Swellable Poly Research Articles

Pathway modulation and substrate partitioning for CO2-assisted hydration of ethylene oxide catalyzed by swelling poly(ionic liquid)s

Amine-functionalized swellable poly(ionic liquid)s (poly[BAVIm]Br-DVIm-n%) were synthesized by free radical copolymerization of amine-functional vinyl imidazolium ionic liquids and ionic cross-linker 1,8-triethylene glycoldiyl-3,3́-divinylimidazolium (DVIm). Poly[BAVIm]Br-DVIm-n% exhibited excellent swelling ability in the water, ethylene carbonate (EC), and ethylene glycol (MEG), and the swelling ratio (Q) decreased with the increase of the content of the crosslinker. The swollen state of poly[BAVIm]Br-DVIm-2.5% in water observed by cryogenic scanning electron microscopy (cryo-SEM) presented densely packed and interconnected pores (0.2–11 μm). Poly[BAVIm]Br-DVIm-n% were used to catalyze CO2-assisted hydration of ethylene oxide (EO) at a low H2O/EO ratio of 1:1, in which poly[BAVIm]Br-DVIm-2.5% with the highest Q in water gave the highest yield (87%) and selectivity (97%) of MEG. Moreover, EC was produced and subsequently disappeared during the process of CO2-assisted hydration of EO. A cascade reaction including the cycloaddition of CO2 with EO (EO + CO2 → EC) and the hydrolysis of the resulting EC (EC + H2O → MEG + CO2) in situ was elaborated. Poly[BAVIm]Br-DVIm-n% containing amine group and imidazolium ionic liquid synergistically catalyzed this cascade reaction, exhibiting a bifunctional effect. Poly[BAVIm]Br-DVIm-2.5% with the H2O, EC, and MEG enrichment ability in H2O/EO, EC/EO, and MEG/EO could spatially isolate EO and H2O, EC, MEG. The substrate partitioning of poly[BAVIm]Br-DVIm-2.5% could promote the two sequential reactions to be orthogonal and inhibit the side-reactions between MEG and EO, thus resulting in a higher reaction rate of poly[BAVIm]Br-DVIm-2.5% (0.0141 h−1) than that of homogeneous catalyst ([BAVIm]Br) (0.0074 h−1). Furthermore, poly[BAVIm]Br-DVIm-n% had good generality and could be reused effectively at least seven times without a significant decrease of its initial activity.

Enhancing the porous structure of swellable poly(acrylic acid-co-acrylamide) crosslinked by N-Maleyl chitosan via introducing foaming agents and non-ionic surfactant

A fast-swelling porous poly (acrylic acid co-acrylamide) crosslinked by N-Maleyl chitosan superabsorbent hydrogels were prepared by free radical graft copolymerization reaction for partially neutralized acrylic acid (AA), acrylamide (Am) using ammonium persulphate (APS) as an initiator, and N-Maleyl chitosan (N-MACH) as crosslinker. The structure of the synthesized hydrogels were investigated by FTIR spectroscopy and scanning electron microscope (SEM). Acetone and sodium bicarbonate were used as porosity generator (porogens) during the polymerization process. Surfactant (span 80) was used as a micelle template and foam stabilizer. The swelling studies showed improvement of hydrogel behavior with increasing of crosslinker concentration. Otherwise, the porous structure and swelling rate of the hydrogels improved by the incorporation of acetone and NaHCO 3 . While the incorporation of span 80 in the gelling process can enhance the porosity structure. Morphological studies showed that the porosity generators and surfactant created highly porous structures. The density of all the highly porous superabsorbents hydrogels (HPSH) synthesized was ranged from 0.6 to 1.04 g/cm 3 . These HPSHs exhibited a higher rate of swelling at time range from 28 to 269 min.

Sustained Release of Vascular Endothelial Growth Factor from Poly(ε-caprolactone-PEG-ε-caprolactone)-b-Poly(l-lactide) Multiblock Copolymer Microspheres.

Vascular endothelial growth factor (VEGF) is the major regulating factor for the formation of new blood vessels, also known as angiogenesis. VEGF is often incorporated in synthetic scaffolds to promote vascularization and to enhance the survival of cells that have been seeded in these devices. Such applications require sustained local delivery of VEGF of around 4 weeks for stable blood vessel formation. Most delivery systems for VEGF only provide short-term release for a couple of days, followed by a release phase with very low VEGF release. We now have developed VEGF-loaded polymeric microspheres that provide sustained release of bioactive VEGF for 4 weeks. Blends of two swellable poly(ε-caprolactone)–poly(ethylene glycol)–poly(ε-caprolactone)-b-poly(l-lactide) ([PCL–PEG–PCL]-b-[PLLA])-based multiblock copolymers with different PEG content and PEG molecular weight were used to prepare the microspheres. Loading of the microspheres was established by a solvent evaporation-based membrane emulsification method. The resulting VEGF-loaded microspheres had average sizes of 40–50 μm and a narrow size distribution. Optimized formulations of a 50:50 blend of the two multiblock copolymers had an average VEGF loading of 0.79 ± 0.09%, representing a high average VEGF loading efficiency of 78 ± 16%. These microspheres released VEGF continuously over 4 weeks in phosphate-buffered saline pH 7.4 at 37 °C. This release profile was preserved after repeated and long-term storage at −20 °C for up to 9 months, thereby demonstrating excellent storage stability. VEGF release was governed by diffusion through the water-filled polymer matrix, depending on PEG molecular weight and PEG content of the polymers. The bioactivity of the released VEGF was retained within the experimental error in the 4-week release window, as demonstrated using a human umbilical vein endothelial cells proliferation assay. Thus, the microspheres prepared in this study are suitable for embedment in polymeric scaffolds with the aim of promoting their functional vascularization.

Periodic buckling of soft 3D printed bioinspired tubes

Buckled surfaces induced by mismatched swelling and elastic properties of materials are commonly observed in nature, such as on cacti and euphorbias. The rational design and mimicry of such buckling surfaces could lead to the development of smart, adaptive, and stimuli responsive devices. We designed a 3D printed tubular structure, composed of soft swellable poly N-isopropylacrylamide (pNIPAM) segments and stiff non-swellable polyacrylamide (pAAM) segments. Similar to the shape change of Saguaro stems after rainfall, the tubes show tunable periodic buckling modes in water at the room temperature. The buckling behavior was harnessed through the development of compressive stresses in the soft swellable segments induced by the constraint of the stiff non-swellable segments. We developed a finite element model to explore the design space of this periodic buckling behavior for the tube, and used a chemo-mechanically coupled constitutive model to describe the swellable hydrogel. Inspired by the classic bar buckling problem, we constructed a phase diagram and discovered a universal design parameter that combines the effects of geometric and material properties to guide the design of periodic buckling tubes for bioinspired functional gel structures.

PEG-imbedded PEO membrane developed by a novel highly efficient strategy toward superior gas transport performance.

Low-molecular-weight poly(ethylene glycol) (PEG) is deliberately incorporated into synthesized swellable poly(ethylene oxide) (PEO) membranes via a facile post-treatment strategy. The membranes exhibit both larger fractional free volume (FFV) and a higher content of CO2-philic building units, resulting in significant increments in both CO2 permeability and CO2/H2 selectivity. The separation performance correlates nicely with the microstructure of the membranes. This study may provide useful insights in the formation and mass transport behavior of highly efficient polymeric membranes applicable to clean energy purification and CO2 capture, and possibly bridge the material-induced technology gap between academia and industry.

Thermal Properties and Crystallinity of Grafted Copolymer Networks containing a Crystallizable Poly(ε-caprolactone) Crosslinker in an aqueous environment

ABSTRACTHere we introduce a multifunctional copolymer network system with adjustable thermomechanical properties, which is also capable to show a substantial water uptake and in this way should allow the additional alteration of the overall elastic properties besides the variation of the crosslinking density. The swelling capacity in water, the thermal properties as well as the crystallinity of a series of grafted copolymer networks named CLEG composed of water swellable poly(ethylene glycol) (PEG) side chains and crystallizable poly(ε-caprolactone) (PCL) segments acting as covalent crosslinker were explored in an aqueous environment.The water swelling capability of the CLEG polymer networks was found to increase from 120% to 240% with increasing weight content of PEG. In contrast to the dry state, where two well separated melting temperatures could be observed for all CLEG samples, in aqueous environment only one melting temperature slightly above 40 °C, was obtained, whereby the overall crystallinity after swelling with water was strongly related to the PCL content in the CLEG polymer networks.

Investigation of swellable poly (N-isopropylacrylamide) based hydrogels for drug delivery

The thermo-sensitive properties of poly (N-isopropylacrylamide) (PNIPA) hydrogels are modified by the addition of hydrophilic acrylamide comonomers and an interpenetrating network of sodium alginate for drug delivery applications near 37 °C. A mathematical model is presented to describe the mass transport kinetics during the hydrogel drug delivery process, which is accompanied by a volume change during phase transition. In this model, the transport in the polymer matrix is described by Fick's second law in cylindrical coordinates, with concentration dependent diffusion coefficients. The moving boundary problems caused by the polymer matrix swelling are also solved by numerical simulation. The models show that the Trypan blue release from the modified PNIPA-based hydrogels is strongly concentration dependent. The sodium alginate component is also shown to effectively facilitate the diffusion process. The results from the simulation are in good agreement with the measurements of diffusion and swelling observed from in vitro experiments. The implications of this work are also discussed for practical drug delivery systems.

An in vitro release study of 5-fluoro-uracil (5-FU) from swellable poly-(2-hydroxyethyl methacrylate) (PHEMA) nanoparticles

Nanomaterials are at the leading edge of the rapidly developing field of nanotechnology. The use of nanoparticles as drug delivery vehicles for anticancer therapeutics has great potential to revolutionize the future of cancer therapy. The present paper concerns both the optimizations of anticancer drug loading and its release from polymeric nanoparticles. The major aim of this study was to design poly (HEMA) nanoparticles as swelling controlled drug release system for anticancer drug. The prepared nanoparticles were characterized by Infra-Red (IR) Spectra, Particle size Analysis, and Scanning Electron Microscopy (SEM). The nanoparticles were loaded with widely used anticancer drug, 5-Fluorouracil, and controlled release of drug was investigated to observe the effects of various parameters such as percent loading of the drug, chemical architecture of the nanocarriers, pH, temperature, and nature of release media on the release profiles. The chemical stability of 5-Fluorouracil (5-FU) was also tested in phosphate buffer saline (PBS) (pH = 7.4) and release was studied in various simulated biological fluids. The prepared nanoparticles could provide a possible pathway for controlled and targeted delivery of anticancer drug, thus causing lower side effects and higher efficacy.

Ring‐opening polymerization of epoxy end‐terminated poly(ethylene oxide) as a route to highly crosslinked materials with exceptional swelling behavior (II)

AbstractHighly swellable poly(ethylene oxide) (PEO) gels were prepared by anionic ring‐opening polymerization of diepoxy end‐capped PEO (3400 g mol−1) and PEO (8000 g mol−1) using dianionic glycerol and glycolic acid initiators at scales of up to 50 g diepoxide. The glycerol‐derived materials swell to almost 20 times their mass in water. The driving force for rapid swelling appears to arise during ‘crystallization’, as segments between crosslinks are forced to pack under conditions that create high‐energy domains within the material. Solvation and therefore swelling are driven by the release of the resulting packing energy. These observations may offer insight into methods for designing other highly swellable materials. When the polyfunctional initiators have groups with different reactivities (e.g. alkoxide versus carboxylate), as might be expected, the more nucleophilic functional group appears to dominate the ring‐opening polymerization process. Copyright © 2007 Society of Chemical Industry

Mechanism of Self-Assembly and Rupture of Cross-Linked Microspheres and Microgels at the Oil−Water Interface

Lightly cross-linked, swellable poly(divinylbenzene-alt-maleic anhydride) microgels were allowed to self-assemble at the oil−water interfaces of a propyl acetate−water suspension and covalently fix...

Protein A immobilization and HIgG adsorption onto porous/nonporous and swellable HEMA-incorporated polyEGDMA microspheres

Both non swellable and swellable poly(EGDMA/HEMA) microbeads were produced by suspension copolymerization. These microbeads were modified by immobilization of a spacer-arm (hexamethylene diamine (HMDA)) and protein A. The optimal values for modifications were as follows: sodium periodate concentration, 1.0 mg ml-1; HMDA concentration, 4 mg ml-1; and glutaraldehyde concentration, 0.070 μg ml-1. Adsorption of protein A onto the plain and periodate oxidized poly(EGDMA/HEMA) microbeads were very close to each other, and were 0.01-0.02 mg protein A on the 1-g Microbeads I and II, respectively. Protein A immobilization on poly(EGDMA/HEMA) microbeads were studied at different temperatures, times, and pHs using single protein solution containing different amounts of proteins. The optimal values for immobilization were as follows: the initial protein A concentration, 0.1 mg ml-1; temperature, 25°C; pH, 9.5; and immobilization time, 120 min. Incorporation of protein A resulted in 1.420 and 1.825 mg protein A on the 1-g Microbeads I and II, respectively. HIgG adsorption capacity on the protein A-incorporated poly(EGDMA/HEMA) microbeads is 27 and 35 mg HIgG g-1 polymer for Microbeads I and II, respectively.

Collagen Immobilization onto P(EGDMA/HEMA) Microbeads for Cell Affinity Systems

Both nonswellable and swellable poly(EGDMA/HEMA) microbeads were produced by suspension copolymerization. These microbeads were modified by immobilization of a spacer-arm (hexamethylene diamine, HMDA) and collagen. The optimal values for modifications were as follows: sodium periodate concentration: 0.467 × 10-2 mmol/mL; HMDA concentration: 3.5 × 10-2 mmol/mL; and glutaraldehyde concentration: 0.70 × 106 mmol/mL. Adsorption of collagen onto plain and periodate oxidized poly(EGDMA/HEMA) microbeads were similar, 0.25 and 0.50 mg collagen/g polymer, respectively. Collagen immobilization on poly(EGDMA/HEMA) microbeads was studied at various temperatures, times, and pH by using protein solution containing various amounts of proteins. The optimal values for immobilizations were as follows: the initial collagen concentration: 0.25 mg/mL; temperature: 4°C; pH 7; and the immobilization time; 120 min. Both fibroblastic 3T3 and epithelial MDBK cells were attached to these unmodified and modified microbeads. The attachments of 3T3 and MDBK cells, especially to the collagen immobilized swellable microbeads were very high. Almost 96% of the 3T3 cells available in the cell culture medium became attached to these microbeads (2297 ± 122 cells per mg of polymer). There was no significant effect by swelling on cell attachment.

Preparation and characterization of microencapsulated gelospheres for controlled oral theophylline delivery

Microencapsulated gelospheres were prepared using the water swellable polymers, poly(vinyl alcohol) and polyacrylamide in which the drug was embedded. Polymeric coating was formed by interfacial polymerization using 1,6 hexamine and sebacoyl chloride. The size, shape, in vitro release, kinetics and in vivo efficiency of the formulation were determined. The shape was found to be spherical with a size range below 100 microm. The per cent drug loaded was found to be higher in the case of gelospheres prepared with polyacrylamide than those prepared with poly(vinyl alcohol). The release rate was found to be near zero order. The AUC was found to be higher in the case of polyacrylamide and polyvinyl alcohol gelospheres as compared to plain drug solution.

A potential cell affinity sorbent: Fibronectin carrying poly(EGDMA/HEMA) microbeads

Both non-swellable and swellable poly(EGDMA/HEMA) microbeads were produced by suspension copolymerization. These microbeads were modified by immobilization of a spacer-arm (hexamethylene diamine, HMDA) and fibronectin. The optimal values for modifications were as follows: the sodium periodate concentration 1.0 mg ml-1; the HMDA concentration 4 mg ml-1; and the glutaraldehyde concentration 0.070 μg ml-1. Adsorption of fibronectin onto the plain and periodate-oxidized poly(EGDMA/HEMA) microbeads were very similar, and were 0.025-0.035 mg fibronectin per g polymer, respectively. Fibronectin immobilization on poly(EGDMA/HEMA) microbeads were studied at different temperature, time and pH using single protein solution containing different amount of proteins. The optimal values for immobilizations were as follows: the initial fibronectin concentration 0.1 mg ml; temperature + 25°C; pH 7; the immobilization time 120 min. Both fibroblastic 3T3 and epithelial MDBK cells were attached to these unmodified and modified microbeads. The attachments of both 3T3 and MDBK cells, especially to the fibronectin-immobilized swellable microbeads, were very high. Almost 96% of the 3T3 cells available in the cell culture medium did attach to these microbeads (2345 ± 98 cells per mg of polymer).

Production and characterization of poly(ethylene glycol dimethacrylate-styrene-glycidyl methacrylate) microbeads

Nonswellable and swellable poly(ethyleneglycol dimethacrylate)-based microbeads that could react directly with the biological molecules were produced by a suspension polymerization procedure. For this purpose, ethyleneglycol dimethacrylate (EGDMA) was copolymerized with glycidyl methacrylate (GMA) in an aqueous suspension medium. Benzoyl peroxide and poly(vinyl alcohol) were used as the initiator and the stabilizer, respectively. The copolymerization provided nonswellable, tranparent, and spherical copolymer microbeads in the size range of 100–300 μm. On the other hand, swellable copolymer microbeads in the aqueous medium were obtained by using toluene as a diluent in the same copolymerization recipe. In a separate group of polymerizations, styrene (St) monomer was also included within the monomer phase to regulate the hydrophobicity of resulting microbeads. Nonswellable and swellable poly-(EGDMA-St-GMA) microbeads were obtained by changing the type and concentration of the ingredients within the monomer phase. The effects of glycidyl methacrylate, styrene, and toluene concentrations on the microbead yield, the average size, and the swellability of microbeads were investigated. In the second part of the study, the interaction of produced microbeads with a selected enzyme (i.e., chymotrypsin) was investigated. The most stable chymotrypsin immobilization was achieved with the swellable poly(EGDMA)-based microbeads including styrene. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1319–1334, 1998

Cibacron Blue F3GA and Zn(II) Containing Poly(Ethylene Glycol Dimethacrylate-Hydroxyethyl Methacrylate) Microbeads for Albumin Adsorption

Swellable poly (ethylene glycol dimethacrylate-hydroxyethyl methacryate) [poly(EGDMA-HEMA] microbeads, in the size range of 150–200 μm, were produced by a modified suspension copolymerization of EGDMA and HEMA. Cibacron Blue F3GA was attached, then Zn(II) ions were incorporated within the microbeads by chelating with the Cibacron Blue F3GA molecules. The maximum amount of Cibacron Blue F3GA attachment was 16.5 μmol/g polymer. Different amounts of Zn(II) ions (0.4–32.4 mg/g polymer were incorporated on the microbeads by changing the initial concentration of Zn(II) ions and medium pH. Bovine serum albumin (BSA) adsorption onto unmodified, Cibacron Blue F3GA-attached and Cibacron Blue F3GA-Zn(II)-derivatized microbeads was investigated. The non-specific adsorption of BSA was very low (0.051 mg/g polymer). Cibacron Blue F3GA attachment significantly increased the BSA adsorption (60.5 mg/g polymer). The maximum BSA adsorption (122 mg/g polymer) was observed at pH 6.0 when Cibacron Blue F3GA-Zn(II)-derivatized microbeads were used. Desorption of BSA was achieved by using 25 mM EDTA (pH 4.9). High desorption ratios (up to 95% of the adsorbed BSA) were observed. It was possible to reuse Cibacron Blue F3GA-Zn(II)-derivatized microbeads without significant losses in the adsorption capacities.

Comparison of albumin binding capacities of three different reactive dye-derivatized poly(ethylene glycol dimethacrylate-hydroxyethyl methacrylate) microbeads

Bovine serum albumin (BSA) adsorption onto dye-derivatized poly(ethylene glycol dimethacrylate-hydroxyethyl methacrylate) [poly(EGDMA-HEMA)] microbeads carrying three different reactive dye ligands (i.e. Congo Red, Cibacron Blue F3GA, and Alkali Blue 6B) was investigated. Swellable poly(EGDMA-HEMA) microbeads, in the size range of 150-200 μm, were produced by a modified suspension copolymerization of EGDMA and HEMA. The dyes were covalently attached to the microbeads. The maximum amounts of dye loadings were 14.5, 16.5, and 23.7 μmol g-1 for Congo Red, Cibacron Blue F3GA, and Alkali Blue 6B, respectively. The maximum BSA adsorption on the dye-derivatized microbeads from aqueous solutions containing different amounts of BSA were 90, 60.5, and 40 mg g-1 for the Congo Red, Cibacron Blue F3GA, and Alkali Blue 6B carrying microbeads, respectively. The maximum BSA adsorptions were observed at pH 6.0 in all cases. Desorption of albumin molecules were achieved by using 1.0 M NaSCN (pH 8.0). High desorption ratios (more than 85% of the adsorbed BSA) were observed in all cases. It was possible to reuse these novel sorbents without significant losses in the adsorption capacities.

Nonswellable and swellable poly(EGDMA) microspheres

In this study, nonswellable and swellable poly(ethylene glycol-dimethacrylate) microspheres, in the size range of 20–177 μm, were produced by conventional and modified suspension polymerizations of ethylene glycol-dimethacrylate (EGDMA) in an aqueous medium. Poly(vinyl alcohol) and benzoyl peroxide were used as the stabilizer and the initiator. A diluent, i.e., toluene, was included in the polymerization recipe of the modified suspension polymerization. The microspheres were characterized by optical microscopy, FTIR, and FTIR-DRS. Highly crosslinked, transparent, and nonswellable poly(EGDMA) microspheres were obtained with the conventional suspension polymerization procedure. While the modified suspension polymerization provided swellable, opaque, and crosslinked copolymer microspheres. © 1996 John Wiley & Sons, Inc.

Nonswellable and swellable poly(EGDMA) microspheres

Nonswellable and swellable poly(EGDMA) microspheres

Swellable ethylene glycol dimethacrylate-hydroxyethylmethacrylate copolymer beads

In this study, Swellable poly(EGDMA/HEMA) beads in the size range of 30–170 μm with different size distributions were produced by suspension copolymerization of ethylene glycol dimethacrylate (EGDMA) and hydroxyethylmethacrylate (HEMA) in aqueous media. Poly(vinyl alcohol) and benzoyl peroxide were used as the stabilizer and the initiator. The diluent, i.e. toluene was included in the recipe of the second group of copolymerizations. The beads were characterized by optical microscopy, FTIR and FTIR-DRS. Crosslinked, transparent, nonporous and Swellable (up to a swelling ratio of 31.2%) poly(EGDMA/HEMA) beads were obtained in which there was no toluene in the recipe. While copolymerizations with toluene provided Swellable (up to a swelling ratio of 57.1%), opaque, porous and crosslinked copolymer beads. In the polymerization (without toluene) HEMA is mainly incorporated on the outer layers (near surface) of the beads. In this case, increase in the EGDMA/HEMA ratio resulted larger beads with wider size distributions, and with lower swellabilities. The porosity of the dry copolymer beads were studied with mercury pycnometric method. Incorporation of toluene within the recipe (in the modified polymerization) caused pronounced effects both on bead size and swellability. Larger beads with broader size distributions, with higher swellabilities were obtained when the relative amount of toluene increased.