Photoinitiated curing of mono‐ and bifunctional epoxides by combination of active chain end and activated monomer cationic polymerization methods

Photoinitiated cationic polymerization of mono‐ and bifunctional epoxy monomers, namely cyclohexeneoxide (CHO), 4‐epoxycyclohexylmethyl‐3′,4′‐epoxycyclohexanecarboxylate (EEC), respectively by using sulphonium salts in the presence of hydroxylbutyl vinyl ether (HBVE) was studied. The real‐time FTIR spectroscopic, gel content determination, and thermal characterization studies revealed that both hydroxyl and vinyl ether functionalities of HBVE take part in the polymerization. During the polymerization, HBVE has the ability to react via both active chain end (ACE) and activated monomer mechanisms through its hydroxyl and vinyl ether functionalities, respectively. Thus, more efficient curing was observed with the addition of HBVE into EEC‐containing formulations. It was also demonstrated that HBVE is effective in facilitating the photoinduced crosslinking of monofunctional epoxy monomer, CHO in the absence of a conventional crosslinker. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4914–4920, 2007     

4-Transitivity and 6-figures in some Moufang-Klingenberg planes

In this paper, the Moufang-Klingenberg plane over a local alternative ring R of dual numbers is studied. It is shown that its collineation group is transitive on quadrangles. It is therefore shown that the coordinatization of these Moufang-Klingenberg planes is independent of the choice of the coordinatization quadrangle. Also, the concept of 6-figures is extended to these Moufang-Klingenberg planes and it is shown that any 6-figure corresponds to only one inversible m ∈ R.     

Aliphatic Polyester/polyhedral Oligomeric Silsesquioxanes Hybrid Networks via Copper‐free 1,3‐dipolar Cycloaddition Click Reaction

In this study, we describe the preparation and characterization of a new class of thermoset hybrid networks containing aliphatic polyester and polyhedral oligomeric silsesquioxanes (POSS). The copper‐free 1,3‐dipolar cycloaddition click reaction of internal alkyne functionalized aliphatic polyester and multifunctional azido POSS with different concentrations led to highly crosslinked thermoset networks. The click reactions performed under ambient conditions (i.e., in tetrahydrofuran at room temperature for 1 day) in the absence of any catalyst. The chemical composition of hybrid networks and homogenous distribution of POSS molecules were confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy with energy dispersive spectroscopy. The swelling ratios of hybrid networks were commonly decreased by increasing POSS‐N₃ content and by changing polar solvents to apolar solvents. Thermogravimetric analysis results demonstrated that the thermal stability of hybrid networks increased with higher POSS feeding ratio. Tensile tests were applied to evaluate the mechanical properties of hybrid networks. Compared to neat aliphatic polyester, the mechanical properties of hybrid networks significantly improved. For instance, the tensile strength were enhanced from 5 MPa to 19 MPa by increasing the concentration of azido functionalized POSS from 10 to 40. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2222–2227     

Role of polydimethylsiloxane in properties of ternary materials based on polyimides containing zeolite Y

Mixed matrix materials, containing poly(dimethylsiloxane), phosphine oxide-based polyimide, and zeolite Y were prepared by means of blending hybridisation. The thermal stability of the materials and the hydrophobic properties were enhanced. The decrease in the glass transition temperature of the materials with the increase in poly(dimethylsiloxane) content supported the polymer-chain flexibility. The pristine polyimide and the zeolite-filled polyimide exhibited the highest transparency. Fourier transform infrared (FTIR) spectroscopy confirmed that the increase in the amount of the lowest molecular mass poly(dimethylsiloxane) ingredient indicated strong alkyl and Si-O-Si stretching modes, whilst the alkyl and Si-O-Si stretching intensity decreased in the presence of the highest amount of and the highest molecular mass poly(dimethylsiloxane). The hydrophobic poly(dimethylsiloxane) moiety created an inverse relationship between the porosity of the materials (surface roughness) and the hydrophilicity. The nanocrystallite domain, identified by X-ray diffraction analysis (XRD) and possessing an exotherm crystallisation peak, occurred in the lowest amount of poly(dimethylsiloxane) with the highest molecular mass-based hybrid material. The nanocrystallite enhanced the storage modulus as determined by the dynamic mechanical analyser (DMA). The nanocrystalline formation resulted in a slight increase in the alkyl stretching and the Si-O-Si stretching of the lowest amount of and the highest molecular mass poly(dimethylsiloxane)-containing material over those of the lowest molecular mass poly(dimethylsiloxane) in the same amounts of material involved.     

Design,synthesis, photochromism and electrochemistry of a novel material with pendant photochromic units

In the present work, the synthesis, photochromism and electrochemistry of a novel material 1, 1-(4-[3,4-bis(2,5-dimethyl-3-thienyl)cyclopent-3-en-1-yl]phenyl)-2,5-di-2-thienyl-1H-pyrrole, with pendant dithienylethene (DTE) photochromic units are described. It should be noted that the system 1 can be reversibly and efficiently switched between open (1o) and closed (1c) states by light in both solution and in the solid poly(methyl methacrylate) matrix. It is also noteworthy that the two isomers (1o and 1c) of this novel system 1 can be smoothly polymerized on ITO by electrochemical means. Surprisingly, the DTE unit in 1 does not retain its photochemical switching properties after immobilization onto ITO. The morphology of the polymer film was investigated by AFM analysis. Furthermore, it was found that the polymer exhibited remarkable electrochromic features that can be switched from green in the neutral state to violet state under applied external potentials without disturbing the photochromic units.