Phosphorus-containing Polymers Research Articles

Conversion of elemental phosphorus under the electron beam irradiation

Abstract This research article describes the results of studies of the processes occurring under the electron beam irradiation of elemental phosphorus in an aqueous medium. Comparisons of the results of white phosphorus samples irradiation using electron accelerators with different technical parameters are presented. The structure of the obtained phosphorus-containing polymers was determined using MALDI mass spectrometry and X-ray fluorescence analysis. A scheme of the formation of macroparticles in the process of irradiation of elemental phosphorus by a beam of accelerated electrons in an aqueous medium is discussed.

Fire retardants giving special properties to fibers and textile materials based on them

The fire-retardant properties of modified polyacrylonitrile fibers with phosphorus-containing polymers, as well as nitrogen and brominecontaining flame retardants, have been studied. It has been shown that, in contrast to low molecular weight fire retardants, polymer and oligomer fire retardants give fibers higher fire-retardant properties. The results of determining the flammability of samples showed that the treatment of polyacrylonitrile fibers with oligomeric flame retardants based on the developed flame retardants improves the fire-retardant properties of fibers and materials based on them. As a result of comprehensive research, it was established that for the manufacture of fire-resistant material it is advisable to use the optimal ratio of “polyacrylonitrile fiber - fire retardant”. Carrying out fire-retardant treatment of polyacrylonitrile material with compositions of 3-chloro-1,2-hydroxypropane with 2,4,6-triamino-1,3,5-triazine makes it possible to obtain fabrics with a reduced fire hazard and with the required strength parameters. Also, in the work, based on kinetic and spectroscopic studies and taking into account literature data, a mechanism of oligomeric fire retardant is proposed, which gives fibers and textile materials special fire resistance properties.

Proliferation and differential regulation of osteoblasts cultured on surface-phosphorylated cellulose nanofiber scaffolds

Phosphorus-containing polymers have received much attention for their excellent ability to regulate bone cell differentiation and calcification. Given the increasing concern about environmental issues, it is promising to utilize “green” biomaterials to construct novel cell culture scaffolds for bone tissue engineering. Herein, surface-phosphorylated cellulose nanofibers (P-CNFs) were fabricated as a novel green candidate for osteoblast culture. Compared with native CNF, P-CNFs possessed shorter fiber morphology with tunable phosphate group content (0–1.42 mmol/g). The zeta-potential values of CNFs were enhanced after phosphorylation, resulting in the formation of uniform and stable scaffolds. The cell culture behavior of mouse osteoblast (MC3T3-E1) cells showed a clear phosphate content-dependent cell proliferation. The osteoblast cells adhered well and proliferated efficiently on P-CNF0.78 and P-CNF1.05, with phosphate contents of 0.78 and 1.05 mmol/g, respectively, whereas the cells grown on native CNF substrate formed aggregates due to poor cell attachment and exhibited limited cell proliferation. In addition, the P-CNF substrates with optimal phosphate content provided a favorable cellular microenvironment and significantly promoted osteogenic differentiation and calcification, even in the absence of a differentiation inducer. The bio-based P-CNFs are expected to mimic the bone components and provide a means to regulate osteoblast proliferation and differentiation in bone tissue engineering.

Effect of Phosphorus-Containing Polymers on the Shoot Dry Weight Yield and Nutritive Value of Mavuno Grass

In an effort to improve fertility, recover degraded areas and increase support for the capacity of livestock on pasture, new forms of fertilizer are being developed. Polymer-coated monoammonium phosphate (MAP) is an innovative source of phosphorus (P) for maintaining forage grass productivity. The aim this study was to evaluate the agronomic efficiency of P rates with the presence and absence of the polymer on the productivity, development and nutritional value of hybrid signalgrass (Urochloa spp.) cv. Mavuno. The field research was conducted on a dystrophic Ultisol. The experiment was arranged in a randomized complete block design with four replications and treatments applied in a factorial scheme (2 × 4) + 1. The treatments included two P sources (uncoated MAP and polymers-coated MAP) at four rates (20, 40, 80 and 160 kg ha−1 of P2O5), and the control received no P fertilization. The measured variables showed no differences between sources with or without polymer. The maximum production of accumulated shoot dry weight yield (SDWY) of the ‘Mavuno’ grass was 20.2 Mg ha−1 with the dose of 114 kg ha−1 of P2O5. The value of crude protein and in vitro dry matter digestibility showed a quadratic response with maximum production of 76.5% and 15.9% for the P2O5 rates of 37.2 and 91.1 kg ha−1, respectively, while the acid detergent insoluble fiber showed a linear increase up to the rate of 80 kg ha−1 of P2O5. No differences were observed in plant height, number of tillers, or the relative chlorophyll content between treatments.

Phosphorus-Containing Polymers as Sensitive Biocompatible Probes for 31P Magnetic Resonance

The visualization of organs and tissues using 31P magnetic resonance (MR) imaging represents an immense challenge. This is largely due to the lack of sensitive biocompatible probes required to deliver a high-intensity MR signal that can be distinguished from the natural biological background. Synthetic water-soluble phosphorus-containing polymers appear to be suitable materials for this purpose due to their adjustable chain architecture, low toxicity, and favorable pharmacokinetics. In this work, we carried out a controlled synthesis, and compared the MR properties, of several probes consisting of highly hydrophilic phosphopolymers differing in composition, structure, and molecular weight. Based on our phantom experiments, all probes with a molecular weight of ~3-400 kg·mol-1, including linear polymers based on poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), poly(ethyl ethylenephosphate) (PEEP), and poly[bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)]phosphazene (PMEEEP) as well as star-shaped copolymers composed of PMPC arms grafted onto poly(amidoamine) dendrimer (PAMAM-g-PMPC) or cyclotriphosphazene-derived cores (CTP-g-PMPC), were readily detected using a 4.7 T MR scanner. The highest signal-to-noise ratio was achieved by the linear polymers PMPC (210) and PMEEEP (62) followed by the star polymers CTP-g-PMPC (56) and PAMAM-g-PMPC (44). The 31P T1 and T2 relaxation times for these phosphopolymers were also favorable, ranging between 1078 and 2368 and 30 and 171 ms, respectively. We contend that select phosphopolymers are suitable for use as sensitive 31P MR probes for biomedical applications.

Synthesis and characterization of phosphorus-containing polymers for the generation of polymer-derived ceramics

Phosphorus-containing polymer networks as precursors to polymer-derived ceramics were prepared using a combination of three monomers (1,3,5-triallyl-1,3,5-triazine-2,4,6-trione or 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, tetraethylene glycol diallyl ether, and isobutyl phosphine). By varying the stoichiometry of these components, it was observed that key properties such as thermal stability, swellability, and ceramic yield after pyrolysis can be modified at will. Optimal stoichiometries to achieve the highest ceramic yields upon pyrolysis, while maintaining swellability, were determined. Cobalt was introduced into the networks by reaction of the tertiary phosphine fragments in the material with CpCo(CO)2. After pyrolysis of the metalated polymers at 800 °C, the resulting ceramics were characterized using scanning electron microscopy-energy dispersive X-ray and X-ray photoelectron spectroscopy.

An investigation of polyphosphinoboranes as flame-retardant materials

Phosphorus-containing polymers are of considerable interest as flame-retardants additives. We report investigations into the flame-retardant properties of a series of polyphosphinoboranes [RR’PBH 2 ] n prepared by iron-catalyzed dehydrocoupling protocols. When cotton towel was impregnated with the polyphosphinoboranes and exposed to a flame, the presence of polyphosphinoborane was found to result in self-extinguishing of the flame leaving behind a charred material. In contrast, under analogous conditions, untreated cotton and cotton treated with polystyrene burnt and was completely consumed. Analysis of the char revealed the formation of phosphoric and boric acids, species commonly invoked for the action of related flame-retardant species. The use of P-disubstituted polyphosphinoboranes was found to slightly slow burning; however, the presence of halogenated groups in the side chain had little effect suggesting that it is the main chain that imparts any flame-retardant effect. Exposure of cotton treated with poly(phenylphosphinoborane) to water was not found to have any effect on flame-retardancy demonstrating the non-leachability of these polymers in aqueous media. • Polyphosphinoboranes were shown to function as flame retardant materials for cotton. • The polymers were prepared by catalytic dehydrocoupling and, in some cases, poly-polymerisation modification. • The polymers display self-extinguishing behaviour. • On impregnation into cotton, the polymers were non-leachable in water.

Ultrafast synthesis of phosphorus-containing polythioethers in the presence of TBD

Phosphorus-based polymers have gained much interest in recent years due to the phosphorus atoms that impart polymers interesting properties. Thus, the synthesis of phosphorus-containing polymers in practical and feasible ways is highly desirable in synthetic polymer chemistry. In this study, we report a new method based on the ultrafast thiol-yne reaction between dithiol-functionalized phosphothioester compounds and electron-deficient alkyne compounds to prepare phosphorus-containing polymers. For this purpose, two dithiol-functionalized phosphothioester compounds were synthesized and reacted with seven structurally different electron-deficient alkyne compounds in chloroform (CHCl3) in 1 min using an organocatalyst, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). The polymerizations proceeded successfully and fourteen phosphothioester-containing polythioethers were achieved with reasonable molecular weights and high yields. The resulting polymers were characterized in detail by NMR, GPC, and DSC measurements. Given the above-mentioned demands in the preparation of phosphorus-containing polymers, the proposed approach in this study offers a rational, robust, time- and energy-saving solution to this aim. More importantly, the proposed method does not require harsh conditions, metal, acid, or base additives.

New approaches to the synthesis of modified red phosphorus under the high-energy radiation

In comparison with white phosphorus, the toxicity of red phosphorus is thousands times smaller. Therefore, red phosphorus is the main modification produced and consumed by industry. Productivity, quality and product range depend on the efficiency of the technological system, on the possibility of modernizing production by introducing new progressive and environmentally friendly technologies using modern equipment. Development of a technological project for the production of red phosphorus is an urgent issue, which is the goal and the task of the research. The article presents the results of the synthesis of phosphorus-containing polymers from the white phosphorus, carried out under the influence of a beam of accelerated electrons.

Heteroatom-doped hollow carbon material as an electrocatalyst for oxygen reduction reaction

The development of highly efficient and stable non-precious metal electrocatalysts is essential for the oxygen reduction reaction (ORR). In this study, a simple polymerization pyrolysis method is proposed to prepare heteroatom-doped hollow carbon nanospheres (NPSC-800) by using Fe-BDC and phosphorus-containing polymers as precursors. The unique structure allows the catalyst to show good catalytic performance (Initial potential of 0.8786 V, a half-wave potential of 0.7576 V, and a diffusion-limited current density of 4.48 mA cm-2). This research provides an effective strategy for the synthesis of heteroatom-doped carbon materials with good ORR catalytic performance.

Synthesis and properties of wholly aromatic phosphorus-containing thermotropic liquid crystal copolyesters with excellent fibre formation ability

ABSTRACT In this study, wholly aromatic phosphorus-containing thermotropic liquid crystal polymers (TLCP) derived from 6-hydroxy-2-naphthenic acid (HNA), terephthalic acid (TA) and 10-(2,5-Dihydroxypheny)-10 h-9-oxa-10-phospha-phenanthrene-10-oxide (DOPO-HQ) are successfully synthesised via one pot melt polymerisation method. Although, the resulted copolyesters are amorphous, high glass transition temperature (182–196 °C) is observed due to the existence of kinked DOPO-HQ unit and crankshaft HNA monomer. The nematic liquid crystal behaviour is found for all of the copolyesters under POM at relatively low temperature (190–207 °C). The copolyesters show good thermal stability and high char yield under both nitrogen and air atmosphere, which of the initial degradation temperature (T5%) and char yield are above 450 °C and 50%, 439 °C and 29%, respectively. Dynamic rheology results show that viscous modulus of the obtained copolyesters are much more prominent under both frequency and temperature sweeping mode, indicating have excellent processing ability. The fibres can be easily drawn from the melt, and exhibit well oriented fibrillated structure. The convenient polymerisation method, excellent thermal stability and fibre formation ability of the phosphorus-containing TLCP endow them much potential use in the safety protection field.

Water-soluble and degradable polyphosphorodiamidates via thiol-ene polyaddition

Water-soluble polyphosphorodiamidates (PPDAs) and structural analog polyphosphates (PPEs) are synthesized by the metal-free radical thiol-ene polyaddition. To ensure complete water-solubility, we transform the thioether functionalities in the polymer backbone to sulfones by oxidation with peroxide. Due to a significant difference in the hydrolytic stability of P-N and P-O bonds, the chemical structure around the phosphorus atom in the main chain controls the degradation kinetics. The pendant ester group is used to further control the degradation rates of the polymers. Under acidic conditions, PPDAs show a fast and pH-dependent hydrolysis rate of the main chain, while PPEs are stable under such conditions, which was monitored by NMR spectroscopy. Under basic conditions, in contrast, the P-O-bonds can be hydrolyzed, while the P-amides are relatively stable. This set of hydrophilic and degradable polymers enlarges the family of phosphorus-containing polymers and might be useful in the field of drug delivery or tissue engineering and to date is the only route to prepare PPDAs by thiol-ene polymerization.

Main-Chain Phosphorus-Containing Polymers for Therapeutic Applications.

Polymers in which phosphorus is an integral part of the main chain, including polyphosphazenes and polyphosphoesters, have been widely investigated in recent years for their potential in a number of therapeutic applications. Phosphorus, as the central feature of these polymers, endears the chemical functionalization, and in some cases (bio)degradability, to facilitate their use in such therapeutic formulations. Recent advances in the synthetic polymer chemistry have allowed for controlled synthesis methods in order to prepare the complex macromolecular structures required, alongside the control and reproducibility desired for such medical applications. While the main polymer families described herein, polyphosphazenes and polyphosphoesters and their analogues, as well as phosphorus-based dendrimers, have hitherto predominantly been investigated in isolation from one another, this review aims to highlight and bring together some of this research. In doing so, the focus is placed on the essential, and often mutual, design features and structure–property relationships that allow the preparation of such functional materials. The first part of the review details the relevant features of phosphorus-containing polymers in respect to their use in therapeutic applications, while the second part highlights some recent and innovative applications, offering insights into the most state-of-the-art research on phosphorus-based polymers in a therapeutic context.

Phosphorus-containing polymers synthesised via nitroxide-mediated polymerisation and their grafting on chitosan by grafting to and grafting from approaches

The phosphorus-based methacrylate monomers (h)MAPC1 have been polymerized by NMP and grafted on chitosan.

New fire-resistant epoxy thermosets: nonisothermal kinetic study and flammability behavior

Abstract New fire-resistant thermosets are prepared based on a bisphenol A-epoxy resin which is thermally crosslinked in the presence of dicyandiamide and two phenols containing phosphorus atoms. The thermosets are characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis (TGA), and microscale combustion calorimetry (MCC) tests. A nonisothermal kinetic study is performed based on processing of TGA data applying the method proposed by Vyazovkin. The lifetime prediction analyses establish that the phosphorus-containing polymers could be used at a constant temperature of 200°C up to 200–780 min. The MCC tests reveal an improvement of the flammability behavior, as well as a significant heat release capacity reduction for phosphorus-containing samples compared to the sample which has no phosphorus component.

Exploring the Contribution of Two Phosphorus-Based Groups to Polymer Flammability via Pyrolysis-Combustion Flow Calorimetry.

From a set of around 100 phosphorus-containing polymers tested in pyrolysis–combustion flow calorimetry, the contributions to flammability of two phosphorus-containing pendant groups (called 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and PO3) were calculated using an advanced method previously proposed and validated. The flammability properties include total heat release (THR) and heat release capacity (HRC) measured in standard conditions, i.e., anaerobic pyrolysis and complete combustion. The calculated contributions are in good agreement with the main modes of action of both phosphorus groups, i.e., flame inhibition for DOPO and char promotion for PO3. Moreover, the results provide first conclusions about the cooperative interaction between phosphorus and nitrogen, as well as the influence of the architecture of tested co-polymers.

Endocytosis of poly(ethylene sodium phosphate) by macrophages and the effect of polymer length on cellular uptake

Phosphorus-containing polymers are taking a growing interest as a bio-applicable material. Anionic poly(phosphodiester) is one type of phosphorus-containing polymer and has a similar backbone structure to teichoic acid (TA), which makes up the cell walls of gram-positive bacteria. In this study, we synthesized a copolymer of ethylene sodium phosphate and butynyl phosphate (P(EP⋅Na/BYP)), which mimics TA and, thus, should be taken up by macrophages by the same mechanism as bacterial cells. In-vitro studies showed that RAW 264.7 mammalian macrophages exhibited higher uptake of P(EP⋅Na/BYP) than L929 mammalian fibroblasts. Further, the uptake of P(EP⋅Na/BYP) by macrophages decreased in the presence of dextran sulfate; this implies that the scavenger receptor contributes to endocytosis of P(EP·Na/BYP). In-vitro studies on P(EP·Na/BYP) with different lengths (38, 85, and 127 phosphate residues) showed that P(EP·Na/BYP) with 127 phosphate residues led to the highest intracellular transportation and the least gene expressions of IL-6 and TNF-α. These results demonstrate that water-soluble poly(phosphodiester) can be used as a modifier to deliver medical drugs to macrophages.

Magnetic nanocomposites based on phosphorus-containing polymers—structural characterization and thermal analysis

Fabrication of magnetic nanocomposites containing iron oxide nanoparticles formed in situ within a phosphorus-containing polymer matrix as well as its structural characterization and its thermal degradation is reported here. Comparative structural studies of the parent polymer and nanocomposites were performed using FTIR spectroscopy, x-ray diffraction, and atomic force microscopy. The results confirmed the presence of dispersed iron oxide magnetic nanoparticles in the polymer matrix. The formed composite combines the properties of porous polymer carriers and magnetic particles enabling easy separation and reapplication of such polymeric carriers used in, for example, catalysis or environmental remediation. Studies on thermal degradation of the composites revealed that the process proceeds in three stages while a significant influence of the embedded magnetic particles on that process was observed in the first two stages. Magnetic force microscopy studies revealed that nanocomposites and its calcinated form have strong magnetic properties. The obtained results provide a comprehensive characterization of magnetic nanocomposites and the products of their calcination that are important for their possible applications as sorbents (regeneration conditions, processing temperature, disposal, etc).

Phospharubber makes its debut

Natural rubber (polyisoprene) and a variety of synthetic analogs such as poly(styrene-butadiene) have been commercially important polymeric materials for going on 200 years. Derek P. Gates and coworkers at the University of British Columbia have now introduced the first phosphorus-containing variants: poly(1-phosphaisoprene) and poly(phospha-1,3-butadiene). Gates’s group has previously focused on using phosphaalkenes as monomers for creating phosphorus-containing polymers for flame retardant, catalyst, and sensor applications. These materials contain functional phosphine units in the polymer backbone. Seeking to expand on the work, Gates and his team prepared phosphadiene monomers that would lead to polymers containing P=C or C=C repeat units, enabling additional functionalization opportunities such as copolymerization and cross-linking (Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201703590). Polymerization of the phosphadienes occurs mostly through their C=C bonds, with the majority of the phosphorus a...

Binding matters: binding patterns control the degradation of phosphorus-containing polymers

Deoxyribonucleic acid is probably the most prominent polyphosphoester (PPE). In materials science, polymers based on esters and amides of phosphoric acid are interesting materials for various applications, ranging from flame-retardant additives to polymers for biomedical applications. This short communication summarises the features of selective degradability in PPEs and polyphosphoramidates, depending on the binding pattern around the central phosphorus. In addition, polyphosphonates carrying stable P–C bonds and main-chain polyphosphorodiamidates show distinctively different hydrolysis kinetics. The applications of such materials may depend on the eventual degradability, but different timescales and different conditions need to be considered. This article summarises recent developments of the field and discusses related applications.