Advanced Materials Based on Polymers and Ionic Liquids

Ionic liquids (ILs) are ambient temperature molten salts, which have attracted considerable attention owing to their unique properties. In this contribution, we review advanced materials composed of ILs and polymers for the basis of a new design protocol to fabricate novel materials. As electrolytes for electrochemical devices, cross‐linked polymers containing ILs (ion gels) are endowed with functional properties inherited from ILs and mechanical consistency derived from polymers. To create such materials, micro‐phase separation of block copolymers and colloidal arrays in the ILs are utilized. Based on the molecular design of task‐specific ILs, the resultant ion gels are applicable as electrolytes for actuator, fuel cell, and secondary battery applications. Thermo‐ and photo‐responsive polymers in ILs are also highlighted, whereby such stimuli elicit changes in the solubility of the self‐assembly of block copolymers and colloidal arrays in the ILs. Further, thermo‐ and photo‐reversible changes in the self‐assembled structure can be exploited to demonstrate sol‐gel transitions and fabricate photo‐healable materials.     

Structural Versatility in Slide‐Ring Gels: Influence of Co‐Threaded Cyclodextrin Spacers

We describe a one‐pot strategy for the fabrication of novel slide‐ring (SR) gels based on supramolecular polyrotaxane structures with cyclodextrin‐derived cross‐links and additional free cyclodextrin ring spacers co‐threaded onto the polymer backbones. Photoinitiated thiol‐yne click coupling leads to facile hydrogel fabrication from pseudo‐polyrotaxanes prepared in situ from β‐cyclodextrin derivatives and bifunctional polyethylene glycol (PEG). The obtained SR gels were characterized by NMR spectroscopy using a polyrotaxane model compound with the ratio of cyclodextrin sliding spacers to PEG backbone controlled by adjusting the feed ratio of the starting materials. This structural tuning leads to dramatic changes in the rheological properties, mechanical properties, and swelling behavior of the SR gels. In addition, the coupling of simple synthetic procedures with enhanced properties offers a versatile approach to novel elastomeric materials. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1156–1165     

PREPARATION AND PROPERTIES OF CLAY/POLY（N-ISOPROPYLACRYLAMIDE-co-A CRYL AMIDE） NANOCOMPOSITE HYDROGELS

A series of clay/poly(N-isopropylacrylamide-co-acrylamide) nanocomposite hydrogels (S-N-M gels) have been successfully prepared by in situ polymerization. The mechanical properties,swelling behavior of S-N-M gels and the transparency changes during polymerization of S-N-M gels have been systematically investigated. Compared to traditional hydrogeb, S-N-M gels show excellent tensile properties and their swelling ratio increases with increasing acrylamide (AAm) content. The results of stress relaxation indicate that the stress loss decreases with increasing AAm content. It was surprisingly found that the transparency during all S-N-M gel synthesis changes abruptly, and the changes become more abrupt with increasing N-isopropylacrylamide content. It was concluded that the fact may be related to the hydrophilicity of copolymers. The weaker the hydrophilicity of copolymer, the more apparent the transparency change during S-N-M gels polymerization. We believe the relationship between hydrophilicity of copolymer and transparency changes will help to design novel nanocomposite hydrogels.     

PREPARATION AND PROPERTIES OF CLAY/POLY(N-ISOPROPYLACRYLAMIDE-co-ACRYL AMIDE)NANOCOMPOSITE HYDROGELS

Polymer hydrogels as a kind of soft materials have attracted increasing scientific and technological interest in past several decades. These materials have been applied widely in many fields [1], such as molecular filter [2,3], superabsorbent [4], and contact lenses [5] etc. However, synthetic polymeric hydrogels are seldom used as mechanical devices due to the lack of mechanical strength. Therefore, it is very imperative to improve their mechanical properties for wider use of polymeric hydrog…     

Water uptake and dye sorption studies of chemically crosslinked highly swollen novel ternary acrylamide‐based hydrogels including citraconic acid and sodium acrylate

Highly swollen hydrogels made by the polymerization of acrylamide (AAm) with some anionic monomers such as citraconic acid (CITA) and sodium acrylate (SA) were investigated as a function of composition to find materials with swelling and dye sorption properties. Highly swollen AAm/CITA/SA or AAm/SA/CITA hydrogels were prepared by free radical solution polymerization in aqueous solutions of AAm with CITA and SA as co‐monomers and two multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and 1,4‐butanediol dimethacrylate (BDMA). Swelling experiments were performed in water at 25°C, gravimetrically. Chemically crosslinked AAm/CITA/SA or AAm/SA/CITA hydrogels were used in experiments on sorption of water‐soluble monovalent cationic dye such as “Nil blue” (Basic Blue 12; BB 12). Equilibrium percentage swelling values of AAm/CITA/SA or AAm/SA/CITA hydrogels were calculated in the range of 1797–22,098%. Some swelling kinetic parameters were found. Diffusion behavior of water was investigated. Water diffusion into the hydrogels was found to be non‐Fickian in character. For sorption of cationic dye, BB 12 into the hydrogels was studied by batch sorption technique at 25°C. AAm/CITA/SA or AAm/SA/CITA hydrogels in the dye solutions showed coloration, whereas AAm hydrogel did not show sorption of any dye from the solution. The sorption capacity of AAm/CITA/SA or AAm/SA/CITA hydrogels was investigated. At the end of the experiments, 21.70–78.91% BB 12 adsorptions were determined. Copyright © 2007 John Wiley & Sons, Ltd.     

(Sodium Alginate/Acrylamide) Semi‐Interpenetrating Polymer Networks and their Usability on Removal of Lead,Cadmium, Nickel Ions

In this study, (sodium alginate (NaAlg)/acrylamide (AAm)) interpenetrating polymer networks (IPN) have been prepared at three different compositions, where the sodium alginate composition varies 1, 2, and 3% (w/v) in 50% (w/v) acrylamide solutions. These solutions have been irradiated with a ⁶⁰Co‐γ source at different doses. The percent conversion was determined gravimetrically and 100% gelation was achieved at the 10.0 kGy dose. The swelling results at pH 7.0 and 9.0 indicated that (NaAlg/AAm)3IPN hydrogel, containing 3% NaAlg showed maximum % swelling in water, with swelling increasing in the order of Ni²⁺>Cd²⁺>Pb²⁺. Diffusion in aqueous solutions of metal ions within (NaAlg/AAm)IPN hydrogels was found to be Fickian character. Diffusion coefficients of (NaAlg/AAm)IPN hydrogels in water and aqueous solutions of metal ions were calculated. The maximum weight loss temperature and half life temperature for NaAlg, PAAm, (NaAlg/AAm)IPN and (NaAlg/AAm)IPN‐metal ion systems were found from thermal analysis studies. In the adsorption experiments, the efficiency of (NaAlg/AAm)IPN hydrogels to adsorb nickel, cadmium and lead ions from water was studied. (NaAlg/AAm)IPN hydrogels showed different adsorption for different aqueous solution of metal ion at pH 7.0. Adsorption isotherms were constructed for the (NaAlg/AAm)IPN‐metal ion systems. S type adsorption in the Giles classification system was found.     

Hyaluronan/Collagen Hydrogels with Sulfated Hyaluronan for Improved Repair of Vascularized Tissue Tune the Binding of Proteins and Promote Endothelial Cell Growth

Innovative biomaterial‐based concepts are required to improve wound healing of damaged vascularized tissues especially in elderly multimorbid patients. To develop functional hydrogels as 3D cellular microenvironments and as carrier or scavenging systems, e.g., for mediator proteins or proinflammatory factors, collagen fibrils are embedded into a network of photo‐crosslinked acrylated hyaluronan (HA), chondroitin sulfate (CS), or sulfated HA (sHA). After lyophilization, the gels show a porous structure and an improved stability against degradation via hyaluronidase. Gels with CS and sHA bind significantly more lysozyme than HA/collagen gels and retard its release. The proliferation and metabolic activity of endothelial cells are significantly increased on sHA gels compared to CS‐ or only HA‐containing hydrogels. These findings highlight the potential of HA/collagen hydrogels with sulfated glycosaminoglycans to tune the protein binding and release behavior and to directly modulate cellular response. This can be easily translated into biomimetic biomaterials with defined properties to stimulate wound healing.     

Conducting hydrogels based on semi‐interpenetrating networks of polyaniline in poly(acrylamide‐co‐itaconic acid) matrix: synthesis and characterization

In this work, acrylamide/itaconic acid copolymeric hydrogels are prepared by free radical polymerization initiated by redox initiators of potassium persulfate and N ,N ,N ′,N ′‐tetramethyl ethylene diamine; N ,N ′methylene bisacrylamide was employed as a crosslinking agent. Aniline monomer was absorbed in the network of poly(acrylamide‐co‐itaconic acid) P(AAm‐co‐IA) hydrogel and followed by gamma radiation induced polymerization at room temperature. The novel semi‐interpenetrating network was comprised of linear polyaniline immersed in P(AAm‐co‐IA) matrix. Electrical conductivity of the hydrogels was measured using four‐probe technique. The conductivities for the prepared hydrogels are found to increase from 5.5 × 10^?7 S cm^?1 for P(AAm‐co‐IA) alone to 4.4 × 10^?3 S cm^?1 for semi‐interpenetrating polymer network P(AAm‐co‐IA)/polyaniline. Thus, a new composite hydrogel with good conductive properties also displaying enhanced mechanical strength and pH sensitivity was prepared. Copyright © 2017 John Wiley & Sons, Ltd.     

Glycopolymeric inhibitors of β‐glucuronidase. III. Configurational effects of hydroxy groups in pendant glyco‐units in polymers upon inhibition of β‐glucuronidase

Two kinds of new glycopolymers, (P(VB‐1‐GlcaH‐co‐AAm), 9 ) and (P(VB‐1‐Glco‐co‐AAm), 10 ), were synthesized through the radical copolymerization of styrene derivatives bearing pendant D ‐glucaric and D ‐gluconic moieties, N‐(p‐vinylbenzyl)‐1‐D ‐glucaramide (VB‐1‐GlcaH, 7 ), and N‐(p‐vinylbenzyl)‐D ‐gluconamide (VB‐1‐Glco, 8 ), with acrylamide (AAm). Glycopolymer 9 bearing the pendant glucaric moiety at the first position inhibited the hydrolysis of a model compound for xenobiotics‐β‐glucuronide conjugates, p‐nitrophenyl β‐D ‐glucuronide, uncompetitively, in contrast to the competitive inhibition in the presence of the corresponding isomeric glycopolymer bearing the pendant D ‐glucaric unit at the sixth position (P(VB‐6‐GlcaH‐co‐AAm), 3 ) reported in our previous article. On the other hand, another copolymer 10 bearing the gluconic moiety was found not to inhibit the hydrolysis as well as the corresponding copolymer bearing pendant gulonic unit (P(VB‐6‐Glco‐co‐AAm), 4 ). These results indicate that the hydrolysis is influenced not only by existence of pendant carboxyl units but also by the direction on the linkage of the glyco‐units to the polymer frame. Therefore the configurational position of hydroxy groups in pendant glyco‐units in macromolecular inhibitors may be essential for the interaction with β‐glucuronidase. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4895–4903, 2006     

Synthesis and characterization of poly(N‐vinyl formamide) hydrogels—A potential alternative to polyacrylamide hydrogels

The synthesis and characterization of solution‐cast, molded gels of N‐vinyl formamide (NVF) has not been previously reported even though NVF is an isomer of acrylamide (AAm) and polyacrylamide (PAAm) hydrogels have many commercial applications. Aqueous NVF solutions were cross‐linked into gels using a novel cross‐linker, 2‐(N‐vinylformamido)ethylether, and the thermally‐activated initiator VA‐044. For a given formulation, PNVF gels swell up to twice that of PAAm gels cross‐linked with N,N′‐methylenebisacrylamide. From swelling and compression measurements, PNVF gels were found to be more hydrophilic than PAAm gels. Flory‐Huggins solubility parameters were χ = 0.38?₂ + 0.48 for PNVF and χ = 0.31?₂ + 0.49 for PAAm, where ?₂ is the polymer volume fraction. The shear moduli for PNVF and PAAm scale with ? and ? respectively, consistent with good solvent behavior, also suggesting PNVF is more hydrophilic than PAAm. Similarity of mechanical properties for both gels as a function of ?₂ suggests that network structures of PNVF and PAAm gels are similar. Fracture strains of both gels declined with ?₂ by the same linear function while fracture stresses were about 500 kPa regardless of formulation. Since NVF is a liquid monomer, less toxic than AAm and can be hydrolyzed to a cationic form, PNVF gels could become technologically significant. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Tailored Synthesis of Various Nanomaterials by Using a Graphene‐Oxide‐Based Gel as a Nanoreactor and Nanohybrid‐Catalyzed CC Bond Formation

New graphene oxide (GO)‐based hydrogels that contain vitamin B₂/B₁₂ and vitamin C (ascorbic acid) have been synthesized in water (at neutral pH value). These gel‐based soft materials have been used to synthesize various metal nanoparticles, including Au, Ag, and Pd nanoparticles, as well as nanoparticle‐containing reduced graphene oxide (RGO)‐based nanohybrid systems. This result indicates that GO‐based gels can be used as versatile reactors for the synthesis of different nanomaterials and hybrid systems on the nanoscale. Moreover, the RGO‐based nanohybrid hydrogel with Pd nanoparticles was used as an efficient catalyst for C? C bond‐formation reactions with good yields and showed high recyclability in Suzuki–Miyaura coupling reactions.     

Oleochemical‐Tethered SBA‐15‐Type Silicates with Tunable Nanoscopic Order,Carboxylic Surface,and Hydrophobic Framework: Cellular Toxicity,Hemolysis, and Antibacterial Activity

Novel silicates were prepared by using silylated natural fatty acids (derived from triglyceride renewable oils) as co‐condensing reagents in presence of tetraethyl orthosilicate (TEOS) and the triblock copolymer, pluronic P123, as a structure directing agent. A series of carboxylic acid functionalized SBA‐15‐type mesoporous silicates were obtained with tunable nanoscopic order and reactive functional groups that allow the conjugation of amino probes by peptide coupling. Photophysical studies of the covalently linked aminopyrene substantiated that the internal framework of these materials have pronounced hydrophobicity. Moreover, phase separation that can emanate from the bulkiness of the starting fatty silanes has been ruled out owing to the absence of excimers after aminopyrene grafting. The hemotoxicity, cytotoxicity, and antimicrobial activity of these novel silicates were then evaluated. Without discrimination, the functionalized silicates show a significant decrease of red blood cell hemolysis as compared to bare SBA‐15‐silica material. Within the modified silicate series, germanium‐free mesoporous silicates induce only a slight decrease in cell viability and, more interestingly, they exhibit negligible hemolytic effect. Moreover, increasing their concentration in the medium reduces the concentration of released hemoglobin as a result of Hb adsorption. Promising antimicrobial properties were also observed for these silicates with a slight dependency on whether phenylgermanium fragments were present within the silicate framework.     

Swelling characterization of novel ternary semi‐IPNs: acrylamide/1‐vinylimidazole/PEG hydrogels

New ternary semi interpenetrating polymer networks (semi‐IPNs) systems containing acrylamide (AAm), 1‐vinylimidazole (VI) and poly (ethylene glycol) (PEG) have been prepared. AAm/VI hydrogels and semi‐IPN's, poly (AAm/VI/PEG) with 0.25, 0.50, 0.75 and 1.00 g of PEG (per 1.00 g AAm) were prepared by free radical solution polymerization in aqueous solution of AAm with VI as comonomer and a multifunctional crosslinker such as 1,4 butanediol dimethacrylate (BDMA). Swelling experiments were performed in water at 25°C, gravimetrically. The influence of VI and PEG content in hydrogels were examined. AAm/VI and AAm/VI/PEG hydrogels showed large extents of swelling in aqueous media, the swelling being highly dependent on the chemical composition of the hydrogels. Percentage swelling ratio of AAm/VI hydrogels and AAm/VI/PEG hydrogels was shown as 650–4167%. The values of equilibrium water content (EWC) of the hydrogels are between 0.8990 and 0.9750. Diffusion behavior was investigated. Water diffusion into hydrogels was found to be non‐Fickian in character. Copyright © 2007 John Wiley & Sons, Ltd.     

Spongy Gels by a Top‐Down Approach from Polymer Fibrous Sponges

Ultralight cellular sponges offer a unique set of properties. We show here that solvent uptake by these sponges results in new gel‐like materials, which we term spongy gels. The appearance of the spongy gels is very similar to classic organogels. Usually, organogels are formed by a bottom‐up process. In contrast, the spongy gels are formed by a top‐down approach that offers numerous advantages for the design of their properties, reproducibility, and stability. The sponges themselves represent the scaffold of a gel that could be filled with a solvent, and thereby form a mechanically stable gel‐like material. The spongy gels are independent of a time‐consuming or otherwise demanding in situ scaffold formation. As solvent evaporation from gels is a concern for various applications, we also studied solvent evaporation of wetting and non‐wetting liquids dispersed in the sponge.     

Swelling behavior of poly{N‐[3‐(dimethylaminopropyl)] methacrylamide‐co‐acrylamide} hydrogels in aqueous solutions of surfactants

Temperature sensitive poly{N‐[3‐(dimethylaminopropyl)]methacrylamide‐co‐acrylamide} [P(DMAPMA‐co‐AAm)] hydrogels were prepared by the free‐radical crosslinking copolymerization of corresponding monomers in water with N,N‐methylenebisacrylamide as the crosslinker, ammonium persulfate as the initiator, and N,N,N′,N′‐tetramethylethylenediamine as the activator. The swelling equilibrium of the P(DMAPMA‐co‐AAm) hydrogels was investigated as a function of temperature in aqueous solutions of the anionic surfactant sodium dodecyl sulfate and the cationic surfactant dodecyltrimethylammonium bromide. In pure water, regardless of the amount of N,N‐methylenebisacrylamide, the P(DMAPMA‐co‐AAm) hydrogels showed a discontinuous phase transition between 30 and 36 °C. However, the transition temperature changed from discontinuous to continuous with the addition of surfactants; this was ascribed to the conversion of nonionic P(DMAPMA‐co‐AAm) hydrogels into polyelectrolyte hydrogels due to the binding of surfactants through hydrophobic interactions. Additionally, the concentrations of free sodium dodecyl sulfate and dodecyltrimethylammonium bromide ions were measured at different temperatures by conductometry, and it was found that the electric conductivity of the P(DMAPMA‐co‐AAm)–surfactant systems depended strongly on the swelling ratio; most notably, it changed drastically near the phase‐transition temperature of the P(DMAPMA‐co‐AAm) hydrogel. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1645–1652, 2006     

聚(2-丙烯酰胺基-2-甲基丙磺酸/丙烯酰胺)水凝胶合成与性能研究

以2-丙烯酰胺基-2-甲基丙磺酸和丙烯酰胺为原料,以PEG6000为成孔剂,采用水溶液法合成多孔性聚(2-丙烯酰胺基-2-甲基丙磺酸/丙烯酰胺)水凝胶,研究了凝胶的溶胀性和电场作用下的退溶胀性能.在凝胶制备过程中,PEG6000分子充当成孔剂,通过综合性能比较和红外光谱测试可知,所得凝胶具有多孔结构,这种孔洞结构有利于水分子的进出.结果显示,当引发剂为0.005 mol/L,交联剂为0.008 mol/L,摩尔比AMPS:PEG6000=100∶1,AMPS:AAm=2∶1时,可得综合性能较好的PAMA凝胶.     

A new specific metal ion chelated‐poly(N‐vinylimidazole) gel sorbents for albumin adsorption‐desorption

Poly(N‐vinylimidazole) (PVIm) hydrogels were prepared by γ‐irradiating binary mixtures of N‐vinylimidazole‐water in a ⁶⁰Co‐γ source having 4.5 kGy/h dose rate. These affinity gels having different swelling ratio of Cu(II)‐chelated, Co(II)‐chelated and plain PVIm in acetate buffer were used in the albumin adsorption studies. Bovine serum albumin (BSA) adsorption on these gels from aqueous solutions containing different amounts of BSA at different pH adjusted with acetate and phosphate buffer was investigated in batch reactors. The adsorption capacities of BSA on/in the gels were decreased dramatically by increasing the ionic strength (I) adjusting with NaCl. BSA adsorption capacities of the metal ion‐chelated gels were higher than the plain PVIm gel even if the swelling ratio of the metal ion‐chelated gels was very low comparing to the PVIm gel. The rigidity of the metal ion‐chelated gel is very high and it can be used for the column applications. More than 95% of BSA were desorbed in 3 h in the desorption medium containing KSCN for PVIm gel and EDTA for metal ion‐chelated gels. These results indicate that PVIm and metal ion‐chelated PVIm gels are very efficient to remove BSA and the different metal ion‐chelated PVIm gels show different affinity for BSA or biomolecules.     

Gelatin‐based photopolymers for bone replacement materials

Gelatin‐based monomers were considered as suitable base component for the 3D structuring of potential bone replacement materials by stereolithographic techniques. Different methacrylate‐based gelatin derivatives were prepared, whereas a polyethylene glycol modified derivative GP4M turned out to have the highest tolerance toward other monomers. These are essential as they allow the tuning of the photoreactivity and the mechanical properties. Cell culture experiments with osteoblast‐ and endothelial‐like cells confirmed negligible cytotoxicity of these monomers. Finally, we were able to show the possibility of producing arbitrary cellular structures with these gelatin‐containing formulations using stereolithography. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009     

Hierarchical Corannulene‐Based Materials: Energy Transfer and Solid‐State Photophysics

We report the first example of a donor–acceptor corannulene‐containing hybrid material with rapid ligand‐to‐ligand energy transfer (ET). Additionally, we provide the first time‐resolved photoluminescence (PL) data for any corannulene‐based compounds in the solid state. Comprehensive analysis of PL data in combination with theoretical calculations of donor–acceptor exciton coupling was employed to estimate ET rate and efficiency in the prepared material. The ligand‐to‐ligand ET rate calculated using two models is comparable with that observed in fullerene‐containing materials, which are generally considered for molecular electronics development. Thus, the presented studies not only demonstrate the possibility of merging the intrinsic properties of π‐bowls, specifically corannulene derivatives, with the versatility of crystalline hybrid scaffolds, but could also foreshadow the engineering of a novel class of hierarchical corannulene‐based hybrid materials for optoelectronic devices.     

Atypical transition temperature dependence of poly(N‐isopropylacrylamide) and poly(N‐isopropylacrylamide‐co‐acrylamide) nanocomposites on the content of exfoliated montmorillonites

Exfoliated montmorillonite (MMT)/poly(N‐isopropylacrylamide) (PNIPAAm) and MMT/poly(N‐isopropylacrylamide‐co‐acrylamide) [P(NIPAAm‐co‐AAm)] nanocomposites were fabricated by soap‐free emulsion polymerization. Interestingly, as the content of MMT was increased from 0 to 10 wt %, the glass transition temperature of MMT/PNIPAAm was decreased from 145 to 122 °C, whereas that of the MMT/P(NIPAAm‐co‐AAm) increased from 95 to 153 °C. Although the lower critical solution temperature (LCST) of 32 °C for the MMT/PNIPAAm nanocomposites in aqueous solutions was slightly increased with the content of MMT, that of the MMT/P(NIPAAm‐co‐AAm) was decreased from 70 to 65 °C. A mechanism that the hydrogen bonds between the amide groups of PNIPAAm were interfered by the exfoliated MMT nano‐platelets for the MMT/PNIPAAm nanocomposites and the preferred absorption of acrylamide units to the MMT nanoplatelets rather than N‐isopropylacrylamide in the MMT/P(NIPAAm‐co‐AAm) nanocomposites was suggested to interpret these unusual transition behavior. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 524–530, 2009