Reactive and Functional Polymers (v.70, #9)

Ring-opening metathesis polymerization of steroid-conjugated norbornenes and gradual release of estrone from a polymer film by Shoujiro Ogawa; Shigenaga Takano; Hiroki Fujimori; Toshihiro Itoh; Shojiro Kaita; Takashi Iida; Yasuo Wakatsuki (563-571).
Steroids (estrone, estradiol, ursodeoxycholic acid, chenodeoxycholic acid, cortisone, prednisone, and dexamethasone) were reacted with either 5-norbornene-2-carboxylic acid chloride or 5-norbornene-2-methanol to form new norbornene derivatives with bioactive and sterically demanding steroid residues bound with an ester linkage. These norbornene-based monomers were polymerized by a ring-opening metathesis polymerization initiated by a ruthenium–carbene complex (Grubbs catalyst) or a ruthenium–vinylidene complex. With a few exceptions, the polymers were soluble in THF, and casting the solution produced films. Solid-state hydrolysis of the estrone-conjugated polymer film showed a slow but steady release of estrone under mild conditions (pH 5.5 or 3.0 at 37 °C).
Keywords: Steroid-bound norbornenes; Ring-opening metathesis polymerization; Ruthenium–vinylidene complex; Grubbs catalyst; Polymer film; Slow delivery of estrone;

Copolymers containing electronically isolated indolyl fragments as materials for optoelectronics by J. Lukstaite; D. Gudeika; J.V. Grazulevicius; S. Grigalevicius; B. Zhang; Z. Xie (572-577).
Monomer and its copolymers containing electronically isolated indolyl fragments were synthesized by multi-step synthetic route. The materials were examined by various techniques including thermogravimetry, differential scanning calorimetry, UV and fluorescence spectrometry as well as electron photoemission technique. The copolymers exhibit initial mass loss temperatures in the range of 259–321 °C and form amorphous films with glass transition temperatures of 102–122 °C. Thin layers of the materials demonstrate ionization potentials of about 5.7 eV. The copolymers were tested as host materials in electro-phosphorescent devices.
Keywords: Electro-active material; Monomer; Copolymer; Ionization potential; Light emitting diode;

Carboxyl-functionalized cross linked polymeric nanocapsules (PAA–CPS) with pH-responsive poly(acrylic acid) (PAA) brushes on the inner wall of the crosslinked polystyrene (CPS) shells have been prepared by the template-polymerization approach via combination of surface-initiated atom transfer radical polymerization (SI-ATRP) and ultraviolet-irradiated crosslinking techniques. The hollow structure of the crosslinked nanocapsules with an inner diameter of about 30–40 nm was confirmed by transmission electron microscopy (TEM). The adsorption experiments showed that the PAA–CPS nanocapsules possess a higher adsorption capacity towards the basic dye methylene blue (MB) than the PtBA–CPS nanocapsules. Furthermore, the MB-loaded PAA–CPS nanocapsules release the dye more rapidly in acidic medium than in a neutral medium.
Keywords: pH-responsive; Cross linked polymeric nanocapsules; Controlled release; Surface-initiated atom transfer radical polymerization; Ultraviolet-crosslinking;

Macroporous organogels were prepared by solution crosslinking various rubbers in benzene at −18 °C. Butyl rubber (PIB), cis-polybutadiene (CBR) and styrene–butadiene rubber (SBR) were used as the rubber components, while sulfur monochloride was the crosslinker in the gel preparation. The organogel networks consist of large pores of 101–102  μm in size caused by the benzene crystals acting as a template during gelation. The networks formed by CBR and SBR showed an aligned porous structure consisting of regular pores, whereas those derived from PIB had irregular pores with a broad pore size distribution due to the phase separation of PIB chains at low temperatures. All organogels were very tough and could be completely compressed without any crack development. Sorption tests showed that the organogels were efficient at removing crude oil, gasoline, diesel, fuel oil and olive oil. The organogels are reusable once they are squeezed, leading to continuous sorption capacities of CBR or SBR gels for crude oil and olive oil of 33–38 g/g and 24–27 g/g, respectively. These sorption capacities are two to three times the capacity of the gels derived from PIB.
Keywords: Organogels; Rubber; Macroporous; Cryogelation; Separation;

Amphiphilic AB2 Y-shaped poly(styrene)-poly(N-isopropylacryamide)2 block copolymer (PS-(PNIPAAm)2) is prepared through selective amidation and Michael additions reactions, using ω-amino PS and ω-amino PNIPAAm chains as arms and 5-maleimidoisophthalic acid (MIPA) as a core. The first step is end-capping PS chains with MIPA via the Michael addition reaction between the amino groups of ω-amino PS and the maleimide group of MIPA. Incorporation of two PNIPAAm chains to PS-MIPA chain ends via amidation reaction between the amino groups of ω-amino PNIPAAm and the carboxylic acid groups of PS-MIPA result in amphiphilic AB2 Y-shaped PS-(PNIPAAm)2 block copolymer. The amphiphilic PS-(PNIPAAm)2 block copolymer forms nanoparticles in aqueous solution, which exhibit a temperature-responsive characteristic due to the presence of PNIPAAm chains. The applications of the polymeric nanoparticles as fluorophore carriers and fluorescent sensors are also studied.
Keywords: Y-shaped copolymer; Amphiphilic copolymer; Micelle; Nanoparticles;

Nonionic polyacrylamide (PAAm) hydrogels were synthesized using three methods: room temperature polymerization, cryo-polymerization, and modified cryo-polymerization. Anionic PAAm hydrogels were obtained after hydrolyzing the nonionic hydrogels under alkaline conditions. The composition of anionic hydrogels was characterized by Fourier transform infrared (FT-IR) spectroscopy and element analysis. Morphological studies showed that the hydrogels exhibited various pore structures when they were synthesized using different methods. An additional mechanism for the formation of cryogels was proposed. Investigation of the swelling properties of the hydrogels and analysis of the swelling kinetics showed that the hydrolyzed PAAm hydrogels had rapid pH-sensitive rates.
Keywords: Porous structure; Polyacrylamide; Hydrogel; Cryo-polymerization; pH-sensitive;

The temperature-swing adsorption (TSA) of heavy metal ions onto 2-(dimethylamino)ethyl methacrylate (DMAEMA) gel has been examined. The DMAEMA gel adsorbs precious metal ions (Pt(IV), Au(III), and Pd(II)) in HCl aqueous media as a result of the electrostatic interactions between the protonated amino groups in the gel and the anionic chloro complexes, while it is inactive against Cu(II) and Ni(II) cations. The amount of Pt(IV) ions adsorbed onto the DMAEMA gel decreases linearly with an increase in temperature. The TSA operation was successfully carried out; the DMAEMA gel repeatedly adsorbed and desorbed Pt(IV) ions in the temperature-swing operation between 20 °C and 60 °C. The TSA technique using the DMAEMA gel is simple, environment-friendly, and potentially applicable in various separation processes for precious metals in industries.
Keywords: Thermosensitive gel; 2-(Dimethylamino)ethyl methacrylate; Temperature-swing adsorption; Precious metal; Platinum;

Synthesis and characterization of photoactive poly(arylene ether sulfone)s containing azobenzene moieties in their main chains by Xiangyu Jiang; Xingbo Chen; Xigui Yue; Jingjing Zhang; Shaowei Guan; Haibo Zhang; Wenyi Zhang; Qidai Chen (616-621).
A series of azobenzene functionalized poly(arylene ether sulfone)s (azo-PAESs) has been synthesized via nucleophilic aromatic substitution polycondensation, and azobenzene chromophores could be introduced into the polymer main chains by copolymerization from azo-monomers. These main chain type azo-PAESs have high glass transition temperatures and good thermal stability. Exposed to an interference pattern laser beam, spin-coated films of the azo-PAESs can form clear and stable surface relief gratings (SRGs). These SRGs show increased thermal stabilities with the content of azo moieties and cannot be fully removed until the temperature increases to 300 °C for azo-PAESs with a content of azo segments above 50%.
Keywords: Azo-polymer; Poly(arylene ether sulfone); Photoactive; Surface relief grating;

Poly(ε-caprolactone) diol functionalized with a cinnamoyl group and its UV-triggered in-plane alignment by Shi-Joon Sung; Jin Ho Yun; Seungwoo Lee; Jung-Ki Park; Dae-Hwan Kim; Kuk Young Cho (622-629).
Stimuli-sensitive biomaterials can present variable and tailored functions under specific external stimuli, thus showing potential for application in various biosciences. Significant efforts have focused on the utilization of light as a stimulus in biomedical applications because of its unique advantages, especially the precise control over its position, movement, and non-contact irradiation. This article highlights the preparation of a photo-reactive oligomer composed of biodegradable moieties and its UV-triggered in-plane molecular orientation, implicating its surface as a potential molecular alignment layer. We focus especially on the alignment of nematic liquid crystalline (LC) molecules on the biodegradable layer with molecular orientation, because they are promising candidates for sensing and interfacial applications.
Keywords: Oligomers; Orientation; Poly(ε-caprolactone); UV–vis spectroscopy;

This paper describes synthesis and characteristics of functional poly(ester-anhydride)s bearing allyl pendant groups. The polymers were obtained by polycondensation of 1,6-bis-p-carboxyphenoxyhexane (CPH) and oligo(3-allyloxy-1,2-propylene succinate) terminated with carboxyl groups (OSAGE). The carboxyl groups in OSAGE and in CPH were converted to mixed anhydride groups by acetylation with acetic anhydride. After that, prepolymers thus obtained were condensed in vacuum to yield poly(ester-anhydride)s. The structure of copolymers was confirmed by NMR spectroscopy. Influence of molecular weight of OSAGE as well as of the CPH and OSAGE content on selected properties of poly(ester-anhydride)s was examined. Poly(ester-anhydride)s were subjected to hydrolytic degradation at 37 °C, in aqueous phosphate buffer solution of pH 7.41 (PBS). The course of degradation was monitored by determination of weight loss of samples and 1H NMR. Fracture surfaces of samples during degradation were examined by scanning electron microscopy.
Keywords: Poly(ester-anhydride); Functional polymer; Hydrolytic degradation;

The macroreticular Rohm & Haas resin A70 and the DuPont silica/nafion microcomposite SAC-13 undergo facile metalation with NiII, PdII, PtII, CuII cationic species to give materials that do react with both molecular hydrogen in the “dry” state and sodium borohydride in the aqueous phase. The distribution of the reduced species in the body of the support particles is sensitive to the reduction protocol.
Keywords: Metal (0) nanoclusters; Commercial macroreticular resin; Silica–nafion microcomposite; Metal–resins nanocomposites;

Covalent grafting of polyacrylamide-based hydrogels to a polypropylene surface activated with functional polyperoxide by S. Varvarenko; A. Voronov; V. Samaryk; I. Tarnavchyk; N. Nosova; A. Kohut; S. Voronov (647-655).
Polyacrylamide (PAAm)-based hydrogels covalently bonded to a polypropylene (PP) substrate have been synthesized using modification of the PP with a new functional polyperoxide (FPP). The FPP initiates radical polymerization from the PP’s surface by decomposing the peroxide groups. Two different approaches for forming the hydrogel network have been used. In the first, a grafted hydrogel network is formed by radical polymerization of the acrylamide on the peroxidized PP substrate (“grafting from”) in the presence of N,N′-methylene-bis-acrylamide (a cross-linking agent) and potassium persulfate (an additional initiator in bulk). In the second approach, a grafted hydrogel network is synthesized by: (i) grafting the PAAm macromolecules from the peroxidized PP substrate and (ii) following intermolecular condensation of the surface-grafted PAAm and adding to the reactive bulk PAAm and poly-N-(hydroxymethyl)acrylamide (used as a cross-linking macromolecule), resulting in the formation of a hydrogel network grafted to the PP substrate.The covalent attachment of hydrogel networks has been verified for both approaches by contact angle measurements, dye adsorption by the hydrogel residues after network removal and extraction, and mechanical failure tests. The intermolecular condensation method has been found to be more advantageous for the formation of covalently bonded hydrogels on the PP substrate, while grafted network formation by radical polymerization was detected only for a limited range of monomer and cross-linking agent concentrations.
Keywords: Grafted hydrogels; Functional polyperoxide; Polyolefin surface;

Polyaniline-coated silver nanowires by Patrycja Bober; Jaroslav Stejskal; Miroslava Trchová; Jiřina Hromádková; Jan Prokeš (656-662).
Two non-conducting chemicals, aniline and silver nitrate, dissolved in formic acid solutions, yielded a composite of two conducting products, polyaniline and silver. As the concentration of formic acid increased, an alternative reaction, the reduction of silver nitrate with formic acid to silver became dominant, and the content of silver in the composites increased. The formation of polyaniline was confirmed by UV–visible, FTIR, and Raman spectroscopies. The typical conductivity of composites was 43 S cm−1 at 84 wt.% of silver. Silver nanowires coated with polyaniline nanobrushes are produced at low concentrations of formic acid, the granular silver particles covered with polyaniline dominate at high acid concentrations.
Keywords: Conducting polymer; Conductivity; Nanowire; Polyaniline; Silver;

The preparation of polyaniline/gold nanocomposites by self-assembly and their electrochemical applications by Qin Xu; Jun Leng; Hong-bo Li; Gui-ju Lu; Yang Wang; Xiao-Ya Hu (663-668).
Polyaniline/gold nanoparticles (PANI/AuNPs) nanocomposites were prepared using a simple self-assembly procedure. Polyvinyl pyrrolidone (PVP) was used as a stabilizing ligand of AuNPs and was shown to prevent the aggregation of AuNPs and to improve the affinity of AuNPs to PANI. By varying the ratio of PANI to AuNPs, the amount of loaded AuNPs was effectively controlled. UV–vis spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and electrochemical methods were used to characterize the nanocomposites. The nanocomposites showed electroactivity in neutral solution, making them promising candidates for various bioanalytical applications. A sensor constructed using PANI/AuNPs nanocomposites showed 6-fold higher electrocatalytic activity toward the oxidation of ascorbic acid than that composed of a pure PANI-modified electrode.
Keywords: Polyaniline; Polyvinyl pyrrolidone; Gold nanoparticles; Self-assembly;

Luminescent oxygen-sensory polymer-coatings composed of platinum tetrakis(pentafluorophenyl)-porpholactone (PtPL) and -porphyrin (PtPP) with poly(trimethylsilylpropyne) (PMSP) were prepared for visualization of the oxygen partial pressure on two parallel planes or a biplanar surface. PMSP formed a smooth and tough coating as a high oxygen-permeable polymer matrix with a thickness of ca. 2 μm, which homogeneously contained the luminescent dye probe, PtPL or PtPP. Under UV light (395 nm) irradiation, the coatings displayed strong magenta and red luminescence with maximum peaks at 750 and 650 nm ascribed to the PtPL and PtPP, respectively. The luminescence of the two coatings was efficiently quenched by oxygen which allowed the development of engineering curve to analyze the oxygen partial pressure. The luminescence intensities of the two coatings were separately monitored in order to allow the simultaneous measurement of the oxygen partial pressure distribution upon two planar surfaces.
Keywords: Polymer coating; Luminescence; Porphyrin; Pressure sensor;

Thioacetate- and mercapto-functionalized hydrogenated natural rubber by Theerachai Pruttisirikul; Pattarapan Prasassarakich; Garry L. Rempel; Napida Hinchiranan (674-683).
Due to the differences in unsaturation levels of constituent rubbers, thioacetate and mercapto functional groups were introduced into hydrogenated natural rubber (HNR) to increase the compatibility of natural rubber (NR)/HNR blends. The effect of thioacetic acid and initiator concentrations including reaction time on the thioacetate content in HNR was investigated. Methanolysis of thioacetate-modified HNR (HNRTA) yielded mercapto-modified HNR (HNRSH). The addition of HNRTA or HNRSH into NR/HNR blends (50/50 wt ratio) increased the tensile strength. The improved mechanical properties of the compatibilized blends were confirmed by scanning electron microscopy, indicating a co-continuous morphology. Furthermore, the susceptibility of the vulcanizates to changes in temperature and ozone were also reported.
Keywords: Hydrogenation; Natural rubber; Functionalization; Compatibilization; Mercapto group;

A series of fast pH-responsive silk sericin (SS)/poly(methacrylic acid) (PMAA) IPN hydrogels were prepared by the simultaneous-IPN method. The structure of the resultant IPN hydrogels was characterized by fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The swelling experimental of the IPNs revealed that the hydrogels displayed definite pH sensitivity under physiological conditions, as well as sharp changes in the mesh size of their network as a function of the composition and pH of the swelling media. Bovine serum albumin (BSA) was chosen as a model protein to evaluate the permeation profile through the IPNs in both the simulated gastric and intestinal pH conditions. In all cases, it was found that the release rate of BSA was lower in acidic media (pH 2.6) and higher in basic media (pH 7.4).
Keywords: Silk sericin; Poly(methacrylic acid); pH sensitivity; Interpenetrating polymer network; Diffusion coefficient;

A selective solid-phase extraction procedure using chemically modified Amberlite XAD-4 with monoaza dibenzo 18-crown-6 ether was investigated for the preconcentration and separation of La(III), Nd(III) and Sm(III) in synthetic solution. Before loading samples on synthesized adsorbent adjust pH 4.5 by suitable buffer solution. The adsorbed rare earth elements were eluted by 2 M hydrochloric acid. Various parameters like preconcentration, breakthrough capacity, flow rate were investigated. The limits of detection (n  = 5) and limits of quantification (n  = 5) for La(III), Nd(III) and Sm(III) were founded 3.9, 4.2 and 7.4 μg L−1 and 13, 15 and 26 μg L−1, respectively. The eluted metal ions were determined by ICP-AES.
Keywords: Solid-phase extraction; Azacrown ether; Lanthanides; Rare earths; Amberlite XAD-4;

A novel photoactive hyperbranched poly(aryl ether ketone) with azobenzene end groups for optical storage applications by Xiangyu Jiang; Hui Wang; Xingbo Chen; Xiujie Li; Lei Lei; Jianxin Mu; Guibin Wang; Shuling Zhang (699-705).
A novel hyperbranched poly(aryl ether ketone) terminated by azobenzene chromophores (azo-HPAEK) was prepared using 1,3,5-tris[4-(4-fluorobenzoyl)phenoxy] benzene (B3) as a core molecule, 4,4′-(hexafluoroisopropylidene) diphenol as an A2 monomer and 4-(4-hydroxyphenylazo) benzonitrile as an end-capping reagent. It is shown that azo-HPAEK exhibits a high glass transition temperature (Tg), excellent thermal stability and homogeneous photochromic behavior. By exposing the spin-coated film to a laser beam interference pattern, azo-HPAEK can be used for rapid (within 30 s) fabrication of surface relief gratings (SRGs), and the azo-HPAEK gratings cannot be totally erased by heating, even at 300 °C. In particular, azo-HPAEK shows a large photoinduced birefringence intensity and good reversible optical storage upon irradiation with 532 nm Nd:YAG laser.
Keywords: Hyperbranched poly(aryl ether ketone); Azobenzene end groups; Photochromic behavior; Surface relief gratings; Photoinduced birefringence;