Polymer Nanofilms Research Articles

Light-/steam-driven polymeric crosslinking with porous multistructure pattern for ultrastable and fast-speed memory

Organic memories typically comprise memristive polymer mediums sandwiched between two electrodes, with the advantages of wet manufacturing and modulated function. However, the issues associated with structural instability, low-speed switch, and hard pattern in polymeric memories are the main obstacles towards practical uses. Here, we present an ultrastable and fast-speed memory array that uses amorphous polymer nanofilm with light-/steam-driven crosslinked porous multistructure as memristive materials. The polymer diode shows nonvolatile rewritable flash memory characteristics, with a high ON/OFF ratio, long retention time, and high speeds of set (70 ns) and reset (845 ns) operations. Impressively, the memory cell undergoes harsh conditions in ultraviolet irradiation and extreme temperatures. By rationally integrating the array with target sensors, an artificial sensory memory architecture is constructed to mimic visual/thermal perception and recording, demonstrating great potential for biomimetic neuromorphic electronics. Our results advance a commercial perspective on memristive organics capable of integration patterns and high performance.

Interfacial self‐assembly growth of mesoporous polydopamine nanofilms for formaldehyde sensing

AbstractMesoporous polymer nanofilms combine the advantages of the unique structure of mesopores, the quasi‐2D configuration of the films, and the inherent properties of polymers, and have become a kind of ideal candidate for the high‐performance micro‐nano devices due to their highly accessible surface area and exposed active sites. However, the facile preparation of polymer nanofilms with well‐defined mesostructures has remained a great challenge due to the lack of synthetic strategies. In this study, we developed a simple soft‐template interfacial co‐assembly strategy to in‐situ construct mesoporous polydopamine nanofilms with uniform thickness (30 nm) and regularly distributed mesopore arrays (average pore size of 12 nm) on surfaces with different types and morphologies. Furthermore, a single‐layer mesoporous polymer nanofilm was directly grown on a quartz crystal microbalance substrate and its performance for sensing formaldehyde was studied. The resulted sensor showed excellent sensing response, fast response/recovery dynamics, and great stability, presenting a great promising landscape for trace detection of formaldehyde gas.

Tailor-made β-ketoenamine-linked covalent organic polymer nanofilms for precise molecular sieving.

The membranes that accurately separate solutes with close molecular weights in harsh solvents are of crucial importance for the development of highly-precise organic solvent nanofiltration (OSN). The physicochemical structures of the membrane need to be rationally designed to achieve this goal, such as customized crosslinked networks, thickness, and pore size. Herein, we synthesize a type of covalent organic polymer (COP) nanofilms with tailor-made thickness and pore structure using a cyclic deposition strategy for precise molecular sieving. By elaborately designing monomer structures and controlling deposition cycle numbers, the COP nanofilms linked by robust β-ketoenamine blocks were endowed with sub-nanometer micropores and a linearly tunable thickness of 10-40 nm. The composite membranes integrating COP nanofilms exhibited adjustable solvent permeance. The membranes further demonstrated steep and finely-regulated rejection curves within the molecular weight range of 200 to 400 Da, where the difference value was as low as 40 Da. The efficient purification and concentration of the antibacterial drug and its intermediate was well achieved. Therefore, the exploited COP nanofilms markedly facilitate the application of microporous organic polymers for precise molecular separation in OSN.

Study of Polymer Nanofilms Using for High-Throughput Screening in the Development of Transdermal Therapeutic System.

We investigated polymer nanofilm (PNF) for use in high-throughput screening (HTS) to promote the development of transdermal therapeutic systems (TTS). The drug permeability of PNF with a 1 : 1 weight mix ratio of poly(L-lactic acid) (PLLA) and poly(methylhydrosiloxane) (PMHS) (PLLA/PMHS (1/1) PNF) and Strat-M® of the transdermal diffusion test membrane, was evaluated using 12 kinds of drugs with the logarithmic value of n-octanol/water partition coefficients of -4.70 to 3.86. The lag time of PLLA/PMHS (1/1) PNF made via polymer alloying was significantly shorter than that of Strat-M® for 10 drug types, and the formation of a highly diffusible PMHS-rich phase accompanying the formation of a sea-island structure was suggested as a contributing factor. Additionally, a high correlation was confirmed between the measured value for the logarithm of the apparent permeability coefficient of PLLA/PMHS (1/1) PNF and the literature values for the logarithm of the apparent permeability coefficient of human skin (r = 0.929). This study shows that PLLA/PMHS (1/1) PNF can reliably predict drug permeability in human skin and can potentially be used in HTS for developing TTS.

Highly sensitive detection of low-concentration sodium chloride solutions based on polymeric nanofilms coated long period fiber grating

Long period fiber gratings (LPFGs) have special advantages in the detection of salt concentrations due to small volume, corrosion resistance and immunity to electromagnetic interference. However, it is very difficult to distinguish low-concentration salt solutions with usual LPFGs owing to the poor sensitivity. In this paper, the detection capability of the LPFG to low-concentration salt solutions was significantly improved by assembling salt-containing poly (diallyldimethylammonium chloride) (PDDA) and salt-containing poly (sodium-p-styrenesulfonate) (PSS). Experimental results showed that, the responsive wavelength range of the LPFG was remarkably broadened in low-concentration salt solutions after assembling nanofilms. The suitable detection range of the PDDA/PSS films coated LPFG for salt concentrations was 0–3%. In such a range, the average refractive index sensitivity and the average salinity sensitivity of the LPFG was as high as 29545.9 nm/RIU and 52.2 nm/% respectively. Compared with the LPFG without nanofilms, the discrimination ability of the PDDA/PSS films coated LPFG to 0–3% salt solutions increased by 568 times. The analysis demonstrated that PDDA and salt in the assembly solutions played a pivotal role in the above effects. The proposed sensor has extensive application prospects in the monitoring of salt concentration in many fields such as seawater, food processing, fermentation process, etc.

2,2'-Biphenol-based Ultrathin Microporous Nanofilms for Highly Efficient Molecular Sieving Separation.

Organic solvent nanofiltration (OSN) is an emerging membrane separation technology, which urgently requires robust, easily processed, OSN membranes possessing high permeance and small solutes-selectivity to facilitate enhanced industrial uptake. Herein, we describe the use of two 2,2'-biphenol (BIPOL) derivatives to fabricate hyper-crosslinked, microporous polymer nanofilms through IP. Ultra-thin, defect-free polyesteramide/polyester nanofilms (≈5 nm) could be obtained readily due to the relatively large molecular size and ionized nature of the BIPOL monomers retarding the rate of the IP. The enhanced microporosity arises from the hyper-crosslinked network structure and monomer rigidity. Specifically, the amino-BIPOL/PAN membrane exhibits extraordinary permselectivity performances with molecular weight cut-off as low as 233 Da and MeOH permeance of ≈13 LMH/bar. Precise separation of small dye mixtures with similar M.W. based on both their charge and molecular size are achieved.

2,2′‐Biphenol‐based Ultrathin Microporous Nanofilms for Highly Efficient Molecular Sieving Separation

AbstractOrganic solvent nanofiltration (OSN) is an emerging membrane separation technology, which urgently requires robust, easily processed, OSN membranes possessing high permeance and small solutes‐selectivity to facilitate enhanced industrial uptake. Herein, we describe the use of two 2,2′‐biphenol (BIPOL) derivatives to fabricate hyper‐crosslinked, microporous polymer nanofilms through IP. Ultra‐thin, defect‐free polyesteramide/polyester nanofilms (≈5 nm) could be obtained readily due to the relatively large molecular size and ionized nature of the BIPOL monomers retarding the rate of the IP. The enhanced microporosity arises from the hyper‐crosslinked network structure and monomer rigidity. Specifically, the amino‐BIPOL/PAN membrane exhibits extraordinary permselectivity performances with molecular weight cut‐off as low as 233 Da and MeOH permeance of ≈13 LMH/bar. Precise separation of small dye mixtures with similar M.W. based on both their charge and molecular size are achieved.

Directed Self-Assembly of Conducting Polymer Nanofilms on Single-Crystalline Ice Facets

Directed Self-Assembly of Conducting Polymer Nanofilms on Single-Crystalline Ice Facets

Simvastatin Nanoparticles Loaded Polymeric Film as a Potential Strategy for Diabetic Wound Healing: In Vitro and In Vivo Evaluation.

The pleiotropic effects of statins are recently explored for wound healing through angiogenesis and lymph-angiogenesis that could be of great importance in diabetic wounds. The aim of the present study is to fabricate nanofilm embedded with simvastatin-loaded chitosan nanoparticles (CS-SIM-NPs) and to explore the efficacy of SIM in diabetic wound healing. The NPs, prepared via ionic gelation, were 173 nm ± 2.645 in size with a zeta potential of -0.299 ± 0.009 and PDI 0.051 ± 0.088 with excellent encapsulation efficiency (99.97%). The optimized formulation (CS: TPP, 1:1) that exhibited the highest drug release (91.64%) was incorporated into the polymeric nanofilm (HPMC, Sodium alginate, PVA), followed by in vitro characterization. The optimized nanofilm was applied to the wound created on the back of diabetes-induced (with alloxan injection 120 mg/kg) albino rats. The results showed a significant (p < 0.05) improvement in the wound healing process compared to the diabetes-induced non-treated group. The results highlighted the importance of nanofilms loaded with SIM-NPs in diabetic wound healing through angiogenesis promotion at the wound site. Thus, CS-SIM-NPs loaded polymeric nanofilms could be an emerging diabetic wound healing agent in the industry of nanomedicines.

Polymeric nano-films with spatially arranged compartments for uranium recovery from seawater

Polymeric thin film composite (TFC) membranes are well-known for their application in aqueous separation processes, these TFC membranes have the proven advantage of such demanding stability, tunable porosity and possibility of incorporating the selective binding sites for one of the challenging chemical separation of Uranium (U) from seawater. Here, in this work we report the preparation of polycondensation polymer (PAR) of a pre-synthesized schiff base having the binding pocket for U, via industrially relevant interfacial polymerization. The large area polymeric nano-films (pTF) of conjugated schiff-base have been prepared at the solvent-non-solvent interface yield the nano-film of tunable thickness ≥ 22 nm. The conjugated monomer develops the electrical double layer with Debye length (λD) < 1 nm thickness, helps in localizing the negative charge on the surface, which polarizes the ions largely present in seawater. The pTF and PAR are characterized for its composition, surface charge, hydrophilicity and microscopic properties. The pTF of ∼22 nm thickness delivered high efficiency of U extraction from natural seawater (UES) ∼16.5 ± 0.7 mg/g in 30 days. It showed >2 times high U to V (Vanadium) selectivity ratio, fast UES kinetics of 0.6 mg/g/d, and reasonable service life of 5 adsorption–desorption cycles. The binding analysis suggests that network of polymeric chains containing conjugated schiff base in pTF provided the micro-pores, decorated with the spatially arranged binding pockets to adsorb U possibly in its octahedral geometry.

Facile Construction of Nanofilms from a Dip-Coating Process to Enable High-Performance Solid-State Batteries.

The use of solid-state electrolytes (SSEs) instead of those liquid ones has found promising potential to achieve both high energy density and high safety for their applications in the next-generation energy storage devices. Unfortunately, SSEs also bring forth challenges related to solid-to-solid contact, making the stability of the electrode/electrolyte interface a formidable concern. Herein, using a garnet-type Li6.5La3Zr1.5Ta0.5O12 (LLZT) electrolyte as an example, we demonstrated a facile treatment based on the dip-coating technique, which is highly efficient in modifying the LLZT/Li interface by forming a MgO interlayer. Using polyvinyl pyrrolidone (PVP) as a coordination polymer, uniform and crack-free nanofilms are fabricated on the LLZT pellet with good control of the morphological parameters. We found that the MgO interlayer was highly effective to reduce the interfacial resistance to 6 Ω cm2 as compared to 1652 Ω cm2 of the unmodified interface. The assembled Li symmetrical cell was able to achieve a high critical current density of 1.2 mA cm-2 at room temperature, and it has a long cycling capability for over 4000 h. Using the commercialized materials of LiFePO4 and LiNi0.83Co0.07Mn0.1O2 as the cathode materials, the full cells based on the LLZT@MgO electrolyte showed excellent cyclability and high rate performance at 25 °C. Our study shows the feasibility of precise and controllable surface modification based on a simple liquid phase method and highlights the essential importance of interface control for the future application of high-performance solid-state batteries.

Optical microfibers integrated with evanescent field triggered self-growing polymer nanofilms.

Hybrid optical fibers have been widely investigated in different architectures to build integrated fiber photonic devices and achieve various applications. Here we proposed and fabricated hybrid microfiber waveguides with self-growing polymer nanofilms on the surfaces of microfibers triggered by evanescent field of light for the first time. We have demonstrated the polymer nanofilm of ∼50 nm can be grown on the microfiber with length up to 15 mm. In addition, the roughness of nanofilm can be optimized by controlling the triggering laser power and exposure duration, and the total transmission loss of the fabricated hybrid microfiber is less than 2 dB within a wide wavelength range. The hybrid polymer nanofilm microfiber waveguides have been characterized and their relative humidity (RH) responses have also been tested, indicating a potential for RH sensing. Our fabrication method may also be extended to construct the hybrid microfibers with different functional photopolymer materials.

Nascent Holes on Spin-Coated Polymer Nanofilms: Effect of Processing and Solvents

Nascent Holes on Spin-Coated Polymer Nanofilms: Effect of Processing and Solvents

5-Sulfoisophthalic acid sodium incorporated polyamide nanofiltration membrane with enhanced separation performance

Highly permeable nanofiltration membrane has attracted great attention in energy-efficient liquid separation. However, the preparation of selective membranes with high permeability and good antifouling capability remains challenging. Here we first reported 5-sulfoisophthalic acid sodium (SSIPA) co-deposition for designing crosslinked polymer nanofilm via interfacial polymerization. The composite membranes composed of thinner sulfated polyamide nanofilms (18.0 ± 2.2 nm) had enhanced hydrophilicity and electronegativity as well as smoother surface and enlarger pore size. The SSIPA integrated polyamide nanofiltration membrane presented approximately 4.8 folds pure water flux of the membrane without SSIPA. The prepared membrane suitable for water desalination had 18.0 and 28.3 LHM/bar pure water permeance with the comparable Na2SO4 rejection of 96.3% and 91.8%, respectively. More importantly, the membrane fabricated with a high proportion of SSIPA achieved better dye/salt fraction performance with dye fluxes of 49.3 LMH/bar as well as superior CR rejection (99.0%) and NaCl passage (97%). At the same time, the natural organic matter (BSA, SA) could be almost completely removed. Significantly, the SSIPA-integrated membrane exhibited excellent long-term stability and antifouling capacity. These novel loose TFC membranes with outstanding separation performance provide potential applications for water desalination and organic separation.

Development of Gold Nanoparticles Decorated Molecularly Imprinted–Based Plasmonic Sensor for the Detection of Aflatoxin M1 in Milk Samples

Aflatoxins are a group of extremely toxic and carcinogenic substances generated by the mold of the genus Aspergillus that contaminate agricultural products. When dairy cows ingest aflatoxin B1 (AFB1)−contaminated feeds, it is metabolized and transformed in the liver into a carcinogenic major form of aflatoxin M1 (AFM1), which is eliminated through the milk. The detection of AFM1 in milk is very important to be able to guarantee food safety and quality. In recent years, sensors have emerged as a quick, low–cost, and reliable platform for the detection of aflatoxins. Plasmonic sensors with molecularly imprinted polymers (MIPs) can be interesting alternatives for the determination of AFM1. In this work, we designed a molecularly–imprinted–based plasmonic sensor to directly detect lower amounts of AFM1 in raw milk samples. For this purpose, we prepared gold–nanoparticle–(AuNP)−integrated polymer nanofilm on a gold plasmonic sensor chip coated with allyl mercaptan. N−methacryloyl−l−phenylalanine (MAPA) was chosen as a functional monomer. The MIP nanofilm was prepared using the light–initiated polymerization of MAPA and ethylene glycol dimethacrylate in the presence of AFM1 as a template molecule. The developed method enabled the detection of AFM1 with a detection limit of 0.4 pg/mL and demonstrated good linearity (0.0003 ng/mL–20.0 ng/mL) under optimized experimental conditions. The AFM1 determination was performed in random dairy farmer milk samples. Using the analogous mycotoxins, it was also demonstrated that the plasmonic sensor platforms were specific to the detection of AFM1.

Robust, self-adhesive, reinforced polymeric nanofilms enabling gas-permeable dry electrodes for long-term application

Robust polymeric nanofilms can be used to construct gas-permeable soft electronics that can directly adhere to soft biological tissue for continuous, long-term biosignal monitoring. However, it is challenging to fabricate gas-permeable dry electrodes that can self-adhere to the human skin and retain their functionality for long-term (>1 d) health monitoring. We have succeeded in developing an extraordinarily robust, self-adhesive, gas-permeable nanofilm with a thickness of only 95 nm. It exhibits an extremely high skin adhesion energy per unit area of 159 μJ/cm2 The nanofilm can self-adhere to the human skin by van der Waals forces alone, for 1 wk, without any adhesive materials or tapes. The nanofilm is ultradurable, and it can support liquids that are 79,000 times heavier than its own weight with a tensile stress of 7.82 MPa. The advantageous features of its thinness, self-adhesiveness, and robustness enable a gas-permeable dry electrode comprising of a nanofilm and an Au layer, resulting in a continuous monitoring of electrocardiogram signals with a high signal-to-noise ratio (34 dB) for 1 wk.

Nonequilibrium behavior of polymer nano films cast from different solvents

Properties of materials are largely determined by the processing conditions. This is especially true of polymers, which typically have much longer relaxation times than processing times and therefore possess out-of-equilibrium chain conformations. Here, we demonstrate that the nonequilibrium behavior of polymer nano films can be tuned by controlling the processing pathways. Films cast from different quality of solvents were aged at room temperature for various times, and then carried out the dewetting experiment above the glass transition temperature. The residual stress and relaxation time strongly depend on the quality of the solvents, and the differences may be caused by the boiling point and interaction parameter. This work offered a pathway for preparing a stable nano film, which is crucial for the durability of nanomaterials and devices.

Sensitive and selective detection of amitrole based on molecularly imprinted nanosensor.

SPR sensor used for amitrole detection was prepared without using any modification. Molecularly imprinted SPR sensor enabled high selectivity for amitrole pesticide. Amino acid-based functional monomer MATrp was integrated as a recognition element. Tailor-made SPR sensor enables real-time monitoring of amitrole pesticide. Synthetic recognition sites provided by MATrp were prepared without labeling.

Tunable Structural Color Images by UV-Patterned Conducting Polymer Nanofilms on Metal Surfaces.

Precise manipulation of light-matter interactions has enabled a wide variety of approaches to create bright and vivid structural colors. Techniques utilizing photonic crystals, Fabry-Pérot cavities, plasmonics, or high-refractive-index dielectric metasurfaces have been studied for applications ranging from optical coatings to reflective displays. However, complicated fabrication procedures for sub-wavelength nanostructures, limited active areas, and inherent absence of tunability of these approaches impede their further development toward flexible, large-scale, and switchable devices compatible with facile and cost-effective production. Here, a novel method is presented to generate structural color images based on monochromic conducting polymer films prepared on metallic surfaces via vapor phase polymerization and ultraviolet (UV) light patterning. Varying the UV dose enables synergistic control of both nanoscale film thickness and polymer permittivity, which generates controllable structural colors from violet to red. Together with grayscale photomasks this enables facile fabrication of high-resolution structural color images. Dynamic tuning of colored surfaces and images via electrochemical modulation of the polymer redox state is further demonstrated. The simple structure, facile fabrication, wide color gamut, and dynamic color tuning make this concept competitive for applications like multifunctional displays.

In situ growth of multifunctional porous organic polymer nanofilms with molecular sieving and catalytic abilities

Porous organic polymers (POPs) have evinced a huge potential for membrane-based separations owing to their impressive surface areas, high mesopore ratio, superior chemical stabilities, and catalytic abilities. In this study, for the first time, an o-hydroxy porous organic polymer (POP) thin film was in situ generated atop a (polyacrylonitrile) HPAN membrane support via diazo-coupling reaction under mild conditions. Analysis by FT-IR, XPS and SEM confirmed the successful formation of a coherent, thin POP nanofilm. Zeta potentials and water contact angle measurements demonstrated that the resultant POP film was hydrophilic (water contact angle = 48°) and negatively charged because of the abundance of hydroxyl groups. The roles of synthesis parameters (e.g., the solution pH and the reaction time) in the membrane microstructure and separation performance were explored in detail. The best-performing composite membranes show a high pure water permeability (66.5 L m−2h−1 bar−1), superior dye retentions (RCR = 99.6%, RDR = 98.0%, RMB = 98.8%), and low divalent salt retention (<15.0%), thus promising for separation of dye/salt mixtures. In addition, the thus-obtained POP film was utilized as the catalyst to yield propylene carbonate in aqueous solution with a high conversion rate of 80% at room temperature. The significance of this study is expected to provide a useful guideline of in situ fabrication of multifunctional POP membranes for separation of dye/salt mixtures and catalysis.