ROMP‐NMP‐ATRP combination for the preparation of 3‐miktoarm star terpolymer via click chemistry

A combination of ring opening metathesis polymerization (ROMP) and click chemistry approach is first time utilized in the preparation of 3‐miktoarm star terpolymer. The bromide end‐functionality of monotelechelic poly(N‐butyl oxanorbornene imide) (PNBONI‐Br) is first transformed to azide and then reacted with polystyrene‐b‐poly(methyl methacrylate) copolymer with alkyne at the junction point (PS‐b‐PMMA‐alkyne) via click chemistry strategy, producing PS‐PMMA‐PNBONI 3‐miktoarm star terpolymer. PNBONI‐Br was prepared by ROMP of N‐butyl oxanorbornene imide (NBONI) 1 in the presence of (Z)‐but‐2‐ene‐1,4‐diyl bis(2‐bromopropanoate) 2 as terminating agent. PS‐b‐PMMA‐alkyne copolymer was prepared successively via nitroxide‐mediated radical polymerization (NMP) of St and atom transfer radical polymerization (ATRP) of MMA. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 497–504, 2009     

Multiarm star block copolymers via Diels‐Alder click reaction

Two types of multiarm star block copolymers: (polystyrene)_m‐poly(divinylbenzene)‐poly(methyl methacrylate)_n, (PS)_m‐polyDVB‐(PMMA)_n and (polystyrene)_m‐poly(divinylbenzene)‐poly(tert‐butyl acrylate)_k, (PS)_m‐polyDVB‐(PtBA)_k were successfully prepared via a combination of cross‐linking and Diels–Alder click reactions based on “arm‐first” methodology. For this purpose, multiarm star polymer with anthracene functionality as reactive periphery groups was prepared by a cross‐linking reaction of divinyl benzene using α‐anthracene end functionalized polystyrene (PS‐Anth) as a macroinitiator. Thus, obtained multiarm star polymer was then reacted with furan protected maleimide‐end functionalized polymers: PMMA‐MI or PtBA‐MI at reflux temperature of toluene for 48 h resulting in the corresponding multiarm star block copolymers via Diels–Alder click reaction. The multiarm star and multiarm star block copolymers were characterized by using ¹H NMR, SEC, Viscotek triple detection SEC (TD‐SEC) and UV. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 178–187, 2009     

Heterograft copolymers via double click reactions using one‐pot technique

The double click reactions (Cu catalyzed Huisgen and Diels–Alder reactions) were used as a new strategy for the preparation of well‐defined heterograft copolymers in one‐pot technique. The synthetic strategy to the various stages of this work is outlined: (i) preparing random copolymers of styrene (St) and p‐chloromethylstyrene (CMS) (which is a functionalizable monomer) via nitroxide mediated radical polymerization (NMP); (ii) attachment of anthracene functionality to the preformed copolymer by the o‐etherification procedure and then conversion of the remaining ? CH₂Cl into azide functionality; (iii) by using double click reactions in one‐pot technique, maleimide end‐functionalized poly(methyl methacrylate) (PMMA‐MI) via atom transfer radical polymerization (ATRP) of MMA and alkyne end‐functionalized poly (ethylene glycol) (PEG‐alkyne) were introduced onto the copolymer bearing pendant anthryl and azide moieties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6969–6977, 2008     

Novel strategy for tailoring of SiO2 and TiO2 nanoparticle surfaces with poly(ε-caprolactone)

A novel strategy was developed for tailoring of SiO₂ and TiO₂ nanoparticle surfaces with poly(ε-caprolactone) (PCL). Thus, a self-curable polyester, poly(2-hydroxypropylene maleate) was adsorbed on the nanoparticle surfaces and heated to 180 °C to give a cross-linked polyester layer with residual hydroxyalkyl groups on their surfaces. Surface-initiated polymerization of ε-caprolactone from hydroxyalkyl groups on the surfaces yielded core-shell nanoparticles with cross-linked core and PCL shells (22.2–71.4%). The organic shell layers around the nanoparticle cores were evidenced by transmission electron microscopy, dynamic light scattering, and thermogravimetric analyses techniques. The core-shell nanoparticles were then employed in preparing the stable and the homogenous dispersions with poly(methyl methacrylate-stat-butyl acrylate) solutions. An application of the solutions onto glass substrates yielded uniform and nearly transparent free standing films (40–60 μm) with good homogeneity as inferred from scanning electron microscopy pictures.     

Exact inversion of decomposable interval type-2 fuzzy logic systems

It has been demonstrated that type-2 fuzzy logic systems are much more powerful tools than ordinary (type-1) fuzzy logic systems to represent highly nonlinear and/or uncertain systems. As a consequence, type-2 fuzzy logic systems have been applied in various areas especially in control system design and modelling. In this study, an exact inversion methodology is developed for decomposable interval type-2 fuzzy logic system. In this context, the decomposition property is extended and generalized to interval type-2 fuzzy logic sets. Based on this property, the interval type-2 fuzzy logic system is decomposed into several interval type-2 fuzzy logic subsystems under a certain condition on the input space of the fuzzy logic system. Then, the analytical formulation of the inverse interval type-2 fuzzy logic subsystem output is explicitly driven for certain switching points of the Karnik–Mendel type reduction method. The proposed exact inversion methodology driven for the interval type-2 fuzzy logic subsystem is generalized to the overall interval type-2 fuzzy logic system via the decomposition property. In order to demonstrate the feasibility of the proposed methodology, a simulation study is given where the beneficial sides of the proposed exact inversion methodology are shown clearly.     

Taming of Singlet Oxygen: Towards Artificial Oxygen Carriers Based on 1,4-Dialkylnaphthalenes

Naphthalene endoperoxides are known as convenient sources of singlet oxygen (O₂, ¹Δ_g), which is the major product of endoperoxide cycloreversion reaction. However, their potential as carriers of ground-state molecular oxygen (O₂, ³Σ_g) similar to artificial oxygen carriers remains largely unexplored. This is due to the extreme reactivity and cytotoxic effects of the released singlet oxygen. We now report that a compound with a bimodular design, which incorporates an endoperoxide and an efficient physical quencher of singlet oxygen, 1,4-diazabicyclo[2.2.2]octane (DABCO), produces exclusively ground-state molecular oxygen. This result, coupled with the fact that oxygen release rates from endoperoxides are highly amenable to fine-tuning in a very broad range, and open to targeting by ligand attachment, raises the potential of these compounds far above any comparable chemical, or even biochemical sources. In cell culture experiments, we showed that the addition of the endoperoxide-quencher conjugate can enhance and sustain cell proliferation.     

Multiarm star triblock terpolymers via sequential double click reactions

Multiarm star triblock terpolymers were obtained by using two different click reactions sequentially: Cu(I) catalyzed azide–alkyne and Diels–Alder. The synthetic strategy is described as follows: (poly(methyl methacrylate))_n‐(polystyrene)_m‐poly(divinyl benzene)) ((PMMA)_n‐(PS)_m‐polyDVB) multiarm star diblock copolymer was first obtained from an azide–alkyne click reaction of (alkyne‐PS)_m‐polyDVB multiarm star polymer with α‐anthracene‐ω‐azide PMMA (anth‐PMMA‐N₃), followed by a Diels–Alder click reaction of the anthracene groups at the star periphery with α‐maleimide poly (tert‐butyl acrylate) (PtBA‐MI) or α‐maleimide poly(ethylene glycol) (PEG‐MI) leading to target (PtBA)_k‐(PMMA)_n‐(PS)_m‐polyDVB and (PEG)_p‐(PMMA)_n‐(PS)_m‐polyDVB multiarm star triblock terpolymers. The hydrodynamic diameter of individual multiarm star triblock terpolymers were measured by dynamic light scattering (DLS) to be ～24–27 nm in consistent with the atomic force microscopy (AFM) images on silicon substrates. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1557–1564, 2010     

Electroless Pd and Ag deposition kinetics of the composite Pd and Pd/Ag membranes synthesized from agitated plating baths

The atomic absorption spectroscopy (AAS) has been successfully utilized for the measurement of the Pd and Ag ion concentrations in the plating baths and to elucidate the effects of temperature, initial metal ion and reducing agent concentrations and agitation on the electroless plating kinetics of Pd and Ag metals. The initial metal ion concentrations for Pd and Ag were varied over a range of 8.2–24.5 mM and 3.1–12.5 mM, respectively. The plating reactions were conducted in a constant temperature electroless plating bath over a temperature range of 20–60 °C and an initial hydrazine concentration range of 1.8–5.4 mM. It was found that the electroless plating of both Pd and Ag were strongly affected by the external mass transfer in the absence of bath agitation. The external mass transfer limitations for both Pd and Ag deposition have been minimized at or above an agitation rate of 400 rpm, resulting in a maximum conversion of the plating reaction at 60 °C and dramatically shortened plating times with the added advantage of uniform deposition morphology. The derivation of the differential rate laws and the estimation of the reaction orders and the activation energies for the electroless Pd and Ag kinetics were conducted via non-linear regression analysis based on the method of initial rates. For a constant-volume batch reactor, the integrated rate law was solved to calculate the conversion and the reactant concentrations as a function of plating time. The model fits were in good agreement with the experimental data. Furthermore, the bath agitation and the plating conditions used in the kinetics study were adopted for the synthesis of 16–20 μm thick composite Pd/Ag membranes (10–12 wt% Ag) and a pure-Pd membrane with a hydrogen selective dense Pd layer as thin as 4.7 μm. While hydrogen permeance of the Pd/Ag membranes A and B at 450 °C were 28 and 32 m³/m²-h-atm^0.5, the H₂ permeance for the 4.7 μm thick pure-Pd membrane at 400 °C was as high as 63 m³/m²-h-atm^0.5_. The long-term permeance testing of all the membranes synthesized from agitated plating baths resulted in a relatively slow leak growth due primarily to the improved morphology obtained via the bath agitation and modified plating conditions.