Polymer Solvent Research Articles

Arabinoxylan in Water through SANS: Single-Chain Conformation, Chain Overlap, and Clustering.

Using small-angle neutron scattering (SANS), we examine the structure and conformational behavior of wheat arabinoxylan (AX) prepared at various concentrations in a sodium phosphate aqueous buffer. As for another major hemicellulose, xyloglucan, we observe a small number of large clusters surrounded by AX chains that behave exactly as a polymer in good solvent with a Flory exponent ν = 0.588. The fit of the data at high q-values to a standard worm-like chain model gives the persistence length lp = 45 Å and cross section of the chains 2Rc = 11-12 Å. In addition, using a dedicated modeling approach, we extract from the SANS data at the intermediate q-range the correlation length ξ of the solutions in the semidilute regime. The decay of ξ with concentration follows a scaling law that further confirms the self-avoiding statistical behavior of the AX chains. This first comprehensive study about the properties of water-soluble AX at different length scales may help in the development of products and processes involving AX as a substitute for fossil carbon molecules.

Removal of undissolved substances in the dissolution-based recycling of polystyrene waste by applying filtration and centrifugation

Polystyrene (PS) is a versatile polymer typically used in applications such as yogurt cups, packaging trays, disk cases and toys. To increase recycling rates of PS, dissolution recycling is being investigated, which involves the liquefication of the polymer in a suitable solvent, allowing deep cleaning of the polymer from impurities. Quite specific to PS is that polystyrene waste contains both general-purpose polystyrene and high-impact polystyrene (HIPS), which is composed of free PS and polystyrene-grafted polybutadiene particles. In this work the potential of filtration and centrifugation is analyzed with the aim of cleaning the polymer from both, insoluble PB-PS particles and pigments (TiO2, Cr/Sb/Ti oxide and carbon black). The dead-end lab scale filtration were performed at room temperature and at pressures between 1.5 and 30 bar. The pigments were successfully removed, yet, filtration of HIPS solutions results in low fluxes due to extreme membrane fouling caused by the PB-PS particles, which was confirmed by the application of pore-blockage filtration models. Alternatively, centrifugation at 14,052 G-force has shown to be a promising alternative to separate the particles from HIPS, resulting in 100% turbidity reduction. Equally, the separation of pigments was successful, highlighting that TiO2 and Cr/Sb/Ti oxide have shorter sedimentation times compared to carbon black. Finally, the two separation processes are tested on a PS rigid packaging waste sample coming from a sorting line and the results show that centrifugation allows a high turbidity reduction and that a two-step separation process starting with centrifugation for PB-PS particles removal can facilitate further downstream cleaning.

Aqueous two-phase system based on pH-responsive polymeric deep eutectic solvent for efficient extraction of aromatic amino acids

Recently, more and more attention has been paid to the construction of stimulus-responsive aqueous two-phase systems (ATPSs) for the extraction and separation of various bioactive compounds. In this work, an ATPS based on a pH-responsive polymeric deep eutectic solvent (PDES) and phosphate salt was constructed for the first time. The pH-response properties of the PDES were studied through a series of experiments. Additionally, the phase formation mechanism was studied through experiments and simulations. This novel PDES-based ATPS was used to extract aromatic amino acids (AAAs). The extraction efficiencies for tyrosine (Tyr), phenylalanine (Phe), and tryptophan (Trp) reached 95.25%, 99.05%, and 99.10%, respectively. By adjusting pH, PDES was recycled and reused. This novel and recyclable PDES-based ATPS could be an efficient method for the extraction of AAAs, which could also be applied used as a versatile and sustainable method for the extraction of other bioactive compounds in the future.

Nonequilibrium thermodynamic modeling of case II diffusion in glassy polymers

In this article, we formulate a nonequilibrium thermodynamic theory for case II diffusion in a glassy polymer. In the model, we integrate the three-dimensional elasto-visco-plasticity of a glassy polymer, the Flory-Rehner theory for polymer network swelling, and the kinetics law for solvent migration with the concentration-dependent diffusivity. Our theory is given in a general 3D tensorial form, which, therefore, can be used to model case II diffusion in glassy polymers with arbitrary geometries and under different mechano-chemical loading conditions. An intrinsic length determined by the combination of the polymer viscosity and solvent diffusivity arises from the theory, which dictates the size-dependent case II diffusion in glassy polymers. The theory developed in the article may provide important guidance for designing semi-permeable membranes, waterproof coating, and drug-delivery systems, where case II diffusion can commonly occur.

Pvp-based deep eutectic solvent polymer: Sustainable Brønsted-Lewis acidic catalyst in the synthesis of α-aminophosphonate and bisindole

Polymeric deep eutectic solvents (PDESs) have emerged for augmentation of the functions of deep eutectic solvents (DESs) as a sustainable material class. Considering the common synthetic limitation of PDESs to the in-situ polymerization of deep eutectic monomers, herein, we have implemented linear polyvinylpyrrolidone (PVP) to develop a simple-to-prepare, atom-economical, cost-effective, and eco-friendly Brønsted-Lewis acidic PDES via ZnCl2 and a quaternization procedure. The prepared PDES was characterized by SEM, EDS, elemental mapping, FT-IR, and TGA techniques. This method enables physicochemical tunation of the PDES by altering the molar ratio of ZnCl2 to PVP monomer repeating units. The PDES was used as a heterogeneous catalyst to promote greener approaches towards biologically significant scaffolds via a multicomponent reaction of aldehydes, amines, and tri(alkyl/aryl)phosphites to synthesize secondary and tertiary α-aminophosphonates (APs), in addition to a carbon–carbon bond-forming reaction to synthesizing bis(indolyl)methanes (BIMs) from aldehydes and indolyl compounds. PDESs proved to be highly efficient catalysts for these transformations, providing mild and high-yielding green protocols for an extensive library of both APs and BIMs. The desired compounds from either transformation group were obtained shortly with good to excellent yields (15–120 min for APs and 100–200 min for BIMs). Examination with BIMs revealed that the protocol is amenable to large-scale production without significant loss of efficiency. In addition, the stability of the PDES catalyst was confirmed from five successful recycles, in which no significant decrease in the activity was monitored.

A comprehensive study of the effect of elevated temperature on the extractability and rate of exaggerated and exhaustive extractions of medical devices

The effectiveness of an elevated temperature on the thermodynamic and kinetic properties of the solvent extraction of medical devices is evaluated in this study. The main objective of the current work is to specifically address the question of how effective a temperature of 50 °C, relative to 37 °C, is in improving the extractability and rate of the exaggerated and exhaustive extractions of medical devices. The extractability at equilibrium is related to the extraction partition coefficient, while the extraction rate is related to the corresponding diffusion coefficient. The partition and diffusion coefficients (or the enthalpies of extraction and diffusional activation energies) of solid-liquid extractions for different polymeric materials, solvents, and types of extractables entities at different temperatures are compiled comprehensively from extensive publications in the literature. The collected partition and diffusion coefficients at different temperatures are used to derive the partition enthalpies and diffusional activation energies in this study. The combined 209 partition enthalpies and 262 diffusional activation energies are then used to calculate the ratios of the partition and diffusion coefficients, when the extraction temperature increases from 37 °C to 50 °C. It is concluded from the study that the maximum improvement in extracted chemical amount with this specific temperature increase is about 3-fold, but the median improvement is only 16%. The most probable improvement is 25%. The maximum improvement (or decrease) in extraction time is 3.2-fold by the change in the diffusional coefficient, but the median value is 1.9-fold. The most probable decrease in extraction time is 2.4-fold. The collected data also allow the calculation of the ratio of the diffusion coefficient for a 10 °C increase, and the results are compared with the “factor 10 rule” in the literature on the relationship between the diffusion coefficient and temperature. The explicit conclusions of the study certainly provide evidences (not assumptions) in designing practical and cost-effective exaggerated and exhaustive extractions in the chemical characterization of medical devices, taking into considerations of extraction cycle time, temperature-dependent chemical stability, and the number of repeated extractions.

Constructing and validating ternary phase diagrams as basis for polymer dissolution recycling

One of the recycling methods for polymer waste is the dissolution-precipitation process, which is based on dissolving the polymer in a suitable solvent followed by contaminant removal by, optionally filtration, and polymer precipitation through the addition of a nonsolvent. As showcased for poly(vinyl chloride) (PVC), a polymer used in the construction sector and for packaging, the current work makes clear that the less studied ternary phase diagrams are a very promising tool for the ideal solvent-nonsolvent selection. Such ternary phase diagrams provide compositional information concerning the phase separation process pushing forward the dissolution-precipitation recycling technology. It is demonstrated that these diagrams can be constructed by connecting the Flory-Huggins theory, Hansen solubility parameters and UNIQUAC activity coefficients. Model validation is performed via cloud point measurements for which one can utilize labour-intensive visual inspection or, as demonstrated in this work, one can also apply dynamic light scattering and turbidimetry, with the latter as the preferred method that is cheaper and faster. Ternary phase diagrams for multiple solvent-nonsolvent systems are theoretically constructed and experimentally validated, considering cyclohexanone-ethanol and THF-ethanol as solvent-nonsolvent pairs. It follows that PVC phase diagrams are inherently different compared to other, more commonly studied polymers, such as polyethersulfone (PES) and that for PVC the addition of a ternary interaction parameter might be required.

Modification of PVDF ultrafiltration membrane for high concentration of nannochloropsis as a raw material for bioethanol: Computations and experiments

Nannochloropsis sp., which is abundant in the ocean and has a high carbohydrate content, has great potential if used as a raw material for bioethanol. However, the low concentration of microalgae in the culture medium (0.5-2 µg/L) and the small size of the microalgae Nannochloropsis sp. (2-8 µm) become problems in the harvesting process. This study aims to increase the concentration of Nannochloropsis sp. during the harvesting process using a LiCl-modified polyvinylidene fluoride (PVDF) membrane. In addition, a computational approach was used to select the best solvent for PVDF and explain the conformational changes of PVDF. The results showed that N-Methyl-2-pyrrolidone is the best solvent for PVDF polymer (the lowest solvation energy is -86.25 Kjmol−1, and the highest binding energy is 1.8 Kjmol−1). The membrane, with the addition of 2% LiCl, had the best performance, increased the microalgae concentration ten times (from 596.4 to 5098 ppm), flux (150 Lm−2h−1bar−1), and rejection (100%). Adding LiCl to the dope solution increased the water flux (from 516 to 614 Lm−2h−1bar−1), changed the PVDF conformation from alpha to beta, and decreased the hydrophobicity of the membrane (from 94.89 to 81.68 °). Layer pore fouling is the fouling that plays a role in reducing microalgae flux during microalgae filtration by Nannochloropsis sp. Meanwhile, the type of washing recommended to overcome layer pore fouling is rinsing by increasing the speed of the filtration flow and immersion in chemical compounds.

Effects of chain length on the structure and dynamics of polyvinyl chloride during atomistic molecular dynamics simulations

ABSTRACT Molecular dynamics (MD) simulations have proven to be useful for predicting and interpreting the conformational and dynamic properties of various polymer-solvent systems. The number of repeat units used to represent a polymer chain in an MD study is intended to provide a balance between the computational demands and the reliability of the specific phenomena being studied. To date, this balance has not received sufficient attention. Here, we investigate how the chain length of an atomistic polymer model influences the structure and dynamics of the polymer in different solvents. Seven different polyvinyl chloride (PVC) models, ranging from 5 to 240 –(CH2CHCl)- repeat units, are studied using atomistic MD simulations in two polar organic solvents: tetrahydrofuran (THF) and dimethylformamide (DMF). After benchmarking our MD results against experimental density data, we calculate polymer end-to-end distances, radii of gyration, radial distribution functions, shape descriptors, end-to-end vector correlation functions, dihedral autocorrelation functions, surface areas, surface electrostatic potentials, glass transition temperature and melt viscosities. Our MD simulations demonstrate that most of these properties converge when approximately 100–120 repeat units are used to represent PVC, and this convergence behaviour is observed in different solvents and at different temperatures.

A diffusion-reaction computational study to reveal the depolymerization mechanisms of epoxy composites for recycling

It has been recently discovered that the thermosetting matrix of engineering composites can be fully depolymerized in organic solvents through covalent bond exchange reactions (BERs) between the polymer network and solvent molecules. This breakthrough enables the eco-friendly and sustainable recovery of valuable fiber reinforcements using mild processing conditions. However, current investigations have been limited to proof-of-concept experimental demonstrations, leaving unanswered questions regarding the influence of temperature, solvent choice, and fiber arrangement on composite depolymerization performance. These factors are crucial for the commercialization and widespread industrial implementation of this technique. To address this significant knowledge gap, this study aims to establish the relationship between composite depolymerization speed and various material and processing conditions. A multiscale diffusion-reaction computational model is defined based on the finite element method, which links the microscale BER rate to the continuum-level composite depolymerization kinetics. Specifically, it reveals how the processing temperature, solvent diffusivity, fiber content, and fiber arrangement affect the overall composite depolymerization speed. The study enhances our understanding of the underlying mechanisms of composite recycling using organic solvents. As a result, it provides valuable insights for industrial stakeholders, allowing them to optimize depolymerization conditions, make informed material selections, and develop suitable business models for waste management.

Evolution of phase diagrams of polymer adsorption over attractive surfaces as a function of flexibility and solvent quality

ABSTRACT We describe the equilibrium conformations of a polymer near an attractive surface for different conditions in solvent quality and polymer stiffness. Using molecular dynamics techniques in a canonical ensemble, we show the evolution of the phase diagrams as function of temperature and surface interaction strength. Phase diagrams show an ampler variety of possible conformations due to changes in solvent quality compared to stiffness for which variations in conformations appear mainly in the degree of adsorption. We show that the adsorption transition is independent of solvent quality and stiffness. When both parameters change simultaneously, solvent effects are stronger than the stiffness secluding the stiff conformations to regions of low temperature and high surface attraction. A remarkable observation is that the radius of gyration perpendicular component to the surface, , signals the adsorption transition at coincidental points for each system independently of solvent and stiffness variations in all simulations, which may be of aid in locating this transition in other systems.

Living/Controlled Anionic Polymerization of Glycolide in Fluoroalcohols: Toward Sustainable Bioplastics.

Ring-opening polymerization (ROP) is a promising approach to accessing well-defined polyesters with superior (bio)degradability and recyclability. However, the living/controlled polymerization of glycolide (GL), a well-known sustainable monomer derived from carbon monoxide/dioxide, has never been reported due to the extremely low solubility of its polymer in common solvents. Herein, we report the first living/controlled anionic ROP of GL in strong protic fluoroalcohols (FAs), which are conventionally considered incompatible with anionic polymerization. Well-defined polyglycolide (PGA, Đ < 1.15, Mn up to 55.4 kg mol-1) and various PGA-based macromolecules are obtained at room temperature for the first time. NMR titration and computational studies revealed that FAs simultaneously activate the chain end and monomer without being involved in initiation. Low-boiling-point FAs and PGA can be recycled through simple distillation and sublimation at 220 °C in vacuo, respectively, providing a promising sustainable alternative for tackling plastic pollution problems.

Nanoparticles produced by laser ablation in organic solvent for polylactic acid-based polymer

Recently packing technology has been rising as a new domain for the application of nanoparticles. Herein the synthesis of polylactic acid (PLA) foils decorated with nanoparticles is investigated. The gold nanoparticles (Au NPs) can play a major role in reducing microbial load in aliment and to improve the food packaging quality. Au NPs have been fabricated by laser ablation in an organic liquid and then the PLA, with Au NP composites, has been manufactured through the drop-casting method. The crystalline nature of the produced nanoparticles, of their size and shape have been probed by transmission electron (TEM) and atomic force microscopies (AFM). The concentration of Au NPs has been evaluated by Rutherford Backscattering Spectrometry (RBS). The optical and electrical properties of composites have been tested by UV–ViS spectroscopy. The improvement of the hydrophobicity of the composite surfaces has been analysed by wettability measurements for implementation in the food packaging field.

Novel Electrospun Composite Membranes Based on Polyhydroxybutyrate and Poly(vinyl formate) Loaded with Protonated Montmorillonite for Organic Dye Removal: Kinetic and Isotherm Studies.

The use of biodegradable polyesters derived from green sources and their combination with natural abundantly layered aluminosilicate clay, e.g., natural montmorillonite, meets the requirements for the development of new sustainable, disposable, and biodegradable organic dye sorbent materials. In this regard, novel electrospun composite fibers, based on poly β-hydroxybutyrate (PHB) and in situ synthesized poly(vinyl formate) (PVF), loaded with protonated montmorillonite (MMT-H) were prepared via electrospinning in the presence of formic acid, a volatile solvent for polymers and a protonating agent for the pristine MMT-Na. The morphology and structure of electrospun composite fibers were investigated through SEM, TEM, AFM, FT-IR, and XRD analyses. The contact angle (CA) measurements showed increased hydrophilicity of the composite fibers incorporated with MMT-H. The electrospun fibrous mats were evaluated as membranes for removing cationic (methylene blue) and anionic (Congo red) dyes. PHB/MMT 20% and PVF/MMT 30% showed significant performance in dye removal compared with the other matrices. PHB/MMT 20% was the best electrospun mat for adsorbing Congo red. The PVF/MMT 30% fibrous membrane exhibited the optimum activity for the adsorption of methylene blue and Congo red dyes.

Green deep‐UV photoresist based on chitosan for microelectronics

AbstractPhotolithography is a core part in microelectronic processes. This technological step implies the use of numerous hazardous carcinogenic compounds in the formulations, the use of solvents for processing synthetic polymers to obtain micro and nanostructures. We proposed the use of chitosan‐based biosourced water‐soluble resins to significantly reduce the environmental impact of the photolithography step, for 193 nm photolithography. We show in this report that chitosan‐based photoresist is suitable for microelectronic application, and in particular, we could significantly improve photosensitivity by adding a water‐soluble photoacid generator (PAG). UV–visible and Fourier transform infrared‐attenuated total reflectance characterizations reveal an increase of the macromolecular chain scission kinetics in the presence of PAG. Moreover, the local decrease of the pH favors the solubility of chitosan in irradiated areas. Finally, the photolithography tests demonstrate that the dose to clear and the optimal dose for photopatterning are divided by a factor of two. Moreover, the physical etching transfer tests show that the presence of PAG does not decrease the transfer performance, making these aqueous‐based formulated resins still more adapted for the fabrication of microelectronic devices.

Quasi-solid polyaniline/poly(vinyl pyrrolidone) blend electrolytes for dye-sensitized solar cells

Conductive polymer blend gel electrolytes can address the instability caused by liquid electrolytes in dye-sensitized solar cells (DSSCs), thereby improving their long-term stability, by reducing leakage, and enhancing electrode adhesion. This work employed in-situ polymerization to synthesize blends of polyvinylpyrrolidone (PVP) and polyaniline (PANI), which were subsequently characterized using ionic conductivity measurements, Scanning Electron Microscopy, X-ray diffraction analysis, and Fourier Transform Infrared Spectroscopy. Consequently, the optimal composition has been chosen to prepare the electrolyte solution using polymer blend, solvents, and iodine-based salts. The conductivity of blend electrolytes has also been found to be affected by the salt concentration. The fabrication of DSSCs has made use of electrolytes with the highest conductivity values. It has been found that dye-sensitized solar cells with polymer gel electrolytes are more robust but less efficient than their conventional counterparts. Solid-state dye-sensitized solar cells were found to maintain their photovoltaic performance for a duration of one week, whereas conventional cells experienced a substantial decline in short-circuit current (∼36%) and open-circuit voltage (∼33.33%) over the same period.

Synthesis and Preclinical Development of a Promising Novel Romidepsin Nanoparticle for the Treatment of Peripheral T‐Cell Lymphoma (PTCL)

Introduction: The HDAC inhibitors are important drugs for the treatment of PTCL. While these drugs produce ORR of 25–30% with short PFS, responses can last over a year. There is still debate on the optimal ways to use HDAC inhibitors. Most HDAC inhibitors are oral with prolonged AUC of exposure. Romidepsin (R) is administered IV and exhibits a half-life of only 3 hours, though biological effects on chromatin may persist for 24–48 hours. A failed Phase 4 study led to the withdrawal of R for R/R PTCL. In an effort to try and create improved alternatives to R with better efficacy and safety, we deployed a proprietary nanochemistry platform to synthesize NanoRomidepsin (NR) particles, identifying a lead molecule that is comparable to or better than the predecessor R. Methods: Using a combinatorial strategy of solvent screening and polymer chemistry, we developed a first-in-class NR therapeutic with a unique and specific Drug/ Polymer/Surfactant ratio. We utilized dynamic Light Scattering (DLS), cryo-electron microscopy (EM) and liquid chromatography-mass spectrometry (LC-MS) to characterize the size, morphology, and drug encapsulation efficiency of the NR nanoparticles. Cell viability, flow cytometry and western blotting (WB) were performed to determine the effect of NR on cytotoxicity, apoptosis, and histone acetylation across a panel of PTCL cell lines. The maximum tolerated dose of NR was based on an in vivo single-dose and repeated dose toxicity study. Pharmacokinetic studies were performed in mice treated at ½ MTD with quantitation of plasma drug levels by LC-MS. Results: Cryo-EM and DLS confirmed that NR had a poly-dispersity index (PDI) between 0.16 to 0.27 and a z-average of 60–70 nm, indicating uniform size and homogenous particle distribution in the desired ranges. The cell viability assays demonstrated that R and NR produced comparable cytotoxicity (IC50 in range of 0.7–1.9 nM). Flow cytometry and WB analysis demonstrated that NR induced apoptosis and increased acetylation of H3/H4 in a time and concentration-dependent manner. In vivo single-dose and repeated dose toxicity assays revealed a clear correlation between dose and weight loss and/or clinical score in both R and NR treated groups. Pharmacokinetic analyses revealed a substantially greater AUC for NR, which was 3- and 25-fold higher compared to R for IP and IV routes of administration respectively. Interestingly, the markedly greater AUC for NR did not appear to be associated with increased in vivo toxicity. Conclusions: We have synthesized a lead nanotherapeutic of R that will be translated to the clinic. In keeping with other nanotherapeutic drugs, nanosizing drugs tend to increase their volume of distribution (Vd), AUC and markedly improve their tolerability. Large scale in vivo modeling of NR is underway. Data on the development and differentiation of our lead NR asset will be presented, as will the strategy for clinical development. The research was funded by: IVY grant, Translational Orphan Blood Cancer Research Initiative Fund Keyword: Molecular Targeted Therapies No conflicts of interests pertinent to the abstract.

On-demand heart valve manufacturing using focused rotary jet spinning

On-demand heart valve manufacturing using focused rotary jet spinning

Pressure of Linear and Ring Polymers Confined in a Cavity.

Nanoscale confinement of polymers in a cavity is central to a variety of biological and nanotechnology processes. Using the discrete WLC model we simulate the compression of flexible and semiflexible polymers of linear and ring topology in a closed cavity. Simulation reveals that polymer pressure inside the cavity increases with the chain stiffness but is practically unaffected by the chain topology. For flexible polymers, the computed dependence of pressure on the cavity size and polymer concentration is consistent with the scaling behavior expected for bulk polymers in a good solvent. However, the scaling behavior of semiflexible polymers is only in partial agreement with the theory prediction, with discrepancies arising from a continuous transition between regimes in chains of moderate lengths. The computed segment density profiles endorse the propensity of semiflexible polymers to concentrate beneath the cavity surface and thus elevate the pressure. The compaction of polymers by compression into the disordered globule or growing toroidal structure is documented.

The Synergistic Effect of Triazine and Phosphaphenanthrene Units on the Physico-Chemical Behavior of Polyimides.

With the aim to develop polymers with appealing, multifunctional characteristics, a series of polyimides were designed by anchoring 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) units on the main polymer chains containing 1,3,5-triazine and several flexible moieties, such as ether, hexafluoroisopropylidene, or isopropylidene. A detailed study was conducted to establish structure-property correlations, with a focus on the synergistic effectiveness of triazine and DOPO moieties on the overall features of polyimides. The results evidenced good solubility of the polymers in organic solvents, their amorphous nature with short-range regular-packed polymer chains, and high thermal stability with no glass transition temperature below 300 °C. Spectrophotometric measurements revealed the existence of a strong charge transfer complex in these polymers that led to a "black" appearance, which generated broad absorption bands spanning on the overall visible range. Nevertheless, these polymers displayed green light emission associated with 1,3,5-triazine emitter. The electrochemical characteristics of the polyimides in solid state demonstrated their strong n-type doping character induced by three different structural elements with electron-acceptance capability. The useful properties of these polyimides, including optical, thermal, electrochemical, aesthetics, and opaqueness, endow them with several possible applications in the microelectronic field, such as protecting layers for the inner circuits against UV light deterioration.