Chain Stiffness Effect On The Properties Of Topological Polymer Brushes Using MD Simulation

Polymer chains are linked by monomers,and their conformations are ever-changing due to the interaction between monomers,interaction with surroundings and the flexibility of polymer chains.Polymer brushes,formed by end monomers of chains grafting onto a substrate,has been widely used in many fields such as colloidal stability and biocompatibility.Molecular dynamic simulations are carried out by LAMMPS software to study the static and dynamic properties of topological polymer brushes by taking into account chain stiffness and their topological structure.It has been found that chain stiffness plays an important role in topological polymer brushes in the aspects of monomer density profile,radius of gyration,bond orientation,and terminal vector.There exists scaling laws for the radius of gyration,indicating that bending interaction is as important as topological constraint.An empirical FENE force in terms of chain stiffness and topological features is obtained by fitting related parameters.The analysis of the polymer end-point vector found that it conforms to the general Gaussian distribution model,but the increase in the stiffness of the chain will make the end vector closer to the polymer brush surface.In the study,it was also found that the effect of chain stiffness on the polymer brushes was saturated.When the chain stiffness was increased to a certain extent,the properties of the polymer brushes were almost unchanged.Marine biofouling,defined as the accumulation of marine on man-made sur-faces,is a worldwide problem affecting maritime and aquatic industries.A variety of functional polymer brushes and coatings have been developed for combating marine biofouling and biocorrosion with much less environmental impact than traditional biocides.In order to study how a substance such as marine algae entering a coating surface,we analyze dynamic properties of polymer brushes composed of polymer chains with topological structures and covered by a layer of linear polymer melt under pressure.After a stable equilibrium,the effect of chain stiffness and topology for penetration is explored by observing the profiles of free polymers and grafted chains.It was implied that under pressure,such kind of penetration depends largely on chain stiffness,while the influence by topological structure seems to be suppressed.