Post‐functionalization of perfluorophenyl ester‐functional acyclic diene metathesis polymer

The acyclic diene metathesis (ADMET) polymerization was utilized for the design of the ADMET polymer (M_n = 21,200 g/mol, M_w/M_n = 1.74) with pendant perfluorophenyl ester functionality using Grubbs first generation catalysis overnight in bulk at 80 °C. Next, a wide variety of functional groups, like benzyl, octyl, propargyl, allyl, and furfuryl was quantitatively incorporated to the ADMET polymer backbone through various amines using activated ester substitution reaction. The ADMET polymers studied in this work were characterized using ¹H, ¹³C, and ¹⁹F NMR, GPC and DSC and displayed a monomodal distribution and a rather broad polydispersity index in the range of ?1.33 to 1.90. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2593–2598     

Chemical composition of natural colophony from Pinus brutia and comparison with synthetic colophony

The compositions of colophony resins obtained from Pinus brutia Ten trees by three different methods (acid paste, carved hole and scraping) from Ayvacik, G?kova and Kemalpa?a in Turkey were analyzed by capillary GC-MS. The main components were the monoterpenes alpha-pinene, beta-pinene, and delta3-carene, and the diterpenic resin acids palustric, abietic, kaur-9(11)-16-en-18-oic and neoabietic acid. The synthetic colophony resins exhibited similar contents to those of the natural resins obtained from the G?kova and Kemalpa?a regions of Turkey. However, colophony resins from Ayvacik exhibited only half the diterpenic acid content as those of the G?kova and Kemalpa?a resins. Out of the three techniques, the carved hole method caused rather different percentages in the constituents of the essential oils.     

Temperature dependent photoluminescence of PECVD a-SiOx:H (x<2)

The temperature dependent visible photoluminescence (PL) property of a-SiO_x:H (x<2) samples prepared in a PECVD system by using SiH₄+CO₂ gas mixture is investigated at a temperature range of 20 K-400 K. One of the two explicitly distinguished PL bands, with varying peak photon energies between 1.70 and 2.05 eV, can be detected at only low temperatures below 200 K, which is attributed to tail-to-tail radiative recombination. Thermal quenching parameter (T_L) of the tail-to-tail PL band is calculated as varying between 120 and 280 K as the atomic oxygen concentration ([O]at.%) of the samples increases. Stokes shift (ΔE_Stokes) of the tail-to-tail PL band is found to change from 85 meV to 420 meV due to band tail widening. The other PL band emerges at 2.1 eV and can be detected at higher temperatures with thermal activation behavior. The activation energies calculated about room temperature vary in the range of 8 meV-50 meV with oxygen concentration. Thermal activation of the 2.1 eV PL band is attributed to the behavior of thermally activated incoherent hopping migration of electrons. These electrons combine with self trapped holes (STHs) to form self trapped excitons (STEs). STEs are localized at intrinsic defects of SiO₂ structure such as oxygen vacancies (E′ centers) and non-bridging oxygen hole centers (NBOHC).     

Automorphisms and Homotopies of Groupoids and Crossed Modules

This paper is concerned with the algebraic structure of groupoids and crossed modules of groupoids. We describe the group structure of the automorphism group of a finite connected groupoid C as a quotient of a semidirect product. We pay particular attention to the conjugation automorphisms of C, and use these to define a new notion of groupoid action. We then show that the automorphism group of a crossed module of groupoids C\mathcal{C}, in the case when the range groupoid is connected and the source group totally disconnected, may be determined from that of the crossed module of groups C_u\mathcal{C}_u formed by restricting to a single object u. Finally, we show that the group of homotopies of C\mathcal{C} may be determined once the group of regular derivations of C_u\mathcal{C}_u is known.     

Synthesis and Spectroscopic Studies of 3,6-Diphenyl-2,5-Dihydropyrrolo[3,4-C]Pyrrole-1,4-Dion’s N,N’-Dialkyl Derivatives

3,6-diaryl-2,5-dihydro-1,4-diketopyrrolo[3,4-c]pyrrole-1,4-dione (DPPD) derivatives are used commercially as red pigments, because of their color strength, brightness, and very low solubility in most common solvents. These products, although highly colored, appear to be of limited value as dyes, since they show a tendency to form an aggregate when incorporated into a solvent. Monoalkyl and dialkyl derivatives of DPPD were synthesized and then characterized with IR, ¹HNMR, UV-Vis absorption and emission spectroscopy. Molar absorption coefficient, singlet energy level and Stokes’ shift values of DPPD derivatives were declared. Monoalkyl and dialkyl derivatives of DPPD’s solubilities were measured from saturated solutions of dimethylformamide (DMF), tetrahydrofuran (THF), dichloromethane (DCM), acetonitrile (ACN) and toluene and they are compared with each other.     

Polymer grafting onto polyurethane backbone via Diels–Alder reaction

The aliphatic polyurethane with pendant anthracene moieties (PU‐anthracene) was prepared from polycondensation of anthracen‐9‐yl methyl 3‐hydroxy‐2‐(hydroxymethyl)‐2‐methylpropanoate (anthracene diol), 1 with hexamethylenediisocyanate in the presence of dibutyltindilaurate in CH₂Cl₂ at room temperature for 10 days. Thereafter, the PU‐anthracene (M_n,GPC = 12,900 g/mol, M_w/M_n = 1.87, relative to PS standards) was clicked with a linear α‐furan protected‐maleimide terminated‐poly(methyl methacrylate) (PMMA‐MI) (M_n,GPC = 2500 g/mol, M_w/M_n = 1.33), or ‐poly(ethylene glycol) (PEG‐MI) (M_n,GPC = 550 g/mol, M_w/M_n = 1.09), to result in well‐defined PU‐graft copolymers, PU‐g‐PMMA (M_n,GPC = 23800 g/mol, M_w/M_n = 1.65, relative to PS standards) or PU‐g‐PEG (M_n,GPC = 11,600 g/mol, M_w/M_n = 1.45, relative to PS standards) using Diels–Alder reaction in dioxane/toluene at 105 °C. The Diels–Alder grafting efficiencies were found to be over 93–99% using UV spectroscopy. Moreover, the structural analyses and the thermal transitions of all copolymers were determined via ¹H NMR and DSC, respectively. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 521–527     

3‐miktoarm star terpolymers using triple click reactions: Diels–Alder,copper‐catalyzed azide‐alkyne cycloaddition,and nitroxide radical coupling reactions

Well‐defined linear furan‐protected maleimide‐terminated poly(ethylene glycol) (PEG‐MI), tetramethylpiperidine‐1‐oxyl‐terminated poly(ε‐caprolactone) (PCL‐TEMPO), and azide‐terminated polystyrene (PS‐N₃) or ‐poly(N‐butyl oxanorbornene imide) (PONB‐N₃) were ligated to an orthogonally functionalized core ( 1 ) in a two‐step reaction mode through triple click reactions. In a first step, Diels–Alder click reaction of PEG‐MI with 1 was performed in toluene at 110 °C for 24 h to afford α‐alkyne‐α‐bromide‐terminated PEG (PEG‐alkyne/Br). As a second step, this precursor was subsequently ligated with the PCL‐TEMPO and PS‐N₃ or PONB‐N₃ in N,N‐dimethylformamide at room temperature for 12 h catalyzed by Cu(0)/Cu(I) through copper‐catalyzed azide‐alkyne cycloaddition and nitroxide radical coupling click reactions, yield resulting ABC miktoarm star polymers in a one‐pot mode. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012