In silico studies of 1,3(R):2,4(S)‐dibenzylidene‐D‐sorbitol as a gelator for polypropylene

Abstract

The organic gelator 1,3(R):2,4(S)‐dibenzylidene‐D‐sorbitol (DBS) self‐organizes to form a 3‐D network at relatively low concentrations in a variety of nonpolar organic solvents and polymer melt. In this work, we have investigated the interactions between DBS molecules in polypropylene (PP) by molecular modeling. We have used quantum mechanics to elucidate the preferred geometry of one molecule and a dimer of DBS, and molecular mechanics and molecular dynamics to simulate pure DBS, pure PP, and mixture of DBS and PP as condensed phases, at various temperatures. It was found that inter‐ and intramolecular H‐bonds between DBS molecules are formed in PP in a much more pronounced manner than those formed in pure DBS. The most significant intermolecular H‐bonds are formed between the terminal hydroxyl groups. The most significant intramolecular H‐bonds are formed between O5 /H‐O6 groups. Due to the H‐bonds, DBS molecules form a rigid structure similar to liquid crystal forming molecules, which might explain their tendency to create nanofibrils. It seems that the aromatic rings do not contribute significantly to the intermolecular interactions. Their main role is probably to stiff the molecular structure. Temperature dependences of inter‐ and intramolecular interactions are different. Whereas intermolecular interactions peak heights decrease when temperature increases for pure DBS, the intramolecular interaction almost does not change. Copyright © 2012 John Wiley & Sons, Ltd.

Influencing the environmental stress cracking resistance of amorphous thermoplastic parts by the example of polycarbonate and water

“…The IKV has also developed approaches to map material effects on different scales using multiscale simulation chains [25]. In order to characterize the stress cracking potential of polycarbonate under the influence of various media, an approach is chosen, which describes the ESC potential using molecular dynamics simulation techniques [13].…”

“…Furthermore, the elastic modulus is connected via the Poissons's ratio and the estimation of Grüneisen and Tobolski to the cohesive energy density CED as proposition of the polymer cohesive energy e coh and the molar volume V [13,27]:…”

“…The cohesion energy density can be understood as a measure for the entirety of the force acting between the considered molecules, which can be calculated in molecular dynamic simulations according to [13,28]. The cohesive energy density is also connected to the solubility parameter δ via equation (3).…”

“…An approach has been developed, where the ESC probability of different media like water, toluene and 1.4-butanediol are described by the solubility parameter for different media concentrations [13]. The named media were chosen because of their different ESC risk.…”

“…This approach was developed within a cooperation of the IKV and the ORT Braude College, Karmiel/Israel. For this, molecular dynamics simulations at an example of PC, water, toluene and 1.4-butanediol are used [13]. It was the first time, molecular dynamics simulations were used for the prediction of ESC.…”