Coarse-grained interaction potentials for poly(ethylene terephthalate) (PET) have been developed using the concept of potential of mean force and employing results of atomistic molecular dynamics simulations of ethylene terephthalate dimer. The end bridging Monte Carlo method has been adopted to handle coarse-grained PET chains. The resulting method permits for thorough, multiscale equilibration of a 100-mer PET melt, and is applicable to a wide range of industrially important polymers. The coarse-grained melt density, characteristic ratio and other conformational properties agree with experiment. Topological analyses of the melt using the CReTA and Z algorithms reveal that the melt is also well equilibrated with respect to entanglement density.

Polyurethane elastomers (PUEs) containing trans-1,4-bis­(isocyanato­methyl)­cyclohexane (1,4-H6XDI) have been synthesized by polymerizing 1,4-H6XDI with poly­(oxytetra­methylene) glycol and 1,4-butanediol. The molecular aggregation state and mechanical properties of these PUEs have been compared with those exhibited by PUE analogues made of MDI and diols. The hard segment chains in the 1,4-H6XDI-based PUEs are found to readily crystallize and form strong hydrogen bonds due to a high symmetry of 1,4-H6XDI molecule. Consequently, the 1,4-H6XDI-based PUEs exhibit well-organized hard segment domains. This leads to their generally superior mechanical properties as compared to those of the well-known MDI-based PUEs. 1,4-H6XDI’s lack of aromatic moieties is expected to greatly enhance color stability of resulting PUEs. All the above features suggest 1,4-H6XDI could replace MDI in a range of applications.

The long-range corrected DFT functionals, LC-BLYP, LC-PBE and CAM-B3LYP with the augmented Dunning-type triple-ζ basis sets represent dynamical polarizabilities at λ = 589.3 nm of 105 medium-sized organic compounds containing C, H, O, N, S, P, F, Cl, Br and I elements with the root mean squared deviations (RMSD) of about 0.34, 0.35, and 0.42 Å 3 , respectively. These errors do not change appreciably when the augmented double-ζ basis sets are used. The functionals with 100% of Hartree−Fock (HF) exchange at long-range perform best for aromatic compounds and the CAM-B3LYP or B3LYP functionals for fully saturated compounds. The degrees of HF exchange in mid-and long-range affect strongly the shape and location of the distributions of absolute errors in polarizability, P(Δα). The differences between functionals belonging to the BLYP and PBE families, and having the same degree of HF exchange, have much smaller effect on the P(Δα) distributions.

The spinodal decomposition of the homopolymer blends has been studied by the numerical integration of the Cahn–Hilliard–Cook equation. We have investigated the time evolution of the morphological measures that characterize quantitatively the interface in the system. For symmetric blends we have found that the Euler characteristic of the interface is negative and increases with time as τ0.75 (connectivity of the domains decreases) regardless of the final quench temperature. The homogeneity index of the interface is constant in this case. This suggests that at the level of the integral geometry quantities (Minkowski functionals), the dynamic scaling hypothesis holds for the evolution of the interface morphology in quenched critical systems. The nonuniversal morphological evolution of the asymmetric blends have been studied. Also, we have shown that the thermal fluctuations can modify significantly the curvature distribution.

The effect of higher α-olefin comonomer on physical properties of short chain branched (SCB) polyethylene (PE) melts at 450 K has been studied using connectivity altering Monte Carlo simulations. The calculated chain dimensions per molecular mass scale with backbone weight fraction, ϕ, as ⟨S 2⟩/M ∼ ϕ1.27±0.03 for the radius of gyration S and ⟨R 2⟩/M ∼ ϕ1.27±0.03 for the end-to-end distance R, in very good agreement with the experiment-based result ⟨R 2⟩/M ∼ ϕ1.30. The observed dependence is consistent with the decrease in the fraction of trans states along the backbone. The entanglement tube diameter, a pp, computed for SCB melts scales as ⟨a pp⟩ ∼ ϕ–0.46±0.01, which is close to the result for model concentrated (⟨R 2⟩ = const) PE solutions created by deleting randomly chosen chains from equilibrated melt configurations of linear PE (⟨a pp⟩ ∼ ϕ–0.41±0.01). The latter result agrees very well with the scaling based on rheological experiments on concentrated hydrogenated polybutadiene (HPB)/C24H50 solutions at 413 K (⟨a pp⟩ ∼ ϕ–0.45). The tube diameter in model athermal PE solutions scales as ⟨a pp⟩ ∼ ϕ–0.6±0.03, in excellent agreement with the scaling based on the neutron spin-echo experiments on athermal HPB/C19D40 solutions at 509 K (⟨a pp⟩ ∼ ϕ–0.6). The computed scaling relationships for both SCB melts and model PE solutions are close to the binary contact model (a pp ∼ ϕ–0.5) and disagree with the packing model (a pp ∼ ϕ–1.27). The solubility parameters calculated for poly(ethylene-co-1-butene) (PEB) melts are in excellent agreement with relative solubility parameters based on SANS analysis of appropriate SCB blends, which scale as δ ∼ ϕ0.18. The SANS-derived relative solubility parameters for poly(ethylene-co-1-hexene) (PEH) and poly(ethylene-1-octene) (PEO) systems scale more weakly (δ ∼ ϕ0.1) and suggest breakdown of a universal correlation. This pattern is followed by simulated relative solubility parameters.