Radical polymerization behavior and molecular weight development of homologous monoacrylate monomers in lyotropic liquid crystal phases

Polymerization in highly ordered lyotropic liquid‐crystalline (LLC) media enables controllable synthesis of polymers possessing interesting nanostructure and physical properties. This study investigates the radical polymerization rate and molecular weight (MW) development of monoacrylates of different aliphatic tail length in a range of LLC phases. Polymerization rate data were acquired using photodifferential scanning calorimetry, and linear polymer MW was determined with gel permeation chromatography. Polymerization occurs much more rapidly, and higher MW is attained in the ordered LLC phases relative to isotropic solutions and neat polymerization. These properties change significantly as a function of LLC phase and monomer structure. A direct relationship is observed between polymer MW formation and the polymerization rate. Definitive changes in rate and MW were observed at phase boundaries, indicating the important role of solvent order. This study demonstrates how solvent ordering effects can be used to control polymer MW and rate of polymerization. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 144–154     

Real‐time Fourier transform infrared study of the free‐radical ultraviolet‐induced polymerization of a hybrid sol–gel. II. The effect of physicochemical parameters on the photopolymerization kinetics

Free‐radical photocurable hybrid sol–gel materials have gained special interest during the last decades. Compared to thermally processed materials, they present the advantages of fast curing, low energy consumption, and spatiotemporal control of the reaction. Although comprehension of the photochemical step is fundamental, little is known about the characteristic of photochemistry in this kind of material. Real‐time Fourier transform infrared spectroscopy was used to study the photopolymerization of a hybrid sol–gel upon ultraviolet irradiation. Various photoinitiator systems were tested for their efficiency in inducing the polymerization of pendant polymerizable moieties anchored on a partially condensed silicate network. The presence of O₂ and the nature of the polymerizable function were shown to be crucial factors in the photoinduced process. The effects of the photoinitiator concentration and light intensity were also studied. These results were explained in terms of classical kinetic models developed for all‐organic photopolymers to point out the distinctive aspects related to the use of photoinitiated polymerization in hybrid sol–gel materials. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 831–840, 2003     

Side‐chain functionalized liquid‐crystalline polymers and blends. IX.* Phase behavior and structure of comb‐shaped liquid‐crystalline ionomers containing calcium ions

Liquid‐crystalline (LC) ionomers containing 2–15 mol % calcium ions were synthesized by the exchange reaction between the nematic LC copolymer, bearing oxycyanobiphenyl mesogenic groups, and the carboxyl groups of acrylic acid, with calcium acetate. The incorporation of 2–3 mol % Ca ions in the LC copolymer leads to some rise in the clearing point and glass‐transition temperature. A further increase in the concentration of metal ions (>5 mol %) is accompanied by induction of the smectic A phase where clearing point and glass‐transition temperatures keep constant values. Phase behavior of the LC ionomers may be understood on the basis of a structural model that considers the dual role of calcium ions in a polymer matrix. Metal ions act as points of noncovalent electrostatic binding of the polymer chains and are capable of forming larger ionic associates (multiplets). The comparison of the phase behavior of sodium and calcium containing LC ionomers shows that the formation of ionic links may lead to the growth of structure defects suppressing a positive influence of charged groups on the mesophase clearing temperature. The orientation behavior of the LC ionomers in the magnetic field was studied. It was shown that the incorporation of calcium ions (3 mol %) in the LC copolymer matrix leads to the growth of orientation order parameter S of the nematic phase. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3953–3959, 2001     

Phase behavior and photo‐responsive studies of photoactive liquid crystalline hyperbranched polyethers containing benzylidene moiety

Two sets of hyperbranched polyether epoxies were synthesized to study the effect of substituent, rigidity, and nature of photoactive unit on the thermal and photoresponsive properties. Each set was comprised of one molecule with an acyclic moiety in the repeating unit, and two molecules with a cyclic moiety of varying rigidity (cycle size) in the repeating unit. Two substituents on aromatic rings in the repeating unit were present in one set, and other set was without a substituent. The mesogenic and photoresponsive properties were studied and correlated to the varied structural parameters. The effects of varied molecular structural parameters on phase behavior and photoresponsive properties were very prominent. Out of six monomeric diols, only four have exhibited liquid crystalline phase while the polymers corresponding to all monomeric diols revealed mesophase. The findings in photoresponsive properties were further supported by molecular modeling studies. The changes in refractive index, photoviscosity, and fluorescence intensity with irradiation time substantiated the spectral pattern observed in UV‐Vis spectroscopy. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2774–2786, 2009     

A novel series of M(II) complexes of 6‐methylpyridine‐2‐carboxylic acid with 4(5)methylimidazole: Synthesis,crystal structures, α‐glucosidase activity,density functional theory calculations and molecular docking

Novel complexes of 6‐methylpyridine‐2‐carboxylic acid and 4(5)methylimidazole, namely [Mn(6‐mpa)₂(4(5)MeI)₂] ( 1 ), [Zn(6‐mpa)₂(4(5)MeI)₂] ( 2 ), [Cd(6‐mpa)₂(4(5)MeI)₂] ( 3 ), [Co(6‐mpa)₂(4(5)MeI)₂] ( 4 ), [Ni(6‐mpa)₂(4(5)MeI)(OAc)] ( 5 ) and [Cu(6‐mpa)₂(4(5)MeI)] ( 6 ), were synthesized for the first time. The structures of complexes 1 – 4 and complexes 5 and 6 were determined using X‐ray diffraction and mass spectrometric techniques, respectively. The experimental spectral analyses for these complexes were performed using Fourier transform infrared and UV–visible techniques. The α‐glucosidase inhibition activity values (IC₅₀) of complexes 1 – 6 were identified in view of genistein reference compound. Moreover, the DFT/HSEh1PBE/6‐311G(d,p)/LanL2DZ level was used to obtain optimal molecular geometry and vibrational wavenumbers for complexes 1 – 6 . Electronic spectral behaviours and major contributions to the electronic transitions were investigated using TD‐DFT/HSEh1PBE/6‐311G(d,p)/LanL2DZ level with conductor‐like polarizable continuum model and SWizard program. Finally, in order to investigate interactions between the synthesized complexes ( 1 – 6 ) and target protein (template structure S. cerevisiae isomaltase), a molecular docking study was carried out.