Polymer–solute interactions in solid–liquid two‐phase partitioning bioreactors

BACKGROUND: Biphasic systems with immiscible solvents have been studied for in situ product removal, and have shown improvements in bioreactor performance, however, problems associated with solvent biocompatibility, bioavailability and operation have been identified. One alternative is the solid–liquid system in which polymer beads are used, absorbing and removing target compounds from the aqueous phase while maintaining equilibrium conditions. This work aims to identify polymer properties that may be important in polymer selection for selected biotransformation molecules including 2‐phenylethanol, cis‐1,3‐indandiol, iso‐butanol, succinic acid and 3‐hydroxybutyrolactone. RESULTS: Relatively hydrophobic compounds (e.g. 2‐phenylethanol) tend to be absorbed by polymers better than hydrophilic ones (e.g. iso‐butanol) based on partition coefficient tests; values as high as 80 were obtained for the former and < 3 for the latter. Owing to the presence of polar functional groups on these compounds, polar polymers such as Hytrel® performed better than non‐polar ones such as Kraton®. Crystallinity and intermolecular hydrogen‐bonding were also found to be important polymer properties. CONCLUSION: Polymers showed excellent results in absorbing hydrophobic compounds such as aromatic alcohols, and positive results in absorbing hydrophilic compounds but to a lesser extent. Grafting hydrophilic functional groups onto polymers may be a promising approach for extending polymer uptake capabilities and is currently being investigated. Copyright © 2009 Society of Chemical Industry     

Utilizing ultraviolet photooxidation as a pre‐treatment of volatile organic compounds upstream of a biological gas cleaning operation

Laboratory experiments were conducted to evaluate the potential to utilize ultraviolet (UV) photooxidation as a pre‐treatment to render recalcitrant volatile organic compounds into more biodegradable compounds. α‐Pinene was selected due to its low water solubility and low biodegradability. α‐Pinene‐contaminated gaseous streams with inlet loadings between 250 and 2500 g m^?3 h^?1 were passed through an annular reactor equipped with a UV lamp that emitted light at 254 nm and 185 nm wavelengths. The outlet stream containing UV photooxidation intermediates was then sparged through nanopure water that was then analyzed for its total organic carbon (TOC) content and subjected to batch biodegradability tests. UV photooxidation effectively degraded α‐pinene with a maximum removal rate of about 700 g m^?3 h^?1. The removal rate followed first order kinetics at low inlet loadings (less than 1200 g m^?3 h^?1) and approached zero order behavior at higher inlet loadings. The principal oxidizing species in the reactor was ozone. Of the total α‐pinene removed, measured as TOC, 50% was converted to water‐soluble and more biodegradable intermediates. The biodegradability of the resultant intermediates was similar to that of methyl ethyl ketone (MEK), which is 3–30 times more biodegradable than α‐pinene. These results show that the use of UV photooxidation is a promising and effective pre‐treatment technique for enhancing the biodegradability of hydrophobic and recalcitrant organic compounds such as α‐pinene. Copyright © 2004 Society of Chemical Industry     

Pneumatic impact ignition of selected polymers in high‐pressure oxygen environments

One likely cause of polymer ignition in high‐pressure oxygen systems is adiabatic‐compression heating of polymers, caused by pneumatic impact. This study investigates ignition by pneumatic impact of selected polymers in high‐pressure oxygen environments. Six polymers commonly used in high‐pressure oxygen systems were tested in a pneumatic‐impact test system at 8.3–37.9 MPa oxygen pressures. The six polymers tested were Teflon^®(polytetrafluoroethylene), Neoflon^®(polychlorotrifluoroethylene), PEEK (polyetheretherketone), Zytel^® 42 (Nylon 6/6), Buna N (nitrile rubber), and Viton^® A (copolymer of vinylidene fluoride and hexafluoropropylene). This study shows that the ignition of polymers due to pneumatic impact could be initiated by a local heterogeneous reaction between the hot oxygen and the oxidation sites of the polymer, and proposes an ignition mechanism. Ignition susceptibility of a material to the pneumatic impact can be expressed by its ignition probability. The ignition probabilities of the six polymers at the various oxygen pressures are presented. There is no good correlation between the ignition probability and the autoignition temperature. Copyright © 2006 John Wiley & Sons, Ltd.     

Medium composition effects on solute partitioning in solid–liquid two‐phase bioreactors

Biphasic systems such as two‐phase partitioning bioreactors (TPPBs) have been used to alleviate biological inhibition by sequestering inhibitory compounds within an immiscible phase. The use of solid polymer beads as this auxiliary phase provides a fully biocompatible alternative to potentially toxic organic solvents. While guidelines exist for the rational selection of the polymer phase, the effect of the aqueous phase composition on molecular sequestration has not been explored in the literature. This work aims to identify aspects of medium composition that influence the partitioning of target molecules into the sequestering phase. Using benzaldehyde as the target molecule and Hytrel G3548L (DuPont) as the polymer phase, pH, temperature, salt and glucose concentrations, as well as ethanol concentrations, were examined for their effects on the partition coefficient. pH and temperature were observed to have no significant effect on benzaldehyde partitioning. Salt and glucose additions increased the partition coefficient by 173% and 30%, respectively, compared with pure reverse osmosis (RO) water, while increasing ethanol concentration was found to decrease the partition coefficient from 44 ( ± 1.6) to 1 ( ± 0.3). Strategic changes to the aqueous phase can be made to improve affinity of the sequestering phase for target molecules. This provides a simple and cost‐effective method to potentially improve TPPB system performance. Copyright © 2010 Society of Chemical Industry     

Analysis of the phase partitioning of additives in rubber‐modified plastics

The phase partitioning of additives in polymer blends has a large impact on the performance of the blend. Therefore, it is necessary to be able to quantify the level of the additives in each phase. A ¹H–NMR method is presented to determine the partitioning of additives between the rubber and rigid phases of a high‐impact polystyrene (HIPS) material. In one case, a HIPS material was modified with 2,6‐di‐tert‐butyl‐4‐methyl‐phenol (Ionol, CAS# 128‐37‐OMF) as a stabilizer for both phases. HIPS materials with varying levels of Ionol were melt‐blended by extrusion and the total level of additives was determined analytically for these standard materials. The ¹H–NMR method was used to determine the level of Ionol in the poly(butadiene) rubber phase. The Ionol was found to preferentially partition into the rubber phase with a partition coefficient of about 2. A second example of the same concept, instead utilizing ¹³C–NMR, involved the analysis of the partition coefficient for both Tinuvin P and Tinuvin 770 (CAS# 2440‐22‐4 and 52829‐07‐9), partitioning between the rigid and rubber phases of an ethylene–propylene–diene‐modified (EPDM) toughened styrene–ran–acrylonitrile (SAN) copolymer. The partition coefficient was determined to be 0.5 for Tinuvin P and 1.3 for Tinuvin 770. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1963–1970, 2001     

ForceSpinning of polyacrylonitrile for mass production of lithium‐ion battery separators

We present results on the Forcespinning^® (FS) of Polyacrylonitrile (PAN) for mass production of polymer nanofiber membranes as separators for Lithium‐ion batteries (LIBs). Our results presented here show that uniform, highly fibrous mats from PAN produced using Forcespinning^®, exhibit improved electrochemical properties such as electrolyte uptake, low interfacial resistance, high oxidation limit, high ionic conductivity, and good cycling performance when used in lithium ion batteries compared to commercial PP separator materials. This article introduces ForceSpinning^®, a cost effective technique capable of mass producing high quality fibrous mats, which is completely different technology than the commonly used in‐house centrifugal method. This Forcespinning^® technology is thus the beginning of the nano/micro fiber revolution in large scale production for battery separator application. This is the first time to report results on the cycle performance of LIB‐based polymer nanofiber separators made by Forcespinning^® technology. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42847.     

A first principles approach to identifying polymers for use in two‐phase partitioning bioreactors

BACKGROUND: Two‐phase partitioning bioreactors (TPPBs) employ an immiscible phase to partition toxic substrates/products to/away from cells to reduce cytotoxicity and improve bioprocess performance. Initially, immiscible organic solvents were used as the sequestering phase, and their selection included consideration of solute–solvent affinity, which can be predicted through first principles consideration of solute activity and phase equilibrium thermodynamics. Polymers can replace organic solvents in such systems, however, their selection has largely been via heuristic means, and a more fundamental approach is necessary for future success in rational polymer identification. RESULTS: Material properties (polymer crystallinity, solubility parameter, and glass transition temperature T_g) were examined across several polymers and polyaromatic hydrocarbons as target solutes. All were shown to influence solute–polymer affinity. CONCLUSION: This first attempt at identifying physical/chemical properties that affect solute–polymer partitioning has been able to demonstrate some clear trends, and has allowed us to formulate a polymer selection guide, based on first principles, to facilitate the selection of solute–polymer pairs for solid–liquid TPPB applications. Copyright © 2012 Society of Chemical Industry     

Solubility parameters of polymers from swelling measurements at 60°C

The swelling behavior of the networks of natural rubber, an epoxidized natural rubber, low-density polyethylene, polystyrene, and poly(methyl methacrylate) are studied in six classes of solvents at 60°C. The data of the swelling coefficient are successfully treated by a modified version of the empirical equation proposed by Gee, as to determine the solubility parameter of a polymer, δ₂. It is found that increasing the temperature would decrease the δ₂'s of these polymers with a common rate of 0.02 (J/mL)^1/2/K. A semiempirical model is proposed to rationalize the present finding satisfactorily. © 1995 John Wiley & Sons, Inc.     

Synthesis of Low Methanol Permeation Polymer Electrolyte Membrane from Polystyrene-Butadiene Rubber

In order to find a low cost polymer electrolyte membrane with low methanol cross-over, the development of novel polymer electrolytes have been actively carried out in recent time as alternatives to Nafion®, which is the state-of-the art membrane. The problems associated with these alternative membranes are higher permeability to the fuel, lower proton attraction and thermal stability. This work therefore was focused on synthesizing low methanol permeable membrane with good proton conductvity and thermal stability from locally available polymer (Polystyrene-butadiene rubber). Results obtained revealed that the synthesized membrane exhibited methanol permeation in the ranges of 2.13 × 10^?7 to 7.58 × 10^?7 mol/cm²s which was lower than that of Nafion® (3.15 × 10^?6 cm²/s). The proton conductivity of the synthesized membrane is in the order of 10^?2 S/cm. The results also show that water and solvent uptake of the synthesized membrane are moderate as compared to that of Nafion®. These results are influenced by the degree of sulphonation and membrane thickness ranging from 0.112 mm?0.420 mm.     

Effect of polar solvents on dynamic moduli of concentrated solutions of polyethylacrylate

There have been many investigations on the effect of solvents on the dynamic moduli of concentrated polymer solutions. However, most of the polymers investigated were nonpolar, such as polystyrenes and polybutadienes. Moreover, the samples were usually model polymers of very narrow molecular weight distribution and were either linear or branched star. Our investigation was on a commercial polymer, which is polar and has long branches but is “gel free.” The solvents used were polar plasticizers. This study was motivated by the frequent observation that a small addition of plasticizers has little effect on the rubbery modulus or has an unexpectedly large reduction of the rubbery modulus, depending on a polymer–plasticizer pair. This work examines concentrated solutions of polyethylacrylate and three plasticizers (DBP, DHP, and DOP) at concentrations above 50% for DBP and DHP and above 80% for DOP. DOP did not dissolve the rubber at the lower concentrations. The temperature range was 30–150°C, and the frequency range was 10⁻²–10² rad/s. The time–temperature correspondence was applicable over the entire range of observation. The rubbery modulus was found to be independent of the plasticizer type at all concentrations. With dilution to 90% of polymer there was only small decrease of the modulus, and with further dilution the modulus decreased with a slope of 1.8 in the double-logarithmic plot of the modulus against concentration. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 69: 1727–1736, 1998     

Dielectric spectroscopy for polymer melt composition measurements

Laboratory and in‐line dielectric spectroscopy studies of molten polymers revealed the ability to make composition measurements of the comonomer concentration along the polymer chains. The dielectric permittivity or capacitance was found to be proportional to the polymer sidechain composition. The length of the polar sidegroup dictated the optimum measurement frequency; i.e., a short sidechain, such as the C‐Cl bond in chlorosulfonated polyethylene, required a high measurement frequency (short relaxation time) due to the rapid mobility of the sidechain, whereas a longer sidechain, such as the vinyl ether sidegroup in Nafion®, required a much lower frequency (longer relaxation time) to orient the sidechain to a measurable extent. For in‐line process studies, a new cylindrical, interdigitated dielectric sensor and associated electronics were developed to make measurements on molten polymers at the exit of an extruder up to 400°C and 3000 lbs/in². In‐line studies of molten polymers revealed a direct relationship between the dielectric signal and the polymer comonomer composition. The sensor represents a non‐invasive, real‐time process composition measurement and can be integrated to provide closed‐loop process control.     

Grafting of butyl acrylate and methyl methacrylate on butyl rubber using electron beam radiation

Being nonpolar in nature, butyl rubber (IIR) has poor compatibility toward polar polymers and fillers. It can be improved by grafting polar substrates on the butyl elastomer. Radiation‐induced polymer processing is getting increasing interest, as it leads to new and improved polymers with desirable and interesting properties. In this investigation, electron beam radiation has been used to graft methyl methacrylate (MMA) and butyl acrylate (BA) on IIR. This process has several advantages over conventional grafting processes such as cationic polymerization (which needs very low temperature and stringent reaction conditions) and solution radical polymerization (which often needs solvent removal and recycling). The grafted polymers were characterized by using ¹H NMR, IR, TGA, and SEM analysis. The degree of grafting increases with a decrease in irradiation dose as well as with an increase in monomer concentration. It was observed that there was a decrease in intrinsic viscosity in irradiated IIR samples, indicating the chain scission. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1340–1346, 2006     

Effect of Emulsification on Surfactant Partitioning in Surfactant-Polymer Flooding

A laboratory surfactant-polymer flooding experiment was performed to study the effect of emulsification on surfactant partitioning. The partition coefficient of petroleum sulfonates (KPS) after emulsification was significantly higher than that under static conditions. The partition coefficient of KPS gradually decreases with the increase of polymer concentration from 1000–3000 mg L⁻¹, indicating that the increase of polymer concentration could protect KPS from the partition loss of emulsification. The lower the oil–water ratio, the higher the partition coefficient. The partition coefficient of KPS of resin and asphaltene was higher than that of crude oil. Alkanes, aromatics, and other polar components in crude oil have a significant influence on the partition of KPS.     

Synthesis of functionalized phenolformaldehyde polymer resins by the reaction of 2,4‐dihydroxyacetophenone formaldehyde resin with various amines and their metal ion uptake properties

A series of functionalized phenolformaldehyde polymer resins have been synthesized by the reaction of 2,4‐dihydroxyacetophenone‐formaldehyde resin with the amines, such as ethanolamine, aminophenol, ethylenediamine, and propylenediamine in dichloromethane. The Schiffbase polymers were characterized by IR and ¹H‐NMR spectroscopic techniques. Thermal stabilities of the polymers were determined by TG and DTA studies. Heavy and toxic metal ions viz., Pb(II), Hg(II), Cd(II), and Cr(VI) have been removed using these polymer resins. Metal uptake efficiency, reusability, effect of pH, effect of time, and effect of initial concentration on the metal uptake were also studied. Amount of metal removed by the resin was determined using atomic absorption spectrophotometry. The retention properties were also tested under competitive conditions and were found to be depend strongly on the pH. Elution of metal ions were investigated in acid media. The uptake behaviour of the resins was approximately described by Freundlich's equation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1501–1509, 2004     

Synthesis and characterization of a novel liquid crystalline star‐shaped polymer based on α‐CD core via ATRP

Well‐defined side‐chain liquid crystalline star‐shaped polymers were synthesized with a combination of the “core‐first” method and atom transfer radical polymerization (ATRP). Firstly, the functionalized macroinitiator based on the α‐Cyclodextrins (α‐CD) bearing functional bromide groups was synthesized, confirmed by ¹H‐NMR, MALDI‐TOF, and FTIR analysis. Secondly, the side‐chain liquid crystalline arms poly[6‐(4‐methoxy‐4‐oxy‐azobenzene) hexyl methacrylate] (PMMAzo) were prepared by ATRP. The characterization of the star polymers were performed with ¹H‐NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermal polarized optical microscopy (POM). It was found that the liquid crystalline behavior of the star polymer α‐CD‐PMMAzo_n was similar to that of the linear homopolymer. The phase‐transition temperatures from the smectic to nematic phase and from the nematic to isotropic phase increased as the molecular weight increased for most of these samples. All star‐shaped polymers show photoresponsive isomerization under the irradiation with Ultraviolet light. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Blending polypropylene with glycidyl methacrylate‐containing polymer to improve adhesion to elastomers

BACKGROUND: Polypropylene (PP) is one of the most widely used polyolefins but gets restricted in surface applications due to its non‐polar nature. Surface properties of films made of PP were modified to improve their adhesion to elastomeric polymers such as thermoplastic polyurethanes (TPU), especially to Pebax^® [poly(ether‐block‐amide)]. RESULTS: Surface modification of PP was brought about by blending it with glycidyl methacrylate (GMA)‐containing polymer to increase its surface energy. Films of modified PP were analyzed to determine the blending efficiency and characterized using contact angle measurements, differential scanning calorimetry, X‐ray photoelectron spectroscopy and scanning electron microscopy. Molecular dynamics simulations were done to determine surface and bulk properties of PP blended with GMA. The computational results correlated very well with the experimental data and revealed that the changes in the surface energy can be linked to the position of the functional group within the sample. T‐Peel tests indicated a 2.4 times increase in adhesion to Pebax^® and only 1.7 times increase in adhesion to TPU compared to unmodified PP. CONCLUSION: The surface energy and enhanced adhesion proved that PP was successfully modified and its surface made more polar. Copyright © 2008 Society of Chemical Industry     

Synthesis and characterization of l-tyrosine based novel polyphosphates for potential biomaterial applications

Starting from the natural amino-acid l-tyrosine, a diphenolic monomeric molecule was developed using carbodiimide mediated solid-phase synthesis techniques. This monomeric molecule was polymerized by reacting it in equimolar proportions with suitable dihalophosphates to yield novel biodegradable polyphosphates containing peptide linkages and phosphoester linkages alternating in the polymer backbone. The biodegradability of such a polymer is expected to arise from the hydrolytic degradability of the phosphoester linkages and the enzymatic degradability of the peptide linkages in the polymer backbone. Design of such a polymer is expected to make a significant contribution to biomaterials research, regarding drug delivery device and tissue engineering scaffold applications. The monomer was obtained by a novel solid phase carbodiimide-mediated amide coupling process. The subsequent polymers were obtained by solution-phase dehydrochlorination polycondensation reactions in the presence of a suitable acid acceptor. The synthesized polymers were characterized by ¹³C NMR, ³¹P NMR and FTIR for their chemical structure, by GPC for their molecular weight distribution, and by DSC and TGA for their thermal transition characteristics.     

New soluble π-conjugated polymers containing 2-diisopropylamino-1,3,5-triazine unit: synthesis,characterization and optical properties

A new type of π-conjugated polymers containing 2-diisopropylamino-1,3,5-triazine were prepared via Sonogashira or Suzuki coupling reaction. The structures of the polymers were performed by FT-IR, ¹H-NMR, UV–vis spectroscopy, photoluminescence spectroscopy, gel permeation chromatography, thermal analysis and X-ray diffraction analysis. These derived polymers were soluble in common organic solvents such as tetrahydrofuran, chloroform, toluene, and showed good thermal stability. Polymers containing 1,4-diethynyl-2,5-bis(dialkoxy)benzene unit in polymer main chain emitted blue-green light in solution phase under UV light irradiation except with polymer containing 9,9-dioctylfluorene(blue light). Acidochromic behaviors of polymers were studied in CHCl₃-CF₃COOH mixtures. 9,9-Dioctylfluorene-containing polymer displayed better acidochromic property and linear relationship between absorbance and concentration with the concentration of CF₃COOH from 5.384?×?10^?4 to 26.92?×?10^?4 mol/L. Electrochemical behaviors of polymers depicted p-doping and some hole-transporting properties. XRD results showed that polymers exhibited certain crystallinity.     

Sulfonation of poly(phthalazinone ether sulfone ketone) by heterogeneous method and its potential application on proton exchange membrane (PEM)

A series of sulfonated PPESK (SPPESKs) were synthesized through a heterogeneous sulfonation process with fuming sulfuric acid as sulfonating agent in a chloroform solvent. Membranes prepared from SPPESKs were investigated and proved to be candidates of proton exchange membrane in fuel cell operating at high temperature and low humidity. The heterogeneous sulfonation reaction is verified to first occur on the interface of the acid phase and the chloroform phase, then went on in the acid phase. SPPESKs with sulfonation degree (DS) up to 2.0 are obtained through a new reprecipitation method. Effects of reaction temperature, reaction time, acid/polymer ratio, and chloroform/polymer ratio on the sulfonation reaction are reported in details. An increase in sulfonation degree results in the increase of hydrophilicity, bringing about a substantial gain in proton conductivity. SPPESK membranes exhibit high water uptake of about 105.4% with DS of 1.01, almost two times higher than that of Nafion® with similar dimensional variation. Conductivity values at 35°C, 60% R.H. ranging from 10^?3 to 10^?2 S/cm were measured, which are comparable to or higher than that of Nafion® 112 (1.635 × 10^?2 S/cm) under the same test condition. Thermogravimetric analysis shows that SPPESK membranes are stable up to 290°C in N₂. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1002–1009, 2007     

Partition of α-lactoalbumin and β-lactoglobulin from goat milk whey utilizing aqueous biphasic systems

This paper presents a study of α-lactoalbumin and β-lactoglobulin proteins partition from goat milk whey in-nature, utilizing aqueous biphasic systems comprised of polymers (polyethylene glycol, polypropylene glycol, polyvinylpyrrolidone), potassium phosphate, and water. The systems were evaluated at 25°C and pH 7.0. The influence of the polymer type, of the polymer molecular weight, and the polymer mass percentage on the partition coefficient of these proteins was assessed. Among the analyzed polymers, the polyethylene glycol (1500) was more indicated. The results showed that the separation technique by aqueous biphasic systems are applicable indicating high efficiency in the whey proteins separation process.