Room‐temperature RAFT copolymerization of 2‐chloroallyl azide with methyl acrylate and versatile applications of the azide copolymers

A new vinyl azide monomer, 2‐chlorallyl azide (CAA), has been synthesized from commercially available reagent in one step. The reversible addition fragmentation chain transfer (RAFT) copolymerization of CAA with methyl acrylate (MA) was carried out at room temperature using a redox initiator, benzoyl peroxide (BPO)/N,N‐dimethylaniline (DMA), in the presence of benzyl 1H‐imidazole‐1‐carbodithioate (BICDT). The polymerization results showed that the process bears the characteristics of controlled/living radical polymerizations, such as the molecular weight increasing linearly with the monomer conversion, the molecular weight distribution being narrow, and a linear relationship existing between ln([M]₀/[M]) and the polymerization time. Chain extension polymerization was performed successfully to prepare block copolymer. Furthermore, the azide copolymers were functionalized by Cu^I‐catalyzed “click” reaction with alkyne‐containing poly(ethylene glycol) (PEG) to yield graft copolymers with hydrophilic PEG side chains. Surface modification of the glass sheet was successfully achieved via the crosslinking reaction of the azide copolymer under UV irradiation at ambient temperature. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1348–1356, 2010     

NMR investigation of effect of dissolved salts on the thermoresponsive behavior of oligo(ethylene glycol)‐methacrylate‐based polymers

The synthesis of thermo‐ and ionic‐responsive copolymers based on polyethylene glycol methyl ether methacrylate (OEGMA) and 2,2,2‐trifluoroethyl acrylate (TFEA) via reversible addition‐fragmentation chain transfer polymerization is described. Reactivity ratios for the copolymerization of OEGMA and TFEA are r_OEGMA = 2.46 and r_TFEA = 0.22, indicating that OEGMA is incorporated more rapidly than TFEA monomers. The copolymers are thermosensitive and exhibit volume phase transitions (lower critical solution behavior) at temperature, which depend on copolymer composition and the presence of added salts in the aqueous solutions. It was found that the copolymers exhibited LCST transitions at temperatures below 353 K only in salt solutions. ¹H NMR measurements indicated that motion of the protons located in and near the hydrophobic main chain are more sensitive to temperature than protons in the hydrophilic OEGMA side chains. The hydrophilic side chains remain largely hydrated; however, the presence of two distinct conformations of the terminal groups of the side chains was confirmed. The influence of OEGMA side chain length, copolymer composition, and salt type on aggregation behavior and dynamics was examined in detail. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2375–2385     

Synthesis of starlike PtBA‐g‐PEO amphiphilic graft copolymer via highly efficient Cu‐catalyzed SET‐NRC reaction at ambient temperature

Two new amphiphilic star graft copolymers bearing hydrophobic poly(tert‐butyl acrylate) backbone and hydrophilic poly(ethylene oxide) (PEO) side chains with different molecular weights were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization and single electron transfer‐nitroxide radical coupling (SET‐NRC) reaction under mild conditions. RAFT homopolymerization of tert‐butyl 2‐((2‐bromopropanoyloxy)methyl)acrylate was mediated by a four‐armed chain transfer agent in a controlled way to afford a well‐defined starlike backbone with a narrow molecular weight distribution (M_w/M_n = 1.26). The target poly(tert‐butyl acrylate)‐g‐PEO (PtBA‐g‐PEO) star graft copolymers were synthesized by SET‐NRC reaction between Br‐containing PtBA‐based starlike backbone and PEO end functionalized with 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) group using copper/N,N,N′,N′,N″‐pentamethyldiethylenetriamine as catalytic system at ambient temperature via grafting‐onto strategy. The critical micelle concentration values of the obtained amphiphilic star graft copolymers in aqueous media and brine were determined by fluorescence probe technique using pyrene as probe. Diverse micellar morphologies were formed by varying the content of hydrophilic PEO segment as well as the initial concentration of stock solution. In addition, poly(acrylic acid)‐g‐PEO double hydrophilic star graft copolymers were obtained by selective acidic hydrolysis of hydrophobic PtBA starlike backbone without affecting PEO side chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Macromolecular brushes synthesized by “grafting from” approach based on “click chemistry” and RAFT polymerization

Well‐defined macromolecular brushes with poly(N‐isopropyl acrylamide) (PNIPAM) side chains on random copolymer backbones were synthesized by “grafting from” approach based on click chemistry and reversible addition‐fragmentation chain transfer (RAFT) polymerization. To prepare macromolecular brushes, two linear random copolymers of 2‐(trimethylsilyloxy)ethyl methacrylate (HEMA‐TMS) and methyl methacrylate (MMA) (poly(MMA‐co‐HEMA‐TMS)) were synthesized by atom transfer radical polymerization and were subsequently derivated to azide‐containing polymers. Novel alkyne‐terminated RAFT chain transfer agent (CTA) was grafted to polymer backbones by copper‐catalyzed 1,3‐dipolar cycloaddition (azide‐alkyne click chemistry), and macro‐RAFT CTAs were obtained. PNIPAM side chains were prepared by RAFT polymerization. The macromolecular brushes have well‐defined structures, controlled molecular weights, and molecular weight distributions (M_w/M_n ≦ 1.23). The RAFT polymerization of NIPAM exhibited pseudo‐first‐order kinetics and a linear molecular weight dependence on monomer conversion, and no detectable termination was observed in the polymerization. The macromolecular brushes can self‐assemble into micelles in aqueous solution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 443–453, 2010     

Star‐like PAA‐g‐PPO well‐defined amphiphilic graft copolymer synthesized by ATNRC and SET‐NRC reaction

A series of well‐defined amphiphilic star graft copolymers consisting of hydrophilic poly(acrylic acid) backbone and hydrophobic poly(propylene oxide) side chains were synthesized by the sequential reversible addition‐fragmentation chain transfer (RAFT) polymerization and atom transfer nitroxide radical coupling (ATNRC) or single electron transfer‐nitroxide radical coupling (SET‐NRC) reaction followed by the selective hydrolysis of poly(tert‐butyl acrylate) backbone. A Br‐containing acrylate monomer, tert‐butyl 2‐((2‐bromopropanoyloxy)methyl)acrylate, was first homopolymerized via RAFT polymerization using a new star‐like chain‐transfer agent with four arms in a controlled way to give a well‐defined star‐like backbone with a narrow molecular weight distribution (M_w/M_n = 1.23). The grafting‐onto strategy was used to synthesize the well‐defined PtBA‐g‐PPO star graft copolymers with narrow molecular weight distributions (M_w/M_n = 1.14–1.25) via ATNRC or SET‐NRC reaction between the Br‐containing PtBA‐based star‐like backbone and poly(propylene oxide) with 2,2,6,6‐tetramethylpiperidine‐1‐oxyl end group using CuBr/PMDETA or Cu/PMDETA as catalytic system. PAA‐g‐PPO amphiphilic star graft copolymers were obtained by the selective acidic hydrolysis of star‐like PtBA‐based backbone in acidic environment without affecting the side chains. The critical micelle concentrations in aqueous media and brine were determined by the fluorescence probe technique. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2084–2097, 2010     

Poly(ethylene imine)‐graft‐poly(ethylene oxide) brush‐like copolymers: Preparation,thermal properties,and selective supramolecular inclusion complexation with α‐cyclodextrin

Poly(ethylene imine)‐graft‐poly(ethylene oxide) (PEI‐g‐PEO) copolymers were synthesized via Michael addition reaction between acryl‐terminated poly(ethylene oxide) methyl ether (PEO) and poly(ethylene imine) (PEI). The brush‐like copolymers were characterized by means of Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. It is found that the crystallinity of the PEO side chains in the copolymers remained unaffected by the PEI backbone whereas the crystal structure of PEO side chains was altered to some extent by the PEI backbone. The crystallization behavior of PEO blocks in the copolymers suggests that the bush‐shaped copolymers are microphase‐separated in the molten state. The PEO side chains of the copolymers were selectively complexed with α‐cyclodextrin (α‐CD) to afford hydrophobic side chains (i.e., PEO/α‐CD inclusion complexes). The X‐ray diffraction (XRD) shows that the inclusion complexes (ICs) of the PEO side chains displayed a channel‐type crystalline structure. It is identified that the stoichiometry of the inclusion complexation of the PEI‐g‐PEO with α‐CD is close to that of the control PEO with α‐CD. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2296–2306, 2008     

Synthesis of poly(ethylene oxide) with pending 2,2,6,6‐tetramethylpiperidine‐1‐oxyl groups and its further initiation of the grafting polymerization of styrene

A new stratagem for the synthesis of amphiphilic graft copolymers of hydrophilic poly(ethylene oxide) as the main chain and hydrophobic polystyrene as the side chains is suggested. A poly(ethylene oxide) with pending 2,2,6,6‐tetramethylpiperidine‐1‐oxyls [poly(4‐glycidyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐co‐ethylene oxide)] was first prepared by the anionic ring‐opening copolymerization of ethylene oxide and 4‐glycidyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl, and then the graft copolymerization of styrene was completed with benzoyl peroxide as the initiator in the presence of poly(4‐glycidyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐co‐ethylene oxide). The polymerization of styrene was under control, and comblike, amphiphilic poly(ethylene oxide)‐g‐polystyrene was obtained. The copolymer and its intermediates were characterized with size exclusion chromatography, ¹H NMR, and electron spin resonance in detail. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3836–3842, 2006     

Water‐soluble poly(ethylene oxide)‐block‐poly(p‐phenylene vinylene) copolymer: Synthesis and characterization

Water‐soluble and photoluminescent block copolymers [poly(ethylene oxide)‐block‐poly(p‐phenylene vinylene) (PEO‐b‐PPV)] were synthesized, in two steps, by the addition of α‐halo‐α′‐alkylsulfinyl‐p‐xylene from activated poly(ethylene oxide) (PEO) chains in tetrahydrofuran at 25 °C. This copolymerization, which was derived from the Vanderzande poly(p‐phenylene vinylene) (PPV) synthesis, led to partly converted PEO‐b‐PPV block copolymers mixed with unreacted PEO chains. The yield, length, and composition of these added sequences depended on the experimental conditions, namely, the order of reagent addition, the nature of the monomers, and the addition of an extra base. The addition of lithium tert‐butoxide increased the length of the PPV precursor sequence and reduced spontaneous conversion. The conversion into PPV could be achieved in a second step by a thermal treatment. A spectral analysis of the reactive medium and the composition of the resulting polymers revealed new evidence for an anionic mechanism of the copolymerization process under our experimental conditions. Moreover, the photoluminescence yields were strongly dependant on the conjugation length and on the solvent, with a maximum (70%) in tetrahydrofuran and a minimum (<1%) in water. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4337–4350, 2005     

Synthesis and characterization of star graft copolymers with asymmetric mixed “V‐shaped” side chains via “click” chemistry on a hyperbranched polyglycerol core

The star graft copolymers composed of hyperbranched polyglycerol (HPG) as core and well defined asymmetric mixed “V‐shaped” identical polystyrene (PS) and poly(tert‐butyl acrylate) as side chains were synthesized via the “click” chemistry. The V‐shaped side chain bearing a “clickable” alkyne group at the conjunction point of two blocks was first prepared through the combination of anionic polymerization of styrene (St) and atom transfer radical polymerization of tert‐butyl acrylate (tBA) monomer, and then “click” chemistry was conducted between the alkyne groups on the side chains and azide groups on HPG core. The obtained star graft copolymers and intermediates were characterized by gel permeation chromatography (GPC), GPC equipped with a multiangle laser‐light scattering detector (GPC‐MALLS), nuclear magnetic resonance spectroscopy and fourier transform infrared. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1308–1316, 2009     

One‐pot synthesis of heterograft copolymers via “graft onto” by atom transfer nitroxide radical coupling chemistry

Heterograft copolymers poly(4‐glycidyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐co‐ ethylene oxide)‐graft‐polystyrene and poly(tert‐butyl acrylate) (poly (GTEMPO‐co‐EO)‐g‐PS/PtBA) were synthesized in one‐pot by atom transfer nitroxide radical coupling (ATNRC) reaction via “graft onto.” The main chain was prepared by the anionic ring‐opening copolymerization of ethylene oxide (EO) and 4‐glycidyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl (GTEMPO) first, then the polystyrene and poly (tert‐butyl acrylate) with bromine end (PS‐Br, PtBA‐Br) were prepared by atom transfer radical polymerization (ATRP). When three of them were mixed each other in the presence of CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) at 90 °C, the formed secondary carbon radicals at the PS and PtBA chain ends were quickly trapped by nitroxide radicals on poly(GTEMPO‐co‐EO). The heterograft copolymers were well defined by ¹H NMR, size exclusion chromatography, fourier transform infrared, and differential scanning calorimetry in detail. It was found that the density of GTEMPO groups on main chain poly(GTEMPO‐co‐EO), the molecular weights of PS/PtBA side chains, and the structure of macroradicals can exert the great effects on the graft efficiency. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6770–6779, 2008     

Successive SET‐LRP and ATRP synthesis of ferrocene‐based PPEGMEA‐g‐PAEFC well‐defined amphiphilic graft copolymer

A series of ferrocene‐based well‐defined amphiphilic graft copolymers, consisting of hydrophilic poly[poly(ethylene glycol) methyl ether acrylate] (PPEGMEA) backbone and hydrophobic poly(2‐acryloyloxyethyl ferrocenecarboxylate) (PAEFC) side chains were synthesized by successive single‐electron‐transfer living radical polymerization (SET‐LRP) and atom transfer radical polymerization (ATRP). The backbone was prepared by SET‐LRP of PEGMEA macromonomer, and it was then treated with lithium di‐isopropylamide and 2‐bromopropionyl bromide at ?78 °C to give PPEGMEA‐Br macroinitiator. The targeted well‐defined graft copolymers with narrow molecular weight distributions (M_w/M_n ≤ 1.32) were synthesized via ATRP of AEFC initiated by PPEGMEA‐Br macroinitiator, and the molecular weights of the backbone and side chains were both controllable. The electro‐chemical behaviors of graft copolymers were studied by cyclic voltammetry, and it was found that graft copolymers were more difficult to be oxidized, and the reversibility of electrode process became less with raising the content of PAEFC segment. The effects of the preparation method, the length of hydrophobic PAEFC segment, and the initial water content on self‐assembly behavior of PPEGMEA‐g‐PAEFC graft copolymers in aqueous media were investigated by transmission electron microscopy. The morphologies of micelles could transform from cylinders to spheres or rods with changing the preparation condition and the length of side chains. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Multisensitive polymers based on 2‐vinylpyridine and N‐isopropylacrylamide *

Poly(2‐vinylpyridine) (P2VP) containing functionalized end groups was synthesized using nitroxyl‐mediated radical polymerization with a hydroxy‐functionalized stable free radical. It was shown that P2VP could be synthesized with variable molar masses and low polydispersities. The transformation of the hydroxy groups to an acrylic ester led to the formation of macromonomers. A free‐radical copolymerization of these macromonomers with N‐isopropylacrylamide gave a graft copolymer with a poly(N‐ispopropylacrylamide) backbone and P2VP side chains. Polymers containing different amounts of the monomers were synthesized. It was possible to vary both the amount of P2VP side chains at a constant chain length of the macromonomer and the chain length at a nearly constant chain number. The behavior of the multifunctional macromolecules at different temperatures and pH values was investigated using dynamic light scattering and DSC. The macromolecules were found to retain the specific properties of the homopolymers. The hydrodynamic radii of the synthesized graft copolymers were both dependent on the temperature and pH value. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3797–3804, 2001     

A novel fluorine‐containing graft copolymer bearing perfluorocyclobutyl aryl ether‐based backbone and poly(methyl methacrylate) side chains

A series of novel graft copolymers consisting of perfluorocyclobutyl aryl ether‐based backbone and poly(methyl methacrylate) side chains were synthesized by the combination of thermal [2π + 2π] step‐growth cycloaddition polymerization of aryl bistrifluorovinyl ether monomer and atom transfer radical polymerization (ATRP) of methyl methacrylate. A new aryl bistrifluorovinyl ether monomer, 2‐methyl‐1,4‐bistrifluorovinyloxybenzene, was first synthesized in two steps from commercially available reagents, and this monomer was homopolymerized in diphenyl ether to provide the corresponding perfluorocyclobutyl aryl ether‐based homopolymer with methoxyl end groups. The fluoropolymer was then converted to ATRP macroinitiator by the monobromination of the pendant methyls with N‐bromosuccinimide and benzoyl peroxide. The grafting‐from strategy was finally used to obtain the novel poly(2‐methyl‐1,4‐bistrifluorovinyloxybenzene)‐g‐poly(methyl methacrylate) graft copolymers with relatively narrow molecular weight distributions (M_w/M_n ≤ 1.46) via ATRP of methyl methacrylate at 50 °C in anisole initiated by the Br‐containing macroinitiator using CuBr/dHbpy as catalytic system. These fluorine‐containing graft copolymers can dissolve in most organic solvents. This is the first example of the graft copolymer possessing perfluorocyclobutyl aryl ether‐based backbone. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Convenient synthesis of thermo‐responsive PtBA‐g‐PPEGMEMA well‐defined amphiphilic graft copolymer without polymeric functional group transformation

A series of well‐defined amphiphilic graft copolymers bearing hydrophobic poly(tert‐butyl acrylate) backbone and hydrophilic poly[poly(ethylene glycol) methyl ether methacrylate)] (PPEGMEMA) side chains were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization and single‐electron‐transfer living radical polymerization (SET‐LRP) without any polymeric functional group transformation. A new Br‐containing acrylate monomer, tert‐butyl 2‐((2‐bromoisobutanoyloxy)methyl)acrylate (tBBIBMA), was first prepared, which can be homopolymerized by RAFT to give a well‐defined PtBBIBMA homopolymer with a narrow molecular weight distribution (M_w/M_n = 1.15). This homopolymer with pendant Br initiation group in every repeating unit initiated SET‐LRP of PEGMEMA at 45 °C using CuBr/dHbpy as catalytic system to afford well‐defined PtBBIBMA‐g‐PPEGMEMA graft copolymers via the grafting‐from strategy. The self‐assembly behavior of the obtained graft copolymers in aqueous media was investigated by fluorescence spectroscopy and TEM. These copolymers were found to be stimuli‐responsive to both temperature and ions. Finally, poly(acrylic acid)‐g‐PPEGMEMA double hydrophilic graft copolymers were obtained by selective acidic hydrolysis of hydrophobic PtBA backbone while PPEGMEMA side chains kept inert. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis of polyallene‐based graft copolymer via 6‐methyl‐1,2‐heptadien‐4‐ol and styrene

A series of well‐defined graft copolymers with a polyallene‐based backbone and polystyrene side chains were synthesized by the combination of living coordination polymerization of 6‐methyl‐1,2‐heptadien‐4‐ol and atom transfer radical polymerization (ATRP) of styrene. Poly(alcohol) with polyallene repeating units were prepared via 6‐methyl‐1,2‐heptadien‐4‐ol by living coordination polymerization initiated by [(η³‐allyl)NiOCOCF₃]₂ firstly, followed by transforming the pendant hydroxyl groups into halogen‐containing ATRP initiation groups. Grafting‐from route was employed in the following step for the synthesis of the well‐defined graft copolymer: polystyrene was grafted to the backbone via ATRP of styrene. The cleaved polystyrene side chains show a narrow molecular weight distribution (M_w/M_n = 1.06). This kind of graft copolymer is the first example of graft copolymer via allene derivative and styrenic monomer. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5509–5517, 2007     

Random and block styrenic copolymers bearing both ammonium and fluorinated side‐groups

1H,1H,2H,2H‐Perfluorooctyloxymethylstyrene (FS) was prepared and copolymerized with chloromethylstyrene (CMS). Conventional radical copolymerization of both these aromatic monomers led to poly(CMS‐co‐FS) random copolymers for which CMS was shown to be more reactive than the fluorinated comonomer. Their controlled radical copolymerization based on degenerative transfer, namely iodine transfer polymerization (ITP), led to various poly(CMS)‐b‐poly(FS) block copolymers. Molecular weights of poly(CMS‐co‐FS) copolymers reached 33,000 g mol^?1 while those of poly(CMS)‐b‐ poly(FS) block copolymers were 22,000 g mol^?1. Their composition ranged from 18 to 61 mol.% in FS. These copolymers were modified via a cationization step, aiming at replacing the chlorine atom in CMS unit by a trimethylammonium group, leading to the formation of cationic sites. The resulting functionalized copolymers exhibited different solubilities. If both copolymerization techniques led to water‐insoluble copolymers, the block architecture enabled incorporating lower FS proportion, resulting in more cationic sites. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

R‐RAFT approach for the polymerization of N‐isopropylacrylamide with a star poly(ε‐caprolactone) core

Reversible addition‐fragmentation chain transfer (RAFT) polymerization is a more robust and versatile approach than other living free radical polymerization methods, providing a reactive thiocarbonylthio end group. A series of well‐defined star diblock [poly(ε‐caprolactone)‐b‐poly(N‐isopropylacrylamide)]₄ (SPCLNIP) copolymers were synthesized by R‐RAFT polymerization of N‐isopropylacrylamide (NIPAAm) using [PCL‐DDAT]₄ (SPCL‐DDAT) as a star macro‐RAFT agent (DDAT: S‐1‐dodecyl‐S′‐(α, α′‐dimethyl‐α″‐acetic acid) trithiocarbonate). The R‐RAFT polymerization showed a controlled/“living” character, proceeding with pseudo‐first‐order kinetics. All these star polymers with different molecular weights exhibited narrow molecular weight distributions of less than 1.2. The effect of polymerization temperature and molecular weight of the star macro‐RAFT agent on the polymerization kinetics of NIPAAm monomers was also addressed. Hardly any radical–radical coupling by‐products were detected, while linear side products were kept to a minimum by careful control over polymerization conditions. The trithiocarbonate groups were transferred to polymer chain ends by R‐RAFT polymerization, providing potential possibility of further modification by thiocarbonylthio chemistry. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Investigation of thiol‐ene addition reaction on poly(isoprene) under UV irradiation: Synthesis of graft copolymers with “V”‐shaped side chains

Poly(isoprene) (PI) with pendant functional groups was successfully synthesized by thiol‐ene addition reaction under 365 nm UV irradiation, and the functionalized PI was further modified and used to prepare graft copolymers with “V”‐shaped side chains. First, the pendant ? SCH₂CH(OH)CH₂OH groups were introduced to PI by thiol‐ene addition reaction between 1‐thioglycerol and double bonds, and the results showed that the addition reaction carried out only on double bonds of 1,2‐addition isoprene units. After the esterification of hydroxyl groups by 2‐bromoisobutyryl bromide, the forming macroinitiator was used to initiate the atom transfer radical polymerization (ATRP) of styrene (St) and tert‐butyl acrylate (tBA), and the graft copolymers PI‐g‐PS ₂ and PI‐g‐PtBA ₂ or PI‐g‐PAA ₂ (by hydrolysis of PI‐g‐PtBA ₂) were obtained, respectively. It was confirmed that the graft density of side chains on PI main chains could be easily controlled by variation of the contents of modified 1,2‐addition isoprene units on PI. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3797–3806, 2010     

Synthesis and characterization of donor–acceptor poly(3‐hexylthiophene) copolymers presenting 1,3,4‐oxadiazole units and their application to photovoltaic cells

We have used Grignard metathesis polymerization to prepare poly(3‐hexylthiophene)‐based copolymers containing electron‐withdrawing 4‐tert‐butylphenyl‐1,3,4‐oxadiazole‐phenyl moieties as side chains. We characterized these copolymers using ¹H and ¹³C nuclear magnetic resonance spectroscopy, thermogravimetric analysis, and gel permeation chromatography. The band gap energy of copolymer was determined from the onset of the optical absorption. The quenching effects were observed in the photoluminescence spectra of the copolymers incorporating pendant electron‐deficient 1,3,4‐oxadiazole moieties on the side chains. The photocurrents of devices were enhanced in the presence of an optimal amount of the 1,3,4‐oxadiazole moieties, thereby leading to improved power conversion efficiencies. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3331–3339, 2010     

Layer structure estimation of three‐dimensional crystal and two‐dimensional molecular film for fluorinated comb copolymers

Comb copolymers containing both hydrogenated and fluorinated side‐chains were prepared by copolymerization using acrylic or methacrylic monomers in several ratios. The crystal structures of these copolymers and layer structures of their organized molecular films were investigated by wide‐angle X‐ray diffraction (WAXD), small‐angle X‐ray scattering (SAXS), and out‐of plane X‐ray diffraction. Further, to selectively estimate the regularity of shorter fluorocarbon side‐chains, organized molecular films of copolymers were investigated by polarized near‐edge X‐ray adsorption fine structure (NEXAFS) spectroscopy. From the results of these measurements, it was inferred that these copolymers formed highly ordered layer structures, and a long spacing was predominantly determined by the arrangement of hydrogenated side‐chains, except in copolymers having extremely high fluorocarbon contents. In the case of the organized molecular films, the fluorinated side‐chains of methacrylate copolymers cannot form a highly ordered arrangement, whereas those of acrylate copolymers were oriented on monolayers. However, in both cases, the hydrogenated side‐chains predominantly formed layer structures in the organized films, and the fluorinated side‐chains did not contribute to the formation of the layer structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 534–546, 2008