•Stable PEG-PDMS segmented copolymer was used for membrane preparation.•Copolymer undergoes surface segregation on membrane surface.•Blend membranes were useful for oil-water emulsion ...separation.•Blend membranes showed fouling release behaviors depending on amount of copolymer.•Membranes showed good antifouling property during oil-water emulsion separation.
Copolymers are used as additive for membrane preparation. Hydrolytic stability of a copolymer is enormous important for use in membrane preparation. Most of the polymers or macromonomers (methacrylate-terminated oligomers) contain vulnerable ester linkage. Herein, a relatively hydrolytically stable segmented amphiphilic copolymer (PDMS-PEG, containing urethane linkage) of poly(dimethylsiloxane) and poly(ethylene glycol) was used for the preparation blend membranes. Membranes were prepared from a blend of copolymer, poly(vinylidene fluoride) (PVDF) and poly(vinyl pyrrolidone) (PVP) by the non-solvent induced phase separation process. The copolymer is miscible with the membrane forming polymer and PVP and influences the properties of the membranes in terms of water wetting, compaction factor, and surface morphology. A membrane PVDF-PVP-copolymer(1.7) prepared by the addition of 1.7% w/w of copolymer in casting solution showed permeate water flux of about 280 L m−2 h−1, and oil rejection of >99%, with flux recovery ratio as high as >99% after filtration of surfactant free and surfactant stabilized oil-in-water emulsions at applied pressure of 0.35 bar. The good antifouling property of the membrane is attributed to the hydration effect of PEG segments and fouling release property of PDMS segments.
Key issues of injectable hydrogels are incapability of loading hydrophobic drugs due to insolubility of drugs in aqueous prepolymer solution as well as in hydrogel matrix, and high water swelling, ...which leads to poor mechanical and bioadhesive properties. Herein, we report that self-assembly of partially long-chain alkylated dextran-graft-poly(2-dimethylamino)ethyl methacrylate copolymer in aqueous solution could encapsulate pyrene, a hydrophobic probe, griseofulvin, a hydrophobic antifungal drug, and ornidazole, a hydrophilic antibiotic. Addition of activated chloride terminated poly(ethylene glycol) (PEG) into the guest molecules loaded copolymer solution produced an injectable dextran-graft-poly(2-dimethylamino)ethyl methacrylate-linked-PEG conetwork hydrogel. The alkylated hydrogels exhibited zero order release kinetics and were mechanically tough (50–54 kPa storage modulus) and bioadhesive (8–9 kPa). The roles of alkyl chains and dextran on the drug loading-release behavior, degradation behavior, gelation time, and the mechanical property of the hydrogels have been studied in details. Additionally, DNA hybrid composite hydrogel was formed owing to the cationic nature of the prepolymer solution and the hydrogel. Controlled alkylation of a prepolymer thus highlights the potential to induce and enhance the hydrogel property.
Herein, we report a simple process for the preparation of homogeneous crosslinked conetwork cation exchange membranes (CEMs). The synthesis strategy is based on sequential reaction of hydrazine ...hydrate and nitrile moieties of random copolymers of poly(acrylonitrile) and poly (2-acrylamido-2-methyl-1-propanesulfonic acid) (PAN-co-PAMPS). Copolymerization of the two monomers enhances miscibility between relatively hydrophobic PAN and hydrophilic ionic PAMPS domains which prevents microphase separation in the membrane matrices. The homogeneous phase co-continuous morphology with no microphase separation in the membrane matrices was confirmed by the homogeneous distribution of color solutes in the membrane matrices as well as by DSC, DMA, TEM, and AFM analyses. Both crosslinked (conetwork) and uncrosslinked copolymers (different composition) acted as CEMs. The CEMs were employed for desalination via electrodialysis. A representative crosslinked CEM (PAN-PAMPS-1) containing 15 mol% PAMPS exhibited the best desalination performance. Crosslinking of the copolymers improves the transport number, desalination performance, and lowers the power consumption of the membranes. This work thus highlights the benefit of crosslinking of ionic random amphiphilic copolymers to obtain CEMs with improved performance during desalination via electrodialysis.
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•Preparation of cation exchange membrane (CEM) from crosslinked PAN-co-PAMPS.•Homogeneous phase ionic domains controls the performance of the CEM.•CEM was used for water desalination by electrodialysis (ED).•The CEM showed about 13.54 mS/cm ionic conductivity with high ED efficacy.•The membrane shows chemical, hydrolytic and oxidative stability.
Multiblock copolymers (MBCs) are fascinating in the field of biology–polymer chemistry interfaces. Synthesizing libraries of MBCs with tailor-made functionality is challenging as it involves multiple ...steps. Herein, a simple synthesis, analogous to polyurethane/Michael addition reactions, has been introduced to obtain a library of derivatizable MBCs. Nucleophilic substitution polymerization (SNP) of poly(ε-caprolactone) and poly(ethylene glycol) blocks containing activated halide termini by primary mono/di/coamines or clickable amines provides functional MBCs. The structure of amines directs the properties of the MBCs. The self-assembly of small molecular weight primary diamine-based MBCs shows controlled release of hydrophobic model guest molecules and therapeutics. The primary diamine (no dangling chain) helps to form MBC micelles having a relatively tight core with a low diffusion property. Antimicrobial property in the MBCs has been introduced by separating the cationic centers from the lipophilic groups using a coamine as a nucleophilic agent and a small molecular weight dihalide as a chain extender. Clickable MBCs were synthesized by changing the structure of the nucleophile to obtain degradable amphiphilic conetworks and hydrogels. Varieties of macromolecular entities could be obtained by switching the nucleophilic agent and introducing a small molecular weight chain extender. This synthesis approach provides an opportunity to tune the chemical functionality, topological structure, and biological properties of macromolecular entities.
We report a novel approach for in situ PEGylation of thin film composite (TFC) reverse osmosis (RO) membrane for sustained performance. The approach was based on use of end-functionalized ...polyethylene glycol (MPD-PEG-MPD or MeO-PEG-MPD) with end groups structure resembling the structure of m-phenylenediamine (MPD), commonly used for preparation of TFC membrane. Michael addition reaction between MPD and acrylate-terminated-polyethylene glycol (AA-PEG-AA or MeO-PEG-AA) produces such type of end-functionality for further use in interfacial polymerization (IFP) with conventionally used trimesoyl chloride (TMC). PEGylated TFC membranes exhibited superior antifouling property during water desalination in presence of fouling agent (protein) compared to non-PEGylated TFC membrane. The best results were obtained with the membranes prepared by addition of 0.25–0.5% (w/v) of AA-PEG-AA or MeO-PEG-AA to the MPD solution (2% w/v in water) for Michael addition reaction prior to IFP with TMC (0.125% w/v in hexane) in as much as the antifouling property was enhanced and the performance (salt rejection efficiency and flux) remained almost unaffected. TFC membranes were characterized by Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), contact angle (θ), scanning electron microscope (SEM), atomic force microscope (AFM) and CHN analyses. The incorporated PEG remained stable in the polyamide network and is mainly attributed to the participation of both MPD and MPD-PEG-MPD or MeO-PEG-MPD in the IFP process.
•Facile in situ PEGylation of TFC RO membranes has been achieved.•Capping with MPD allows easy incorporation of PEG in the TFC membrane.•PEGylated membranes exhibit enhanced hydrophilicity/antifouling property.•Morphological stability and stability of incorporated PEG have been evaluated.
We synthesized agarose–polycaprolactone (Agr-PCL) bicomponent and Agr–polyethylene glycol–PCL (Agr-PEG-PCL) tricomponent amphiphilic co-network (APCN) gels by the sequential nucleophilic substitution ...reaction between amine-functionalized Agr and activated halide terminated PCL or PCL-b-PEG-b-PCL copolymer for the sustained and localized delivery of hydrophilic and hydrophobic drugs. The biodegradability of the APCNs was confirmed using lipase and by hydrolytic degradation. These APCN gels displayed good cytocompatibility and blood compatibility. Importantly, these APCN gels exhibited remarkably high drug loading capacity coupled with sustained and triggered release of both hydrophilic and hydrophobic drugs. PEG in the APCNs lowered the degree of phase separation and enhanced the mechanical property of the APCN gels. The drug loading capacity and the release kinetics were also strongly influenced by the presence of PEG, the nature of release medium, and the nature of the drug. Particularly, PEG in the APCN gels significantly enhanced the 5-fluorouracil loading capacity and lowered its release rate and burst release. Release kinetics of highly water-soluble gemcitabine hydrochloride and hydrophobic prednisolone acetate depended on the extent of water swelling of the APCN gels. Cytocompatibility/blood compatibility and pH and enzyme-triggered degradation together with sustained release of drugs show great promise for the use of these APCN gels in localized drug delivery and tissue engineering applications.
We report the preparation of dense and porous amphiphilic conetwork (APCN) membranes through the covalent interconnection of poly(vinylidene fluoride)-graft-poly(2-dimethylamino)ethyl methacrylate ...(PVDF-g-PDMAEMA) copolymers with telechelic poly(ethylene glycol) (PEG) or α,α-dichloro-p-xylene (XDC). The dense APCN membranes exhibit varying solvent swelling and mechanical properties depending on the compositions and overall crystallinity. The crystallinity of both PVDF (20−47%) and PEG (9–17%) is significantly suppressed in the dense APCNs prepared through the interconnection of PVDF-g-PDMAEMA with reactive PEG as compared to the APCN membranes (48–53%) prepared with XDC as well as mechanical blend of PVDF-g-PDMAEMA plus nonreactive PEG. The dense APCN membranes exhibit a good transport number of monovalent ions and ionic conductivity. The APCN membrane interconnected with PEG and containing binary ionic liquids exhibits a room-temperature lithium ion conductivity of 0.52 mS/cm. On the other hand, APCN ultrafiltration (UF) membranes exhibit organic solvent-resistant behavior. The UF membrane obtained by interconnecting PVDF-g-PDMAEMA with telechelic PEG shows low protein fouling propensity, higher hydrophilicity, and water flux as compared to membranes prepared using XDC as the interconnecting agent. The significant effect of the covalent interconnection of the amphiphilic graft copolymers with telechelic PEG or XDC on the overall properties provides a good opportunity to modulate the properties and performance of APCN membranes.
Layer-by-layer (LbL) self-assembly of oppositely charged polyelectrolytes (PEs) is usually performed on a conventional ultrafiltration base substrate (negative zeta potential) by depositing a ...cationic PE as a first layer. Herein, we report the facile and fast formation of high performance molecular selective membrane by the nonelectrostatic adsorption of anionic PE on the polyvinylidene fluoride (PVDF, zeta potential −17 mV) substrate followed by the electrostatic LbL assembly. Loose nanofiltration membranes have been prepared via both concentration-polarization (CP-LbL, under applied pressure) driven and conventional (C-LbL, dipping) LbL self-assembly. When the first layer is poly(styrene sodium) sulfonic acid, the LbL assembled membrane contains free −SO3 – groups and exhibits higher rejection of Na2SO4 and lower rejection of MgCl2. The reversal of salt rejection occurs when the first layer is quaternized polyvinyl imidazole (PVIm-Me). The membrane (five layers) prepared by first depositing PStSO3Na shows higher rejection of several dyes (97.9 to >99.9%), higher NaCl to dye separation factor (52–1800), and higher dye antifouling performance as compared to the membrane prepared by first depositing PVIm-Me (97.5–99.5% dye rejection, separation factor ∼40–200). However, the C-LbL membrane requires a longer time of self-assembly or higher PE concentration to reach a performance close to the CP-LbL membranes. The membranes exhibit excellent pressure, pH (3–12), and salt (60 g L–1) stability. This work provides an insight for the construction of low fouling and high-performance membranes for the fractionation of dye and salt based on the LbL self-assembly sequence.
Self-assembly of a copolymer with compact hydrophobic core, good stability at physiological condition and responsive nature towards stimuli is beneficial for sustained release application. Diffusion ...mediated release from a self-assembly at normal physiological conditions limits its application. Herein, extremely simple self-assemblies of poly(amidoamine)-graft-alkyl (PAMAM-g-alkyl) copolymers have been designed based on the N-alkylation (alkyl = C-8, C-10, C12, and C-18) of linear PAMAM to elucidate the differences in properties of the hydrophobic core and to select the appropriate self-assembly for triggered release application. The synthesis of PAMAM-g-alkyl copolymers allows us to assess the influence of alkyl chain length on the critical micelle concentration, stability, core hydrophobicity, core compactness, and encapsulation-release performance of the self-assemblies. The C18 chains facilitate the formation of compact micellar core with higher hydrophobicity, higher encapsulation property, and extended stability at pH 7.4. The C18 bearing micelles showed lowest (20–26% w/w) release of guest molecules at pH 7.4 while triggered the release (65–80% w/w) at pH 5. The triggered release behavior of the self-assembly is attributed to the leakage of guest molecules through partial dissociation of the copolymer chains followed by the creation of release channel. The effect of alkyl chain length on the micellar stability was further probed by Förster Resonance Energy Transfer (FRET) between two hydrophobic chromophores. The design of this type of simple self-assembly is beneficial to encapsulate hydrophobic guest molecules for sustained release application.
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•Spontaneous self-assembly of poly(amidoamine)-graft-alkyl copolymers is reported.•PH-triggered leakage of guest molecules, rather than complete disassembly occurred.•Compactness/hydrophobicity of micelle core is related to the chain length of alkyl.•Loading of hydrophobic guest depends on type of alkyl chains.•Self-assembly shows acidic pH-mediated triggered release of guest/drug molecules.
•TFNC nanofiltration membranes were used for the removal of toxic heavy metal ions.•Treatment of piperazine membrane with PEI or PEI-PEG and Ag salt gave TFNC membrane.•The TFNC membranes showed high ...rejection of Pb, Hg, Cd and Cu ions.•TFNC membranes showed anti-biofouling and anti-organic fouling properties.•TFNC membranes possessed low surface charge and smaller pore size than pristine one.
Propensity towards anti-organic fouling, anti-biofouling property and low rejection of multivalent cation (monovalent counter ion) restricts the application of the state-of-art poly(piperazineamide) poly(PIP) thin film composite (TFC) nanofiltration (NF) membrane for the treatment of water containing toxic heavy metal ions, organic fouling agents and microbes. Herein, we report the preparation of thin film nanocomposite (TFNC) NF membranes with improved heavy metal ions rejection efficacy, anti-biofouling property, and anti-organic fouling properties compared to that of poly(PIP) TFC NF membrane. The TFNC NF membranes were prepared by the interfacial polymerization (IP) between PIP and trimesoyl chloride followed by post-treatment with polyethyleneimine (PEI) or PEI-polyethylene glycol conjugate and then immobilization of Ag NP. The IP was conducted on a polyethersulfone/poly(methyl methacrylate)-co-poly(vinyl pyrollidone)/silver nanoparticle (Ag NP) blend ultrafiltration membrane support. The TFNC membranes exhibited >99% rejection of Pb2+, 91–97% rejection of Cd2+, 90–96% rejection of Co2+ and 95–99% rejection of Cu2+ with permeate flux ∼40Lm−2h−1 at applied pressure 0.5MPa. The improved heavy metal ions rejection efficacy of the modified NF membranes is attributed to the development of positive surface charge as well as lowering of surface pore size compared to that of unmodified poly(PIP) TFC NF membrane.
