Search

Polyurethane elastomers with amphiphilic ABA tri-block co-polymers as the soft segments robustly show record-high tensile strength and simultaneously increased ductility via producing small and uniform hard domains.

Constructing electrocatalysts with plentiful active sites, great mass transfer ability, and high electrical conductivity is critical to realize efficient hydrogen evolution reaction (HER). Hierarchically porous cobalt phosphide/N-doped nanotubular carbon networks (CoP/NCNs) that have all the features were fabricated in this work. For the fabrication, the polymeric worm-like micelles (PWs) with a large aspect ratio were coated by a uniform nanolayer of Zn-Co zeolitic imidazolate frameworks (Zn-Co-ZIFs) on their surface, resulting in the hybrid nanofibers PWs@Zn-Co-ZIFs (HPWs). Inheriting the randomly curved and entanglement properity of PWs, the rigid HPWs formed hybrid networks with the packing voids sized tens to 200 nm. Then, the hybrid networks were treated by pyrolysis-oxidation-phosphidation and ZnO-removal processes, leading to the hierarchically porous CoP/NCNs. In the CoP/NCNs, there are plentiful CoP nanoparticles embedded on the surface of conductive carbon network and fully exposed. When used for HER electrocatalyst, the CoP/NCNs only need small overpotentials (98 and 118 mV in acid and alkaline electrolyte) at 10 mA cm−2. This novel strategy is instructive for tailoring hierarchically porous transition metal phosphide/carbon nanocomposites as promising electrocatalysts.

We report the first example of the fabrication of pure, single-chain Janus particles (SCJPs). The SCJPs were prepared by double-cross-linking an A-b-B diblock copolymer in a common solvent. Inevitably, the double-cross-linking led to a mixture containing not only SCJPs but also multichain particles and irregular single-chain particles. Under well-controlled conditions, the SCJPs in the mixture self-assemble with high exclusivity to form regularly structured macroscopic assemblies (MAs) with a crystal-like appearance that precipitate from the suspension. Pure SCJPs that are uniform in size, shape and Janus structure were efficiently prepared by collection and dissociation of the MAs. Block copolymers with different structural parameters were successfully used for the exclusive self-assembly (ESA), and pure SCJPs with varied structural parameters were produced, confirming the reliability of the ESA method.

Herein, we report an example of self-driven morphological transition and the unique dissociation behavior of polymeric assemblies. Polymeric nanogels were introduced into the shell of polymeric assemblies and used as a powerful platform to endow the assemblies with unique properties and behaviors. It is exhibited that the nanogel can host an intrananogel cross-linking reaction and thus contracts automatically to change the geometrical packing parameters of the building blocks, driving morphological transitions of the assemblies; the transitions are self-driven without any external stimuli. Additionally, when the nanogels in the shell expand, the assemblies dissociate into small fragments even when the core is in a frozen state; in existing studies, polymeric assemblies with a frozen core cannot dissociate, except the core becomes dynamic under the stimuli. Both the self-driven morphological transition and the dissociation behavior are unique and have never been reported before.

Polydiacetylenes in either the blue or red phase have been extensively reported and studied in depth, while the fabrication of a pure bluish-green phase (PBG) polydiacetylene that has a remarkably long effective conjugation length is still an unachieved long-sought goal. Here, we report the facile fabrication of PBG polydiacetylene and its composites through the deliberate annealing suspensions of stabilizer-free crystals of the diacetylene monomer and diacetylene/metal ion composites, respectively, followed by UV-induced polymerization. Furthermore, it is confirmed that the composition with metal ions not only increases the conjugation length, but also tunes the type of the third-order nonlinear optical absorption (NLA) of the polydicetylene; different NLA types of the polydicetylene were obtained. To the best of our knowledge, this is the first example of the same linear conjugated polymer having different NLA types without the need for any chemical modification.

Fluorescent organic-inorganic composite materials exhibiting "turn-on" response are often based on conjugated small molecules. Conjugated polymers, however, often exhibit a "turn-off" response in combination with metal ions. Here we present fluorescent turn-on behavior of a branched poly(ethylene imine)-poly(acrylic acid)-Ag

Composite worm-like micelles (CWMs) that encapsulate a large number of superparamagnetic magnetite nanoparticles (SMNPs) within the core while still having a small width should have a high magnetic resonance sensitivity and simultaneously a desirable circulation behaviour in biological systems. However, the preparation of such CWMs is still a challenge. Herein we report the fabrication of CWMs via two-stage self-assembly of SMNPs guided by a block copolymer and DNA, respectively. First, poly(ethylene glycol)-b-poly(4-vinylpyridine) co-assembled with SMNPs to form spherical composite micelles, guiding the clustering of multiple SMNPs within the core of the micelles. Then, at the second stage, DNA co-assembled with and guided the linear aggregation and fusion of the micelles, resulting in the CWM encapsulating a large number of SMNPs in the linear core. As a proof of concept, CWMs with a T2 relaxivity as high as 704 mM−1 s−1 and a low MRI detection limit of 2.2 μg mL−1 (∼0.02 nM CWMs) were prepared; it is significant that the T2 relaxivity of the SMNPs assembled in the CWMs is around 20 times that of the same SMNPs in the same amount but individually dispersed in the suspension. Additionally, although heavily loaded with SMNPs, the CWMs have a width as small as 20.5 nm and a core–shell structure with PEG as the shell. These features should make the CWMs very promising in their use as ultra-sensitive magnetic resonance imaging probes.

Ultrasound-controlled drug release is a very promising technique for controlled drug delivery due to the unique advantages of ultrasound as the stimulus. For this technique, the polymer assemblies that are sufficiently stable in the suspensions but dissociable under a gentle ultrasound treatment are very desirable. In most cases, such polymer assemblies were constructed by few specific polymers. Few examples of the polymer assemblies that are formed by common linear polymers while able to respond strongly to a gentle ultrasound treatment have been reported, because the chain entanglements within the assemblies resist efficiently the ultrasound-induced shearing force; notably, the ultrasound treatment should be gentle enough and incapable of breaking the polymer chains, otherwise it will damage biological tissues. In this study, we report that through intermediate intrachain-crosslinking of one block of a common diblock copolymer, and then self-assembly of the crosslinked polymer in the selective solvent for the uncrosslinked block, vesicles, worm-like micelles and spherical micelles that are highly regular and stable in the suspensions but dissociable under a gentle ultrasound treatment were prepared. The intermediate crosslinking restricts the chain entanglements within the assemblies remarkably, and thus enhances greatly ultrasound-responsiveness for the polymer assemblies. In addition, during the self-assembly, the as-crosslinked block chains are still flexible and less entangled and thus more dynamic, making the crosslinked polymer much more capable than its precursor in forming regular assemblies with various morphologies. Since most of common polymers either are crosslinkable or can be modified to be crosslinkable, this approach is a general method for preparing the strongly ultrasound-responsive polymer assemblies with different compositions, morphologies and structures.

Graphene-like g-C3N4 nanosheets (NSs) have been successfully synthesized with a modified polymerization process of melamine by cocondensation with volatile salts. Volatile ammonium salts such as urea–NH4Cl/(NH4)2SO4/(NH4)3PO4 were added with melamine to modulate the thermodynamic process during polymerization and optimize the structure formation in situ. The surface area, surface structure, and surface charge state of the obtained g-C3N4 NSs could be controlled by simply adjusting the mass ratio of the melamine/volatile ammonium salt. As a consequence, the g-C3N4 NSs exhibited much higher activity than bulk g-C3N4 for the photocatalytic degradation of target pollutants (rhodamine B, methylene blue, and methyl orange), and it also exhibited greater hydrogen evolution under visible light irradiation with an optimal melamine/volatile ammonium salt ratio. The as-prepared g-C3N4 NSs with melamine–urea–NH4Cl showed the highest visible light photocatalytic H2 production activity of 1853.8 μmol·h–1·g–1, which is 9.4 times higher than that of bulk g-C3N4 from melamine. The present study reveals that the synergistic effect of the enhanced surface area, surface structure, and surface charge state is the key for the enhancement of photocatalytic degradation and hydrogen evolution, which could be controlled by the proposed strategy. The result is a good explanation for the hypothesis that adding properly selected monomers can truly regulate the polymerization process of melamine, which is beneficial for obtaining g-C3N4 NSs without molecular self-assembly. Considering the inexpensive feedstocks used, a simple synthetic controlling method provides an opportunity for the rational design and synthesis, making it decidedly appealing for large-scale production of highly photocatalytic, visible-sensitizable, metal-free g-C3N4 photocatalysts.

Hyaluronan (HA) fragments have been proposed to elicit defensive or pro-inflammatory responses in many cell types. For articular chondrocytes in an inflammatory environment, studies have failed to reach consensus on the endogenous production or effects of added HA fragments. The present study was undertaken to resolve this discrepancy. Cultured primary human articular chondrocytes were exposed to the inflammatory cytokine IL-1β, and then tested for changes in HA content/size in conditioned medium, and for the expression of genes important in HA binding/signaling or metabolism, and in other catabolic/anabolic responses. Changes in gene expression caused by enzymatic degradation of endogenous HA, or addition of exogenous HA fragments, were examined. IL-1β increased the mRNA levels for HA synthases HAS2/HAS3 and for the HA-binding proteins CD44 and TSG-6. mRNA levels for TLR4 and RHAMM were very low and were little affected by IL-1β. mRNA levels for catabolic markers were increased, while type II collagen (α1(II)) and aggrecan were decreased. HA concentration in the conditioned medium was increased, but the HA was not degraded. Treatment with recombinant hyaluronidase or addition of low endotoxin HA fragments did not elicit pro-inflammatory responses. Our findings showed that HA fragments were not produced by IL-1β-stimulated human articular chondrocytes in the absence of other sources of reactive oxygen or nitrogen species, and that exogenous HA fragments from oligosaccharides up to about 40 kDa in molecular mass were not pro-inflammatory agents for human articular chondrocytes, probably due to low expression of TLR4 and RHAMM in these cells. Electronic supplementary material The online version of this article (10.1007/s10753-019-01043-9) contains supplementary material, which is available to authorized users.

In this work, hybrid carbon/ZnxCo3−xO4 (ZCO) nanotube (HCNT) networks have been efficiently prepared, using highly pure, uniform and long core-crosslinked polymeric worm-like micelles (PWs) with a small diameter and a 3D interacting shell as the 1D template. The HCNTs have a diameter of 50 nm, a channel of 30 nm width, and a hybrid porous wall in which large amounts of open micropores (ca. 5 nm) and ZCO nanoparticles (NPs

Porous materials with well-defined porosity have advantages in a wide range of applications, including filtration media, catalysis, and electrodes. The bottom-up fabrication of inverse opals have promised to provide those nanostructures, but fabrication of these materials is often plagued with large numbers of defects and macro-scale cracks. Here, we present a method for making nanostructured porous clay films with well defined pore size that are crack free over a large area (multiple cm2).

Despite the existence of potent anti-inflammatory biological drugs e.g., anti-TNF and anti IL-6 receptor antibodies, for treating chronic inflammatory and autoimmune diseases, these are costly and not specific. Cheaper oral available drugs remain an unmet need. Expression of the acute phase protein Serum Amyloid A (SAA) is dependent on release of pro-inflammatory cytokines IL-1, IL-6 and TNF-α during inflammation. Conversely, SAA induces pro-inflammatory cytokine secretion, including Th17, leading to a pathogenic vicious cycle and chronic inflammation. 5- MER peptide (5-MP) MTADV (methionine-threonine-alanine-aspartic acid-valine), also called Amilo-5MER, was originally derived from a sequence of a pro-inflammatory CD44 variant isolated from synovial fluid of a Rheumatoid Arthritis (RA) patient. This human peptide displays an efficient anti-inflammatory effects to ameliorate pathology and clinical symptoms in mouse models of RA, Inflammatory Bowel Disease (IBD) and Multiple Sclerosis (MS). Bioinformatics and qRT-PCR revealed that 5-MP, administrated to encephalomyelytic mice, up-regulates genes contributing to chronic inflammation resistance. Mass spectrometry of proteins that were pulled down from an RA synovial cell extract with biotinylated 5-MP, showed that it binds SAA. 5-MP disrupted SAA assembly, which is correlated with its pro-inflammatory activity. The peptide MTADV (but not scrambled TMVAD) significantly inhibited the release of pro-inflammatory cytokines IL-6 and IL-1β from SAA-activated human fibroblasts, THP-1 monocytes and peripheral blood mononuclear cells. 5-MP suppresses the pro-inflammatory IL-6 release from SAA-activated cells, but not from non-activated cells. 5-MP could not display therapeutic activity in rats, which are SAA deficient, but does inhibit inflammations in animal models of IBD and MS, both are SAA-dependent, as shown by others in SAA knockout mice. In conclusion, 5-MP suppresses chronic inflammation in animal models of RA, IBD and MS, which are SAA-dependent, but not in animal models, which are SAA-independent.

Polydiacetylenes (PDAs), an organic layered compound, show a series of intriguing properties, such as thermochromism and fluorescence emission in the red-phase. However, their irreversible color change, and weak and single-color fluorescence emitted only from the red-phase PDAs, have limited their applications. Herein, we report double-reversible PDA-Tb3+ nanosheets of which both the color and the fluorescence can be reversibly switched between two colors. PDA-Tb3+ nanosheets have the nearly defect-free intercalated structure in which a layer of Tb3+ ions was intercalated in between each two PDA bilayers to tether almost all of the carboxyl groups at the end of the side chains of the PDA. When the PDA is in the blue phase, the PDA-Tb3+ nanosheets emit the green fluorescence of Tb3+ ions. When the PDA is in the red phase, the Tb3+ fluorescence disappears while the intrinsic red fluorescence of PDA is effectively enhanced through the fluorescence resonance energy transfer (FRET) process; the PDA-Tb3+ nanosheets emit stronger red fluorescence compared with the PDA in red phase. Moreover, the tethering of almost all of the carboxyl groups at the end of the side chains of the PDA endows the nanosheets with the double reversibility in both the color and fluorescence transitions.

Nanosized polymeric Janus particles (NPJPs) have important applications in a variety of theoretical and practical research fields. However, the methods that are versatile and can prepare NPJPs highly efficiently are very limited. Herein, we reported a two-step thermodynamically controlled preparation of NPJPs with a high yield using a diblock copolymer as the precursor. At the first step, A-b-B coassembled in the solution with a partner diblock copolymer C-b-B to form the mixed shell micelles (MSMs) with B core and A/C mixed shell. Then, intramicellarly covalently cross-linking the A block chains resulted in the complete phase separation of A and C chains in the mixed shell, leading to the direct conversion of the MSMs into NPJPs. The first step, diblock copolymer micellization, is known as a thermodynamically controlled process, and we also made the second step, conversion from MSMs to NPJPs, be thermodynamically controlled due to the application of covalent cross-linking. As the result, the conversion e...

We report the fabrication of a polypyrrole-coated interfacial solar membrane using a versatile dip-coating method, which enables solar vapor generation efficiency of 72% for the purpose of desalination. This next-generation method of thermal desalination membrane uses solar thermal energy as a heat source to vaporize salt and brackish water. The polypyrrole thin film is tightly attached to individual non-conductive polypropylene fibers in a mesh. The dip-coating method can be applied to different types of membranes, regardless of the wetting property, conductivity, or surface curvature.

Herein, efficient fabrication of polymersomes that have unique and nonequilibrium morphologies is reported. Starting from preparing big polymeric vesicles sized around 2 µm with a flexible but crosslinkable structure, a controllable morphological transformation process from the vesicles via prolate vesicles and the pearl-chain-like structure, which are the two intermediate structures, to vesicle-end-capped tubes is conducted. Significantly, each of the intermediates is a regular polymersome and occupies a distinct phase space in the transformation process and thus can be separately processed and prepared. By crosslinking the structures, respectively, regular polymersomes with unique but stable morphologies are fabricated. Furthermore, the 1D polymersomes contain narrow necks. These narrow necks are sensitive to ultrasound vibration and broken by gentle ultrasound treatment to form regular open-ended tubes and open-ended vesicles, which are nonequilibrium but stable morphologies and difficult to prepare by existing methods.

We report the first example of endowing the surface structure of a polymeric assembly with nearly atomic-level precision. The solenoidal wrapping of a DNA chain around the surface of a nanofibre transcribes the precise sequence structure of the DNA onto the nanofibre surface, resulting in a precise surface structure.

Polyelectrolyte multilayers (PEMs), assembled from weak polyelectrolytes, have often been proposed for use as smart or responsive materials. However, such response to chemical stimuli has been limited to aqueous environments with variations in ionic strength or pH. In this work, a large in magnitude and reversible transition in both the swelling/shrinking and the viscoelastic behavior of branched polyethylenimine/poly(acrylic acid) multilayers was realized in response to exposure with various polar organic solvents (e.g., ethanol, dimethyl sulfoxide, and tetrahydrofuran). The swelling of the PEM decreases with an addition of organic content in the organic solvent/water mixture, and the film contracts without dissolution in pure organic solvent. This large response is due to both the change in dielectric constant of the medium surrounding the film as well as an increase in hydrophobic interactions within the film. The deswelling and shrinking behavior in organic solvent significantly enhances its elasticity, resulting in a stepwise transition from an initially liquid-like film swollen in pure water to a rigid solid in pure organic solvents. This unique and recoverable transition in the swelling/shrinking behaviors and the rheological performances of weak polyelectrolyte multilayer film in organic solvents is much larger than changes due to ionic strength or pH, and it enables large scale actuation of a freestanding PEM. The current study opens a critical pathway toward the development of smart artificial materials.

We report a facile and versatile method for fabrication of multiheteroatom-doped hierarchically porous carbon with a large specific surface area, using the 3D network constructed by ZIF-8 coated wormlike micelles as template. The uniform and highly pure wormlike micelles developed in our laboratory is essential, because they not only are responsible for the formation of hierarchical porosity, but also play as a versatile platform for multiheteroatoms doping. In a primary experiment, S, N, B, and P heteroatoms were doped conveniently and the resultant porous carbons have the excellent oxygen reduction reaction performance comparable to the commercial 20% Pt/C.

A method for specific quantification of hyaluronan (HA) concentration using AlphaScreen® (Amplified Luminescent Proximity Homogeneous Assay) technology is described. Two types of hydrogel-coated and chromophore-loaded latex nanobeads are employed. The proximity of the beads in solution is detected by excitation of the donor bead leading to the production of singlet oxygen, and chemiluminescence from the acceptor bead upon exposure to singlet oxygen. In the HA assay, the donor bead is modified with streptavidin, and binds biotin-labeled HA. The acceptor bead is modified with Ni(II), and is used to bind a specific recombinant HA-binding protein (such as HABP; aggrecan G1-IGD-G2) with a His-tag. Competitive inhibition of the HA-HABP interaction by free unlabeled HA in solution is used for quantification. The assay is specific for HA, and not dependent on HA molecular mass above the decasaccharide. HA can be quantified over a concentration range of approximately 30-1600 ng/mL using 2.5 μL of sample, for a detectable mass range of approximately 0.08-4 ng HA. This sensitivity of the AlphaScreen assay is greater than existing ELISA-like methods, due to the small volume requirements. HA can be detected in biological fluids using the AlphaScreen assay, after removal of bound proteins from HA and dilution or removal of other interfering proteins and lipids.

Fluorescent organic–inorganic composite materials exhibiting “turn-on” response are often based on conjugated small molecules. Conjugated polymers, however, often exhibit a “turn-off” response in combination with metal ions. Here we present fluorescent turn-on behavior of a branched poly(ethylene imine)-poly(acrylic acid)-Ag+ ion complex in a thin film. The material is characterized by UV–vis, spectrofluorometry, XPS, and ICP-MS. The turn-on response is exhibited only with all three components present, implying that the optically active metal coordination complex contains amine and carboxylic acid groups. This behavior is observed in the solid state, meaning this material could be easily integrated into devices. We demonstrate sensing of formaldehyde vapor as well as halide containing solutions based on fluorescence quenching. This fluorescent material is simply made using the layer-by-layer technique and commercially available polymers.

Layer-by-layer assembly of films containing metal ions was investigated. A complex between various metal ions and branched polyethyleneimine is formed in solution and then assembled into multilayer films with poly(acrylic acid). The metal-ligand complex formation results in brightly colored materials that deposit as thick layers. Cu(2+)-containing films were chosen as a model for studying the disassembly of these films in response to various stimuli, including pH, salt, and surfactants. The range of pH instability corresponds to the pH range over which pores are formed in the film. We demonstrate controllable disassembly of these materials, which could be used for antifungal or antibacterial applications.

Omniphobic and slippery coatings from lubricant-infused, textured surfaces have recently been shown to have superior properties including low contact angle hysteresis and low sliding angles. Here, we present an omniphobic slippery surface prepared by infusing a fluorinated lubricant into a porous polyelectrolyte multilayer. These surfaces repel water and decane with sliding angles as low as 3°. One advantage of polyelectrolyte multilayers is the ease with which they can coat nonplanar surfaces, demonstrated here.

The increased requirement of a clean and efficient green energy source promotes the development of hydrogen-based economy. In order to lower the cost of manufacturing, the future development of the next generation of hydrogen separation membrane is necessary. This chapter summarized the hydrogen separation membrane technology, the membrane separation mechanism, the polymer material selection and membrane structure design, current industrial market and separation modules, as well as the future development of the next generation hydrogen separation membrane.

Amino-bearing polymers, coated with apatite or similar minerals, have attracted significant attention for their potential in medical applications. In this study, an amino-terminated hyperbranched polybenzimidazole (HBPBI) membrane was used as a substrate for apatite growth. The membrane was soaked in solutions of CaCl2, Na2HPO4 and SBF to yield an apatite coating. The structure and morphology of the layers were characterized by FTIR-ATR, XRD and FESEM. The results indicate that the high densities of amino, imide and imidazole groups on the amino-terminated HBPBI membrane provide active sites for the growth of apatite.

Although emulsion applications of microscale graphene sheets have attracted much attention recently, nanoscale graphene platelets, namely, graphene quantum dots (GQDs), have been rarely explored in interface science. In this work, we study the interfacial behaviors and emulsion phase diagrams of hydrophobic-functionalized graphene quantum dots (C18-GQDs). Distinctive from pristine graphene quantum dots (p-GQDs), C18-GQDs show several interesting surface-active properties including high emulsification efficiency in stabilizing dodecane-in-water emulsions. We then utilize the C18-GQDs as surfactants in miniemulsion polymerization of styrene, achieving uniform and relatively small polystyrene nanospheres. The high emulsification efficiency, low production cost, uniform morphology, intriguing photoluminescence, and extraordinary stability render C18-GQDs an attractive alternative in surfactant applications.

Controlled wetting at surfaces and interfaces is an important area of research with numerous potential commercial applications. Both superhydrophobicity and superhydrophilicity can be used to enable applications such as self-cleaning, dropwise condensation, or antifogging. Many strategies for creating such surfaces center around biomimicry, replicating the structure of the lotus leaf, for example. Given the potential impact, creating surfaces with these properties using any number of fabrication is of great interest. One very promising fabrication technique, however, for creating these surfaces is the layer-by-layer (LbL)-directed self-assembly of polyelectrolytes and other charged materials. LbL is a sequential adsorption technique wherein a surface is exposed to first a solution of one charge and then a solution of the opposite charge. LbL has many advantages, including the ability to incorporate many different types of materials and therefore functionality, the ability to conformally coat substrates of complex geometry, and environmentally friendly aqueous processing. This review describes recent progress in using LbL to create surfaces with controlled wetting. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42767.

Self-healing is the ability of a material to repair mechanical damage. The lifetime of a coating or film might be lengthened with this capacity. Water enabled self-healing of polyelectrolyte multilayers has been reported, using systems that grow via the interdiffusion of polyelectrolyte chains. Due to high mobility of the polyelectrolyte chains within the assembly, it is possible for lateral diffusion to heal over scratches. The influence of metal ions and nanoparticles on this property has, however, not been previously studied. Here we demonstrate that the incorporation of silver nanoparticles reduced in situ within the branched poly(ethyleneimine)–poly(acrylic acid) polyelectrolyte multilayer structure speeds the ability of the multilayer assembly to self-heal. This enhancement of property seems to not be due to changes in mechanical properties but rather in enhanced affinity to water and plasticization that enables the film to better swell.

A series of CR 2 (OH)-diarylpyrimidine derivatives (CR 2 (OH)-DAPYs) featuring a hydrophobic group at CH(OH) linker between wing I and the central pyrimidine were synthesized and evaluated for their anti-HIV activity in MT-4 cell cultures. All the target compounds except for compound 3k displayed inhibitory activity against HIV-1 wild-type with EC 50 values ranging from 7.21 ± 1.99 to 0.067 ± 0.006 μM. Among them, compound 3d showed the most potent anti-HIV-1 activity (EC 50 = 0.067 ± 0.006 μM, SI > 592), which was approximately 2-fold more potent than the reference drugs nevirapine (NVP) and delaviridine (DLV) in the same assay. In addition, the binding modes with HIV-1 RT and the preliminary SAR studies of these new derivatives were also investigated.

Over the course of this grant, our group worked on ionomer (ethylene-co-methacrylic acid or EMAA) and metal ion (primarily Cu2+ and Ag+) containing polyelectrolyte assemblies. We are interested in how the strength of complexation between polymers and crosslink density can influence properties, including mechanical properties. Using electrostatic directed self-assembly, or the layer-by-layer technique, allows for the modulation of secondary interactions within these thin films and coatings. This in term can result in the variation of a range of mechanical properties, including toughness, modulus, hardness, and the ability to self-heal. We have found that ionomer assemblies can be made into free-standing thin films, and that the toughness of these materials is dependent on both the assembly conditions and post-assembly annealing. Additionally, we have shown that for copper ion containing films, the ions act as crosslinking agents increasing hardness and modulus. On the other hand, incorporation of Ag ions increases the ability of these thin films to self-heal.

Coatings with controllable wettability are of interest in a number of applications. Modulation of surface wettability is often necessary for these applications. It has been demonstrated many times that surface topography is key to the ability to make superhydrophobic surfaces, but at the same time surface chemistry is key. The layer-by-layer technique of fabricating coatings based on the complexation of oppositely charged polyelectrolytes can be a versatile method for producing precisely controlled thin films with a wide range of properties. In order to control wettability, hierarchical textures are generally needed, but the underlying surface energy of the material is also important. Generally, these films are made out of commercially available polymers, thereby limiting the range of available surface energies. Ion exchange of the counterions on the surface of the film is one way to modify materials properties, but we show that co-assembly with a surfactant is another way to achieve an even greater range of surface wettabilities. Our films have contact angles of as high as 110° with ion exchange and even up to 140° with surfactant co-assembly without any added texture to the surfaces. Co-assembly with a surfactant has not been widely studied with respect to polyelectrolyte multilayers and may prove to be a more general method to modify film properties.