Synthesis and optical properties of organic–inorganic hybrid semi‐interpenetrating polymer network gels containing polyfluorenes

Organic–inorganic hybrid semi‐interpenetrating polymer network (semi‐IPN) gels containing polyfluorenes (PFs) are synthesized by hydrosilylation reaction of joint and rod molecules in toluene, where PFs are poly(9,9‐dihexylfluorene‐2,7‐diyl) (PF6) or, poly(9,9‐dioctylfluorene‐2,7‐diyl) (PF8), joint molecules are 1,3,5,7‐tetramethylcyclotetrasiloxane (TMCTS), or 1,3,5,7,9,11,13,15‐octakis(dimethylsilyloxy)pentacyclo‐[9,5,1,1,1,1]octasilsesquioxane (POSS), and rod molecules are 1,5‐hexadiene (HD) or 1,9‐decadiene (DD). The semi‐IPN gels containing low molecular weight PF6 show higher photoluminescence efficiency (?_g) than the toluene solution of PF6L (?_s). The semi‐IPN gels composed of long rod molecule of DD and cubic joint molecule of POSS show the most effective increase in the emission intensity. The emission intensity of PF6L increases as formation of the network in the POSS‐DD semi‐IPN gel. The POSS‐DD semi‐IPN gels containing high molecular weight PF6 and PF8 also show the increase of emission intensity than those of the toluene solutions. The semi‐IPN synthesized in cyclohexane show syneresis and phase separation between network structure and PF chains. The semi‐IPN gels containing PF8 show emission peaks at 450 and 470 nm derived from β‐sheet structure of PF8. A systematic study clears correlation between emission property and network structure and/or composition of semi‐IPN gels. The semi‐IPN gels provide emissive self‐standing soft materials with high efficiency and in a narrow wavelength range emission. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 973–984     

A novel pH‐ and thermo‐sensitive PVP/CMC semi‐IPN hydrogel: Swelling,phase behavior,and drug release study

Poly(N‐vinyl‐pyrrolidone) (PVP) hydrogel has been considered as a very interesting and promising thermosensitive material. The most vital shortcoming of PVP hydrogel as thermosensitive material is that it does not exhibit thermosensitivity under usual conditions. In this work, semi‐interpenetrating polymer network (semi‐IPN) hydrogels based on PVP and carboxymethylcellulose (CMC) were prepared. The volume phase transition temperature (VPTT) of the hydrogels was determined by swelling behavior and differential scanning calorimetry (DSC). The results showed that the VPTT was significantly dependent on CMC content and the pH of the swelling medium. The amount of CMC in the semi‐IPN hydrogels was 0.050, 0.075, and 0.100 g, the VPTT in buffer solution of pH 1.2 was 29.9 °C, 27.5 °C and 24.5 °C, respectively. In addition, the VPTT occurred in buffer solution of pH 1.2, but did not appear in alkaline medium. Bovine serum albumin (BSA) as a model drug was loaded and the in vitro release studies were carried out in different buffer solutions and at different temperatures. The results of this study suggest that PVP/CMC semi‐IPN hydrogels could serve as potential candidates for protein drug delivery in the intestine. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1749–1756, 2010     

Miscibility and properties of polyurethane/benzyl starch semi‐interpenetrating polymer networks

We successfully prepared a series of transparent materials with semi‐interpenetrating polymer networks (semi‐IPNs) from castor‐oil‐based polyurethane (PU) and benzyl starch (BS). The miscibility, morphology, and properties of the semi‐IPN films were investigated with attenuated total reflection/Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical thermal analysis, scanning electron microscopy, wide‐angle X‐ray diffraction, electron spin resonance (ESR), ultraviolet–visible spectroscopy, and tensile testing. The results revealed that the semi‐IPN films had good or certain miscibility with BS concentrations of 5–70 wt % because of the strong intermolecular interactions between PU and BS. With an increase in the concentration of BS, the tensile strength and Young's modulus of the semi‐IPN materials increased. The ESR data confirmed that the segment volume of PU in the semi‐IPNs increased with the addition of BS; that is, the chain stiffness increased as a result of strong interactions between PU and BS macromolecules. It was concluded that starch derivatives containing benzyl groups in the side chains more easily penetrated the PU networks to form semi‐IPNs than those containing aliphatic groups, and this led to improved properties. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 603–615, 2005     

Synthesis and characterization of κ‐carrageenan/poly(N,N‐diethylacrylamide) semi‐interpenetrating polymer network hydrogels with rapid response to temperature

In this study, a novel classical thermo‐ and salt‐sensitive semi‐interpenetrating polymer network (semi‐IPN) hydrogel composed of poly(N,N‐diethylacrylamide) (PDEAm) and κ‐carrageenan (KC) was synthesized by free radical polymerization. The structure of the hydrogels was studied by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). FTIR and SEM revealed that the semi‐IPN hydrogels possessed the structure of H‐bonds and larger number of pores in the network. Compared to the PDEAm hydrogel, the prepared semi‐IPN hydrogels exhibited a much faster response rate to temperature changes and had larger equilibrium swelling ratios at temperatures below the lower critical solution temperature (LCST). The salt‐sensitive behavior of the semi‐IPN hydrogels was dependent on the content of KC. In addition, during the reswelling process, semi‐IPN hydrogels showed a non‐sigmoidal swelling pattern. Copyright © 2008 John Wiley & Sons, Ltd.     

Antimicrobial loading into and release from poly(ethylene glycol)/poly(acrylic acid) semi‐interpenetrating hydrogels

Electrostatic interactions within a semi‐interpenetrating network (semi‐IPN) gel can control the postsynthesis loading, long‐term retention, and subsequent release of small‐molecule cationic antibiotics. Here, electrostatic charge is introduced into an otherwise neutral gel [poly(ethylene glycol) (PEG)] by physically entrapping high‐molecular‐weight poly(acrylic acid) (PAA). The network structure is characterized by small‐angle neutron scattering. PEG/PAA semi‐IPN gels absorb over 40 times more antibiotic than PAA‐free PEG gels. Subsequent soaking in physiological buffer (pH 7.4; 0.15 M NaCl) releases the loaded antibiotics for periods as long as 30 days. The loaded gels elute antibiotics with diffusivities of 4.46 × 10^?8 cm²/s (amikacin) and 2.08 × 10^?8 cm²/s (colistin), which are two orders of magnitude less than those in pure PEG gels where diffusion is controlled purely by gel tortuosity. The release and hindered diffusion can be understood based on the partial shielding of the charged groups within the loaded gel, and they have a significant effect on the antimicrobial properties of these gels. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 64–72     

Preparation and properties of poly(N‐isopropylacrylamide)/poly(N‐isopropylacrylamide) interpenetrating polymer networks for drug delivery

A novel poly(N‐isopropylacrylamide) (PNIPA)/PNIPA interpenetrating polymer network (IPN) was synthesized and characterized. In comparison with conventional PNIPA hydrogels, the shrinking rate of the IPN hydrogel increased when gels, swollen at 20 °C, were immersed in 50 °C water. The phase‐transition temperature of the IPN gel remained unchangeable because of the same chemical constituent in the PNIPA gel. The reswelling kinetics were slower than those of the PNIPA hydrogel because of the higher crosslinking density of the IPN hydrogel. The IPN hydrogel had better mechanical strength because of its higher crosslinking density and polymer volume fraction. The release behavior of 5‐fluorouracil (5‐Fu) from the IPN hydrogel showed that, at a lower temperature, the release of 5‐Fu was controlled by the diffusion of water molecules in the gel network. At a higher temperature, 5‐Fu inside the gel could not diffuse into the medium after a burst release caused by the release of the drug on the surface of the gel. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1249–1254, 2004     

Preparation and properties of organic–inorganic hybrid gel films based on polyvinylpolysilsesquioxane synthesized from trimethoxy(vinyl)silane

Polyvinylpolysilsesquioxane (PVPS) organic–inorganic hybrid gel films comprising polyethylene and siloxane backbone linkages were prepared through two routes: trimethoxy(vinyl)silane (VTS) was first subjected to radical polymerization of the vinyl groups, followed by acid‐catalyzed hydrolytic polycondensation of the trimethoxysilyl groups (route A) to afford PVPS; in the second route PVPS was prepared in reverse order (route B). PVPS gel films were transparent and homogeneous. We find that the mechanical and heat‐resisting properties correlate both to the degree of polymerization and the degree of cross‐linking. Copyright © 2003 John Wiley & Sons, Ltd.     

Terpyridine‐modified poly(vinyl chloride): Possibilities for supramolecular grafting and crosslinking

Commercially available poly(vinyl chloride) (PVC) was covalently modified with terpyridine supramolecular binding units in a two‐step reaction. First, PVC was modified with aromatic thiols to introduce OH functionalities into the polymer backbone, which were subsequently reacted with an isocyanate‐functionalized terpyridine binding unit. The resulting functionalized material contained metal‐ion binding sites, which could be used for grafting and crosslinking reactions. A grafting experiment was performed with a small organic terpyridine ligand. The complexation of the modified PVC with several transition‐metal ions was studied with ultraviolet–visible spectroscopy and gel permeation chromatography. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2964–2973, 2003     

Influence of the type of epoxy hardener on the structure and properties of interpenetrated vinyl ester/epoxy resins

The morphology–toughness relationship of vinyl ester/cycloaliphatic epoxy hybrid resins of interpenetrating network (IPN) structures was studied as a function of the epoxy hardening. The epoxy was crosslinked via polyaddition reactions (with aliphatic and cycloaliphatic diamines), cationic homopolymerization (via a boron trifluoride complex), and maleic anhydride. Maleic anhydride worked as a dual‐phase crosslinking agent by favoring the formation of a grafted IPN structure between the vinyl ester and epoxy. The type of epoxy hardener strongly affected the IPN morphology and toughness. The toughness was assessed by linear elastic fracture mechanics, which determined the fracture toughness and energy. The more compact the IPN structure was, the lower the fracture energy was of the interpenetrated vinyl ester/epoxy formulations. This resulted in the following toughness ranking: aliphatic diamine > cycloaliphatic diamine ≥ boron trifluoride complex > maleic anhydride. For IPN characterization, the width of the entangling bands and the surface roughness parameters were considered. Their values were deduced from atomic force microscopy scans taken on ion‐etched surfaces. More compact, less rough IPN‐structured resins possessed lower toughness parameters than less compact, rougher structured ones. The latter were less compatible according to dynamic mechanical thermal and thermogravimetric analyses. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5471–5481, 2004     

Effect of Sodium Alginate on the Properties of Thermosensitive Hydrogels

Sodium alginate (SA ) was combined with poly(N ‐isopropylacrylamide) (PNIPAAm ) to prepare thermosensitive hydrogels through semi‐interpenetrating polymer network (semi‐IPN ) and fully interpenetrating polymer network (full‐IPN ). The thermosensitive, swelling, mechanical, and thermal properties of pure PNIPAAm , SA /PNIPAAm semi‐IPN , and Ca‐alginate/PNIPAAm full‐IPN hydrogels were investigated. The formation of semi‐IPN and full‐IPN significantly improved the hydrogels’ swelling capability and mechanical properties without altering their thermosensitivity. 5‐Fluorouracil (5‐Fu) was selected as a model drug to study the release behaviors of the hydrogels. It was found that in vitro controlled drug release from semi‐IPN hydrogels showed an initial release burst, followed by a slower and sustained release, before reaching equilibrium. Full‐IPN hydrogels showed slow and sustained release during the whole process. Temperature and pH were found to affect the rate of drug release. Ca‐alginate/PNIPAAm full‐IPN hydrogels have potential application as drug delivery matrices in controlled drug release.     

Hydrogel‐like elastic membrane consisting of semi‐interpenetrating polymer networks based on a phosphorylcholine polymer and a segmented polyurethane

To obtain a hydrogel‐like elastic membrane, we prepared semi‐interpenetrating polymer networks (IPNs) by the radical polymerization of methacrylates such as 2‐methacryloyloxyethyl phosphorylcholine (MPC), 2‐hydroxyethylmethacrylate, and triethyleneglycol dimethacrylate diffused into segmented polyurethane (SPU) membranes swollen with a monomer mixture. The values of Young's modulus for the hydrated semi‐IPN membranes were less than that for an SPU membrane because of higher hydration, but they were much higher than that for a hydrated MPC polymer gel (non‐SPU). According to a thermal analysis, the MPC polymer influenced the segment association of SPU. The diffusion coefficient of 8‐anilino‐1‐naphthalenesulfonic acid sodium salt from the semi‐IPN membrane could be controlled with different MPC unit concentrations in the membrane, and it was about 7 × 10² times higher than that of the SPU membrane. Fibroblast cell adhesion on the semi‐IPN membrane was effectively reduced by the MPC units. We concluded that semi‐IPNs composed of the MPC polymer and SPU may be novel polymer materials possessing attractive mechanical, diffusive‐release, and nonbiofouling properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 68–75, 2003     

Rheological and swelling behavior of semi‐interpenetrating networks of polyacrylamide and scleroglucan

Preparation and characterization of novel semi‐interpenetrating polymer network (semi‐IPN) hydrogels based on partially hydrolyzed polyacrylamide (HPAM) and scleroglucan solution crosslinked with chromium triacetate are described. Effects of scleroglucan concentration on the gelation process and swelling behavior of synthesized hydrogels in different media were investigated using dynamic rheometery and swelling tests, respectively. Oscillatory shear rheology showed that the limiting storage modulus of the semi‐IPN gels increased with increase in scleroglucan concentration. It was also found that the viscous energy dissipating properties of the semi‐IPN gels decreased with increase in the crosslinker concentration of the gelation system. In addition, the loss factor slightly decreased by increasing the scleroglucan content, indicating that the viscous properties of this gelling system decreased more than its elastic properties. The swelling tests showed that the equilibrium swelling ratio (ESR) of the semi‐IPN networks decreased with increase in scleroglucan content, due to the decrease of ionic groups of polyelectrolyte hydrogel. However, the semi‐IPN gels showed lower salt sensitivity in synthetic oil reservoir water as compared with HPAM gels. Therefore, these semi‐IPN hydrogels may be considered potentially good candidates for enhanced oil recovery (EOR) applications. Copyright © 2009 John Wiley & Sons, Ltd.     

Study of the effect of poly(vinyl alcohol) concentration on the gelation point of poly(vinyl alcohol) poly(acrylic acid) semi‐IPN systems as determined by viscoelastic measurements

We report on the determination of the gelation point of semi‐interpenetrating polymer networks (semi‐IPNs) composed of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAAc) formed by a sequential method. The evolution of the viscoelasticity during the gelation reaction of acrylic acid (AAc) in solutions of PVA has been monitored through the sol‐gel transition with dynamic mechanical experiments. The gelation time of the system increased with PVA concentration; however, the molecular structure of the gel, composed of swollen clusters, is rather independent of the presence of PVA. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1944–1949, 2005     

Structural design of stimuli‐responsive bioconjugated hydrogels that respond to a target antigen

Stimuli‐responsive bioconjugated hydrogels that can respond to a target antigen (antigen‐responsive hydrogels) were prepared by introducing antigen‐antibody bindings as reversible crosslinks into the gel networks. The preparation conditions of the antigen‐responsive hydrogels and the mechanism of the antigen‐responsive behavior were investigated, focusing on bioconjugated hydrogel structures. This article also focuses on the effect of semi‐interpenetrating polymer network (semi‐IPN) structures on the antigen‐responsive swelling/shrinking behavior of bioconjugated hydrogels with antigen‐antibody bindings. The preparation conditions and the network structures of the bioconjugated hydrogels are discussed in relation to designing antigen‐responsive hydrogels. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2144–2157, 2009     

Biodegradation of plasticized poly(vinyl chloride) containing cellulose

The plasticized poly(vinyl chloride) (PVC‐P) and its blend with cellulose (PVC‐P/cell) were prepared by means of extrusion. The samples were then biodegraded in forest soil as well as in soil enriched with cellulolytic microorganisms. Moreover, the samples were vaccinated with chosen species of fungi whose direct effect on polymer was then observed. The course of biodegradation was monitored in terms of, and by means of the following: weight loss, carbon dioxide evolved, attenuated total reflectance infrared (FTIR‐ATR) spectroscopy, gel permeation chromatography (GPC), as well as visual and microscopic observation (OM, SEM). The mechanical properties of samples were studied using the standard tensile tests. It was found that biodegradation in soil occurs in PVC‐P and this process is accelerated in the composition of PVC‐P with cellulose. The biodecomposition yield of PVC‐P/cellulose blends (calculated as relative percentage weight loss) is several dozen times higher than that of PVC‐P. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 903–919, 2007     

Synthesis of poly(vinylidene fluoride) (PVdF)/silica hybrids having interpenetrating polymer network structure by using crystallization between PVdF chains

High transparent and homogeneous poly(vinylidene fluoride) (PVdF)/silica hybrids were obtained by using an in‐situ interpenetrating polymer network (IPN) method. The simultaneous formation of PVdF gel resulting from the physical cross‐linking and silica gel from sol–gel process prevented the aggregation of PVdF in silica gel matrix. To form the physical cross‐linking between PVdF chains, the cosolvent system of dimethylformaide (DMF) and γ‐butyrolactone was used. The obtained PVdF/silica hybrids had an entangled combination of physical PVdF gel and silica gel, which was called a “complete‐ IPN” structure. The physical cross‐linking between PVdF chains in silica gel matrix was confirmed by differential scanning calorimetry (DSC) measurements. The miscibility between PVdF and silica phase was examined by scanning electron microscopy (SEM) and tapping mode atomic force microscopy (TM‐AFM) measurements. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3543–3550, 2005     

室温固化蓖麻油聚氨酯/乙烯基聚合物互穿网络材料的一些规律及其性能

研究了蓖麻油与甲苯二异氰酸酯及丙烯酸酯或苯乙烯等乙烯基单体在室温下生成的互穿网络聚合物(IPN)的一些规律及其性能.用红外光谱追踪表明,聚氨酯的生成快于甲基丙烯酸甲酯的聚合.研究IPN凝胶点指出.凝胶点时间随聚氨酯含量增加及聚苯乙烯含量减少而缩短.丙烯酸甲酯在生成IPN过程中凝胶的生成速度要比苯乙烯的场合快.丙烯酸丁酯、丙烯腈或丙烯酸甲酯与蓖麻油聚氨酯生成的IPN的抗张强度在聚氨酯占一半时呈现最大值.透射电镜观察表明,生成速率较快的聚氨酯的微区存在于聚丙烯酸甲酯中.聚丙烯酸甲酯与蓖麻油聚氨酯形成的IPN在tanδ-T,曲线上呈现一个宽的玻璃化转变温度.     

Functionalization of the active chain ends of poly(vinyl chloride) obtained by single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization: Synthesis of telechelic α,ω‐di(hydroxy)poly(vinyl chloride)

The chloroiodomethyl chain ends of poly(vinyl chloride) (PVC) obtained by the single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization of vinyl chloride initiated with iodoform were quantitatively functionalized by the reaction with 2‐allyloxyethanol (CH₂?CHCH₂OCH₂CH₂OH). This reaction was performed in dimethyl sulfoxide at 70 °C and was catalyzed by sodium dithionite/sodium bicarbonate. The resulting product is the first example of telechelic PVC [α,ω‐di(hydroxy)PVC]. A possible mechanism for this reaction was suggested. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1255–1260, 2005     

Homo‐ and copolymers of hexafluoroisopropyl methacrylate and α‐fluoroacrylate with alkyl vinyl ethers: Microstructure and thermal properties

A study is reported, dealing with the microstructure and thermal behavior of the homopolymers of 1,1,1,3,3,3‐hexafluoroisopropyl methacrylate (HFIM) and 1,1,1,3,3,3‐hexafluoroisopropyl α‐fluoroacrylate (HFIFA), as well as of their copolymers with various vinyl ethers. The aim of this work was a better understanding of the role that fluorine content and distribution—first in the monomer and then along the ensuring macromolecular chain—play in determining the polymerizability of the selected vinyl monomers, and the final properties of the polymeric material. Primary (n‐butyl, isobutyl, 2‐ethylhexyl), secondary (cyclohexyl), and tertiary (tert‐butyl) vinyl ethers were employed as the comonomers. A general tendency towards comonomer alternation was observed upon radical initiated copolymerization with HFIFA. On the other hand, the relatively more electron‐rich HFIM did not usually yield strictly alternating sequences, unless the bulky tert‐butyl vinyl ether was employed. The incorporation of electron‐rich vinyl ether monomers within a partially fluorinated polymeric chain by simple radical initiated process was considered particularly interesting in view of the possible application of these materials as water‐repellent protective coatings. In this case, the fluorinated units should provide the low energy surface (water repellency) and, possibly, photo‐ and thermostability, whereas the vinyl ether counits should grant improved adhesion and adequate film‐forming properties. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 32–45, 2001     

Preparation of poly(vinylalcohol)/poly(acrylamide‐co‐vinyl imidazole)/γ‐Fe2O3 semi‐IPN nanocomposite and their application for removal of heavy metal ions from water

A series of magnetic semi‐interpenetrating polymer network (semi‐IPN) hydrogels was prepared in one‐stage strategy composed of linear poly(vinyl alcohol) (PVA) chains and magnetic γ‐Fe₂O₃ nanoparticles entrapped within the cross‐linked poly(acrylamide‐co‐vinylimidazole) (poly(AAm‐co‐VI)) network. The influence of PVA, weight ratio of AAm:VI, γ‐Fe₂O₃, and MBA on the swelling properties of the obtained nanocomposite hydrogels was evaluated. The prepared magnetic semi‐IPN hydrogels were fully characterized and used as absorbent for removal of Pb(II) and Cd(II) from water. Factors that influence the metal ion adsorption such as solution pH, contact time, initial metal ion concentration, and temperature were studied in details. The experimental results were reliably described by Langmuir adsorption isotherms. The adsorption capacity of semi‐IPN nanocomposite for Pb(II) and Cd(II) were175.80 and 149.76 mg g^?1, respectively. The kinetic experimental data indicated that the chemical sorption is the rate‐determining step. According to thermodynamic studies, Pb(II) and Cd(II) adsorption on the hydrogels was endothermic and also chemical in nature. The prepared magnetic PVA/poly(AAm‐co‐VI) semi‐IPN hydrogels could be employed as efficient and low‐cost adsorbents of heavy metal ions from water. Copyright © 2016 John Wiley & Sons, Ltd.