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Multicomponent (two, three, and four component) amphiphilic conetworks (APCNs) with tunable swelling behaviors were fabricated through the ring opening polymerization and click chemistry utilizing various combinations of azide and alkyne functionalized poly (ethylene glycol) (PEG) and poly (caprolactone) (PCL) precursors. Prepare azido‐terminated star‐shaped PCL, azido‐terminated PEG, alkyne‐terminated PEG, and propargylated pentaerythritol were characterized by hydrogen‐1 proton nuclear magnetic resonance (1H NMR) and Fourier‐transform infrared (FT‐IR) spectroscopy. The morphology and thermal behavior of the APCNs were studied by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The swelling behavior of APCNs could be manipulated through an establishment of a balance between hydrophilic segments, hydrophobic segments, and cross‐linking density. The 2,4‐dichlorophenoxyacetic acid (2,4‐D) herbicide was entrapped in APCNs as a model agrochemical to study the release profile from APCNs. The obtained results showed that the release of 2,4‐D could be controlled by the swelling degree of APCNs. Finally, the biodegradability rates of APCNs were investigated in agricultural soil. The results exhibited that the decrease in the swelling degree led to decreased degradation rate of APCNs. According to obtained results, these APCNs could be used as biomaterials for the controlled release of agrochemicals. [ABSTRACT FROM AUTHOR]

In consequence of some unique properties, such as nanophase separation, biocompatibility and mechanical stability, amphiphilic polymer conetworks (APCNs) have received significant attention in recent years. APCNs are composed of hydrophilic and hydrophobic polymer chains connected with covalent bonds. The unique properties of APCNs make them suitable for many specialized applications. Although APCNs were widely investigated and described in the literature, this is the first study on the swelling behavior of these materials in the solutions of physiologically relevant salts. Homopolymer polyelectrolyte hydrogels are known to suffer phase transition like rapid gel collapse at a certain salt concentration in the solutions of bi- or multivalent metal salts. Systematic swelling investigation of poly(methacrylic acid)- l- polyisobutylene (PMAA- l -PIB) conetwork series in CaCl 2 salt solutions led to unexpected findings. Our results indicate that these polyelectrolyte APCNs do not behave the same way in salt solutions as the homopolymer hydrogels, i.e. APCNs do not suffer gel collapse, the change of the swelling degree remains continuous with increasing salt concentration. The gel contraction was reversible by changing the solute to NaOH solution, i.e. the gels returned to their original volume by reswelling. This non-collapsing swelling means that the presence of hydrophobic polymer segments as cross-linkers in amphiphilic polyelectrolyte gels radically change the swelling behavior of such materials, which become substantially different from that of homopolymer polyelectrolyte gels. [ABSTRACT FROM AUTHOR]

ABSTRACT Well-defined star-shaped hydrophobic poly(ε-caprolactone) (PCL) and hydrophilic poly(ethylene glycol) (PEG) amphiphilic conetworks (APCNs) have been synthesized via the combination of ring opening polymerization (ROP) and click chemistry. Alkyne-terminated six arm star-shaped PCL (6-s-PCL x-CCH) and azido-terminated PEG (N3-PEG-N3) are characterized by 1H NMR and FT-IR. The swelling degree of the APCNs is determined both in water and organic solvent. This unique property of the conetworks is dependent on the nanophase separation of hydrophilic and hydrophobic phases. The morphology and thermal behaviors of the APCNs are investigated by SEM and DSC respectively. The biocompatibility is determined by water soluble tetrazolium salt reagents (WST-1) assay, which shows the new polymer networks had good biocompatibility. Through in vitro release of paclitaxel (PTX) and doxorubicin (DOX), the APCNs is confirmed to be promising drug depot materials for sustained hydrophobic and hydrophilic drugs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 407-417 [ABSTRACT FROM AUTHOR]

ABSTRACT A series of amphiphilic conetworks (APCNs) is synthesized through crosslinking of well-defined tri-arm star diblock copolymers via atom transfer radical polymerization. A new three-arm initiator is synthesized to initiate the polymerization of 2-hydroxyethyl methacrylate (HEMA) via 'core-first' method. The resulting star HEMA homopolymers with well-defined molecular weight and narrow polydispersity are used as macroinitiator to incorporate allyl methacrylate to get the star diblock copolymers. Then, the precursors with allyl pendant groups are fully crosslinked with polyhydrosiloxanes through hydrosilylation. The so-prepared APCNs exhibit unique properties of microphase separation of hydrophilic (HI) and hydrophobic (HO) phases with small channel size, a variable swelling capacity, excellent biocompatibility, and outstanding mechanical strength (2 ± 0.5 MPa). The properties of APCNs depend on the ratio of HI to HO, which can be regulated via precise synthesis of the star diblock copolymers. The APCNs show well-controlled drug release to choline theophyllinate, suggesting a promising intelligent drug carrier for controlled release. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2537-2545 [ABSTRACT FROM AUTHOR]

A series of poly(methacrylic acid)- l-polyisobutylene anionic amphiphilic conetworks with hydrophobic polyisobutylene (PIB) content between 33% and 70% (w/w) is synthesized by the macromonomer method using a new approach by applying ethoxyethyl-protected methacrylic acid (EEMA) comonomer. To remove the protecting group after copolymerization of EEMA with PIB-dimethacrylate, acidic hydrolysis and thermal treatment are attempted, and the success of the deprotection is monitored by different techniques. Comparing the two protective group removal steps, it is found that, in contrast to homopolymers of EEMA, the acidic hydrolysis is more favorable than the thermal deprotection due to anhydride formation during the latter process in the conetworks. Distinct glass transitions are obtained by differential scanning calorimetry (DSC) indicating phase separation in the resulting conetworks. The swelling ability of the obtained conetworks in polar and nonpolar solvents proves the amphiphilic nature of these materials. Due to the polyacidic component of the conetworks, their water swollen gels have pH-sensitive, intelligent swelling behavior in aqueous media. Because of the relatively high stability of EEMA, the applied protection-deprotection strategy can be easily utilized in several other designed polymer syntheses. [ABSTRACT FROM AUTHOR]

Thermoresponsive amphiphilic conetworks comprising poly(2-ethyl-2-oxazoline) (PEtOx), 2-hydroxyethyl methacrylate, and 2-hydroxypropyl acrylate segments have been studied as new platforms for delivery of drug with limited solubility. Series of conetworks of varied composition were synthesized and swelling kinetics in aqueous media and ethanol were followed. The platforms were loaded with the hydrophobic drug ibuprofen by swelling in its ethanol solution. The structure and properties of the drug carriers were investigated by scanning electron microscopy and differential scanning calorimetry. The release kinetics profiles of ibuprofen from the studied platform were established. The investigation proved the feasibility of the PEtOx-based amphiphilic conetworks as highly effective platforms for sustained ibuprofen delivery. [ABSTRACT FROM AUTHOR]

Abstract: Amphiphilic polymer conetworks were synthesized by the end-linking of ABA triblock copolymers using optimal (minimal) amount of cross-linker in pursuit of nanoscale phase separated materials with a long-range order. Small-angle neutron scattering (SANS) was employed to investigate the structure of the conetworks in D2O. The measurements revealed single SANS correlation peaks, indicating a short-range, liquid-like order within the conetworks, similar to that observed in counterparts prepared using super-optimal amount of cross-linker. This was attributed to the relatively low molecular weight of the chains and the constraints of end-linking. Thus, a reduced loading of cross-linker did not affect the structure of the conetworks. In contrast, the conetwork structure was significantly affected by the polymer architecture at minimal cross-linker loading, with much less intense SANS correlation peaks exhibited by the BAB triblock and the statistical copolymer end-linked conetworks, and the randomly cross-linked statistical conetwork. [Copyright &y& Elsevier]

This paper focuses on the improvement of hydrophicility and water content of poly(dimethylsiloxane) (PDMS) by bonding a hydrophilic macromer, hydroxyl-terminated linear poly(ethylene glycol) (PEG), into a highly hydrophobic macromer, hydroxyl-terminated linear PDMS to prepare amphiphilic conetworks (APCNs) with the crosslinkers, tetraethoxysilane (TEOS) and bis[(3-methyldimethoxysilyl)propyl]-polypropylene oxide (BMPPO), which also functioned as a compatibilizer. Fourier transform infrared results clearly demonstrated the occurrence of the hydrolysis reactions between the terminal hydroxyl groups on the terminal of the two polymer chains and the alkoxy groups in TEOS and BMPPO. Differential scanning calorimetry results and X-ray diffraction obviously showed the presence of the two phases in the conetworks. The contact angle (CA) indicated the wettability of the conetworks increased in the surfaces, that is, CA values decreased significantly from 105° in PDMS to 55° in the PEG/PDMS APCN (10/1 mol ratio), and the swelling degrees of the APCNs increased from ca. 0 to 60 % when the PEG/PDMS mol ratio was larger than 4/1. The APCNs with such high hydrophilicity and the good mechanical properties should be useful as biomaterials. [ABSTRACT FROM AUTHOR]

In our work, first a telechelic bromoisobutyrate-ended polyisobutylene macroinitiator was synthesized via quasiliving carbocationic polymerization and subsequent chain end modification. In the second step, quasiliving atom transfer radical polymerization (ATRP) of poly(ethylene oxide) methacrylate using the macroinitiator was performed. When ethyleneglycol dimethacrylate was further polymerized on the formed triblock copolymer, a conetwork with a unique structure was obtained. [ABSTRACT FROM AUTHOR]

Abstract: A Grubbs–Hoveyda-Type metathesis catalyst bearing a tris(perfluoroalkyl)silyl tag was immobilized in the fluorophilic phase of amphiphilic conetworks (APCNs). This catalytic system was applied to ring-closing metathesis (RCM) reactions in aqueous media. Different substrates were evaluated and with 10mol% of catalyst at 60°C good conversions were observed. Reuse of the catalytic system was possible, but resulted generally in lower conversions. [Copyright &y& Elsevier]

Abstract: Model amphiphilic conetworks based on cross-linked block copolymers of the hydrophilic ionizable 2-(dimethylamino)ethyl methacrylate (DMAEMA, 25 nominal units per block) and the hydrophobic n-butyl methacrylate (BuMA, 5 nominal units per block) bearing three, five, seven and nine blocks were synthesized using group transfer polymerization. 1,4-Bis(methoxytrimethylsiloxymethylene)cyclohexane and ethylene glycol dimethacrylate were used as the bifunctional initiator and the cross-linker, respectively. Network synthesis was performed by sequential monomer/cross-linker additions to the reaction flask, which was pre-loaded with tetrabutylammonium bibenzoate (polymerization catalyst), tetrahydrofuran (THF, solvent), and initiator. All linear conetwork precursors were characterized using gel permeation chromatography and proton nuclear magnetic resonance spectroscopy and found to have molecular weights (MWs) and compositions reasonably close to the theoretically expected values. All polymer conetworks were characterized in terms of their degree of swelling (DS) in THF, in neutral water, and in aqueous media as a function of the solution pH. It was found that the DSs were highest in acidic pH due to the repulsive forces and the osmotic pressure developed by the ionization of the DMAEMA units. Intermediate values of the DSs were observed in THF, whereas the lowest DSs were measured in neutral water. In THF, the DSs increased with the MWs of the (final) linear (co)polymer precursors, while in acidic water the DSs increased with the DMAEMA content in the (co)networks. [Copyright &y& Elsevier]

Despite the great interest in nanoconfined materials nowadays, nanocompartmentalized poly(ionic liquid)s (PILs) have been rarely investigated so far. Herein, we report on the successful alkylation of poly(1-vinylimidazole) with methyl iodide in bicontinuous nanophasic poly(1-vinylimidazole)-l-poly(tetrahydrofuran) (PVIm-l-PTHF) amphiphilic conetworks (APCNs) to obtain nanoconfined methylated PVImMe-l-PTHF poly(ionic liquid) conetworks (PIL-CNs). A high extent of alkylation (~95%) was achieved via a simple alkylation process with MeI at room temperature. This does not destroy the bicontinuous nanophasic morphology as proved by SAXS and AFM, and PIL-CNs with 15–20 nm d-spacing and poly(3-methyl-1-vinylimidazolium iodide) PIL nanophases with average domain sizes of 8.2–8.4 nm are formed. Unexpectedly, while the swelling capacity of the PIL-CN dramatically increases in aprotic polar solvents, such as DMF, NMP, and DMSO, reaching higher than 1000% superabsorbent swelling degrees, the equilibrium swelling degrees decrease in even highly polar protic (hydrophilic) solvents, like water and methanol. An unprecedented Gaussian-type relationship was found between the ratios of the swelling degrees versus the polarity index, indicating increased swelling for the nanoconfined PVImMe-l-PTHF PIL-CNs in solvents with a polarity index between ~6 and 9.5. In addition to the nanoconfined structural features, the unique selective superabsorbent swelling behavior of the PIL-CNs can also be utilized in various application fields. [ABSTRACT FROM AUTHOR]

A unique l-cysteine conjugated antifouling amphiphilic conetwork (APCN) is synthesized through end-crosslinking of well-defined triblock copolymers poly(allyl methacrylate)-b-poly(ethylene glycol)-b-poly(allyl methacrylate) via a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and thiol-ene "click" chemistry. The synthesized poly(ethylene glycol) macro-RAFT agent initiates the polymerization of allyl methacrylate in a controlled manner. The vinyl pendant groups of the precursor partially conjugate with l-cysteine and the rest fully crosslink with mercaptopropyl-containing siloxane via thiol-ene click chemistry under UV irradiation into APCNs, which show distinguished properties, that is, excellent biocompatibility, more than 39.6% water content, 101 barrers oxygen permeability, optimized mechanical properties, and more than 93% visible light transmittance. What's more, the resultant APCNs exhibit eminent resistance to protein adsorption, where the bovine serum albumin and lysozyme adsorption are decreased to 12 and 21 µg cm -2 , respectively. The outstanding properties of APCNs depend on the RAFT controlled method, which precisely designs the hydrophilic/hydrophobic segments and eventually greatly improves the crosslinking efficiency and homogeneity. Meantime, the l-cysteine monolayer can effectively reduce the surface hydrophobicity and prevent protein adsorption, which exhibits the viability for antifouling surface over and under ophthalmic devices, suggesting a promising soft contact lens., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel approach to zero-order constant-rate drug delivery from contact lenses is presented. Quasi-Case II non-Fickian transport is achieved by nonuniform drug and diffusivity distributions within three-layer bimodal amphiphilic conetworks (β-APCNs). The center layer is a highly oxygen permeable β-APCN matrix, which contains the drug and exhibits a high drug diffusivity. The outer β-APCN layers contain no-drug and are loaded with vitamin E, which slows diffusion. In contrast to single-layer neat-polymer and vitamin E-loaded films that display first-order "burst" kinetics, it is demonstrated experimentally and by modeling that the combined effect of nonuniform distribution of drug loading and diffusion constants within the three-layer lens maintains low local drug concentration at the lens-fluid interface and yields zero-order drug delivery. The release rates of topical antibiotics provide constant-rate therapeutic-level delivery with appropriate oxygen permeability for at least 30 h, at which time ≈25% of the drug was released., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)