Dendrimer‐like miktoarm star terpolymers: A3‐(B‐C)3 via click reaction strategy

Two samples of dendrimer‐like miktoarm star terpolymers: (poly(tert‐butyl acrylate))₃‐(polystyrene‐poly(ε‐caprolactone))₃ (PtBA)₃‐(PS‐PCL)₃, and (PS)₃‐(PtBA‐poly(ethylene glycol)₃ were prepared using efficient Cu catalyzed Huisgen cycloaddition (click reaction). As a first step, azido‐terminated 3‐arm star polymers PtBA and PS as core (A) were synthesized by atom transfer radical polymerization (ATRP) of tBA and St, respectively, followed by the conversion of bromide end group to azide. Secondly, PS‐PCL and PtBA‐PEG block copolymers with alkyne group at the junction as peripheral arms (B‐C) were obtained via multiple living polymerization mechanisms such as nitroxide mediated radical polymerization (NMP) of St, ring opening polymerization (ROP) of ε‐CL, ATRP of tBA. Thus obtained core and peripheral arms were linked via click reaction to give target (A)₃‐(B‐C)₃ dendrimer‐like miktoarm star terpolymers. (PtBA)₃‐(PS‐PCL)₃ and (PS)₃‐(PEG‐PtBA)₃ have been characterized by GPC, DSC, AFM, and SAXS measurements. (PtBA)₃‐(PS‐PCL)₃ did not show any self‐organization with annealing due to the miscibility of the peripheral arm segments. In contrast, the micro‐phase separation of the peripheral arm segments in (PS)₃‐(PtBA‐PEG)₃ resulted in self‐organized phase‐separated morphology with a long period of ～ 13 nm. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5916–5928, 2008     

One‐pot preparation of 3‐miktoarm star terpolymers via click [3 + 2] reaction

The preparation of 3‐miktoarm star terpolymers using nitroxide mediated radical polymerization (NMP), ring opening polymerization (ROP), and click reaction [3 + 2] are carried out by applying two types of one‐pot technique. In the first one‐pot technique, NMP of styrene (St), ROP of ε‐caprolactone (ε‐CL), and [3 + 2] click reaction (between azide end‐functionalized poly(ethylene glycol) (PEG‐N₃)/or azide end‐functionalized poly(methyl methacrylate) (PMMA‐N₃) and alkyne) are carried out in the presence of 2‐(hydroxymethyl)‐2‐methyl‐3‐oxo‐3‐(2‐phenyl‐2‐(2,2,6,6‐tetramethylpiperidin‐1‐yloxy)ethoxy) propyl pent‐4‐ynoate, 2 , as an initiator for 48 h at 125 °C (one‐pot/one‐step). As a second technique, NMP of St and ROP of ε‐CL were conducted using 2 as an initiator for 20 h at 125 °C, and subsequently PEG‐N₃ or azide end‐functionalized poly(tert‐butyl acrylate (PtBA‐N₃) was added to the polymerization mixture, followed by a click reaction [3 + 2] for 24 h at room temperature (one‐pot/two‐step). The 3‐miktoarm star terpolymers, PEG‐poly(ε‐caprolactone)(PCL)‐PS, PtBA‐PCL‐PS and PMMA‐PCL‐PS, were recovered by a simple precipitation in methanol without further purification. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3588–3598, 2007     

ABCD 4‐miktoarm star quarterpolymers using click [3 + 2] reaction strategy

Two samples of ABCD 4‐miktoarm star quarterpolymer with A = polystyrene (PS), B = poly(ε‐caprolactone) (PCL), C = poly(methyl methacrylate) (PMMA) or poly(tert‐butyl acrylate) (PtBA), and D = poly(ethylene glycol) (PEG) were prepared using click reaction strategy (Cu(I)‐catalyzed Huisgen [3 + 2] reaction). Thus, first, predefined block copolymers of different polymerization routes, PS‐b‐PCL with azide and PMMA‐b‐PEG and PtBA‐b‐PEG copolymers with alkyne functionality, were synthesized and then these blocks were combined together in the presence of Cu(I)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as a catalyst in DMF at room temperature to give the target 4‐miktoarm star quarterpolymers. The obtained miktoarm star quarter polymers were characterized by GPC, NMR, and DSC measurements. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1218–1228, 2008     

The Inhomogeneous Quantum Invariance Group of The Two Parameter Deformed Boson Algebra

We consider two parameter deformed boson algebra and investigate the inhomogeneous invariance quantum group of this system. We find the R-matrix which collects all information about the non-commuting structure of the quantum group. We extend our study to the d-dimensional case.     

Sonochemical decay of C.I. Acid Orange 8: Effects of CCl4 and t-butyl alcohol

Sonochemical degradation of aryl-azo-naphthol dyes represented by C.I. Acid Orange 8 was investigated at 300 kHz to assess the operational parameters and the impacts of rate enhancers (CCl₄) and rate inhibitors (t-butyl alcohol). It was found that the degradation of the dye was accelerated with increased concentrations of CCl₄ via the accumulation of reactive chlorine species and the hindrance of OH radical combination reactions with atomic hydrogen. The addition of t-butyl alcohol at all test concentrations inhibited the degradation of the dye regardless of the quantity of OH radicals (or H₂O₂) in solution. The inhibition was explained by the competition of the dye and t-butyl alcohol at the gas–liquid interface. Finally, the rate of dye degradation in the presence of both reagents at their effective concentrations was found to be considerably slower than that with CCl₄, showing that the formation of reactive chlorine species was remarkably suppressed by the rapid reaction of t-butyl alcohol at the gas–liquid interface.     

Quantum Fisher Information of N Particles in the Superposition of W and GHZ States

We investigate the quantum Fisher information of a multipartite entangled state of N particles in a superposition of W and GHZ states. We find that the mean quantum Fisher information per particle (RMQFI) decreases with respect to the number of the particles and the peak is observed between 0.6 and 0.8 values of the superposition coefficient of W state. We present the behavior of RMQFI for N from 2 to 10 and discuss some interesting results.     

An examination of the effect of polarization on the radiation losses of bent optical fibres

It has long been recognized that the bending losses in weakly guiding optical fibres are independent of the polarization for large bend radius. Here, we show this fact using the volume equivalent current method. The procedure is then applied to a helically bent fibre and it is shown that the radiation from the helical fibre is also independent of the polarization as long as the fibre is weakly guiding.     

Determination of the Steady-State Response of Viscoelastically Point-Supported Rectangular Orthotropic Plates

In the present study, the steady-state response to a sinusoidally varying concentrated force acting at the center of a rectangular point-supported orthotropic elastic plate is analyzed. The equation of the plate is represented by finite-difference expressions. By using the ordinary finite-difference technique, the problem is reduced to the solution of a system of algebraic equations. The influence of mechanical properties of the plate material on the vibration modes and the steady-state response of the plate is investigated numerically. Also, the effect of location of the point supports is studied. The problems considered are solved within the framework of the Kirchhoff-Love hypothesis.     

Ultrasensitive detection of endotoxins using computationally designed nanoMIPs

Novel molecularly imprinted polymer nanoparticles (nanoMIPs) were designed for endotoxin from Escherichia coli 0111:B4, using computational modeling. The screening process based on binding energy between endotoxin and each monomer was performed with 21 commonly used monomers, resulting in the selection of itaconic acid, methacrylic acid and acrylamide as functional monomers due to their strong binding interaction with the endotoxin template. The nanoMIPs were successfully synthesized with functional groups on the outer surface to aid in the immobilization onto sensor surface. The solid phase photopolymerization approach used for the synthesis of nanoMIPs ranging from 200 to 235 nm in diameter. The limit of detection and K_D were significantly improved when endotoxin samples were prepared using a novel triethylamine method. This improved the efficiency of gold nanoparticle functionalization by targeting the subunits of the endotoxin. Compared to the vancomycin MIP control, the endotoxin MIPs displayed outstanding affinity and selectivity towards the endotoxin with K_D values in the range of 4.4–5.3 × 10⁻¹⁰ M, with limits of detection of 0.44 ± 0.02 ng mL⁻¹ as determined by surface plasmon resonance (SPR) sensor when itaconic acid was used as the functional monomer. The MIP surface can be regenerated >30 times without significant loss of binding activity making this approach highly cost effective for expensive analyte templates. The combination of molecular modeling and solid phase synthesis enabled the successful synthesis of nanoMIPs capable of recognition and ultrasensitive detection of endotoxins using the highly sensitive SPR biosensor with triethylamine method.     

Analytical regularization based analysis of a spherical reflector symmetrically illuminated by an acoustic beam

A mathematically accurate and numerically efficient method of analysis of a spherical reflector, fed by a scalar beam produced by a complex source-point feed, is presented. Two cases, soft and hard reflector surface, are considered. In each case the solution of the full-wave integral equation is reduced to dual series equations and then further to a regularized infinite-matrix equation. The latter procedure is based on the analytical inversion of the static part of the problem. Sample numerical results for 50-lambda reflectors demonstrate features that escape a high-frequency asymptotic analysis.