with application areas in a broad spectrum. Therefore understanding their interfacial behaviour is essential. Under good solvent conditions, drop spreading causes changes in wettability on the brush surface and results in a finite contact angle. This feature was observed by placing a hexadecane drop on a dry hydrophobic poly lauryl methacrylate (PLMA) brush layer. These polymer brushes were synthesized via ARGET-ATRP to obtain high and low grafting densities and different chain lengths. In a closed chamber, that contained an excess of hexadecane, the spreading of the drop on the polymer brushes was followed by an optical microscope. As a result of the complex dynamics between the drop and the substrate, a halo of a few millimetres in width forms around the macroscopic contact line. A numeric model was extended to simulate such a droplet spreading on a swollen brush for understanding the coupled spreading, evaporation, condensation and wicking dynamics. A continuous gradual flux from liquid to brush, liquid to vapor, and brush to vapor can explain the partially wetting of the polymer brushes in this non-equilibrium state. Understanding the spreading dynamics of a droplet on hydrophobic surfaces will be crucial to explaining the mechanism of the halo formation.

Humidity control is a crucial element for a wide variety of experiments. Yet, often naive methods are used that do not yield stable regulation of the humidity, are slow, or are inflexible. PID-based electropneumatic humidistats solve these problems, but commercial devices are not widespread, typically proprietary and/or prohibitively expensive. Here we describe OpenHumidistat: a free and open-source humidistat for laboratory-scale humidity control that is affordable (

G. Julius Vancso, Jian Ji, Kazuhiko Ishihara, M. Cristina L. Martins and Shaoyi Jiang introduce the Journal of Materials Chemistry B themed collection on bioinspired surfaces engineering for biomaterials.

Colloidal assemblies of mesoporous suprastructures provide effective catalysis in an advantageous volume-confined environment. However, typical fabrication methods of colloidal suprastructures are carried out under toxic or harmful conditions for unstable biomolecules, such as, biocatalytic enzymes. For this reason, biocatalytic enzymes have rarely been used with suprastructures, even though biocatalytic cascade reactions in confined environments are more efficient than in open conditions. Here, multimodal enzyme- and photocatalyst-carrying superstructures with efficient cascade reactions for colorimetric glucose detection are demonstrated. The suprastructures consisting of various functional nanoparticles, including enzyme-carrying nanoparticles, are fabricated by surface-templated evaporation driven suprastructure synthesis on polydimethylsiloxane-grafted surfaces at ambient conditions. For the fabrication of suprastructures, no additional chemicals and reactions are required, which allows maintaining the enzyme activities. The multimodal enzymes (glucose oxidase and peroxidase)-carrying suprastructures exhibit rapid and highly sensitive glucose detection via two enzyme cascade reactions in confined geometry. Moreover, the combination of enzymatic and photocatalytic cascade reactions of glucose oxidase to titanium dioxide nanoparticles is successfully realized for the same assay. These results show promising abilities of multiple colloidal mixtures carrying suprastructures for effective enzymatic reactions and open a new door for advanced biological reactions and enzyme-related works.

Synergistic strategies by combining nanoreactors and prodrugs hold tremendous potential in anticancer treatment. However, precise death of target cancer cells remains a significant challenge due to the absence of an elaborate cancer targeting strategy. Here, a dual-targeting approach that combines the action of H2O2-producing folate receptor-targeted nanoreactors with a cyclooxygenase-2 (COX-2) targeted prodrug is reported. A folate-modified silica nanoreactor encapsulating glucose oxidase (GOX) is prepared to generate H2O2, which induces oxidative stress and allows the activation of the prodrug by targeted intracellular delivery. A novel prodrug bearing both COX-2 targeting Celecoxib and SN-38 anticancer agent with an H2O2-cleavable thioketal linker to activate the drug is presented. By dual-targeting, the generated H2O2 from GOX triggers the cleavage of a thioketal linker in the prodrug to produce the active form of the SN-38 anticancer drug in cancer cells inducing synergistic cell death. This dual-targeting strategy with a synergistic potency can aid in developing selective and effective anticancer therapeutics.

This Thesis describes the design, synthesis and applications of a series of gold nanoparticle-stimuli-responsive hydrogel nanocomposites. PFSs are a fascinating class of redox-active metallopolymers with a backbone consisting of alternating redox-active ferrocene and organosilane units. PFS-based redox-responsive hydrogels are used as foundry for the in-situ formation of gold nanoparticles (AuNPs) in this Thesis. Taking advantage of the combination of a thermo-responsive PNIPAM hydrogel and the photothermal effect of the AuNPs，the deformation and surface morphology changes of the hydrogel composites can be controlled by both temperature and light irradiation. By designing different anisotropic hydrogel structures, a variety of applications including wrinkling bilayers and actuators are explored in this Thesis. Regarding stoichiometry investigations, we considered the electrochemical redox process during AuNP formation and offer a model explaining the source of the electrons in addition to ferrocene.

To synthesize new (bio)degradable alternatives to commodity polymers, adapting natural motives can be a promising approach. We present the synthesis and characterization of degradable polyethylene (PE)-like polyphosphoesters, which exhibit increased degradation rates due to an intra-molecular transesterification similar to RNA. An α,ω-diene monomer was synthesized in three steps starting from readily available compounds. By acyclic diene metathesis (ADMET) polymerization, PE-like polymers with molecular weights up to 38 400 g mol−1 were obtained. Post-polymerization functionalization gave fully saturated and semicrystalline polymers with a precise spacing of 20 CH2 groups between each phosphate group carrying an ethoxy hydroxyl side chain. This side chain was capable of intramolecular transesterification with the main-chain similar to RNA-hydrolysis, mimicking the 2′-OH group of ribose. Thermal properties were characterized by differential scanning calorimetry (DSC (Tmca. 85 °C)) and the crystal structure was investigated by wide-angle X-ray scattering (WAXS). Polymer films immersed in aqueous solutions at different pH values proved an accelerated degradation compared to structurally similar polyphosphoesters without pendant ethoxy hydroxyl groups. Polymer degradation proceeded also in artificial seawater (pH = 8), while the polymer was stable at physiological pH of 7.4. The degradation mechanism followed the intra-molecular “RNA-inspired” transesterification which was detected by NMR spectroscopy as well as by monitoring the hydrolysis of a polymer blend of a polyphosphoester without pendant OH-group and the RNA-inspired polymer, proving selective hydrolysis of the latter. This mechanism has been further supported by the DFT calculations. The “RNA-inspired” degradation of polymers could play an important part in accelerating the hydrolysis of polymers and plastics in natural environments, e.g. seawater., RNA-inspired degradation of polyethylene-like polyphosphoesters accelerates the backbone hydrolysis dramatically to guarantee seawater-degradable plastics.

In this work, a transparent and free-standing ionic gel as the dielectric layer for polarization switching in leaky ferroelectric thin films is reported. By applying an electric field over an ionic liquid dielectric layer used as an electrostatic field gated capacitor, one can avoid electronic conduction. The association of the electrical double layer with depolarization at the solid-liquid interface contributes to the reversible switching in PbZrxTi1-xO3 (x = 0.6) (PZT). Using such ionic gels, the anisotropic ferroelastic switching from mono-c-domain toward a-domain is studied in PZT grown on CaF2 substrates. Our results demonstrate that an electrostatic field, induced by the free-standing ionic gel, is an effective and promising way to investigate leaky ferroelectrics.

Polyimide networks are key in the development of stable, resilient, and efficient membranes for separation applications under demanding conditions. To this aim, the controlled design of the network's nanostructure and its properties are needed. However, such control remains a challenge with currently available synthesis methods. Here, we present a simple nanofabrication approach that allows the controlled nanoconfinement, growth, and covalent attachment of polyimide (PI) networks inside the mesopores of γ-alumina layers. The attachment of the PI network on the γ-alumina layer was initiated via different prefunctionalization steps that play a pivotal role in inducing the in situ polymerization reaction at the pore entrance and/or at the inner pore surface. The nanoconfinement was found to be limited to the 1.5 μm-thick γ-alumina supporting layer at maximum, and the resulting hybrid PI/ceramic membranes showed stable performance in a variety of solvents. These PI/ceramic membranes were found to be very efficient in the challenging separation of small organic dye molecules such as Rhodamine B (479 g mol-1) from toxic solvents such as dimethylformamide or dioxane. Therefore, this technique opens up possibilities for a multitude of separations. Moreover, the PI synthesis approach can be applied to other applications that also rely on porosity and stability control, such as for advanced insulation and anticorrosion.

Hydrated salts (salt hydrates) are highly promising low-temperature phase change materials (PCMs) due to their high cohesive energy density and low cost. However, they exhibit phase separation, liquid leakage, and inherent supercooling, which hinder their applications in sustainable building technology. Here, we describe the design of a highly stable emulsion gel system (EmulGels) that exhibits nonflammable and shape-memory characteristics. Oleophilic paraffin and hydrophilic hydrated salts, both of which are excellent PCMs typically existing in separate phases, are combined harmoniously in a gel by a templating water-in-oil Pickering emulsion. Latent heat values of the prepared EmulGels were up to 213.2 J/g (eicosane/disodium hydrogen phosphate dodecahydrate = 1:3). No leakage of eicosane was noticed after heating the EmulGels at 60 °C for 30 min, and the latent heat value remained almost unchanged following 500 thermal cycles. The EmulGel was specifically designed to enable dual-phase crosslinking, which effectively enhanced its shape stability, slowed down loss of water of crystallization in hydrated salts, and decreased the degree of supercooling. Nonflammable characteristic typically found in hydrated salts was also exhibited by the EmulGel, in combination with good mechanical properties. The materials characteristics make EmulGels ideal candidates to serve as building construction interlayers for effective thermal building management.

The application of functional porous materials for tackling challenges in the areas of environment, energy, and healthcare has attracted distinguished interest. Cellulose within this class of materials, which is one of the most abundant and renewable polymers, provides attractive alternatives to synthetic plastics for numerous applications. The inherent properties of hydrophilicity, biodegradability and the rich chemistry enabled by its hydroxyl groups make cellulose easy to modify and functionalize. When cellulosic materials are endowed with controlled (micro)porous structures, a range of applications becomes feasible due to the combined advantages of controlled porosity, high specific surface area, and the intrinsic materials’ properties of cellulose. For example, porous cellulosic materials with precise surface modification and engineered pore structure have been employed in molecular delivery, catalyst support, absorption, separation, and thermal insulation. In this Thesis, we presented different structure designs and surface modification methods of cellulosic porous materials which have great potential for application in the areas of environment, energy, and healthcare. Firstly, we designed cellulosic porous materials with a Janus structure. This unique structure with different wettability provides these materials with novel application opportunities. We explored the application of this Janus structure in hemostatic wound dressing and in evaporators for seawater desalination, and obtained superior results compared with some commercial products and results shown in other published work. Second, based on our previous work and the widely researched polymer PFS, we used a post-modification and physical mixing method to prepare two kinds of porous materials. One is a wearable heater and the other is a catalyst support. In order to further explore the combination of cellulose and PFS, we added some PFS structures in the outlook chapter, hoping to broaden the functionalization options of cellulosic porous materials. Overall, the results presented in this thesis were realized by introducing novel structure and surface modification methods for porous materials with the aim of gaining access to new application areas, and to hopefully give inspiration to researchers in the development of advanced cellulosic porous materials.

The current spraying of agrochemicals is unselective and ineffective, consuming a high amount of fungicides, which endangers the environment and human health. Cellulose-based nanocarriers (NCs) are a promising tool in sustainable agriculture and suitable vehicles for stimuli-responsive release of agrochemicals to target cellulase-segregating fungi, which cause severe plant diseases such as Apple Canker. Herein, cellulose was modified with undec-10-enoic acid to a hydrophobic and cross-linkable derivative, from which NCs were prepared via thiol-ene addition in miniemulsion. During the crosslinking reaction, the NCs were loaded in situ with hydrophobic fungicides, Captan and Pyraclostrobin. NCs with average sizes ranging from 200 to 300 nm and an agrochemical-load of 20 wt% were obtained. Cellulose-degrading fungi, e.g. Neonectria. ditissima which is responsible for Apple Canker, lead to the release of fungicides from the aqueous NC dispersions suppressing fungal growth. In contrast, the non-cellulase segregating fungi, e.g. Cylindrocladium buxicola, do not degrade the agrochemical-loaded NCs. This selective action against Apple Canker fungi, N. ditissima, proves the efficacy of NC-mediated drug delivery triggered by degradation in the exclusive presence of cellulolytic fungi. Cellulose NCs represent a sustainable alternative to the current unselective spraying of agrochemicals that treats many crop diseases ineffectively.

Copolymerization is the general approach to combine properties of different polymers in a single material. We prepared the first trimethylene carbonate (TMC) phosphoester (PE) copolymers by statistical copolymerization using either stannous octanoate or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as the respective catalyst. Variation of comonomer feed, reaction temperature and solvent, resulted in a library of copolymers with molar masses of up to 83,000 g/mol and moderate molar mass dispersities (

Background: Porous polyethylene (PPE) implants are used for the reconstruction of tissue defects but have a risk of rejection in case of insufficient ingrowth into the host tissue. Various growth factors can promote implant ingrowth, yet a long-term gradient is a prerequisite for the mediation of these effects. As modification of the implant surface with nanocarriers may facilitate a long-term gradient by sustained factor release, implants modified with crosslinked albumin nanocarriers were evaluated in vivo. Methods: Nanocarriers from murine serum albumin (MSA) were prepared by an inverse miniemulsion technique encapsulating either a low- or high-molar mass fluorescent cargo. PPE implants were subsequently coated with these nanocarriers. In control cohorts, the implant was coated with the homologue non-encapsulated cargo substance by dip coating. Implants were consequently analyzed in vivo using repetitive fluorescence microscopy utilizing the dorsal skinfold chamber in mice for ten days post implantation. Results: Implant-modification with MSA nanocarriers significantly prolonged the presence of the encapsulated small molecules while macromolecules were detectable during the investigated timeframe regardless of the form of application. Conclusions: Surface modification of PPE implants with MSA nanocarriers results in the alternation of release kinetics especially when small molecular substances are used and therefore allows a prolonged factor release for the promotion of implant integration.

Poly(glycerol-sebacate-urethane) (PGS-U) is an attractive candidate as a super-elastic and biocompatible scaffold for inserting nanoparticles and polymers with a straightforward synthesis. Herein, a series of PGS-U scaffolds with various crosslink densities was prepared for subsequent polypyrrole (PPy) polymerization. The in-situ polymerization of PPy was employed to deposit the PPy particles throughout the scaffolds, and the continuous electrically conductive pathways were built within the scaffolds. Moreover, due to their favorable mechanical and anti-bacterial properties, zinc oxide (ZnO) nanoparticles were embedded within the scaffold. The composition of the scaffolds was confirmed by different characterization techniques, including FTIR, FE-SEM, and EDX. Static and cyclic compression tests were conducted to evaluate the mechanical performance of scaffolds under dry and hydrated conditions. All scaffolds presented high structural stability and full shape recovery after releasing the load. They were thermally stable up to at least 200 °C. The addition of PPy boosted the electrical conductivity, and the inclusion of ZnO particles improved the surface hydrophilicity and anti-bacterial behavior of the scaffolds. Altogether, this study suggests the further developments of these nanocomposites as satisfactory electrically conductive scaffolds for tissue engineering applications.

Marine plastic pollution is a worldwide challenge making advances in the field of biodegradable polymer materials necessary. Polylactide (PLA) is a promising biodegradable polymer used in various applications; however, it has a very slow seawater degradability. Herein, we present the first library of PLA derivatives with incorporated “breaking points” to vary the speed of degradation in artificial seawater from years to weeks. Inspired by the fast hydrolysis of ribonucleic acid (RNA) by intramolecular transesterification, we installed phosphoester breaking points with similar hydroxyethoxy side groups into the PLA backbone to accelerate chain scission. Sequence-controlled anionic ring-opening copolymerization of lactide and a cyclic phosphate allowed PLA to be prepared with controlled distances of the breaking points along the backbone. This general concept could be translated to other slowly degrading polymers and thereby be able to prevent additional marine pollution in the future.

The quartz crystal microbalance (QCM) measurement technique is utilized in a broad variety of scientific fields and applications, where surface and interfacial processes are relevant. However, the costs of purchasing QCMs is typically high, which has limited its employment in education as well as by scientists in developing countries. In this article, we present an open-source QCM, built on the OpenQCM project, and using an impedance-based measurement technique (QCM-I), which can be built for

Cellulose–poly(ferrocenylsilane) (PFS) polyionic liquid (PIL) composite sponges are fabricated by codissolution of cellulose and PFS-PIL, followed by solvent exchange and freeze-drying. The hybrid sponges are used to in situ produce and immobilize palladium nanoparticles (Pd NPs), leading to Pd NP-decorated porous supports. The formation of Pd NPs is confirmed by TEM and XPS measurements. The as-prepared cellulose/PFS-PIL@Pd sponges exhibit a high catalytic activity in the reduction of 4-nitrophenol (4-NiP) to 4-aminophenol (4-AmP). As a variety of metal NPs may be immobilized using this method, these sponges constitute a promising new class of catalytic porous supports.

PolyPOSS-imide membranes are promising for separating H2 from larger molecules (CO2, N2, CH4) at temperatures up to 300 °C. Their fabrication involves two steps: interfacial polymerization of POSS and 6FDA, followed by thermal imidization. This work provides a systematic study of the effects of cations on membrane properties and performance. For this, two distinct POSS molecules were used: functionalized with -NH3+Cl− or, so far unexplored, -NH2. The ammonium groups are partially deprotonated by using three different bases, LiOH, NaOH, and KOH. We demonstrate that the introduced cations affect the film thickness but not the molecular composition of the polyamic acid. All polyamic acids can be imidized, but the cations reduce the imidization kinetics as well as the loss of organic crosslinkers. For flat disc membranes, at 200 °C, the absence of cations results in comparable permeability combined with higher selectivity for H2/N2. This, and the possibility to discard adding a base, motivated a scale-up study of the new POSS. For tubular membranes, much higher ideal and mixed gas selectivities are found than for membranes where NaOH was added. Results indicate that the new route allows more reproducible production of defect free membranes and has potential for larger-scale polyPOSSimide fabrication.