Polymer Support Research Articles

Waste-Minimized Cyanosilylation of Carbonyls Using Fluoride on Polymeric Ionic Tags in Batch and under Continuous Flow Conditions

Herein, we report the development of a tailor-made fluoride-based heterogeneous catalyst, POLITAG-F, for the waste-minimized continuous production of cyanohydrin silyl ethers. The careful designing of the polymeric support and the choice of fluoride ion as the anionic species resulted in the improvement of catalytic efficiency and allowed the effective conversion of different carbonyls (aldehydes, ketones, and unsaturated ketones). The POLITAG-F catalyst, employed under flow conditions, led to the conversion of large amounts (over 100 mmol) of the substrate with a productivity of 0.1 mmol min–1. In addition, flow conditions allowed to minimize the waste production reaching an associated E-factor value of 0.04. An exhaustive evaluation of the environmental impact of our protocol has been reported by considering several green metrics (process mass intensity, atom economy, and reaction mass efficiency) and also the benign index and the safety hazard index of the process.

Nitto to invest big in oligonucleotides

Nitto Denko plans to spend about $225 million to increase capacity in its oligonucleotide contract manufacturing business by early 2023. The Japanese firm says it will expand process and analytical development at the unit’s headquarters in Milford, Massachusetts. Nitto also says it will construct a new building and oligo production line. Future plans include spending a similar amount to expand capacity for the polymer support needed to make oligos.

Contact Lenses as Ophthalmic Drug Delivery Systems: A Review.

Ophthalmic drugs used for the treatment of various ocular diseases are commonly administered by eye drops. However, due to anatomical and physiological factors, there is a low bioavailability of the active principle. In order to increase the drug residence time on the cornea to adequate levels, therapeutic contact lenses have recently been proposed. The polymeric support that constitutes the contact lens is loaded with the drug; in this way, there is a direct and effective pharmacological action on the target organ, promoting a prolonged release of the active principle. The incorporation of ophthalmic drugs into contact lenses can be performed by different techniques; nowadays, the soaking method is mainly employed. To improve the therapeutic performance of drug-loaded contact lenses, innovative methods have recently been proposed, including the impregnation with supercritical carbon dioxide. This updated review of therapeutic contact lenses production and application provides useful information on the most effective preparation methodologies, recent achievements and future perspectives.

Physical adsorption used to the immobilization of Burkholderia cepacia lipase into powder polymeric supports

This study aims to combine distinctive supports with a feasible, easy and cleaning method to lipase immobilization. Commercial lipase from Burkholderia cepacia is physically adsorbed using polymeric powders such as polyhydroxybutyrate (PHB), polyhydroxybutyrate-co-hydroxyvalerate (PHBV) and copolymer styrene-divinylbenzene (St-DVB). It is found that the immobilization on PHB has a high amount of the lipase per support mass (1065 U g−1). The activation energy also shows a value higher than the lipase immobilized onto both PHBV (348 U g−1) and St-DVB (355 U g−1). FTIR, TG, DSC and XRD techniques are used to polymer powders and immobilized lipase characterization. Morphological arrays, loss masses, enthalpy values and crystallinity degrees are evaluated. In order to analyze the morphological aspects of the raw polymers after alcohol treatment (before immobilization) and the immobilized lipase, the optical microscopy analysis is used. The immobilized Burkholderia cepacia lipase provides distinctive behavior in the polymer powders.

Poly(2,6-diphenyl-p-phenylene oxide) supported iron catalysts for the synthesis of lower olefins via Fischer–Tropsch reaction

A porous polymer, based on 2,6-diphenyl-p-phenylene oxide (PPPO) was used as support material for Fischer–Tropsch to Olefin (FTO) reaction. In an effort to understand the effect of support on the transport of reaction intermediates formed on the surface and its relation with the product selectivity, PPPO supported iron catalyst was prepared, characterized and tested under FTO conditions. Alkali promoters were used to improve the olefin selectivity. It was shown that iron oxide formed by the calcination of iron nitrate seemed to be less prone to reduction compared to the direct use of hematite. A high C2–C4 olefin to paraffin ratio (O/P) was achieved over the alkali promoted and PPPO supported iron catalysts. Alkali promotion apparently suppressed the hydrogenation of α-olefins to paraffins and methane formation but at the expense of catalytic activity. It was shown that highly stable catalysts with improved olefin selectivity can be prepared by using poly(2,6-diphenyl-p-phenylene oxide) polymeric supports.

Immobilization of nitrifying bacteria on composite based on polymers and eggshells for nitrate production

Nitrification is a key step in biological nitrogen transformation which depends on the performance of specialized microorganisms. Generally, nitrifying bacteria present a low growth rate and performance which can be improved when immobilized as a biofilm. The development of new materials suitable for the immobilization of nitrifying microorganisms is very important in nitrification and wastewater treatment. In this study, the effect of eggshell powder on biofilm formation by Nitrosomonas europaea an ammonium-oxidizing bacteria and Nitrobacter vulgaris a nitrite-oxidizing bacteria, on new polymeric supports were analyzed. Polylactic acid, polyvinyl chloride and polystyrene were tested to produce polymer-eggshells powder composites and used as biofilm supports for nitrifying bacteria. The support material was characterized to identify the most suitable polymer-eggshells powder combination for the cell adhesion and biofilm formation. The nitrification results showed a highest nitrate production of 42mg NO3--N/L with polylactic acid-eggshell composite, with the best surface properties for cellular adhesion. Finally, scanning electron microscopy micrographs confirmed the best biofilm formed on polylactic acid-eggshell.

Modification of polyethylene terephthalate track etched membranes by planar magnetron sputtered Ti/TiO2 thin films

This study investigates the surface modification of polyethylene terephthalate track-etched membranes by planar magnetron sputtering of titanium and titanium dioxide thin films to improve its hydrophilicity and photocatalytic activity. After cold plasma treatment to enhanced adhesion, Ti thin films were deposited by planar magnetron sputtering and TiO2 thin films by reactive magnetron sputtering in an Ar-O2 gas atmosphere. The morphology of the deposited thin films was characterised using atomic force microscopy and scanning electron microscopy. The pores retained a mostly circular shape. However, the modified track membrane's surface pore diameter reduced from 0.2 µm to 0.15 µm for Ti coated samples and 0.08 µm for Ti-TiO2 coated samples. Structural studies using X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy and Raman spectroscopy of Ti and TiO2 thin films revealed the intricate composition of the sputtered thin films which was a result of the complexity of sputtering on top of the porous polymer support. Additional investigations in surface wettability and bandgap showed a significant change in the track membrane surface's hydrophilicity and photocatalytic properties after depositing TiO2-Ti, adding to the self-cleaning properties of the coated TM. The bandgap of the film was 3.1 eV and of the indirect type. Both Ti and TiO2-Ti sputtering over the TM surface significantly reduced the water contact angle from 72° for untreated PET to 43° and 45° for Ti-TM and TiO2-Ti-TM, respectively. This study shows that planar magnetron sputtering is a viable approach to surface modification of a porous polymeric support, such as track-etched membranes. The sputtered coating enhanced membrane hydrophilicity, thereby reducing the chance of surface fouling by organic substances, which leads to improved self-cleaning properties.

The effect of treatment with sodium carbonate and hydrogen on the activity and selectivity of polymeric Pd-containing catalysts for hydrogenation of acetylene compounds

Catalytic hydrogenation of the triple carbon-carbon bond of acetylene compounds is an important industrial process. High selectivity to the olefin compound should be provided in the process. This study considers the effect exerted by sodium carbonate treatment of the palladium catalysts containing super-cross-linked polystyrene (SPS) on their activity and selectivity in the hydrogenation of 2-methyl- 3-butin-2-ol and phenylacetylene. The effect of such treatment was shown to depend on the chosen palladium precursor and the type of polymeric support (non-functionalized SPS or that containing ternary amino groups). At atmospheric pressure of hydrogen and a temperature of 90 °C in a toluene medium, the 1%-Pd/SPS catalysts treated with Na2CO3 provided a 98 % selectivity in the hydrogenation of 2-methyl-3-butin-2-ol (at a 95 % conversion of the substrate), while selectivity in the hydrogenation of phenylacetylene reached 99.5 %.

Dilation-Responsive Microshape Programing Prevents Vascular Graft Stenosis.

Shape memory materials have been successfully applied to minimally invasive implantation of medical devices. However, organ-movement-specific shape programing at a microscale level has never been demonstrated despite significant unmet needs. As vein-to-artery grafting induces vein dilation and stenosis, a polymeric self-enclosable external support (SES) is designed to wrap the vascular out-wall. Its micropores are programmed to increase sizes and interconnections upon dilation. Vessel dilation promotes venous maturation, but overdilation induces stenosis by disturbed blood flow. Therefore, the unique elastic shape-fixity of SES provides a foundation to enable a stable microscale shape transition by maintaining the vein dilation. The shape transition of micropore architecture upon dilation induces beneficial inflammation, thereby regenerating vasa vasorum and directing smooth muscle cell migration toward adventitia with the consequent muscle reinforcement of veins. This game-changer approach prevents the stenosis of vein-to-artery grafting by rescuing ischemic disorders and promoting arterial properties of veins.

Unlocking large compressive strains in thin active elastocaloric layers

• • Durable composites enabling compression of elastocaloric layers are demonstrated. • • Elastocaloric materials can be in any thin-layer geometry, e.g., strip, plate, foil. • • Composites achieve 8.1 K temperature change at 2.5% strain. • • Mechanical and thermal properties are stable after 104 loading cycles at 2% strain. Elastocaloric cooling attracts broad interest and rapidly growing attention due to its potential for high efficiency and low environmental impact. While it is common knowledge that triggering reversible entropy and temperature changes with stress applied in compression prevents rapid failures of materials, realizing this regime in elastocaloric systems is highly challenging because nearly all geometries suited for efficient heat transfer are prone to buckling even under modest loads. This work describes a concept of a novel composite, where an active NiTi layer is embedded into a polymer support structure such that the elastocaloric material is entirely in compression when the assembly is subjected to bending. The active layer achieves 8.1 K temperature change at 2.5% compressive strain without buckling. After 10,000 cycles at 2% compressive strain, the composite maintains mechanical integrity without degradation of the elastocaloric effect. The results show that NiTi and, potentially, other elastocalorically active materials in geometries previously thought impossible can be successfully implemented in regenerative cooling systems operating in compression.

Application of ionic liquid-polymer gel membrane in toluene/n-heptane separation

The separation of aromatic and alkane is one of the most important and challenge chemical separation process. This study reports the high-efficiency separation of aromatics/alkanes in the pervaporation process based on a series of novel ionic liquid gel membranes. The ionic liquid gel membrane was characterized by FT-IR, SEM, AFM, TGA, and XRD techniques. The results revealed that the IL was maintained in the three-dimensional structure of polymer support and the membrane kept its stability when the temperature was over 300 °C. The relevant parameters i.e. polymer concentration, IL concentration, IL type, film-forming temperature, membrane thickness, feed concentration, operating temperature and feed flow rate on membrane process were investigated. The optimal membrane was prepared when the P(VDF-HFP) and [Amim][Tf2N] concentrations were 15 wt% and 45 wt%, the film-forming temperature was 15 °C and the membrane thickness was 120 μm. When the initial toluene concentration was 50 wt% and the flow rate was 200 mL/min, the best flux (120 g·m−2·h−1) and separation factor (11.3) were observed at 25 °C. Moreover, the separation factor was over 10 and the flux maintained at the same level after working continuously for 30 h, which indicates that the membrane has good stability.

Aligned Networks of Engineered Fibrillar Fibronectin Guide Cellular Orientation and Motility

The extracellular matrix (ECM) influences biological processes associated with tissue development and disease progression. However, robust cell‐free techniques to control fiber alignment of naturally derived ECM proteins, such as fibronectin (Fn), remain elusive. It is demonstrated that controlled hydrodynamics of Fn solutions at the air/fluid interface of porous tessellated polymer scaffolds (TPSs) generates suspended 3D fibrillar networks with alignment across multiple length scales (<1, 1–20 μm, extended to >1 mm). The direction of the fluid flow and the architecture of the polymeric supports influence protein solution flow profiles and, subsequently, the alignment of insoluble Fn fibrils. Aligned networks of fibrillar Fn characteristically alter fibroblast phenotype, indicated by increased directional orientation, enhanced nuclear and cytoskeletal polarity, and highly anisotropic and persistent cell motility when compared with nonaligned 3D networks and 2D substrates. Engineered extracellular matrices (EECMs) establish a critically needed tool for both fundamental and applied cell biology studies, with potential applications in diverse areas such as cancer biology and regenerative medicine.

Effect of sorption on the active concentration of polymer support fluids

Solutions of partially hydrolysed polyacrylamides (PHPAs) are regularly used as excavation-support fluids for the construction of bored piles. Their use in grab-excavated diaphragm walls is also de...

Preparation of PolyHIPE monolithic materials functionalization by tris(2-aminoethyl)amine

The developments of monolithic materials rapidly in nowadays hold an impressively strong position in separation science as well as in other areas of chemistry. In this research are presented functionalization of PolyHIPE monolithic materials by tris(2-aminoethyl) amine. Monolithic polymer supports and scavengers were synthesized via nucleophilic displacement of chlorine in poly(4-vinyl benzyl chloride-co-divinylbenzene) as PolyHIPE materials. Porous copolymers of DVB/DVB were prepared by emulsion templating using high internal phase emulsions (HIPEs) as precursors for monoliths. The properties of the final products synthesized were functionalized with an amino group, at a different ratio of amine/chloromethyl groups, in different time refluxed were explored. PolyHIPE functionalized with tris(2-aminoethyl)amine to yield a product with high degrees of conversion. The extent of the functionalization reactions was investigated by a range of qualitative and quantitative techniques: FTIR, CHN analysis, potentiometric measurements, and (BET) measurements have been performed.

The capable Pd complex immobilized on the functionalized polymeric scaffold for the green benzylation reaction

The Pd complex immobilized on the functionalized polymeric support was prepared by the functionalization of the 4‐(benzyloxy)benzyl chloride polymer with 5‐phenyl‐1‐H‐tetrazole and the subsequent complexation with PdCl2. Then, it was characterized with different methods and used as catalyst in the green benzylation reaction of various aryl cyanamides with benzyl bromide and K2CO3 in EtOH at 60°C for the appropriate times. Also, the antibacterial properties of the Pd polymer‐supported complex were studied against a number of gram‐positive and gram‐negative bacteria, and in some cases, it has the same effect as a tetracycline standard antibiotic against Bacillus thuringiensis (a gram‐positive bacterium) and Serratia marcescens (a gram‐negative bacterium).

Pore Tuning of Metal‐Organic Framework Membrane Anchored on Graphene‐Oxide Nanoribbon

AbstractAlthough the pore structures and gas transport properties of metal‐organic frameworks (MOFs) have been tuned mainly by modifying the framework building blocks, a pore‐tuned zeolitic imidazolate framework (ZIF)‐8 layer is directly grown on graphene oxide nanoribbons (GONR)‐treated polymer substrate. Oxygen‐containing functional groups and GONR dangling‐carbon bonds facilitated the spontaneous growth of ZIF‐8 oriented to the (100) grain on the GONR surface and also enhanced the rigidity by strongly anchoring the ZIF‐8 layer by metal‐carbon chemisorption. Gas permeation and molecular simulation results confirmed that the effective aperture size of ZIF‐8 is adjusted to 3.6 Å. As a result, ultrafast H2 permeance of 7.6 × 10−7 mol m−2 Pa s is achieved while blocking large hydrocarbon molecules. In particular, the membrane showed exceptionally enhanced hydrogen selectivity for the mixture separation than ideal selectivity, owing to the competitive transport between H2 and large hydrocarbon molecules, and the separation performance surpassed those of ZIF membranes previously fabricated on polymeric supports.

Evaluation of Performance of Functionalized Amberlite XAD7 with Dibenzo-18-Crown Ether-6 for Palladium Recovery.

Due to the increased demand for palladium, as well due to its reduced availability in nature, its recovery from diluted waste solutions becomes a necessity, and perhaps an emergency. As a result of economic and technological development, new materials with improved adsorbent properties that are more efficient for metallic ions’ recovery were synthesized and introduced to market. The goal of this study was to obtain a new adsorbent material by functionalizing through impregnation a commercial polymeric support that was both inexpensive and environmentally friendly (Amberlite XAD7) with crown ether (di-benzo-18-crown-6—DB18C6). Crown ethers are known for their ability to form complexes within metallic ions, by including them inside of the ring, regardless of its atomic size. Adsorbent material was prepared by impregnation using the solvent-impregnated resin method (SIR). To highlight the presence of crown ether on the resin surface, a new synthesized material was characterized by scanning electron microscopy (SEM), elemental analysis X-ray energy dispersive spectroscopy (EDX) and Fourier transform infrared spectroscopy (FT-IR). The specific surface of the adsorbent material was also determined by the Brunauer–Emmett–Teller (BET) method. Adsorbent performances of the prepared material were highlighted by kinetic, thermodynamic and equilibrium studies and a possible mechanism was also proposed. The influence of specific parameters for the adsorption process (contact time, temperature, Pd(II) initial concentration) on the maximum adsorption capacity was pursued.

Modified polystyrene spheres/graphene oxide decorated with silver nanoparticles as bactericidal material

This work describes the preparation of a composite material consisting of Graphene oxide (GO) nanosheets impregnated with silver nanoparticles (AgNPs) synthesized by reduction in situ of adsorbed Ag+ by NaBH4 and over modified polystyrene spheres (PS). PS/GO-AgNPs water dispersion and its film deposited over a polymeric support were tested for their antibacterial activity. The PS/GO-AgNPs composite was characterized by UV–vis spectra, transmission electron microscopy, X-ray diffraction, and scanning electron microscopy. The results obtained by these techniques confirmed the formation of PS/GO composite, they also confirmed the attachment of AgNPs to the GO sheets. The antibacterial activity of this composite was evaluated in seven different bacteria. PS/GO-AgNPs composite performed efficiently in bringing down the count of Bacilus cereus, Escherichia coli, Pseudomonas aeroginosa, Aeromonas hydrophila and Salmonella typhimurium from 106 cfu mL-1 to zero with 200 mg L-1 of PS/GO-AgNPs in water. Results from inhibition halo showed that films containing PS/GO-AgNPs have inhibited the growth of all microbial species in the same magnitude compared to GO-AgNPs. The water dispersed PS/GO-AgNPs composite enabled them to be easily deposited on surfaces, for example, walls or floors in contaminated environments present in hospitals, by a simple spray method to act as a biocidal material, avoiding the undesirable presence of nanoparticle materials (GO-AgNPs) suspended on air.

Polymer supported cross-linked enzyme aggregates (CLEAs) of lipase B from Candida antarctica: An efficient and recyclable biocatalyst for reactions in both aqueous and organic media

Lipase B from Candida antarctica (CAL-B) was immobilised on epoxy-activated polymer support functionalised with polyethyleneimine (PEI) via preparation of enzyme aggregates by precipitation with polyethylene glycol (PEG 600). This involves adsorption of the aggregates on the functionalised polymer followed by cross-linking with glutaraldehyde. The apparent activity of the immobilised enzyme was found to be 750 TBU/g at optimum pH 7.5 and temperature 30 °C. The immobilisation yield was 24%. The immobilised enzyme was used for desymmetrization of cis-3,5-diacetoxy-1-cyclopentene in aqueous buffer (70% yield, >99% e.e.) and methyl tert-butyl ether (95% yield and > 99% e.e) to obtain (1 R,4S)-4-hydroxycyclopent-2-en-1-yl acetate. The immobilised enzyme could be recycled (5 times) in both aqueous buffer and organic solvents. Further, the expensive polymer support was also recycled (5 times) after the immobilised enzyme lost its activity by washing with 1 N HCl.

Molecular Docking and Antibacterial Studies of Pyranopyrazole Derivatives Synthesized Using [Pap-Glu@Chi] Biocatalyst Through a Greener Approach

In the present work, papain enzyme was immobilized on a polymer support chitosan through a linkage of glutaraldehyde to form the [Pap-Glu@Chi] biocatalyst through the covalent bonding method. The immobilization of papain on Chitosan was confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) which revealed the change in morphology of chitosan due to immobilization of papain through glutaraldehyde. Thus prepared heterogeneous biocatalyst was used for the four-component synthesis of pyranopyrazole derivatives by the reaction of substituted aromatic aldehydes, malononitrile, ethylacetoacetate and hydrazine hydrate affording excellent yields within short reaction times at moderate temperature. The catalyst exhibited significant activity up to six cycles. Synthesized compounds were checked for their molecular docking activity using AutoDock Vina against the bacterial protein receptors (PDB code 2VF5 and 1BAG) obtained from the RCSB Protein Data Bank. Significant binding energy values obtained from docking studies revealed good interaction between synthesized compounds and bacterial protein receptor. Synthesized compounds were tested against human pathogenic bacterial strains Escherichia coli, Salmonella typhi, Bacillus subtilis, Pseudomonas aeruginosa along with Gentamicine as a reference antibiotic using disk diffusion method. The compounds were found to exhibit moderate-to-high antibacterial activity.