285 research outputs found

    Thermal Degradation of Adsorbed Bottle-Brush Macromolecules: Molecular Dynamics Simulation

    Full text link
    The scission kinetics of bottle-brush molecules in solution and on an adhesive substrate is modeled by means of Molecular Dynamics simulation with Langevin thermostat. Our macromolecules comprise a long flexible polymer backbone with LL segments, consisting of breakable bonds, along with two side chains of length NN, tethered to each segment of the backbone. In agreement with recent experiments and theoretical predictions, we find that bond cleavage is significantly enhanced on a strongly attractive substrate even though the chemical nature of the bonds remains thereby unchanged. We find that the mean bond life time decreases upon adsorption by more than an order of magnitude even for brush molecules with comparatively short side chains $N=1 \div 4$. The distribution of scission probability along the bonds of the backbone is found to be rather sensitive regarding the interplay between length and grafting density of side chains. The life time declines with growing contour length LL as L0.17\propto L^{-0.17}, and with side chain length as N0.53\propto N^{-0.53}. The probability distribution of fragment lengths at different times agrees well with experimental observations. The variation of the mean length L(t)L(t) of the fragments with elapsed time confirms the notion of the thermal degradation process as a first order reaction.Comment: 15 pages, 7 figure

    Cytology, biochemistry and molecular changes during coffee fruit development

    Full text link

    THE MUTAROTATION OF THE ALCOHOLATE AND ALDEHYDROL OF ALDEHYDO-GALACTOSE PENTAACETATE

    No full text

    Carbohydrate Nomenclature

    No full text

    Maltotriose and its Crystalline β-D-Hendecaacetate

    No full text

    Benzylsulfonyl as N-Blocking Group in Amino Sugar Nucleoside Synthesis

    No full text
    corecore