bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of well‐defined PNIPAM‐b‐(PEA‐g‐P2VP) double hydrophilic graft copolymer via sequential SET‐LRP and ATRP and its “schizophrenic” Micellization behavior in aqueous media
Authors: Feng Chun , Li Yongjun , Yang Dong , Li Yaogong , Hu Jianhua , Zhai Sujuan , Lu Guolin , Huang Xiaoyu 
Published: November 2009

AbstractA series of well‐defined double hydrophilic graft copolymers, consisting of poly(N‐isopropylacrylamide)‐b‐poly(ethyl acrylate) backbone and poly(2‐vinylpyridine) 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 sequential SET‐LRP of N‐isopropylacrylamide and 2‐hydroxyethyl acrylate at 25 °C using CuCl/tris(2‐(dimethylamino)ethyl)amine as the catalytic system. The obtained diblock copolymer was transformed into the macroinitiator by reacting with 2‐chloropropionyl chloride. Next, grafting‐from strategy was used for the synthesis of poly(N‐isopropylacrylamide)‐b‐[poly(ethyl acrylate)‐g‐poly(2‐vinylpyridine)] double hydrophilic graft copolymer. ATRP of 2‐vinylpyridine was initiated by the macroinitiator at 25 °C using CuCl/hexamethyldiethylenetriamine as the catalytic system. The synthesis of both the backbone and the side chains are controllable. Thermo‐ and pH‐responsive schizophrenic micellization behaviors were investigated by 1H NMR, fluorescence spectroscopy, dynamic light scattering, and transmission electron microscopy. Unimolecular micelles with PNIPAM‐core formed in acidic environment (pH = 2) with elevated temperature (T ≥ 32 °C), whereas the aggregates turned into spheres with PEA‐g‐P2VP‐core accompanied with the lifting of pH values (pH ≥ 5.3) at room temperature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 15–23, 2010
Making “smart polymers” smarter: Modern concepts to regulate functions in polymer science
Authors: Börner Hans G. , Kühnle Hans , Hentschel Jens 
Published: November 2009

AbstractThis highlight summarizes recent attempts and advances of macromolecular sciences to abstract the biological concept of regulation and import it into synthetic polymer systems. The differences of “responsive switching” exploited in smart polymers and “regulation” present in the biological world of proteins are evident. Therefore, the biomimetic regulation might advance the possibilities of polymer science beyond these of established “smart polymers” and makes precise regulation of functions through signaling events, signal transduction and even complex regulative circuits possible. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1–14, 2010
A minimal amount of acrylonitrile turns the nitroxide‐mediated polymerization of methyl methacrylate into an almost ideal controlled/living system
Authors: Nicolas Julien , Brusseau Ségolène , Charleux Bernadette 
Published: November 2009

AbstractNitroxide‐mediated controlled/living free‐radical polymerization of methyl methacrylate initiated by the SG1‐based alkoxyamine BlocBuilder was successfully performed in bulk at 80–99 °C with the help of a very small amount of acrylonitrile (AN, 2.2–8.8 mol %) as a comonomer. Well‐defined PMMA‐rich P(MMA‐co‐AN) copolymers were prepared with the number‐average molar mass, Mn, in the 6.1–32 kg mol−1 range and polydispersity indexes as low as 1.24. Incorporation of AN in the copolymers was demonstrated by 1H and 13C NMR spectroscopy, and its effect on the chain thermal properties was evaluated by DSC and TGA analyses. Investigation of chain‐end functionalization by an alkoxyamine group was performed by means of 31P NMR spectroscopy and chain extensions from a P(MMA‐co‐AN)‐SG1 macroinitiator. It demonstrated the very high proportion of SG1‐terminated polymer chains, which opened the door to block copolymer synthesis with a high quality of control. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 34–47, 2010
Photoresponsive oil sorbers
Authors: Kulawardana Erandimala U. , Neckers Douglas C. 
Published: November 2009

AbstractA photoresponsive oil sorber (POS) with a hydrophobic, photoresponsive core and shell has been synthesized via suspension polymerization. Lauryl acrylate, isodecyl acrylate, and tert‐butylstyrene were used as monomers, 4‐(methacrylamino)azobenzene (Azo‐M) used as photoresponsive monomer, and bis(methacryloylamino)azobenzene (Azo‐CL‐M) used as photoresponsive surface crosslinker. The POS prefers nonpolar solvents. It absorbed 15 times its dry weight in toluene, 19 times its dry weight in chloroform, and 16 times its dry weight in dichloromethane. Rapid and photoresponsive desorption of solvent (86% of solvent expulsed in 30 min) was characteristic. POS is an excellent gasoline absorber rapidly increasing its body weight in its presence. The new POS is less dense than water, and can potentially be used for cleaning oil spills on water. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 55–62, 2010
Copolymerization of vinylidene fluoride and acrylic acid in supercritical carbon dioxide
Authors: Firetto Vanessa , Scialdone Onofrio , Silvestri Giuseppe , Spinella Alberto , Galia Alessandro 
Published: November 2009

AbstractThe free‐radical copolymerization of vinylidene fluoride (VDF) and acrylic acid (AA) was carried out in supercritical carbon dioxide using both precipitation and dispersion techniques in the presence of an ammonium carboxylate perfluoropolyether compound. Formation of a copolymer was confirmed by variable contact time CP MAS NMR spectroscopy. Macromolecular matrices were significantly enriched in AA with respect to the initial feed composition and we found that the nonfluorinated monomer has a much higher reactivity ratio with respect to VDF. The cumulative concentration, crystallinity, and water affinity of the synthesized copolymers could be modified changing the initial feed composition, the density of the polymerization mixture, the specific interfacial area of the polymer phase, and the polymerization time. The solubility of the macromolecular product in water was greatly affected by its composition. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 109–121, 2010
Investigation of nitrogen‐rich energetic polymers based on alkylbridged bis‐(1‐methyl‐tetrazolylhydrazines)
Authors: Klapötke Thomas M. , Sproll Stefan M. 
Published: November 2009

AbstractNitrogen‐rich energetic polymers were synthesized by the polyaddition reaction of 1,2‐bis(5‐monomethylhydrazinyl‐1H‐tetrazolyl)ethane (1a), 1‐methyl‐1,2‐bis(5‐monomethylhydrazinyl‐1H‐tetrazolyl)ethane (1b), and 1,4‐bis(5‐mono‐methylhydrazinyl‐1H‐tetrazolyl)butane (1c) with hexamethylene diisocyanate. The experiments showed that neither a polymerization from solution or bulk was possible. Therefore, a new method for the polymerization of tetrazolyl hydrazines had to be developed. The formed polymers were characterized by vibrational spectroscopy (IR) and elemental analysis. The energetic properties were investigated by bomb calorimetric measurements along with calculations using the EXPLO5 software. The thermal stability was investigated by DSC measurements. The properties render the polymers into promising compounds regarding an application as energetic binder. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 122–127, 2010
Microwave‐assisted derivatization of cellulose in an ionic liquid: An efficient, expedient synthesis of simple and mixed carboxylic esters
Authors: Possidonio Shirley , Fidale Ludmila C. , El Seoud Omar A. 
Published: November 2009

AbstractMicrowave (MW)‐assisted cellulose dissolution in ionic liquids (ILs) has routinely led either to incomplete biopolymer solubilization, or its degradation. We show that these problems can be avoided by use of low‐energy MW heating, coupled with efficient stirring. Dissolution of microcrystalline cellulose in the IL 1‐allyl‐3‐methylimidazolium chloride has been achieved without changing its degree of polymerization; regenerated cellulose showed pronounced changes in its index of crystallinity, surface area, and morphology. MW‐assisted functionalization of MCC by ethanoic, propanoic, butanoic, pentanoic, and hexanoic anhydrides has been studied. Compared with conventional heating, MW irradiation has resulted in considerable decrease in dissolution and reaction times. The value of the degree of substitution (DS) was found to be DSethanoate > DSpropanoate > DSbutanoate. The values of DSpentanoate and DShexanoate were found to be slightly higher than DSethanoate. This surprising dependence on the chain length of the acylating agent has been reported before, but not rationalized. On the basis of the rate constants and activation parameters of the hydrolysis of ethanoic, butanoic, and hexanoic anhydrides in aqueous acetonitrile (a model acyl transfer reaction), we suggest that this result may be attributed to the balance between two opposing effects, namely, steric crowding and (cooperative) hydrophobic interactions between the anhydride and the cellulosic surface, whose lipophilicity has increased, due to its partial acylation. Four ethanoate‐based mixed esters were synthesized by the reaction with a mixture of the two anhydrides; the ethanoate moiety predominated in all products. The DS is reproducible and the IL is easily recycled. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 48: 134–143, 2010
Phosphorus ligands for iron(III)‐mediated ATRP of styrene via generation of activators by monomer addition
Authors: He Dan , Xue Zhigang , Khan Mohd Yusuf , Noh Seok Kyun , Lyoo Won Seok 
Published: November 2009

AbstractStyrene polymerization via generation of activators by monomer addition (GAMA) for atom transfer radical polymerization (ATRP) has been examined extensively with bulk FeX3 and FeX2 at 110 °C in conjunction with various phosphorus‐bearing ligands. It was found that GAMA possesses advantages over normal ATRP. Most importantly, narrower polydispersity index (PDI) values were observed from the styrene polymerizations with Fe(III) over those with Fe(II). Every instance of 2‐(diphenylphosphino)‐N,N′‐dimethyl‐[1,1′‐biphenyl]‐2‐amine and 2‐(diphenylphosphino) pyridine with the Fe(III) system were controlled excellently without addition of any radical initiator or reducing agent additives. Initiator type was found to exert a significant factor to influence on the controllability of polymerization. The initiation of 1‐phenylethyl chloride and methyl‐2‐chloropropionate gave rise to formation of polymers with narrow PDI (1.05–1.20), whereas those from 1‐phenylethyl bromide increased to 1.35. The GAMA of bulk styrene exhibited the best performance in terms of both rate and controllability compared with toluene and anisole. Both formation of block copolymer from the macroinitiator and efficient perturbation of polymerization with 2,2,6,6‐tetramethylpiperidine 1‐oxyl provided firm evidence to support the living and radical characteristics for the GAMA of styrene. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 144–151, 2010
Grafting polymer chains bearing an N‐succinimidyl activated ester end‐group onto primary amine‐coated silica particles and application of a simple, one‐step approach via nitroxide‐mediated controlled/living free‐radical polymerization
Authors: Parvole Julien , Ahrens Lucas , Blas Hélène , Vinas Jérôme , Boissière Cédric , Sanchez Clément , Save Maud , Charleux Bernadette 
Published: November 2009

AbstractIn a first part, the alkoxyamine initiator derived from BlocBuilder® based on the nitroxide SG1 and bearing an N‐succinimidyl ester function was used to synthesize a variety of well‐defined polymers with the activated ester group at the α‐end. The grafting of those polymer chains onto primary‐amine functionalized Stöber silica particles was performed in soft conditions at room temperature and was studied as a function of the polymer chain length, the type of solvent, and the concentrations of both polymer and amine. Polymer grafting densities were mainly in the 0.1–0.2 chain nm−2 range. To increase the grafting density in simple experimental conditions, a direct one‐step method was then proposed: the primary‐amine modified silica, the N‐succinimidyl ester functionalized alkoxyamine, and the monomer were all introduced into the reaction medium at once. This technique allowed grafting and chain growth to take place simultaneously at the polymerization temperature (i.e., 120 °C for styrene), in a single step, and produced hybrid particles with very high grafting density, up to 0.9 chain nm−2, and long polymer chains. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 173–185, 2010
Dicarboxylic imide‐substituted poly(p‐phenylene vinylenes) with high electron affinity
Authors: Qu Hemi , Luo Jing , Zhang Xiaojie , Chi Chunyan 
Published: November 2009

AbstractSynthesis of n‐type organic semiconductors with high electron mobilities, good environmental stability, and good processability is an urgent task in current organic electronics. This is because most of π‐conjugated materials are p‐type and prefer to transport positive hole carriers. In this article, a series of new dicarboxylic imide‐substituted poly(p‐phenylene vinylenes) (DI‐PPVs) were first synthesized. They exhibited a high electron affinity of 3.60 eV and thus are able to transport electrons. The polymers showed tunable solubility in common organic solvents and high chemical and thermal stability. They remain rigidity of the PPV backbone, and strong interchain π‐stacking was observed in thin films by X‐ray diffraction measurement. All these suggested that these polymers could serve as good candidates as n‐type semiconductors in organic electronic devices such as n‐channel field‐effect transistors and all polymer‐based solar cells. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 186–194, 2010
Thermophysical analysis of SU8‐modified microstructures created by visible light lithography
Authors: Rodriguez Ponce Daniel , Lozano Karen , Eubanks Thomas , Harb Ahmad , Ferrer Domingo , Lin Yuankun 
Published: November 2009

AbstractSU8 has been modified with photoinitiators Rose Bengal, H‐NU 470 and H‐NU 535, to conduct visible light lithography. The thermophysical properties of the lithographically transformed modified SU8 photoresins were investigated. The influence of the concentration of visible light photosensitizer and photoinitiator as well as exposure time to visible laser on thermal stability and curing kinetics were analyzed. Significant differences in the thermophysical properties were observed in these three photoinitiator groups of modified SU8 photoresins. These results provide with usable quantitative information regarding resin formulation to optimize lithography processing parameters, and therefore, the ultimate properties of lithographically formed microstructures. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 47–54, 2010
Cold crystallization behavior of polyamide 6 in PS‐g‐PA6 graft copolymers
Authors: Shi Dean , Wang Xiao‐Yang , Shi Hengchong , Yin Jing‐Hua , Li Robert K. Y. , Hu Guo‐Hua 
Published: November 2009

AbstractTEM micrographs show that the PA grafts of PS‐g‐PA6 graft copolymers, which are obtained directly by extracting homo‐PA6 out from the homo‐PA6/PS‐g‐PA6 blends, are in the form of wormlike structure. The wormlike PA6 domains can shrink into droplets after annealing at 250 °C for 15 min. The diameter of the droplet determined by TEM and SAXS is in the range of 50–60 nm. This article reports on a unique crystallization behavior of the PA6 grafts in PS‐g‐PA6 graft copolymers. In a DSC cooling scan, PA6 grafts do not crystallize from the melt with a cooling rate of 10 °C/min. However, there is a cold crystallization peak around 65 °C in the subsequent heating scan. This cold crystallization phenomenon, which has not yet been reported in the literature till now, follows well the homogeneous nucleation mechanism and is depressed at relatively slow cooling rates (2 °C/min) or even completely eliminated after annealing within a specific temperature range. It may be caused by the slow diffusion or transport rate of the less flexible PA6 grafts to the crystal fronts when crystallization takes place around its glass transition temperature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 65–73, 2010
Human prostate sphere‐forming cells represent a subset of basal epithelial cells capable of glandular regeneration in vivo
Authors: Garraway Isla P. , Sun Wenyi , Tran Chau P. , Perner Sven , Zhang Bao , Goldstein Andrew S. , Hahm Scott A. , Haider Maahum , Head Christian S. , Reiter Robert E. , Rubin Mark A. , Witte Owen N. 
Published: November 2009

AbstractBACKGROUNDProstate stem/progenitor cells function in glandular development and maintenance. They may be targets for tumor initiation, so characterization of these cells may have therapeutic implications. Cells from dissociated tissues that form spheres in vitro often represent stem/progenitor cells. A subset of human prostate cells that form prostaspheres were evaluated for self‐renewal and tissue regeneration capability in the present study.METHODSProstaspheres were generated from 59 prostatectomy specimens. Lineage marker expression and TMPRSS‐ERG status was determined via immunohistochemistry and fluorescence in situ hybridization (FISH). Subpopulations of prostate epithelial cells were isolated by cell sorting and interrogated for sphere‐forming activity. Tissue regeneration potential was assessed by combining sphere‐forming cells with rat urogenital sinus mesenchyme (rUGSM) subcutaneously in immunocompromised mice.RESULTSProstate tissue specimens were heterogeneous, containing both benign and malignant (Gleason 3–5) glands. TMPRSS‐ERG fusion was found in approximately 70% of cancers examined. Prostaspheres developed from single cells at a variable rate (0.5–4%) and could be serially passaged. A basal phenotype (CD44+CD49f+CK5+p63+CK8−AR−PSA−) was observed among sphere‐forming cells. Subpopulations of prostate cells expressing tumor‐associated calcium signal transducer 2 (Trop2), CD44, and CD49f preferentially formed spheres. In vivo implantation of sphere‐forming cells and rUGSM regenerated tubular structures containing discreet basal and luminal layers. The TMPRSS‐ERG fusion was absent in prostaspheres derived from fusion‐positive tumor tissue, suggesting a survival/growth advantage of benign prostate epithelial cells.CONCLUSIONHuman prostate sphere‐forming cells self‐renew, have tissue regeneration capability, and represent a subpopulation of basal cells. Prostate 70: 491–501, 2010. © 2009 Wiley‐Liss, Inc.
Androgen receptor CAG repeat length is not associated with the risk of incident symptomatic benign prostatic hyperplasia: Results from the prostate cancer prevention trial
Authors: Kristal Alan R. , Price Douglas K. , Till Cathee , Schenk Jeannette M. , Neuhouser Marian L. , Ockers Sandy , Lin Daniel W. , Thompson Ian M. , Figg William D. 
Published: November 2009

AbstractBACKGROUNDTo examine whether androgen receptor (AR) CAG repeat length was associated with the risk of incident benign prostatic hyperplasia (BPH).METHODSA nested case‐control study of 416 BPH cases and 527 controls drawn from Prostate Cancer Prevention Trial placebo‐arm participants who were free of BPH at baseline. BPH was assessed over 7 years and was defined as receipt of medical or surgical treatment, two scores > 14 on the International Prostate Symptom Score (IPSS), or two increases in IPSS ≥ 5 with at least one score ≥ 12.RESULTSCompared to men with AR repeat length ≤ 19, the covariate‐adjusted odds ratios [95% CI] were 1.07 [0.73, 1.57] and 0.90 [0.55, 1.45]) for repeat length 20–24 and ≥25, respectively. There was a weak association of AR repeat length with baseline serum testosterone (T) (Spearman r = 0.09, p < 0.02); however, control for or stratification by T did not change study results. Further, results did not differ when stratified by body mass index or baseline concentration of 3α‐diol glucoronide, and were similar for all BPH definitions.CONCLUSIONSThere were no associations of AR CAG repeat length and BPH risk. Knowledge of AR CAG repeat length provides no clinical useful information for the prevention of symptomatic BPH. Prostate 70: 584–590, 2010. © 2009 Wiley‐Liss, Inc.
Hepsin cooperates with MYC in the progression of adenocarcinoma in a prostate cancer mouse model
Authors: Nandana Srinivas , Ellwood‐Yen Katharine , Sawyers Charles , Wills Marcia , Weidow Brandy , Case Thomas , Vasioukhin Valeri , Matusik Robert 
Published: November 2009

AbstractBACKGROUNDHepsin is a cell surface protease that is over‐expressed in more than 90% of human prostate cancer cases. The previously developed Probasin‐hepsin/Large Probasin‐T antigen (PB‐hepsin/LPB‐Tag) bigenic mouse model of prostate cancer demonstrates that hepsin promotes primary tumors that are a mixture of adenocarcinoma and neuroendocrine (NE) lesions, and metastases that are NE in nature. However, since the majority of human prostate tumors are adenocarcinomas, the contribution of hepsin in the progression of adenocarcinoma requires further investigation.METHODSWe crossed the PB‐hepsin mice with PB‐Hi‐myc transgenic mouse model of prostate adenocarcinoma and characterized the tumor progression in the resulting PB‐hepsin/PB‐Hi‐myc bigenic mice.RESULTSWe report that PB‐hepsin/PB‐Hi‐myc bigenic mice develop invasive adenocarcinoma at 4.5 months. Further, histological analysis of the 12‐ to 17‐month‐old mice revealed that the PB‐hepsin/PB‐Hi‐myc model develops a higher grade adenocarcinoma compared with age‐matched tumors expressing only PB‐Hi‐myc. Consistent with targeting hepsin to the prostate, the PB‐hepsin/PB‐Hi‐myc tumors showed higher hepsin expression as compared to the age‐matched myc tumors. Furthermore, endogenous expression of hepsin increased in the PB‐Hi‐myc mice as the tumors progressed.CONCLUSIONSAlthough we did not detect any metastases from the prostates in either the PB‐hepsin/PB‐Hi‐myc or the PB‐Hi‐myc mice, our data suggests that hepsin and myc cooperate during the progression to high‐grade prostatic adenocarcinoma. Prostate 70: 591–600, 2010. © 2009 Wiley‐Liss, Inc.
NMR characterization of an engineered domain fusion between maltose binding protein and TEM1 β‐lactamase provides insight into its structure and allosteric mechanism
Authors: Wright Chapman M. , Majumdar Ananya , Tolman Joel R. , Ostermeier Marc 
Published: November 2009

AbstractRG13 is a 72 kDa engineered allosteric enzyme comprised of a fusion between maltose binding protein (MBP) and TEM1 β‐lactamase (BLA) for which maltose is a positive effector of BLA activity. We have used NMR spectroscopy to acquire [15N, 1H]‐TROSY‐HSQC spectra of RG13 in the presence and absence of maltose. The RG13 chemical shift data was compared to the published chemical shift data of MBP and BLA. The spectra are consistent with the expectation that the individual domain structures of RG13 are substantially conserved from MBP and BLA. Differences in the spectra are consistent with the fusion geometry of MBP and BLA and the maltose‐dependent differences in the kinetics of RG13 enzyme activity. In particular, the spectra provide evidence for a maltose‐dependent conformational change of a key active site glutamate involved in deacylation of the enzyme‐substrate intermediate. Proteins 2010. © 2009 Wiley‐Liss, Inc.