Cross-linked Polyethylene Glycol Diacrylate Research Articles

Hydrogels based on crosslinked polyethylene glycol diacrylate and fish skin gelatin

The aim of this work was to develop hydrogels based on poly(ethylene glycol diacrylate) (PEGDA) and fish gelatin for potential biomedical applications such as wound healing, drug delivery and biosensors. The hydrogels were prepared via in situ Michael addition of ammonia crosslinker to PEGDA in the presence of cold-water fish skin gelatin that was used as an additive. The fabrication conditions and properties of the hydrogels were examined using various amounts of fish gelatin to evaluate the influence of its concentration on gelation time, crosslinking density and swelling behavior of the hydrogels. FTIR spectra confirmed the formation of the crosslinked hydrogels and the degree of conversion (DC) of the double bonds for the hydrogels containing 5, 7.5 and 10 % w/v of gelatin was between 72 and 80 %. Fish skin gelatin had a strong effect on the dimentional stability and water absorbing properties of the hydrogels and the system containing 7.5 % w/v gelatin exhibited the longest swelling time of 18 h. The hydrophobicity of the hydrogels was achieved by covalent grafting of the residual double bonds with thiol-containing small hydrocarbon molecules using thiol-ene click chemistry reaction conditions, leading to the increase of the water contact angle from 0° to 60-73°.

Surface Passivation Method for the Super-repellence of Aqueous Macromolecular Condensates.

Solutions of macromolecules can undergo liquid-liquid phase separation to form droplets with ultralow surface tension. Droplets with such low surface tension wet and spread over common surfaces such as test tubes and microscope slides, complicating in vitro experiments. The development of a universal super-repellent surface for macromolecular droplets has remained elusive because their ultralow surface tension requires low surface energies. Furthermore, the nonwetting of droplets containing proteins poses additional challenges because the surface must remain inert to a wide range of chemistries presented by the various amino acid side chains at the droplet surface. Here, we present a method to coat microscope slides with a thin transparent hydrogel that exhibits complete dewetting (contact angles θ ≈ 180°) and minimal pinning of phase-separated droplets in aqueous solution. The hydrogel is based on a swollen matrix of chemically cross-linked polyethylene glycol diacrylate of molecular weight 12 kDa (PEGDA), and can be prepared with basic chemistry laboratory equipment. The PEGDA hydrogel is a powerful tool for in vitro studies of weak interactions, dynamics, and the internal organization of phase-separated droplets in aqueous solutions.

In vitro enzymatic degradation of the PTMC/cross-linked PEGDA blends.

Introduction: Poly(1,3-trimethylene carbonate) (PTMC) is a flexible amorphous polymer with good degradability and biocompatibility. The degradation of PTMC is critical for its application as a degradable polymer, more convenient and easy-to-control cross-linking strategies for preparing PTMC are required. Methods: The blends of poly(trimethylene carbonate) (PTMC) and cross-linked poly(ethylene glycol) diacrylate (PEGDA) were prepared by mixing photoactive PEGDA and PTMC and subsequently photopolymerizing the mixture with uv light. The physical properties and in vitro enzymatic degradation of the resultant PTMC/cross-linked PEGDA blends were investigated. Results: The results showed that the gel fraction of PTMC/cross-linked PEGDA blends increased while the swelling degree decreased with the content of PEGDA dosage. The results of in vitro enzymatic degradation confirmed that the degradation of PTMC/cross-linked PEGDA blends in the lipase solution occurred under the surface erosion mechanism, and the introduction of the uv cross-linked PEGDA significantly improved the resistance to lipase erosion of PTMC; the higher the cross-linking degree, the lower the mass loss. Discussion: The results indicated that the blends/cross-linking via PEGDA is a simple and effective strategy to tailor the degradation rate of PTMC.

Cellulose Nanocrystals Chiral Nematic Coating with Reversible Multiple-Stimuli-Responsive Coloration

Due to their unique chiral nematic structure and special optical property, cellulose nanocrystals (CNCs) have drawn enormous attention. However, the inherent brittleness and rigidity limit their application in coatings or free-standing films. In this work, we designed and fabricated a novel iridescent coating with multiple-stimuli-responsive coloration through photochemical cross-linking with CNCs, poly(ethylene glycol) diacrylate (PEGDA), and erythritol. The as-prepared coatings exhibited improved mechanical strength because of the introduction of covalent organic frameworks and the internal hydrogen-bonding interaction of CNCs, cross-linked PEGDA networks, and erythritol that provided efficient energy dissipation. Interestingly, the CNC coating was able to distinguish similar organic liquids, including the skeletal isomers (1-propanol/2-propanol), halogenated hydrocarbons (chloroform/dichloromethane), and homologous compounds (methanol/ethanol), quickly by the change in surface color when immersed in various organic solvents. In addition, the CNC coating exhibited reversible humidity sensitivity with wide color changes from cyan to yellow-green, salmon pink, red, and colorless under 30–98% air relative humidity (RH). Based on the reversible discoloration of CNC coating, the anti-counterfeiting performance on CNC coating was presented, and the handwriting of saline solution appeared reversibly when stimulated with ethanol. Thus, the reversible allochroic CNC-based coating platform with multiple-stimuli-responsiveness has the potential to be developed as solvent sensors, test papers, and encryption tools.

Boosting the performances of lithium metal batteries through in-situ construction of dual-network self-healing gel polymer electrolytes

As an alternative to conventional liquid electrolytes, self-healing gel polymer electrolytes (SHGPEs) can effectively increase the safety performance and lifetime of lithium metal batteries (LMBs). However, the poor mechanical properties and unfavorable ionic conductivity limit its further use. Herein, based on a simple in situ polymerization strategy, a novel dual-network structure self-healing gel polymer electrolyte (DN-SHGPE) with mechanical strength and self-healing properties is designed and prepared. The brush copolymer PEG-UPy contains a large amount of dynamic urethane-pyrimidine (UPy) dimer, acting as the first network, which gives GPE great self-healing ability and increases the safety and cycle lifetime of lithium batteries. The second network is cross-linked polyethylene glycol diacrylate (PEGDA), which ensures the dimensional stability and mechanical qualities of GPE. In comparison to the unmodified polymer electrolyte PEG-UPy, DN-SHGPE exhibits better ionic conductivity, excellent mechanical property, and good thermal stability, as well as good interaction stability with Li metal anode. When assembled with LiFePO4 and lithium metal electrodes, the resultant cells show a high reversible specific capacity and good rate capability.

Highly Skin-Compliant Polymeric Electrodes with Synergistically Boosted Conductivity toward Wearable Health Monitoring.

Despite rapid advances in stretchable electrodes, successful examples of polymeric dry electrodes are limited. Especially in wearable health monitoring, it is urgent to develop biocompatible electrodes that possess intrinsic skin-compliance while maintaining a high conductivity. Herein, a strategy is demonstrated to synergistically regulate the interpenetration behavior and molecular crystallinity in the blend via embedding a novel double network, i.e. physically cross-linked poly(vinyl alcohol) (PVA) and covalently cross-linked polyethylene glycol diacrylate (PEGDA), into the PEDOT:PSS matrix. The favorable interaction energy between PVA and PEGDA enables well-distributed microstructure with finer phase separation in the film, affording a low Young's modulus of 16 MPa with a high conductivity of 442 S/cm. Consequently, the optimal polymeric electrode can acquire high-quality electromyogram (EMG) and electrocardiogram (ECG) signals. Our results provide a feasible approach for producing skin-compliant polymeric electrodes toward next-generation health monitors.

Thermotolerant and fireproof gel polymer electrolyte toward high-performance and safe lithium-ion battery

Poly(ethylene oxide) (PEO) and its derivatives based gel polymer electrolytes (GPEs) are severely limited in advanced and safe lithium-ion batteries (LIBs) owing to the intrinsically high flammability of liquid electrolytes and PEO. Directly adding flame retardants to the GPEs can suppress their flammability and thus improve the safety of LIBs, but results in deteriorative electrochemical performance. Herein, a novel GPE with chemically bonded flame retardant (i.e. diethyl vinylphosphonate) in cross-linked polyethylene glycol diacrylate matrix, featuring both high-safety and high-performance, is designed. This as-prepared GPE storing the commercial 1 mol L−1 LiPF6 electrolyte resists high temperature of 200 °C and cannot be ignited as well as possesses a high ionic conductivity (0.60 mS cm−1) and good compatibility with lithium. Notably, the LiFePO4/Li battery with this GPE delivers a satisfactory capacity of 142.2 mA h g−1 and a superior cycling performance with a capacity retention of 96.3% and a coulombic efficiency of close to 100% for 350 cycles at 0.2 C under ambient temperature. Furthermore, the battery can achieve steady charge–discharge for 100 cycles with a coulombic efficiency of 99.5% at 1 C under 80 °C and run normally even at a high temperature of 150 °C or under the exposure to butane flame. Differential scanning calorimetry manifests significantly improved battery safety compared to commercial battery systems. This work provides a new pathway for developing next-generation advanced LIBs with enhanced performance and high safety.

Intramolecular Vibrational Energy Relaxation of CO2 in Cross-Linked Poly(ethylene glycol) Diacrylate-Based Ion Gels.

Ultrafast two-dimensional infrared spectroscopy (2D-IR) and Fourier transform infrared spectroscopy (FTIR) were used to measure carbon dioxide (CO2) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]), cross-linked low-molecular-weight poly(ethylene glycol) diacrylate (PEGDA), and an ion gel composed of a 50 vol % blend of the two. The center frequency of the antisymmetric stretch, ν3, of CO2 shifts monotonically to lower wavenumbers with increasing polymer content, with the largest line width in the ion gel (6 cm-1). Increasing polymer content slows both spectral diffusion and vibrational energy relaxation (VER) rates. An unexpected excited-state absorbance peak appears in the 2D-IR of cross-linked PEGDA due to VER from the antisymmetric stretch into the bending mode, ν2. Thirty-two response functions are necessary to describe the observed features in the 2D-IR spectra. Nonlinear least-squares fitting extracts both spectral diffusion and VER rates. In the ion gel, CO2 exhibits spectral diffusion dynamics that lie between that of the pure compounds. The kinetics of VER reflect both fast excitation and de-excitation of the bending mode, similar to the ionic liquid (IL), and slow overall vibrational population relaxation, similar to the cross-linked polymer. The IL-like and polymer-like dynamics suggest that the CO2 resides at the interface of the two components in the ion gel.

Effect of poly(ethylene glycol)-derived crosslinkers on the properties of thermosensitive hydrogels

Three crosslinkers, poly(ethylene glycol) diacrylate (PEGDA), glycerol ethoxylate triacrylate (GETA) and citric acid-(PEG acrylate)3 (CA-PEGTA) derived from poly(ethylene glycol) (PEG) were synthesized at first. The three series of poly (N-isopropylacrylamide) (PNIPAAm) hydrogels were prepared by photopolymerization with the crosslinkers and compared with a hydrogel based on commercial crosslinker, N,N′-methylene bis-acrylamide (NMBA). The influence of the crosslinker structures and contents on the swelling behaviour, mechanical properties, and drug release of the hydrogels was investigated. The results showed that the hydrogels based on PEGDA and NMBA exhibited the highest and the lowest swelling ratio, respectively. The content of crosslinker of all hydrogel series showed good thermosensitivity and thermo-reversibility. The critical gel transition temperature (CGTT) appeared at 32 °C for the hydrogel based on NMBA, but appeared at about 34 °C for other hydrogels due to higher hydrophilicity of the crosslinker. In the mechanical properties, three-arms crosslinker GETA and CA-PEGTA led to higher mechanical strength than a linear crosslinker PEGDA. A hydrogel based on GETA (NG6) showed the highest shear modulus of 656.9 kPa and Young’s modulus of 1655.0 kPa. The hydrogels containing higher content of crosslinker revealed lower swelling ratio and higher mechanical strength. In the drug release, the hydrogels with higher swelling ratios showed higher drug absorbed. The highest release percentage of caffeine and vitamin B12 for hydrogel based on PEGDA (NP6) could reach 68.3% and 75.4%, respectively. In addition, the bound water and toxicity of the hydrogels were also investigated.

Ceramic-Doped in Cross-Linked Solid Polymer Electrolyte for Solid-State Batteries

Replacing liquid electrolytes with solid-state Li-ion conductors is one way to achieve safe rechargeable batteries with high energy density. Semi-interpenetrating polymer network (s-IPN) was synthesized from the mixture of poly(propylene carbonate), poly(ethylene glycol) methyl ether acrylate, poly(ethylene glycol) diacrylate (PEGDA), and lithium bis(trifluoromethane)sulfonamide salt via one-pot thermal curing method. The crosslinker PEGDA content and salt concentration were optimized and the best result was abtained at a molar ratio of EO:Li ∼ 14:1. The electrolyte with higher salt concentration had lower ionic conductivity, consistent with higher glass transition temperature of poly(ethylene glycol) chain. Differential scanning calorimetry has shown a low degree of crystallinity when lithium lanthanum zirconate doped tantalum (LLZTO) was added to the s- IPN electrolyte which corresponds to an increase in ionic conductivity, 4.5 x 10-4 S/cm at 40°C. The resulting composite polymer electrolyte (CPE) showed high electrochemical stability up to 5.5 V. Lithium plating and stripping at 0.1 mA/cm2 at room temperature revealed a stable Li/electrolyte interface and no dendrite formation. Cycling performance of a full solid-state cell made with the CPE using LiFePO4 as the cathode will be discussed. Figure 1

Poly(ethylene glycol) Composite Hydrogels with Natural Zeolite as Filler for Controlled Delivery Applications

In this study, composite hydrogels based on crosslinked polyethylene glycol diacrylate (PEGDA) and natural zeolite, with potential applications for the controlled release of phytoextracts, were synthesized by radical polymerization and characterized herein for the first time. The influence of various synthesis parameters, such as the use of distilled water or rose hip extract as reaction medium, or the percentage of the zeolite in the composite hydrogel upon the morphology, swelling kinetics and the rheological properties was investigated. By conducting polymerization of PEGDA in the rose hip extract, the crosslinking reaction yield was almost 100%, because of the chain transfer reactions of the polyphenols from the rose hip extract. Rose hip release tests were used to evaluate the release profiles of the natural bioactive substances from phytoextracts. The results showed that the hydrogel loaded with 3% zeolite displayed the lowest burst release and the slowest release rates of the extract.

Simultaneous improvement of mechanical properties and electromagnetic interference shielding performance in eco-friendly polylactide composites via reactive blending and MWCNTs induced morphological optimization

Poly (l-lactide) (PLLA) based ternary nanocomposites were fabricated by introducing in situ crosslinked poly(ethylene glycol) diacrylate (CPEGDA) as the rubbery toughening modifier and multiwall carbon nanotubes (MWCNTs) as the conductive fillers. Due to the incorporation of MWCNTs, the domain size of CPEGDA became smaller and MWCNTs were selectively distributed in PLLA continuous phase, facilitating to balance the stiffness and toughness. Rheological investigation showed that the formation of a double network of CPEGDA and MWCNTs resulted in constrained molecular mobility, thus greatly increasing the modulus and viscosity at low frequencies and long-time relaxation strength. The low percolation threshold of MWCNTs in electrical conductivity was found to be 0.19 vol% and the electromagnetic interference shielding effectiveness (EMI SE) of 26.4 dB was achieved with incorporating 2.4 vol% of MWCNTs. This work could provide a novel way to fabricate PLLA based eco-friendly nanocomposites with simultaneous superior mechanical properties and excellent EMI shielding performance.

A photonic pH sensor based on photothermal spectroscopy

Although the determination of pH is a standard laboratory measurement, new techniques capable of measuring pH are being developed to facilitate modern technological advances. Bio-industrial processing, tissue engineering, and intracellular environments impose unique measurement requirements on probes of pH. We describe a fiber optic-based platform, which measures the heat released by chromophores upon absorption of light. The optical fibers feature fiber Bragg gratings (FBG) whose Bragg peak redshifts with increasing temperature. Using anthocyanins (pH-sensitive chromophores found in many plants), we are able to correlate visible light absorption by a solution of anthocyanins to heat released and changes in FBG signal over a pH range of 2.5–10. We tested the ability of this platform to act as a sensor coating the fiber within a layer of crosslinked polyethylene glycol diacrylate (PEG-DA). Incorporating the anthocyanins into the PEG, we find that the signal magnitude increases over the observed signal at the same pH in solution. Our results indicate that this platform is viable for assessing pH in biological samples and point at ways to optimize performance.

Surface grafting of zwitterionic and PEGylated cross-linked polymers toward PVDF membranes with ultralow protein adsorption

It remains a major challenge to prepare membranes with minimal protein adsorption for bio-related applications. In this work, modified polyvinylidene difluoride (PVDF) membranes having ultralow protein adsorption were prepared by grafting zwitterionic and PEGylated cross-linked polymers onto the membrane surface. The PVDF membrane was first treated with alkaline and tethered with cross-linked polyethylene glycol diacrylate (CPEGDA) via ATRP. By reacting the abundant alkene group at the periphery of CPEGDA with cystine or monomethyl PEG thiol (MPEG-SH, Mn = 200, 600, 2000) by thio-ene reaction, the membrane surface was tethered with high density protein repellent groups. The PVDF-g-CLPEG2000 membrane shows the best performance and its bovine serum albumin (BSA) and bovine serum fibrinogen (BFG) adsorptions can be lowered to only 1/50 and 1/40 that of the original PVDF membrane, respectively. Similar fouling tendencies were observed in the dynamic filtration process. This work addresses the significance of cross-linked grafting on altering membrane surface properties.

Direct 3D printing of monolithic ion exchange adsorbers

Monolithic adsorbers with anion exchange (AEX) properties have been 3D printed in an easy one-step process, i.e. not requiring post-functionalization to introduce the AEX ligands. The adsorber, 3D printed using a commercial digital light processing (DLP) printer, was obtained by copolymerisation of a bifunctional monomer bearing a positively charged quaternary amine as well as an acrylate group, with the biocompatible crosslinker polyethylene glycol diacrylate (PEGDA). To increase the surface area, polyethylene glycol was introduced into the material formulation as pore forming agent. The influence of photoinitiator (Omnirad 819) and photoabsorber (Reactive Orange 16, RO16) concentration was investigated in order to optimize printing resolution, allowing to reliably 3D print features as small as 200 μm and of highly complex Schoen Gyroids. Protein binding was measured on AEX adsorbers with a range of ligand densities (0.00, 2.03, 2.60 and 3.18 mmol/mL) using bovine serum albumin (BSA) and c-phycocyanin (CPC) as model proteins. The highest equilibrium binding capacity was found for the material presenting the lowest ligand density analysed (2.03 mmol/mL), adsorbing 73.7 ± 5.9 mg/mL and 38.0 ± 2.2 mg/mL of BSA and CPC, respectively. This novel 3D printed material displayed binding capacities in par or even higher than commercially available chromatographic resins. We expect that the herein presented approach of using bifunctional monomers, bearing commonly used chromatography ligands, will help overcome the material limitations currently refraining 3D printing applications in separation sciences.

Vapor-based synthesis of bilayer anti-corrosion polymer coatings with excellent barrier property and superhydrophobicity

Bilayer polymer coatings that consisted of a highly cross-linked polyethylene glycol diacrylate (PEGDA) bottom layer and nanostructured poly(perfluorodecyl acrylate-co-ethylene glycol diacrylate) (P(PFDA-co-EGDA)) top layer were synthesized via a single-step vapor deposition method. The vapor-synthesized PEGDA single-layer film exhibits excellent barrier performance with oxygen permeability of 0.0066 Barrer, which is more than 16-fold smaller than that of commercial PET packaging film. The P(PFDA-co-EGDA) layer, grown on top of PEGDA, shows conical array structure. Such nanostructure combined with the low surface energy of PFDA moiety enables superhydrophobicity of the coating with water contact angle of 159°. The achieved superhydrophobicity is stable over more than 168 h upon immersion in NaCl solution. The bilayer coating structure imparts a synergistic effect to minimize both the diffusion of water and ions and permeation of oxygen, resulting in a significant drop of corrosion rate to 2.19 × 10−7 mm year−1, a more than 104-fold decrease compared to bare copper.

Poly(propylene carbonate) Interpenetrating Cross-Linked Poly(ethylene glycol) Based Polymer Electrolyte for Solid-State Lithium Batteries

Solid polymer electrolyte based on semi-interpenetrating polymer network (s-IPN) was synthesized from the mixture of poly(propylene carbonate) (PPC), poly(ethylene glycol) methylether acrylate (PEGMEA), poly(ethylene glycol) diacrylate (PEGDA), and lithium bis(trifluoromethane)sulfonimide (LiTFSI) salt via one-pot thermal curing method. The crosslinker PEGDA content and salt concentration were optimized. The ionic conductivity, lithium-ion transference number and electrochemical stability window of the s-IPN electrolyte were correlated with its thermal and physical properties. Differential scanning calorimetry measurements have shown a low degree of crystallinity in this s-IPN electrolyte. The electrolyte with higher salt concentration has lower ionic conductivity, consistent with higher glass transition temperature of poly(ethylene glycol) chain. The ionic conductivity was further enhanced by dispersion of lithium-ion conductive ceramic powder, lithium lanthanum zirconate (LLZO) into the s-IPN matrix. The optimized s-IPN has potential as a baseline material for future solid-state electrolyte designs.

Poly(propylene carbonate) Interpenetrating Cross-Linked Poly(ethylene glycol) Based Polymer Electrolyte for Solid-State Lithium Batteries

Lithium-ion conducting solid polymer electrolytes (SPEs) are promising materials to replace flammable liquid electrolytes to solve the safety and performance issues in conventional rechargeable lithium batteries [1]. Poly(ethylene oxide) (PEO) has been studied extensively as baseline materials for SPEs. It is well known that pure PEO crystallizes at room temperature, hampering lithium ion migration and resulting in low ionic conductivity. This drawback hinders PEO based SPEs applied in real battery configuration that usually requires ionic conductivity greater than 10-4 S cm-1 at 25 ℃. In general, suppression of polymer crystallinity is favorable for SPEs to enhance the ionic conductivity [2]. Here, we synthesized a semi-interpenetrating polymer network (s-IPN) from the mixture of poly(propylene carbonate) (PPC), poly(ethylene glycol) methylether acrylate (PEGMEA), poly(ethylene glycol) diacrylate (PEGDA), and lithium bis(trifluoromethane) sulfonimidate (LiTFSI) salt using one-pot thermal curing method. The amorphous PPC performs as film forming agent, whereas the crosslinked network with PEG pendants provides lithium conducting channel. The s-IPN architecture inhibits the phase segregation of two different polymers. Curing temperature, crosslinker PEGDA content and salt concentration were optimized carefully to attain a flexible film with ionic conductivity reaching 5×10-6 S cm-1 at ambient temperature. The ionic conductivity and working potential window were correlated with the thermal and physical properties of the s-IPN electrolytes. Differential scanning calorimetry measurements have shown a decrease in the crystallinity of the s-IPN electrolytes. The electrolyte with higher salt concentration has lower ionic conductivity, consistent with higher glass transition temperature of PEG chain. The ionic conductivity was further enhanced by incorporating lithium ion conductive ceramic powder, lithium lanthanum zirconate (LLZO) as a filler into the s-IPN matrix, even though LLZO aggregation occurred during film forming. The optimized s-IPN has potential as a baseline material for future solid-state electrolyte designs. Acknowledgements We gratefully acknowledge the financial support from the NASA MIRO Program #NNX15AP44A and the National Science Foundation under Award #162-6449.

Fabrication of drug-loaded hydrogels with stereolithographic 3D printing

3D printing (3DP) technologies have been attracting much recent interest as new methods of fabricating medicines and medical devices. Of the many types of 3DP available, stereolithographic (SLA) printing offers the unique advantage of being able to fabricate objects by cross-linking resins to form networked polymer matrices. Because water can be entrapped in these matrices, it is possible in principle to fabricate pre-wetted, drug-loaded hydrogels and devices. Here, SLA printing was used to prepare ibuprofen-loaded hydrogels of cross-linked polyethylene glycol diacrylate. Hydrogels containing up to 30% w/w water, and 10% w/w ibuprofen, were successfully printed. Dissolution profiles showed that drug release rates were dependent on water content, with higher water content hydrogels releasing drug faster. The conclusion is that SLA 3DP offers a new manufacturing route to pharmaceutical hydrogels.

Crosslinked PEG and PEBAX Membranes for Concurrent Permeation of Water and Carbon Dioxide.

Membrane technology can be used for both post combustion carbon dioxide capture and acidic gas sweetening and dehydration of natural gas. These processes are especially suited for polymeric membranes with polyether functionality, because of the high affinity of this species for both H2O and CO2. Here, both crosslinked polyethylene glycol diacrylate and a polyether-polyamide block copolymer (PEBAX 2533©) are studied for their ability to separate CO2 from CH4 and N2 under single and mixed gas conditions, for both dry and wet feeds, as well as when 500 ppm H2S is present. The solubility of gases within these polymers is shown to be better correlated with the Lennard Jones well depth than with critical temperature. Under dry mixed gas conditions, CO2 permeability is reduced compared to the single gas measurement because of competitive sorption from CH4 or N2. However, selectivity for CO2 is retained in both polymers. The presence of water in the feed is observed to swell the PEG membrane resulting in a significant increase in CO2 permeability relative to the dry gas scenario. Importantly, the selectivity is again retained under wet feed gas conditions. The presence of H2S is observed to only slightly reduce CO2 permeability through both membranes.