Synthesis of PEG‐functionalized poly(diphenylacetylene)s and their gas permeation properties

The polymerizations of 1‐(3‐methylphenyl)‐2‐(4‐trimethylsilyl)phenylacetylene ( 1a ) and 1‐(4‐methylphenyl)‐2‐(4‐trimethylsilyl)phenylacetylene ( 1b ) were carried out with TaCl₅‐n‐Bu₄Sn to give relatively high‐molecular‐weight polymers ( 2a and 2b ) (M_n > 5 × 10⁵). The obtained polymers were brominated by using benzoyl peroxide and N‐bromosuccinimide first, followed by substitution reaction of three types of polyethylene glycol. When diethylene glycol was used as a reagent on substitution reaction of meta‐substituted polymer, PEG‐functionalized poly(diphenylacetylene) with the highest content of oxyethylene unit [ 4a(2) ] was obtained, and the degree of substitution was 0.60. The degrees of substitution decreased to 0.15 and 0.08 when the polyethylene glycols with higher molecular weights were used. PEG‐substitution reaction to the para‐substituted polymers was difficult to proceed, and hence the degree of substitution was 0.18 even when diethylene glycol was used. The CO₂/N₂ separation factor of PEG‐functionalized polymer [ 4a(2) ] was as large as 28.8, although that of 2a was 7.41. The other PEG‐functionalized polymers also exhibited high CO₂ permselectivity, and their CO₂/N₂ separation factors were over 20. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Density measurement of polymer/CO2 single‐phase solution at high temperature and pressure using a gravimetric method

The densities of two polymer/CO₂ single‐phase solutions, poly(ethylene glycol) (PEG)/CO₂ and polyethylene (PE)/CO₂, were measured at temperatures higher than melting temperature of the polymer under CO₂ pressures in the range 0–15 MPa using a newly‐proposed gravimetric method. A magnetic suspension balance (MSB) was used for the density measurement under the high pressure CO₂: A thin disc‐shaped platinum plate was submerged in the considered polymer/CO₂ single‐phase solution in the MSB high‐pressure cell. The weight of the plate was measured while keeping CO₂ pressure and temperature in the sorption cell at a specified level. Since the buoyancy force exerted on the plate by the polymer/CO₂ solution reduced the apparent weight of the plate, the density of the polymer/CO₂ solution could be calculated by subtracting the true weight of the plate from its measured weight. Experimental results showed that the density of PE/CO₂ solution increased with the increase of CO₂ pressure and the density of PEG/CO₂ solution decreased with the increase of CO₂ pressure. To differentiate the effect of CO₂ dissolution in polymer from that of mechanical pressure, the density of polymer/CO₂ solution was compared with the density of neat polymer under the given mechanical pressure, which was calculated using the Sanchez–Lacombe equation of state and Pressure–Volume–Temperature data of the polymer. The comparison could elucidate that the dissolution of CO₂ in polymer reduced density of both PEG/CO₂ and PE/CO₂ systems but the degree of CO₂ induced‐density reduction was different between two polymer/CO₂ systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Particle size and distribution of biodegradable poly‐D,L‐lactide‐co‐poly(ethylene glycol) block polymer nanoparticles prepared by nanoprecipitation

A biodegradable block copolymer, poly‐D ,L ‐lactide (PLA)‐co‐poly(ethylene glycol) (PEG), was prepared by the ring‐opening polymerization of lactide with stannous caprylate [Sn(Oct₂)] as a catalyst; then, the PLA–PEG copolymer was made into nanoparticles by nanoprecipitation under different conditions. The average molecular weight and structure of PLA–PEG were detected by ¹H‐NMR and gel permeation chromatography. The sizes and distributions of the nanoparticles were investigated with a laser particle‐size analyzer. The morphologies of the nanoparticles were examined by transmission electron microscopy. The effects of the solvent–nonsolvent system, operation conditions, and dosage of span‐80 on the sizes and distributions of the nanoparticles are discussed. The results show that acetone–water was a suitable solvent–nonsolvent system and the volume ratio of the nonsolvent phase to the solvent phase (O/W) (v/v), the concentration of PLA–PEG in the solvent phase, and the dosage of span‐80 had important effects on the particle sizes and distributions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1884–1890, 2005     

Formation of deagglomerated PLGA particles and PLGA-coated ultra fine powders by rapid expansion of supercritical solution with ethanol cosolvent

Rapid expansion of supercritical solution (RESS) was used for preparing polymer particles and polymer coating of ultra fine powders. The polymer of pharmaceutical interest was Poly(lactic-co-glycolic acid) (PLGA with PLA: PGA ratio of 85: 15 and MW of 50,000–75,000) and the simulated core particles were 1.4-μm SiO₂ and 70-nm TiO₂ particles. The supercritical solution was prepared by dissolving PLGA in supercritical carbon dioxide with ethanol as a cosolvent. Supercritical solution of CO₂-PLGA was sprayed through capillary nozzles to ambient conditions, resulting in formation of submicron PLGA particles. Similarly, rapid expansion of supercritical solution of CO₂-PLGA suspended with the core particles could provide solvent evaporation and deposition of submicron PLGA particles on the surface of the core particles, resulting in the formation of coating films on dispersed particles of SiO₂ and agglomerates of TiO₂. The influences of the core particle size, spray nozzle diameter as well as powder-to-polymer weight ratio were also investigated and discussed with respect to the coating performance.     

High-pressure CO2-enhanced polymer interdiffusion and dissolution studied with in situ ATR-FTIR spectroscopic imaging

A novel application of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic imaging to study polymer interdiffusion and dissolution under high-pressure or supercritical carbon dioxide environments has been demonstrated. Miscible systems of polyvinylpyrrolidone (PVP) and poly(ethylene glycol) (PEG) of different molecular weights have been chosen for this investigation. These systems were subjected to a controlled pressure of CO₂ and the interfacial area of contact between the two polymers was studied by ATR-FTIR imaging in situ. Using this spectroscopic imaging approach, the phenomenon of polymer interdiffusion enhanced by CO₂ dissolved in both polymers was investigated as a function of time. The evolution of spatially resolved images as a function of time was studied with FTIR imaging and the corresponding concentration profiles for both polymers were obtained. The chemical specificity of FTIR imaging also allowed us to measure the amount of CO₂ dissolved in each domain of the polymer system. Effects of PEG molecular weight and pressure of CO₂ on the mechanism and the rate of polymer interdiffusion was investigated. This approach has not only shown the ability to visualise the process of interdiffusion but also demonstrated the ability of high-pressure CO₂ to ‘tune’ the rate of interdiffusion, this information is important for a better understanding of CO₂-induced mixing of polymeric materials.     

Effect of molecular weight on spherulitic growth rate of poly(ϵ‐caprolactone) and poly(ϵ‐caprolactone)‐b‐poly(ethylene glycol)

The spherulitic growth rates of a series poly (?‐caprolactone) homopolymers and poly(?‐caprolactone)‐b‐ poly(ethylene glycol) (PCL‐b‐PEG) block copolymers with different molecular weights but narrow polydispersity were studied. The results show that for both PCL homopolymers and PCL‐b‐PEG block copolymers, the spherulitic growth rate first increases with molecular weight and reaches a maximum, then decreases as molecular weight increases. Crystallization temperature has greater influence on the spherulitic growth rate of polymers with higher molecular weight. Hoffman–Lauritzen theory was used to analyze spherulitic growth kinetics and the free energy of the folding surface (σ_e) was derived. It is found that the values of σ_e decrease with molecular weight at low molecular weight level and become constant for high molecular weight polymers. The chemically linked PEG block does not change the values of σ_e significantly. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Fluid phase behavior modeling of CO2 + molten polymer systems using cubic and theoretically based equations of state

Phase equilibrium data of CO₂ + molten polymer systems are of great relevance for chemical engineers because these are necessary for the optimal design of polymer final‐treatment processes. This kind of processes needs information about gas solubilities in polymers at several temperatures and pressures. In this work, CO₂ solubilities in molten polymers were modeled by the perturbed chain‐statistical associating fluid theory (PC‐SAFT) equation of state (EoS). For comparison, the solubilities were also calculated by the lattice gas theory (LGT) EoS, and by the well‐known Peng‐Robinson (PR) cubic EoS. To adjust the interactions between segments of mixtures, there were used classical mixing rules, with one adjustable temperature‐dependent binary parameter for the PC‐SAFT and PR EoS, and two adjustable binary parameters for the LGT EoS. The results were compared with experimental data obtained from literature. The results in terms of solubility pressure deviations indicate that the vapor–liquid behavior for CO₂ + polymer systems is better predicted by the PC‐SAFT model than by LGT and PR models. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.     

Effects of polymers as direct CO2 thickeners on the mutual interactions between a light crude oil and CO2

In this paper, two commercial polymers with relatively low molecular weights, poly vinyl ethyl ether (PVEE) and poly 1-decene (P-1-D), are tested as direct thickeners for CO₂ and their detailed effects on the mutual interactions between a light crude oil and polymer-thickened CO₂ are experimentally studied under different reservoir pressures. More specifically, the polymer cloud-point pressures are measured at different known polymer solubilities in supercritical CO₂. The equilibrium interfacial tensions (IFTs) and onset pressures of quick polymer dissolution into CO₂ are measured for the polymer?pure CO₂ systems. The polymer-swelling effect due to pure CO₂ dissolution is observed and examined. To study the mutual interactions between the light crude oil and polymer-thickened CO₂, their equilibrium IFTs are measured and their so-called minimum miscibility pressures (MMPs) and onset pressures of the initial quick light-hydrocarbons extraction by CO₂ are determined. The oil-swelling effect due to polymer-thickened CO₂ dissolution is also visualized and analyzed. All the experimental data for polymer-thickened CO₂ are compared with those for pure CO₂.     

Effects of THF as cosolvent in the preparation of polydimethylsiloxane/polyethersulfone membrane for gas separation

Polydimethylsiloxane/polyethersulfone (PDMS/PES) asymmetric membranes are widely applied in gas separation. However, the effects of common cosolvent on these membranes remain unknown. In order to study the changes in membrane morphology and gas separation properties, asymmetric PDMS/PES membranes were prepared. The studied parameters were types of cosolvents, tetrahydrofuran (THF) concentration, evaporation time, and PDMS concentration. Membrane morphology was examined using scanning electron microscopy and gas separation was conducted using pure CO₂, N₂, CH₄, and Hat 25°C. The addition of cosolvent into the polymer solution decreased the dope viscosity and delayed liquid–liquid demixing during phase inversion. Macrovoids formation was observed in substructure layer after adding THF and these macrovoids elongated with the reduction in THF content. There were microvoids formed on top of macrovoids and microvoids layer became thicker due to the increasing evaporation time of solvents before coagulation in nonsolvent. The PDMS coating on the PES membrane formed a dense skin layer and exhibited higher selectivity compared to the uncoated membrane. Membrane contained THF cosolvent with 60 s evaporation time and 3 wt% coated PDMS is the optimum membrane among other membranes in this work. The CO₂/N₂ selectivity was enhanced by 73.3% with CO₂ permeance of 44.86 GPU. POLYM. ENG. SCI., 54:2177–2186, 2014. © 2013 Society of Plastics Engineers     

Competitive hydrogen bonding mechanisms underlying phase behavior of triple poly(N‐vinyl pyrrolidone)–poly(ethylene glycol)–poly(methacrylic acid‐co‐ethylacrylate) blends

Differential scanning calorimetry (DSC) of triple blends of high molecular weight poly(N‐vinyl pyrrolidone) (PVP) with oligomeric poly(ethylene glycol) (PEG) of molecular weight 400 g/mol and copolymer of methacrylic acid with ethylacrylate (PMAA‐co‐EA) demonstrates partial miscibility of polymer components, which is due to formation of interpolymer hydrogen bonds (reversible crosslinking). Because both PVP and PMAA‐co‐EA are amorphous polymers and PEG exhibits crystalline phase, the DSC examination is informative on the phase state of PEG in the triple blends and reveals a strong competition between PEG and PMAA‐co‐EA for interaction with PVP. The hydrogen bonding in the triple PVP–PEG–PMAA‐co‐EA blends has been established with FTIR Spectroscopy. To evaluate the relative strengths of hydrogen bonded complexes in PVP–PEG–PMAA‐co‐EA blends, quantum‐chemical calculations were performed. According to this analysis, the energy of H‐bonding has been found to diminish in the order: PVP–PMAA‐co‐EA–PEG(OH) > PVP–(OH)PEG(OH)–PVP > PVP–H₂O > PVP–PEG(OH) > PMAA‐co‐EA–PEG(? O? ) > PVP–PMAA‐co‐EA > PMAA‐co‐EA–PEG(OH). Thus, most stable complexes are the triple PVP–PMAA‐co‐EA–PEG(OH) complex and the complex wherein comparatively short PEG chains form simultaneously two hydrogen bonds to PVP carbonyl groups through both terminal OH‐groups, acting as H‐bonding crosslinks between longer PVP backbones. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

CO2 foaming of poly(ethylene glycol)/polystyrene blends: Relationship of the blend morphology,CO2 mass transfer,and cellular structure

When polymer blends are foamed by physical foaming agents, such as CO₂ or N₂, not only the morphology and viscosity of the blend polymers but also the solubility and diffusivity of the physical foaming agents in the polymers determine the cellular structure: closed cell or open cell and monomodal or bimodal. The foam of poly(ethylene glycol) (PEG)/polystyrene (PS) blends shows a unique bimodal (large and small) cellular structure, in which the large‐size cells embrace a PEG particle. Depending on the foaming condition, the average size of the large cells ranges from 40 to 500 μm, whereas that of small cells becomes less than 20 μm, which is smaller than that of neat PS foams. The formation mechanism of the cellular structure has been investigated from the viewpoint of the morphology and viscosity of the blend polymer and the mass‐transfer rate of the physical foaming agent in each polymer phase. The solubility and diffusivity of CO₂, which determine the mass‐transfer rate of CO₂ from the matrix to the bubbles, were measured by a gravimetric measurement, that is, a magnetic suspension balance. The solubility and diffusivity of CO₂ in PS differed from those in PEG: the diffusion coefficient of CO₂ in PEG at 110°C was 3.36 × 10^?9 m²/s, and that in PS was 2.38 × 10^?10 m²/s. Henry's constant in PEG was 5600 cm³ (STP)/(kg MPa) at 110°C, and that in PS was 3100 cm³ (STP)/(kg MPa). These differences in the transport properties, morphology of the blend, and CO₂‐induced viscosity depression are the control factors for creating the unique cellular structure in PEG/PS blends. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1899–1906, 2005     

Cationic polyelectrolytes,XII. PEG-precursor for water-soluble cationic polymers with tertiary n-atoms in the main chain

Water-soluble cationic polymers were obtained by polyaddition of poly(ethylene glycol) (PEG) diglycidylethers (M?_n of PEG were 396, 587, 1437 and 3554, resp.) with asymmetrical diamines such as N,N-dimethyl-1,3-diaminopropane and N,N-diethyl-1,3-diaminopropane. The cationic polymer properties depend on the PEG initial molecular weight and on the diamine reactivity too. PEG with M?_n = 396 had the best behaviour in these reactions. The polyelectrolyte feature of cationic polymers was emphasized both in dilute aqueous solutions and in 2M aqueous NaCl solutions. The polyelectrolyte behaviour in 2M aqueous NaCl solution is determined by the PEG chain presence.     

Batch production of micron size particles from poly(ethylene glycol) using supercritical CO2 as a processing solvent

The major advantage of using supercritical carbon dioxide (CO₂) as a solvent in polymer processing is an enhancement in the free volume of a polymer due to dissolved CO₂, which causes a considerable reduction in the viscosity. This allows spraying the polymer melt at low temperatures to produce micron size particles. We have used supercritical CO₂ as a solvent for the generation of particles from poly(ethylene glycol) (PEG) of different molecular weights. Since PEG is a hydrophilic compound, it is a most commonly used polymer for encapsulating a drug. PEG particles with different properties may allow keeping a good control over the release of the drug. It has been possible to produce particles with different size, size distribution, porosity and shape by varying various process parameters such as molecular weight, temperature, pressure and nozzle diameter. A flow and a solidification model have been applied in order to have a theoretical insight into the role of different parameters.     

Synthesis of star polymer poly(ethylene glycol)3–poly(N,N‐dimethyl acrylamide) and its application in protein resistance and separation

A star polymer composed of three poly(ethylene glycol) (PEG) arms and one poly(N,N‐dimethyl acrylamide) (PDMA) arm (PEG₃–PDMA) was synthesized by amidation and atom‐transfer radical polymerization. The structure of PEG₃–PDMA was confirmed by ¹H‐NMR and gel permeation chromatography results. The surface adsorption and protein‐resistance behaviors of the star polymer PEG₃–PDMA, diblock copolymer PEG–PDMA, and homopolymer PEG were investigated by a quartz crystal microbalance with dissipation. The results indicate that the PEG₃–PDMA coating could reduce protein adsorption to 13% at least, more effectively than the PEG–PDMA coating; this indicated that the protein‐resistance properties depended on the PEG chain density and surface coverage. If PEG₃–PDMA were to be used as the physical coating in capillary zone electrophoresis, it could yield a well‐suppressed eletroosmotic flow with greater stability and separate proteins with a lower relative standard deviration (RSD) of protein migration time and a higher separation efficiency than a bare fused‐silica capillary in a broad pH range. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of different experimental conditions on biodegradable polylactide membranes prepared with supercritical CO2 as nonsolvent

There is increasing interest in the application of supercritical CO₂ (SCCO₂) in the preparation of polymer membranes. Membrane formation with SCCO₂ as a nonsolvent is analogous to the conventional immersion precipitation process using an organic nonsolvent. Polylactide membranes were prepared with SCCO₂ as the nonsolvent under different experimental conditions such as different polymer concentrations, different depressurization rates, and different nonsolvent compositions. The effects of these conditions on the cross‐sectional structure were investigated through scanning electron microscopy. In addition, solvent‐induced crystallization and CO₂‐induced crystallization were studied. The crystallinity of PLA membranes prepared with different solvents or at different pressures was characterized by wide‐angle X‐ray diffraction and differential scanning calorimetry. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 831–837, 2005     

Carbon Membranes Prepared from a Polymer Blend of Polyethylene Glycol and Polyetherimide

Through a dip‐coating technique, carbon membranes were produced from a polymer blend consisting of the thermally stable polymer polyetherimide (PEI) and the thermally labile polymer polyethylene glycol (PEG). The PEG/PEI carbon membranes were synthesized on an alumina support coated with an Al₂O₃ intermediate layer. The polymer blend ratio and carbonization temperature influenced the structure and permeation performance of the derived carbon membranes. The porosity of the PEG/PEI carbon membranes increased with higher PEG content in the blends. However, the derived carbon membranes tended to lose gas permeability with raising the carbonization temperatures. The carbon membranes were successfully optimized in order to achieve the highest CO₂/CH₄ and CO₂/N₂ selectivities.     

Hydrolytic degradation and crystallization behavior of linear 2‐armed and star‐shaped 4‐armed poly(l‐lactide)s: Effects of branching architecture and crystallinity

“Linear” aliphatic polyesters composed of two poly(l ‐lactide) arms attached to 1,3‐propanediol and “star‐shaped” ones composed of four poly(l ‐lactide) arms attached to pentaerythritol (2‐L and 4‐L polymers, respectively) with number‐average molecular weight (M_n) = 1.4–8.4 × 10⁴g/mol were hydrolytically degraded at 37°C and pH = 7.4. The effects of the branching architecture and crystallinity on the hydrolytic degradation and crystalline morphology change were investigated. The degradation mechanism of initially amorphous and crystallized 2‐L polymers changed from bulk degradation to surface degradation with decreasing initial M_n; in contrast, initially crystallized higher molecular weight 4‐L polymer degraded via bulk degradation, while the degradation mechanism of other 4‐L polymers could not be determined. The hydrolytic‐degradation rates monitored by molecular‐weight decreases decreased significantly with increasing branch architecture and/or higher number of hydroxyl groups per unit mass. The hydrolytic degradation rate determined from the molecular weight decrease was higher for initially crystallized samples than for initially amorphous samples; however, that of 2‐L polymers monitored by weight loss was larger for initially amorphous samples than for initially crystallized samples. Initially amorphous 2‐L polymers with an M_n below 3.5 × 10⁴g/mol crystallized during hydrolytic degradation. In contrast, the branching architecture disturbed crystallization of initially amorphous 4‐L polymers during hydrolytic degradation. All initially crystallized 2‐L and 4‐L polymers had δ‐form crystallites before hydrolytic degradation, which did not change during hydrolytic degradation. During hydrolytic degradation, the glass transition temperatures of initially amorphous and crystallized 2‐L and 4‐L polymers and the cold crystallization temperatures of initially amorphous 2‐L and 4‐L polymers showed similar changes to those reported for 1‐armed poly(l ‐lactide). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41983.     

Copolyester of trimellitic acid,glycerol, and poly(ethylene glycol): Synthesis and characterization

A series of copolyesters having a broad range of biodegradable crosslinks were synthesised by FeCl₃‐catalyzed polyesterification of trimellitic acid and glycerol containing a small mol percent of poly(ethylene glycol) (PEG) of varied molecular weights. The polymer samples designated as I (1.5% PEG 2000), II (4.5% PEG 2000), III (7.5% PEG 2000), IV (1.5% PEG 4000), V (4.5% PEG 4000), VI (7.5% PEG 4000), VII (1.5% PEG 6000), VIII (4.5% PEG 6000), and IX (without PEG) are insoluble and moderately tough‐to‐elastic solids and were characterized by their swelling values in ethanol, glass transition temperatures (T_g), IR spectra, and X‐ray diffractograms. Sample IX (0% PEG) has the lowest equilibrium swelling (12% at 25°C) and the highest T_g (155°C) and, therefore, the highest crosslink density. The swelling increases and the T_g decreases as the PEG content or PEG molecular weight in a glycerol–PEG combination increases, indicating a corresponding decrease in the crosslink density of the polymers. Further, the equilibrium swelling value increases with increasing temperature. The IR spectra of the polymers indicate the formation of ester bonds at the expense of COOH and OH groups. The X‐ray diffractograms show their semicrystalline nature. The percent crystallinity values of 53, 52, 49, and 46 for II, III, V, and VII, respectively, and 54 for IX showed that the percent crystallinity decreases with an increasing PEG content and molecular weight in the same way as do the T_g values. Thus, higher T_g values are associated with a higher percent crystallinity, that is, with structures of higher order. The synthesized polymer samples with varied crosslink (biodegradable) densities are expected to be very suitable as matrices for controlled drug delivery over a varied period of time. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 343–346, 2004     

Enhanced CO2 separation performance by PVA/PEG/silica mixed matrix membrane

This article focused on segregation of low concentration CO₂ from CO₂/N₂ mixture gas by implementing high‐performance facilitated transport mixed matrix membranes (MMMs) in large‐scale carbon capture techniques. These advanced, novel CO₂‐selective membrane materials were developed by embedding silica nanoparticles at different loading into the poly(vinyl alcohol) (PVA)/poly(ethylene glycol) (PEG) matrix using solution casting. In situ sol–gel technique was applied for the synthesis of the hydrophilic SiO₂ nanoparticles. The compatibility of filler‐polymer matrix plays a crucial role in the optimization of the membrane performance. The dispersion and interaction of the filler into the polymer matrix were confirmed by thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, X‐ray diffraction, field emission scanning electron microscopy, contact angle tests, and swelling ratio analysis. Field emission scanning electron microscopy analysis of the synthesized MMMs established the homogeneous dispersion of the fillers in the polymer matrix. Owing to its good compatibility with PVA/PEG matrix, the inclusion of fillers significantly increased the overall separation efficiency of CO₂ within the membrane. Compared to pristine PVA/PEG membrane, PVA/PEG/silica membrane with 3.34 wt % silica loading showed pronounced improvement in its gas separation properties with 78% augmentation in CO₂ permeability and 45% enhancement in CO₂/N₂ selectivity for fixed conditions pertaining to sweep side water flow rate of 0.04 mL/min and 100 °C temperature. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46481.     

Synthesis and characterization of amine‐functionalized amphiphilic block copolymers based on poly(ethylene glycol) and poly(caprolactone)

A series of amine‐functionalized block copolymers, poly(caprolactone)‐block‐poly(ethylene glycol) (PCL‐b‐PEG), were synthesized by ring‐opening bulk polymerization (ROP) of ε‐caprolactone (ε‐CL) initiated through the hydroxyl end of the amino poly(ethylene glycol) (PEG) used as a macroinitiator in the presence of stannous 2‐ethylhexonoate [Sn(Oct)₂]. The polymerization and end functionality of the polymer were studied by different physicochemical techniques (¹H NMR, Fourier transform infrared and X‐ray photoelectron spectroscopy, gel permeation chromatography and thermogravimetric analysis). Thermal, crystalline and mechanical properties of the polymer were thoroughly analyzed using differential scanning calorimetry, wide‐angle X‐ray diffractometry and tensile testing, respectively. The results showed a linear improvement in crystallinity and mechanical properties of the polymer with the content of PEG. Thus the synthesized functional polymers can be used as excellent biomaterials for the delivery of polyanions, as well as macroinitiators for the synthesis of A–B–C‐type block copolymers. Copyright © 2006 Society of Chemical Industry