Effect of Poly(vinyl butyral) Comonomer Sequence on Adhesion to Amorphous Silica: A Coarse-Grained Molecular Dynamics Study

Abstract

Modulating a comonomer sequence, in addition to the overall chemical composition, is the key to unlocking the true potential of many existing commercial copolymers. We employ coarse-grained molecular dynamics (MD) simulations to study the behavior of random-blocky poly­(vinyl butyral-co-vinyl alcohol) (PVB) melts in contact with an amorphous silica surface, representing the interface found in laminated safety glass. Our two-pronged coarse-graining approach utilizes both macroscopic thermophysical data and all-atom MD simulation data. Polymer–polymer nonbonded interactions are described by the fused-sphere SAFT-γ Mie equation of state, while bonded interactions are derived using Boltzmann inversion to match the bond and angle distributions from all-atom PVB chains. Spatially dependent polymer–surface interactions are mapped from a hydroxylated all-atom amorphous silica slab model and all-atom monomers to an external potential acting on the coarse-grained sites. We discovered an unexpected complex relationship between the blockiness parameter and the adhesion energy. The adhesion strength between PVB copolymers with intermediate VA content and silica was found to be maximal for random-blocky copolymers with a moderately high degree of blockiness rather than for diblock copolymers. We attribute this to two main factors: (1) changes in morphology, which dramatically alter the number of VA beads interacting with the surface and (2) a non-negligible contribution of vinyl butyral (VB) monomers to adhesion energy because of their preference to adsorb to zones with low hydroxyl density on the silica surface.

Sequence Effects on the Salt-Enhancement Behavior of Polyelectrolytes Adsorption

“…The sequence regulation of monomers may affect the micro- and macroscopic properties of polymers such as adsorption, conductivity, and degradability. − A molecular dynamics simulation based genetic algorithm has demonstrated the sequence-specific effects in compatibilization, where highly nonregular sequences allowed the potential to yield larger reductions in interfacial tension between two species than either blocky or alternating sequence. PEs and polyampholytes (PAs) complexation and adsorption are also sensitive to monomer sequencing.…”

SAFT-γ-Mie Cross-Interaction Parameters from Density Functional Theory-Predicted Multipoles of Molecular Fragments for Carbon Dioxide, Benzene, Alkanes, and Water

“…However, the other Mie parameters have a one-to-one mapping. This scaling of the energy parameter has since been successfully applied to parameterization of polymeric systems. − The question then arises, in our extended combining rules, should the multipole moment be applied to the energy parameter of the EOS or the simulation? We address each of these cases, referred to as the Curve-Fit and Scaled-Fit , respectively.…”

“…SAFT-γ-Mie has been developed into a predictive and transferable methodology, capable of describing a molecule as discrete segments. The resulting methodology is similar to coarse-grained (CG) representations of compounds in molecular dynamics (MD) simulations and so was extended into a coarse-graining formalism. − CG simulations with this method have covered equilibria and interfacial phenomena of traditional thermodynamic systems involving combinations of CO 2 , H 2 O, and alkanes. ,− Further successful applications of SAFT-γ-Mie coarse-graining include complex systems containing greenhouse gases and refrigerants, tetrahydrofuran, and perfluoro alkanes, , as well as polymeric systems. − Despite the growing number of examples illustrating the power of this coarse-graining method, developing unlike-pair interaction parameters for a growing number of compounds is nontrivial and often requires additional parameter fitting to the experimental data of mixtures, which is scarce.…”

Structural Transitions of Anionic, Cationic, and Nonionic Surfactant Solutions Confined between Amorphous SiO2 Slabs: Molecular Dynamics Simulations

“…17 In another work, Walker et al employed coarse-grained molecular dynamics (MD) simulations to study the behavior of random-blocky poly(vinyl butyral-co-vinyl alcohol) (PVB) melts in contact with an amorphous silica surface, representing the interface found in laminated safety glass. 18 In this work, we simulated aqueous solutions of different surfactants confined between amorphous SiO 2 walls. The model surfactants include SDS, N-(2-hydroxyethyl)-N,Ndimethyloctan-1-aminium chloride (HEDMOAC), 2-(decanoyloxy)-N-(2-(decanoyloxy)ethyl)-N,N-dimethylethan-1aminium chloride (DDEDMEAC), 2-((octyloxy)methoxy)ethan-1-ol (OMEO), and tetraoctylammonium bromide (TOABr) (see Scheme 1).…”