Enzymes can be a renewable source of catalytic agents and thus be interesting for sustainable approaches to create and modify functional materials. Here, thin hydrogel layers were prepared as thin coatings on hard substrates by immobilized horseradish peroxidase. Hydrophilic 4-arm star shaped telechelics from oligo(ethylene glycol) bearing on average 55% end groups derived from aromatic amino acids served as monomers and enzymatic substrates. Shifts of the contact angle from 84° to 62° for the wetting process and of zeta potential towards the neutral range illustrated an alteration of physicochemical properties of the model surfaces by a hydrophilic shielding. Time-of-flight secondary ion mass spectrometry (ToF-SIMS), quartz crystal microbalance and atomic force microscopy (AFM) experiments enabled the qualitative and quantitative proof of hydrogel deposition at the interface with thicknesses in the medium nanometer size range. Conceptually, as the immobilized enzyme becomes entrapped in the hydrogel and the crosslinking mechanism bases on a radical reaction after enzymatic activation of the monomers with a limited diffusivity and lifetime, the formed network material can be assumed to be inhomogeneous on the molecular level. On the macroscale, however, relative homogeneity of the coating was observed via ToF-SIMS and AFM mapping. As an exemplary functional evaluation in view of bioanalytical applications, the thrombogenicity of the coating was studied in static tests with human blood from several donors. In the future, this “coating-from” approach may be explored for cell culture substrate coatings, for protein/biofilm repellence in technical applications, or in bioanalytical devices.

We investigate the structure of neutral and charged bottlebrush polymers in salt-free solutions at different polymer concentrations. In particular, we use molecular dynamics simulations by utilizing a coarse-grained bead-spring model that includes an explicit solvent and complementary experiments made by small angle neutron scattering (SANS). We find that the charged groups along the side chains exert significant repulsive forces, resulting in polymer swelling and backbone stretching. In addition to the primary polyelectrolyte peak, we find that bottlebrush polymers exhibit an additional peak in the form and static structure factors, a feature that is absent in neutral polymers. We show that this additional peak describes the intra-molecular correlations between the charged side chains.

The novelty of this study was to investigate for the first time in literature the influence of Bombyx mori silkworm cocoon’s age on the properties of silk fibroin-based materials, during all stages of cocoon processing to obtain the fibroin film. The study started with the premise that the cocoon age could cause modifications on fibroin properties during processing and, consequently, a possible interference on the characteristics of the final product. Characterizations were performed using batches of cocoons produced in different years, named C0 (fresh cocoons) and C6 (six-year-old cocoons). The influence of cocoon’s aging was observed on dialyzed dispersion regarding the molecular weight, particle size, and conformation. C6 films showed a more crystalline structure and higher thermal resistance than C0 films. The findings reported in this work are relevant for the reproducibility of fibroin-based materials, and the cocoon age is a key factor that should be considered in the preparation of fibroin-based materials.

Biological entities are capable of amazing material feats, such as self-organization, self-repair, self-replication, and self-immolation. Indeed, the most intriguing feature of living biomaterials, whether they are tissues, cells, or intracellular structures, is their ability to autonomously sense, decide, and perform work without the need of a project manager. The effect is multiscale—from enzymes to full organisms, each level is capable of such autonomous activities. Further, each scale has similar energy-using units that work together to compose the larger-scale material. For instance, autonomous cells work together to create tissues. In this article, we will discuss some of the outstanding and desirable properties of active biological materials that we might consider mimicking in future materials. We will discuss how such active materials are powered and explore some fundamental lessons we can learn to direct future fundamental scientific inquiries to begin to understand and use these properties to make synthetic, autonomous materials of the future.

The mechanical properties of organic electronic materials and interfaces play a central role in determining the manufacturability and reliability of flexible and stretchable organic electronic devices. The synergistic effects of mechanical stress and deformation, together with other operating parameters such as temperature and temperature cycling, and exposure to solar radiation, moisture, and other environmental species are particularly important for longer-term device stability. We review recent studies of basic mechanical properties such as adhesion and cohesion, stiffness, yield behavior, and ductility of organic semiconducting materials, and their connection to underlying molecular structure. We highlight thin-film metrologies to probe the mechanical behavior, including when subjected to simulated operational conditions. We also report on strategies for improving reliability through interface engineering and tailoring material chemistry and molecular structure. These studies provide insights into how these metrologies and metrics inform the development of materials and devices for improved reliability.

We perform molecular dynamics (MD) simulations to understand thermally triggered shape memory behavior of a thermoplastic polyurethane (TPU) elastomer with an enhanced coarse-grained (CG) model. Hard and soft phases of shape memory polymers (SMPs) are known as fixed and reversible phase, respectively. Fixity depends on the content of hard segments due to their restricted mobility. On the contrary, recovery depends on the dynamic motion of the soft segments as well the degree of cross-linking, which is also affected by the quantity of hard segment. Several CG models of the TPU are constructed varying the weight percentage of soft segments to observe their effects on shape recovery and fixity. All of the models are equilibrated at 300K (above glass transition, Tg: 200-250 K) and deformed under uniaxial loading with NPT (isothermal-isobaric) ensembles. The deformed state is cooled to 100K (below Tg) and further equilibrated to estimate the shape fixity. Shape recovery is predicted by heating and equilibrating the structures back to 300K. By the end of this study, we may answer how much the shape fixities and recoveries are changed for varying concentration of hard segments from thermomechanical cycles with CGMD simulations.

Efficient water desalination constitutes a major challenge for the next years and reverse osmosis membranes will play a key role to achieve this target. In this work, a high-performance reverse osmosis nanocomposite membrane was prepared by interfacial polymerization in presence of multiwalled carbon nanotubes. The effect of carbon nanotubes on the chlorine resistance, antifouling and desalination performance of the nanocomposite membranes was studied. We found that the addition of carbon nanotubes not only improved the membrane performance in terms of flow and antifouling, but also inhibited the chlorine degradation of these membranes. Several reports have acknowledged the benefits of adding carbon nanotubes to aromatic PA nanocomposite membranes, but little attention has been paid to the mechanisms related to the improvement of flow rate, selectivity and chlorine tolerance. We carried out a comprehensive study of the chemical and physical effects of carbon nanotubes on the fully crosslinked polyamide network. The chemical structure, chlorine resistance and membrane degradation was studied by several analytical techniques, permeation and fouling studies, whereas the microstructure of the nanocomposite was studied by small and wide angle X-ray scattering, high resolution transmission electron microscopy, and molecular dynamics. We found that the addition of the nanotube affects the interfacial polymerization, resulting in a polymer network with smaller pore size and higher sodium and chlorine rejection. We simulated the hydration of the membrane in seawater and found that the radial distribution function of water confined in the pores of the nanocomposite membrane exhibited smaller clusters of water molecules, thus suggesting a dense membrane structure. We analysed the network mobility and found that the nanotube provides mechanical stability to the polymer matrix. This study presents solid evidence towards more efficient and robust reverse osmosis membranes using carbon nanotubes as mechanical reinforcing and chlorine protection additive.

Directed self-assembly (DSA) of block copolymers is a promising alternative nanolithographic technology aimed at producing sub-40 nm patterns. One important opportunity for DSA is the creation of periodic arrays of lines and spaces. The two most common methods for line-space applications are chemoepitaxy (typically using a lamella-forming PS-b-PMMA diblock) and graphoepitaxy (typically using cylinder-forming block copolymers with a Si-containing minority block). Mesoscale modeling, such as Self-Consistent Field Theory (SCFT), has by now become an important tool in formulation screening and predicting polymer morphologies and defect types and probabilities. Here, we use SCFT to study the morphology of cylinder-forming PS-b-PDMS diblocks in rectangular trenches with grafted PS-brushes. The targeted morphology is 2 cylinders per trench (3X multiplication). We compute phase diagrams and determine equilibrium morphologies as a function of brush thickness and guiding weir height. Using those equilibrium morphologies as starting points, we also compute structures and free energies of typical defects, including dislocation and disclination dipoles, broken lines, and bridges. The predicted defect structures and probabilities are in a reasonable qualitative agreement with recent experimental results.

New organic materials with semiconductor behavior were prepared from diphenyldiacetylene and aromatic amines with withdrawing groups by Reisch-Schulte reaction and characterized by IR, RMN spectroscopy. The obtained materials share the property of having electron withdrawing groups joint to the attached aromatic ring, it seems this feature accounts in large fashion to improve the semiconducting behavior of this kind of substances, this topic was studied by means theoretical calculations and the results are also discussed. The calculations were carried out by means the Gaussian09 software and all the involved species were geometrically optimized.

In the last decades the interest in organic conductors has growth, so they have become the object of study of many research groups that are interested in developing new materials with important conducting properties. The charge transfer complexes (CTC) represent an important kind of organic conductors, because they exhibit high conductivity values, as well as versatility for their design.

In this work, the charge transfer complex (CTC) formed by substituted pyrrole and tetrathiofulvalene (TTF) was obtained by means electrochemical synthesis, the resultant colored mix was characterized by Mass spectrometry, NMR and EPR studies, its intrinsic electronic behavior was measured by a four point probe method, besides theoretical calculations were carried out on the possible structures of the resultant molecular adduct. All the results show that there is a net transfer of an electron between both organic moieties in a solution giving place to a semiconductor species.

Biological systems routinely produce nanoscopic molecular structures withconsiderably less dispersion in size and shape than encountered in mostmanufactured materials. Indeed, Biological structures are frequently andessentially monodisperse. An example of this uniformity, combined with anintriguing geometry, is the nanometer-scale protein nanorings produced byinteraction of the protein tubulin with certain hydrophobic tri-, tetra- andpentapeptides originally extracted as natural products from marine biosystems.Different peptides produce different sized nanorings, but we focus on thoseproduced by binding to tubulin of the cyclic depsipeptide cryptophycin. Thenanorings that form upon binding of this ligand show a sharp mass distributionindicating that the nanorings are made of 8 tubulin dimers of 100 kDa.

In this submission, we demonstrate how a combination of fluorescence correlationspectroscopy, dynamic light scattering, electron microscopy, analyticalultracentrifugation, small-angle neutron scattering, and modeling is applied toreveal interactions of tubulin and cryptophycin in solution and to characterizetheir structures. We find that the cryptophycin-tubulin nanorings(∼25 nm diameter) are single-walled, appear rigid, are composed of 8tubulin dimers in a single closed ring, and are stable upon dilution tonanomolar concentrations.

Similar studies with a different peptide, the linear pentapeptide dolastatin 10,demonstrated that binding of this peptide to tubulin produces larger nanorings(14 tubulin dimers, ∼45 nm diameter rings), with slightly differentproperties. The ability to adjust the ring size with different peptides, andproduce uniform nanorings with properties that differ slightly between sizeclasses, makes the tubulin-peptide ring structures an appealing structuralsystem.

A high-throughput crystallographic investigation on several crystals of photosynthetic reaction center covalently bound to an ad-hoc synthesized artificial antenna (AE600) is presented. The investigation did not show a preferential binding site of the antenna molecule AE600 to the reaction center in the solid phase. An accurate crystallographic study allowed identifying a lysine residue sitting on periplasmic side of the protein as one of the bioconjugation sites. The residue sits on subunit M of the protein, in close proximity to the bacteriochlorophylls of the reaction center involved in the light absorption and conversion processes. Distances obtained from the crystallographic structure confirm that energy transfer between the antenna and the protein proceed with the Förster resonance mechanism.

Biomineralization is the matrix-directed calcification of tissue in living organisms. The deposition of different polymorphs of calcium phosphate or calcium carbonate is a highly regulated process. It may involve cell-controlled mechanisms with vesicular delivery of inorganic material to the extracellular matrix and cell-independent processes mediated by dedicated matrix proteins. These proteins promote the formation of microscopic crystals of defined size and shape, which combine to form bio-inorganic materials with unique properties. Successful biomineralization is correlated with structural elements, such as matrix proteins involved in the nucleation process. Circular dichroism (CD) is a spectroscopic technique for the determination of a secondary structure of proteins and has therefore been applied for studying numerous biomineralization promoter proteins. This article reviews and compares CD data on matrix proteins from different contexts, such as eggs, seashells, and teeth. It highlights the potential of CD for secondary structure determination and quantification and points out pitfalls that may lead to misinterpretation of CD spectra. The data suggest that most biomineralization promoter proteins contain domains of different secondary structure with predominantly unordered conformation. However, they may acquire a higher degree of order initiated by environmental factors such as pH, presence of cations, or charged surfaces.

Poly(acrylamide-co-2-hydroxyethyl methacrylate), hydrogel microparticles were prepared by free radical copolymerization of acrylamide (AAm) and 2-hydroxyethyl methacrylate (2-HEMA) using an inverse emulsion polymerization technique, employing ethylene glycol dimethylacrylate (EGDMA) as crosslinker in the presence of w/o emulsifiers span-80 and span-85 (sorbitol mono-oleate) above the lower critical solution temperature. Water absorption capacity and characteristics of the hydrogel microparticles were analyzed by Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). Thus, microparticles were submitted to a gravimetric study on their ability to absorb and to retain distilled water at 25°C. One gram of microparticles absorbed at least 15 g of water. By varying the relative ratio between the continuous phase (hexane and emulsifiers) and the dispersed phase (monomers, initiator and crosslinker), non-agglomerated dispersed particles with nearly spherical shape were obtained having a narrow size distribution in the range from 10 to 20 µm. At a constant value of the emulsifier, and as a result of increasing the stirring rate, a particle size reduction was observed from 13 to 7 µm. The PAAm and PHEMA structures of synthesized hydrogel were confirmed using FTIR analysis. Additionally, through thermal analysis the P(AAm-HEMA) hydrogel showed an increase of water retention and thermal stability due to PAAm addition.

The chemical synthesis of the copolymers poly(3-HT-co-EDOT-co-fluorene) and poly(3-HT-co-EDOT-co-TDR1) is reported. The first copolymer is derived of 3-hexylthiophene (3-HT), 3,4-ethylenedioxythiophene (EDOT) and 2,2'- (9,9-dioctyl-9H-fluorene-2,7-diyl) bisthiophene (fluorene). The second copolymer is derived of 3-hexylthiophene (3-HT), 3,4-ethylenedioxythiophene (EDOT) and (E)-2-(ethyl(4-((4-nitrophenyl)diazenyl)phenyl)amino)ethyl 2-(thiophen-3-yl)acetate (TDR1). Their physicochemical characterization by 1H NMR, FT-IR, DSC-TGA, GPC, UV-vis, cyclic voltammetry was carried out. These copolymers combine the high electron density and low oxidation potential of EDOT with the high charge mobility and processability of 3-HT. These are candidates for applications as active or barrier layer in electronic devices (bulk heterojuntion organic solar cells) or as functional membranes (e.g., sensors).

We present a nano-patterning process for semiconducting polymeric composites that could potentially be utilized for the development of polymer-based data storage devices. Nano-patterning (writing) operates on the basis of the mechanical interaction between the electrically unbiased tip of an atomic force microscope and the surface of polymeric composite films. Via friction forces, the tip/sample interaction produces a local increase of molecular disorder in the polymer matrix, inducing a localized lowering in the conductivity of the organic semiconductor. Herein we suggest a figure of merit for quantifying the efficiency of pattern formation and we address the dependence of the writing process on the thermal annealing temperature of the composite film. Control experiments on composite films deposited on substrates with different roughness suggest that the writing effect is invariant to the roughness of the substrate. The potential storage density of the writing process depends on the tip curvature.

So far we ignore how brain stores memory. Neurons communicate by pulses where the charges are carried between them by ions flowing through channels. Those pulses present a characteristic maximum related to the conformational movements of the channel protein opening and closing. Electrochemical responses from dense gel electrodes of conducting polymers mimic those pulses. Here we proved that the biomimetic pulse includes simultaneously electrical, chemical and conformational information related to the energy stored by the initial conformational packed state of the polymer. This energetic memory increases linearly with the potential used to reduce and pack (write) the initial state: hundreds of different values can be written (stored) in a full reproducible way (multivalent memory). Every state constitutes a chemo-ionic-conformational (CHEMICONF) memory. Each multivalent memory is read and erased by the reverse electrochemical reaction. Crosslinking states produce permanent memories not erased while reading. Developing CHEMICONF memories can provide new hypothesis to reveal brain memory mechanisms.

Crosslinked poly[ethylene-co-(vinyl acetate)] (cPEVA) has been recently introduced as a polymer material, which can be functionalized with various shape-memory effects by solely altering the thermomechanical treatment called programming.

In this study two series of cPEVAs with different vinyl acetate contents of 18 wt% (cPEVA18) and 28 wt% (cPEVA28) comprising different crosslink densities were investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) in the temperature range of -130 °C to 120 °C. DMTA tests were performed in torsion mode, because such movements are highly relevant in the context of complex shape changes in shape-memory polymer based devices. Finally, the obtained DMTA results were compared with DMTA conducted in tension mode. Swelling experiments revealed a gel content in the range from 81% to 90% for cPEVA18 samples while for cPEVA28s a complete conversion was observed. The degree of swelling was found to decrease substantially with increasing crosslink density for both cPEVA series.

The influence of VA content and extent of crosslinking on the appearance of the respective melting (Tm) and glass transition (Tg) as well as the thermomechanical properties of cPEVA systems could be demonstrated by discussing both DSC and DMTA results. The temperature range of mechanical stability correlates with the VA content and is determined by decreasing Tm values. The cross links do barely alter the stiffness of a PEVA up to the Tm rang, but lead to constant mechanical rigidity in the rubbery range above Tm.

Organic films with a thickness of few nanometers are potentially useful components in many practical and commercial applications such as sensors, detectors, displays and electronic circuit components. In this context, the Langmuir-Blodgett (LB) method is one the most promising techniques for preparing these films.

In this work, we report the synthesis and characterization of three new amphiphilic organometallic compounds with ferrocene units, which consist of one ferrocenyl aminocarbene with the general formula FcC=Cr(CO)5NH(CH2)15CH3, and two ferrocenyl amides with the general formula FcC=MNH(CH2)15CH3 where M = S or Se. These new derivatives have been synthesized to study the influence of long alkyl side chain and the hydrophilic head on the film organization behavior at the air-water interface.

The Langmuir-Blodgett (LB) technique was focused for building ordered nanostructures in molecular assemblies of ferrocenyl derivatives, which are apt to form a stable and transferable monolayer film. The π-A isotherm, hysteresis, Brewster angle microscopy (BAM) and film stability were used to characterize the behavior of a monolayer film at the air-water interface. Z- type LB films were prepared from molecular monolayers which were transferred onto glass substrates. These films were characterized by atomic force microscopy (AFM), UV-Visible spectra and X-ray diffraction (DRX) techniques.

A multi-block associative polyelectrolyte based on poly(methacrylic acid-ra-styrene) [MAA-S] and poly(octadecyl methacrylate) [ODMA] was synthesized through stepwise nitroxide-mediated solution polymerizations. The obtained polymer has a heptablock copolymer structure, alternating MAA-S as hydrophilic blocks (theoretical degree of polymerization [DPT] of 250), and ODMA as hydrophobic blocks (DPT = 15). Rheological properties, in the linear-response regime, of aqueous solutions (polymer content = 1.5 wt.%) were studied as a function of the amount of blocks on the polymer using steady-shear and creep-compliance experiments. Rheological experiments demonstrate that the viscoelastic behavior of the polymer bearing an ODMA block in terminal position greatly differs from that of the polymer with MAA-S block terminations. The former behaves as a newtonian fluid on a wider range of shear rates than the latter, which exhibit a shear-thinning behavior, even at low shear rates, independently of the molecular weight and number of blocks.