Synthesis of Poly(ethylene oxide)s with 1,2,4‐Triazol‐4‐yl End Groups – Macroligands for Bistable Metal‐Polymer Complexes

Summary: Poly(ethylene oxide) methyl ether 4H‐1,2,4‐triazol‐4‐yl ( 1 ) has been synthesized as a novel macroligand. ESI‐MS (electrospray ionisation mass spectrometry), MALDI‐TOF (matrix‐assisted laser desorption ionisation time‐of‐flight) MS as well as NMR spectroscopy were used for the accurate determination of number‐average molecular weights ( ), the crucial parameter for subsequent synthesis of metal‐polymer complexes of four different samples 1a – d . Reaction of polymer 1a with [Fe(H₂O)₆](nps)₂ (nps = 3‐nitrophenylsulfonate) gave [Fe( 1a )₃](nps)₂, a bistable metal‐polymer complex that exhibited low‐spin (LS) to high‐spin (HS) transitions around T_1/2 = 257 K, accompanied by a change in colour from violet (LS) to slightly yellow (HS).

The structure of [Fe( 1a )₃](nps)₂ and its magnetic properties.     

Synthesis and photoproperties of Eu(III)‐bearing star polymers as luminescent materials

Water‐soluble luminescent material was developed by introducing europium (Eu(III)) ions into the core of a star polymer. Living radical polymerization was used to obtain the star polymer. The strategy to introduce Eu(III) ions into the star polymer was studied using poly(methyl methacrylate) as an arm. The best Eu(III) ion introduction was obtained by simultaneous introduction, resulting in about 30 µmol/g‐polymer, which needed only one step for synthesis. The utilization of a hydrophilic polymer such as poly(ethylene oxide) (PEO) as an arm produced a water‐soluble star polymer. The Eu(III)‐bearing PEO star polymer obtained in this study was water soluble and showed fluorescence. In addition, it was stable in water after 1 month. The Eu(III)‐bearing star polymer exhibited luminescent properties under UV light irradiation with relatively high quantum yields of 60% in organic solution and 19% in aqueous solution. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2527–2535     

Ru(II)(tpy)2‐functionalized hydrogels: Synthesis,reversible responsiveness,and coupling with the belousov‐zhabotinsky reaction

This work aims at developing an approach to Ru(II)(Tpy)₂‐functionalized hydrogels and exploring the coupling of the hydrogels with the Belousov‐Zhabotinsky (BZ) reaction. Based on free radical polymerization, two synthetic routes are developed. The first one is the direct gelation by copolymerization of acrylamide as hydrophilic component and Ru(II)(Tpy)₂ as the functional group. The second one is carried out through a combined approach. A terpyridine‐containing hydrogel is first prepared and then post‐functionalized by coordination between Ru(III)(Tpy)Cl₃ and terpyridine groups in the hydrogel network. Utilizing the synthetic hydrogels, the reversible redox responsiveness, the coupling with the BZ reaction, the occurrence and the self‐oscillating properties of the BZ reaction in the hydrogel networks are studied. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2214–2222     

Synthesis of imidazole‐terminated hyperbranched polymers with POSS‐branching points and their pH responsive and coordination properties

An imidazole‐terminated hyperbranched polymer with octafunctional POSS branching units denoted as POSS‐HYPAM‐Im was prepared by the polymerization of excess amounts of tris(2‐aminoethyl)amine with the first‐generation methyl ester‐terminated POSS‐core poly(amidoamine)‐typed dendrimer, reacting with methyl acrylate, and ester‐amide exchange reaction with 3‐aminopropylimidazole. The imidazole‐terminated hyperbranched poly(amidoamine) denoted as HYPAM‐Im was also synthesized with 1‐(3‐aminopropyl)imidazole from a methyl ester‐terminated hyperbranched poly(amidoamine) by the ester‐amide exchange reaction. The transmittance of the POSS‐HYPAM‐Im solution drastically decreased when the solution pH was greater than 8.2. On the other hand, the transmittance of the HYPAM‐Im solution gradually decreased when the solution pH at 8.5 and was greater than 9. Spectrophotometric titrations of the hyperbranched polymer aqueous solutions with Cu²⁺ ions indicated the variation of the coordination modes of POSS‐HYPAM‐Im from the Cu²⁺–N₄ complex to the Cu²⁺–N₂O₂ complex and the existence of the only one complexation mode of Cu²⁺–N₄ between Cu²⁺ ion and HYPAM‐Im with increasing the concentrations. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2695–2701     

Poly(N‐phenylmaleimide‐co‐acrylic acid)–copper(II) and poly(N‐phenylmaleimide‐co‐acrylic acid)–cobalt(II) complexes: Synthesis,characterization, and thermal behavior

The free‐radical copolymerization of N‐phenylmaleimide (N‐PhMI) with acrylic acid was studied in the range of 25–75 mol % in the feed. The interactions of these copolymers with Cu(II) and Co(II) ions were investigated as a function of the pH and copolymer composition by the use of the ultrafiltration technique. The maximum retention capacity of the copolymers for Co(II) and Cu(II) ions varied from 200 to 250 mg/g and from 210 to 300 mg/g, respectively. The copolymers and polymer–metal complexes of divalent transition‐metal ions were characterized by elemental analysis, Fourier transform infrared, ¹H NMR spectroscopy, and cyclic voltammetry. The thermal behavior was investigated with differential scanning calorimetry (DSC) and thermogravimetry (TG). The TG and DSC measurements showed an increase in the glass‐transition temperature (T_g) and the thermal stability with an increase in the N‐PhMI concentration in the copolymers. T_g of poly(N‐PhMI‐co‐AA) with copolymer composition 46.5:53.5 mol % was found at 251 °C, and it decreased when the complexes of Co(II) and Cu(II) at pHs 3–7 were formed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4933–4941, 2005     

Hyperbranch‐polyethyleniminated functional polymers. I. Synthesis,characterization of novel ABA type of dumbbell‐like polyethyleniminated polyoxypropylenediamines,and their complexing properties with copper(II) ions in aqueous solution

Novel ABA‐type dumbbell‐like water‐soluble copolymers [D230(EI)₄, D400(EI)₄, and D400(EI)₈] were synthesized by introducing ethylenimine (EI) groups into both sides of polyoxypropylenediamines via a simple in situ ethylamination of polyoxypropylenediamine with 2‐chloroethylamine hydrochloride. The structures of the resultant polymers were identified by Fourier transform infrared spectroscopy and ¹H NMR. The percentages of primary, secondary, and tertiary amine present were determined by the potentiometric titration method after treatments with the appropriate chemicals of salicylaldehyde and acetic anhydride. The surface tension and solubilizing behavior of pyrene in the presence of these polymers in aqueous medium were also investigated, and the efficiency to reduce the surface tension and solubilizing behavior of pyrene depends on the attachments of EI to polymer backbone. The chelating properties of these polymers were examined quantitatively by ultraviolet–visible (UV–vis) spectroscopy in the presence of Cu²⁺ ions in aqueous solution, and continuous variation analysis revealed that the most stable complex is formed at the normality ratio of [N]/[Cu²⁺] = 3.0. UV–vis spectroscopy and transmission electron microscopy were used to evaluate the dumbbell‐like water‐soluble copolymer, D400(EI)₈, as a stabilizer for preparing colloidal noble metal nanoparticles (Au and Pt) in aqueous solution. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1360–1370, 2003     

Synthesis and characterization of water‐soluble barbiturate‐ and thiobarbiturate‐functionalized polystyrene

The synthesis and characterization of barbiturate‐ and thiobarbiturate‐functionalized polystyrene from polystyrene homopolymer by polymer‐modification reactions is discussed. Polystyrene homopolymer quantitatively functionalized at the para postion with diethyl oxomalonate functionality was subjected to a condensation reaction with urea and thiourea in the presence of sodium methoxide in methanol. This reaction proceeded essentially to quantitative conversion to the barbiturate‐ (BAPS) and thiobarbiturate‐functionalized polystyrenes (TBAPS) as estimated by ¹H NMR, UV, and IR spectroscopies. Thus, several copolymers of styrene with barbiturate‐ and thiobarbiturate‐functionalized styrene were synthesized. The detailed characterizations of quantitatively functionalized polystyrene using gel permeation chromatographic, IR, UV, and ¹H NMR spectroscopic techniques as well as thermogravimetric analysis are discussed. An application of the newly synthesized polymer in removing Cu(II) ions from aqueous solution is demonstrated. This is the first report on the synthesis of BAPS and TBAPS by the polymer‐modification route or otherwise. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 731–737, 2002; DOI 10.1002/pola.10154     

End‐functionalization of semiconducting species with dendronized terpyridine–Ru(II)–terpyridine complexes

Semiconducting oligomers and polymers decorated with two or one dendronized tpy‐Ru(II)‐tpy metallocomplexes are presented. Initially, free terpyridine end‐functionalized semiconducting oligomers (distyrylanthracene, quinquephenylene, mono‐ and trifluorenes) were prepared while in a second approach, atom transfer radical polymerization was employed for the preparation of side‐chain oligomeric and polymeric (oxadiazole)s using a terpyridine initiator. These terpyridine‐bearing oligomers and polymers were complexated with a Percec‐type first‐generation (G1) dendronized terpyridine–Ru(III)Cl₃ monocomplex, having two dodecyloxy groups. All oligomeric and polymeric metallocomplexes were characterized via NMR spectroscopies for their structural perfection and via UV‐Vis and PL spectroscopies for their optical properties. The existence of the organic semiconducting blocks in combination with the terpyridine–Ru(II)–terpyridine groups afforded hybrid metallo‐semiconducting species presenting the optical features of both their components. Moreover, their thin‐film morphologies were investigated through atomic force microscopy, revealing, in some cases, an organization tendency in the nanometer scale. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1939–1952, 2009     

Coordination of nickel and copper dithiolate to 2,2′‐bipyridine‐based π‐conjugated polymers

π‐Conjugated polymers (Poly1–Poly3) containing a 2,2′‐bipyridine (bpy) unit were subjected to coordination to nickel and copper dithiolate for the purpose of manipulating the photophysical properties. The absorption maximum peak of Poly1 [maximum wavelength (λ_max) = 446 nm] redshifted by 36 nm upon the coordination of bpy to NiCl₂, which produced Poly1–NiCl₂. A further bathochromic shift was observed in the spectrum of Poly1–mntNi [mntNi = (maleonitrile dithiolate)nickel; λ_max = 499 nm] bearing the dithiolate ligand, which stemmed from the extension of the conjugated system over the nickel dithiolate moiety through the bpy unit. An increase in the [Ni]/[bpy] ratio in Poly1–mntNi rendered the original maximum peak at 446 nm smaller and the lower energy charge‐transfer peak at 499 nm larger; the isosbestic points remained at 380 and 475 nm. The green fluorescence (λ_max = 504 nm) emitted from Poly1 markedly diminished upon the coordination of nickel dithiolate because of the effective energy transfer. The absorption maximum peak of Poly1–mntNi in chloroform at 499 nm blueshifted to 471 nm when the volume ratio of the chloroform/N,N‐dimethylformamide solvent reached 10:90. The coordination of nickel dithiolate to Poly2 and Poly3 also brought about redshifts of the absorption maximum peaks of as much as 55 and 61 nm, respectively. The absorption maximum peak of Poly1–(phenyldithiolate)nickel(pdtNi) (λ_max = 474 nm) redshifted by 28 nm in comparison with that of Poly1, whereas the magnitude of the shift of Poly1–bis(thiophenoxide)nickel(btpNi) bearing two thiophenoxide ligands was 20 nm. Poly1–mntCu with a tetrahedral copper center was also investigated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2631–2639, 2004     

Terpyridine‐substituted,fluorescent polymers and their chelation with zinc ion: The ligand‐to‐metal ratio and optical properties

Soluble, fluorescent, terpyridine‐substituted, conjugated polymers were prepared and characterized. The polymer chains included a defined oligo(phenylenevinylene) fragment, on which the terpyridine‐functional group was attached. The polymers were blue‐fluorescent with emission peaks at 400–427 nm in tetrahydrofuran solutions. Upon chelation with the Zn(II) cation, the emission maxima were shifted to a longer wavelength by as much as 113 to 506–526 nm. A model compound was also prepared to aid the structural characterization. The ratio of terpyridine to Zn²⁺ in the polymer complex was found to be 1:1 on the basis of spectroscopic evidence, which included mass spectrometry, ¹H NMR, and Job titration. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2338–2345, 2006     

Synthesis of porphyrin‐end‐functionalized polycyclohexane with well‐controlled and defined polymer chain structure

Tetraphenylporphyrin‐end‐functionalized polycyclohexane (H₂TPP‐PCHE) and its metal complexes (MTPP‐PCHE) were synthesized as the first successful example of porphyrin‐end‐functionalized transparent and stable polymers with a well‐controlled and defined polymer chain structure. Chloromethyl‐end‐functionalized poly(1,3‐cyclohexadiene) (CM‐PCHD) was synthesized as prerequisite prepolymer by the postpolymerization reaction of poly(1,3‐cyclohexadienyl)lithium and chloro(chloromethyl)dimethylsilane. CM‐end‐functionalized PCHE (CM‐PCHE) was prepared by the complete hydrogenation of CM‐PCHD with p‐toluenesulfonyl hydrazide. H₂TPP was incorporated onto the polymer chain end by the addition of 5‐(4‐hydroxyphenyl)‐10,15,20‐triphenylporphyrin to CM‐PCHE. The complexation of H₂TPP‐PCHE and Zn(OAc)₂ (or PtCl₂) yielded a zinc (or platinum) complex of H₂TPP‐PCHE. H₂TPP‐PCHE and MTPP‐PCHE were readily soluble in common organic solvents, and PCHE did not inhibit the optical properties of the H₂TPP, ZnTPP, and PtTPP end groups. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Preparation of nano‐chitosan Schiff‐base copper complexes and their anticancer activity

A new kind of nano‐chitosan Schiff‐base Cu complexes with particle sizes of 350 nm were prepared by combination of nano‐chitosan, Cu and Schiff‐base, and characterized by FT‐IR spectra, TEM, DLS and elemental analysis. The modes and mechanism of interaction of the copper complexes with DNA were studied by the fluorescent probe method and electrophoresis analysis. The results suggest that the Cu complexes bound to DNA by electrostatic and intercalation modes. The anticancer activity of the Cu complexes was evaluated by Sulforhodamine B (SRB) assay in vitro. Nano‐chitosan and their Schiff‐base Cu complexes inhibited the growth of the liver cancer cell lines SMMC‐7721 in vitro. The inhibition rate of Schiff‐base Cu complexes was higher than that of nano‐chitosan. Nano‐chitosan combining with Schiff‐base and Cu improved their anticancer activity, which ascribed to the synergistic effect between the chitosan matrix and the planar construction of the Cu complexes. Copyright © 2008 John Wiley & Sons, Ltd.     

Two main chain polymeric metal complexes as dye sensitizers for dye‐sensitized solar cells based on the coordination of the ligand containing 8‐hydroxyquinoline and phenylethyl or fluorene units with Eu(III)

Two novel main chain polymeric metal complexes containing 8‐hydroxyquinoline europium complexes and phenylethyl or fluorene units: 1,4‐Dioctyloxy‐2,5‐bis[2‐(8‐hydroxyquinoline)‐vinyl]‐benzene Eu(III) (3) and 2,7‐bis[2‐(8‐hydroxyquinoline)‐vinyl]‐9,9′‐diocthylfluorene Eu(III) (4) with donor–acceptor‐π‐conjugated structure (D‐π‐A) have been synthesized and investigated as dye sensitizers for dye‐sensitized solar cells dyes (DSSCs). They have been determined and studied by FT‐IR, TGA, DSC, GPC, Elemental analysis, UV–vis absorption spectroscopy, photoluminescence spectroscopy, cyclic voltammetry, and application in dye‐sensitized solar cells (DSSCs) as dye sensitizers. On the basis of optimized dye and molecular structure, they have shown solar‐to‐electricity conversion efficiency 2.25% for 3 (J_sc = 4.77 mA cm^?2, V_oc = 630 mV, FF = 0.75) and 3.04% for 4 (J_sc = 6.33 mA cm^?2, V_oc = 640 mV, FF = 0.75), under the illumination of AM1.5G, 100 mW/cm². The IPCE of 3 and 4 are 30% and 46% at 400 nm, respectively. Besides, they showed good stabilities with thermal decomposition temperatures at 280 °C and 225 °C, respectively, which are suitable for DSSCs. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1943–1951, 2010     

Synthesis and characterization of poly(isobutylene‐co‐isoprene)‐derived macro‐monomers

Allylic halide displacement from brominated poly(isobutylene‐co‐isoprene) (BIIR) by carboxylate nucleophiles is used to prepare elastomer derivatives containing pendant polymerizable functionality. These solvent‐borne substitutions are conducted under homogeneous and phase‐transfer catalyzed reaction conditions to synthesize acrylate and vinylbenzoate esters in high yield. The resulting macro‐monomer derivatives are shown to crosslink efficiently with peroxide initiation to give high modulus, thermoset products that cannot otherwise be accessed from isobutylene‐rich elastomers. The extent of cure, as measured by the storage modulus of the vulcanizate, scales with RCH=CH₂ content, and can be extended by co‐oligomerization of pendant unsaturation with that contained within multifunctional coagents. An alternate approach involving the introduction of pendant sulfonyl azide functionality is described, wherein thermal decomposition to nitrene intermediates supports an efficient crosslinking process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis of new Azo‐based liquid crystalline polymers and their selective sensing behaviors to alkali metal ions

We report novel liquid crystalline (LC) polymers containing pendant azobenzene moieties with n‐dodecyl substituents and ethyleneoxy spacers of different lengths and describe their selective detection behaviors to alkali metal ions. The new azopolymers produce homogenous smectic phases with a typical fan‐shaped texture. UV‐Vis and ¹H NMR studies confirm that the azopolymers selectively bind to Li⁺ and Na⁺, but do not complex with K⁺, Ba²⁺, Mg²⁺, or Ca²⁺. Both the ethyleneoxy spacer and azobenzene units participate in binding to Li⁺ and Na⁺ cations in solution. Interestingly, after formation of the complexed structure, the ratio of cis to trans conformer is considerably increased suggesting stronger interactions of the cis conformer with alkali metal ions. Irradiation of the complexed structure with 365 nm UV induces conversion of the uncomplexed trans to the cis. These findings suggest a great potential of the LC azopolymers as selective sensors or separation membranes for alkali metal ions. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1713–1723     

Synthesis of norbornenes containing cationic mono‐ and di(cyclopentadienyliron)arene complexes and their ring‐opening metathesis polymerization

A number of classes of polynorbornenes containing cationic iron moieties within their side chains were prepared via ring‐opening metathesis polymerization with a ruthenium‐based catalyst. The iron‐containing polymers displayed excellent solubility in polar organic solvents. The weight‐average molecular weights of these polymeric materials were estimated to be in the range of 18,000–48,000. Thermogravimetric analysis of these polymers showed two distinct weight losses. The first weight loss was in the range of 204–260 °C and was due to the loss of the metallic moieties, whereas the second weight loss was observed at 368–512 °C and was due to the degradation of the polymer backbone. Cyclic voltammetry studies of the iron‐containing polymers showed that the 18 e^? cationic iron centers underwent a reduction to give the neutral 19 e^? complexes at half‐wave potential (E_1/2) = ?1.105 V. Photolysis of the metallated polymers led to the isolation of the norbornene polymers in very good yields. Differential scanning calorimetry studies showed a sharp increase in the glass‐transition temperatures up to 91 °C when rigid aromatic side chains were incorporated into the norbornene polymers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3053–3070, 2006     

Advancing the Solid State Properties of Metallo‐Supramolecular Materials: Poly(ε‐caprolactone) Modified π‐Conjugated Bis(terpyridine)s and their Zn(II) Based Metallo‐Polymers

A set of rigid π‐conjugated bis(terpyridine) macroligands with poly(ε‐caprolactone) (pCL) on their side chains was synthesized and investigated. The introduced pCL chains gave rise to enhanced processability and film‐forming properties of the materials. Blue photoluminescence with high quantum yields was observed in dilute solution and in the solid state, indicating that intermolecular aggregation of the π‐conjugated systems was effectively suppressed. The macroligands were further used for coordination with zinc(II) ions leading to new metallo‐polymers with high solubility, improved film‐forming behavior and promising photophysical properties with respect to potential OLED applications.

     

Synthesis and characterization of multifunctional polymers via atom transfer radical polymerization of N‐(ω′‐alkylcarbazolyl) methacrylates initiated by Ru(II) polypyridyl chromophores

A series of poly(N‐(ω′‐alkylcarbazoly) methacrylates) tris(bipyridine) Ru‐centered bifunctional polymers with good filming, thermal, and solubility properties were synthesized and characterized. Atom transfer radical polymerization (ATRP) of N‐(ω′‐alkylcarbazoly) methacrylates in solution was used, where Ru complexes with one and three initiating sites acted as metalloinitiators with NiBr₂(PPh₃)₂ as a catalyst. ATRP reaction conditions with respect to polymer molecular weights and polydispersity indices (PDI) of the target bifunctional polymers were examined. Electronic absorption and emission spectra of the resultant functional polymers provided evidence of chromophore presence within a single polymeric chain. The thermal properties of all polymers were also investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), and these analyses have indicated that these polymers possess higher thermal stabilities than poly(methyl methacrylate) (PMMA) obtained via free radical polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6057–6072, 2005     

Synthesis of novel dithienothiophene‐ and 2,7‐carbazole‐based conjugated polymers and H‐bonded effects on electrochromic and photovoltaic properties

Three kinds of dithienothiophene/carbazole‐based conjugated polymers ( P1–P3 ), which bear acid‐protected and benzoic acid pendants in P2 and P3 , respectively, were synthesized via Suzuki coupling reaction. Interestingly, P1 – P3 exhibited reversible electrochromism during the oxidation processes of cyclic voltammogram studies, and P3 (with H‐bonds) revealed the best electrochromic property with the most noticeable color change. According to powder X‐ray diffraction (XRD) analysis, these polymers exhibited obvious diffraction features indicating bilayered packings between polymer backbones and π‐π stacking between layers in the solid state. Compared with the XRD data of P2 (without H‐bands), H‐bonds of P3 induced a higher crystallinity in the small‐angle region (corresponding to a higher ordered bilayered packings between polymer backbones), but with a similar crystallinity in the wide angle region indicating a comparable π‐π stacking distance between layers. Moreover, based on the preliminary photovoltaic properties of PSC devices ( P1 – P3 blended individually with PCBM acceptor in the weight ratio of 1:1), P3 (with H‐bonds) possessed the highest power conversion efficiency of 0.61% (with J_sc = 2.26 mA/cm², FF = 29.8%, and V_oc = 0.9 V). In contrast to P2 (without H‐bands), the thermal stability, crystallinity, and electrochromic along with photovoltaic properties of P3 were generally enhanced due to its H‐bonded effects. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Thermoregulated phase‐transfer catalysis via PEG‐armed Ru(II)‐bearing microgel core star polymers: Efficient and reusable Ru(II) catalysts for aqueous transfer hydrogenation of ketones

Thermoregulated phase‐transfer catalysis for the transfer hydrogenation of 2‐octanone in 2‐propanol/H₂O biphasic media was achieved with ruthenium‐bearing microgel‐core star polymers with amphiphilic, thermosensitive poly(ethylene glycol) (PEG) arms [Ru(II)‐PEG star], which were directly prepared by the ruthenium‐catalyzed living radical polymerization in conjunction with a phosphine ligand‐carrying styrene derivative. The star polymers were first placed in the aqueous (lower) layer at room temperature and immediately moved into the organic (upper) layer at 100 °C, and once again, moved down to the aqueous layer (lower) upon cooling the solution to room temperature. The Ru(II)‐PEG star catalyst was clearly superior to the original Ru(II) catalyst and related non‐microgel catalysts [Ru(II)‐PEG block] in terms of activity and recovery/recycle, due to the unique designer structure of the microgel‐core star polymers. Other substrates (less hydrophobic alkyl ketones and aromatic ketone) were also efficiently hydrogenated into the corresponding sec‐alcohols with the star catalyst in aqueous media. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 373–379, 2010