Polymeric materials display distinguished characteristics which stem from the interplay of phenomena at various length and time scales. Further development of polymer systems critically relies on a comprehensive understanding of the fundamentals of their hierarchical structure and behaviors. As such, the inherent multiscale nature of polymer systems is only reflected by a multiscale analysis which accounts for all important mechanisms. Since multiscale modelling is a rapidly growing multidisciplinary field, the emerging possibilities and challenges can be of a truly diverse nature. The present review attempts to provide a rather comprehensive overview of the recent developments in the field of multiscale modelling and simulation of polymeric materials. In order to understand the characteristics of the building blocks of multiscale methods, first a brief review of some significant computational methods at individual length and time scales is provided. These methods cover quantum mechanical scale, atomistic domain (Monte Carlo and molecular dynamics), mesoscopic scale (Brownian dynamics, dissipative particle dynamics, and lattice Boltzmann method), and finally macroscopic realm (finite element and volume methods). Afterwards, different prescriptions to envelope these methods in a multiscale strategy are discussed in details. Sequential, concurrent, and adaptive resolution schemes are presented along with the latest updates and ongoing challenges in research. In sequential methods, various systematic coarse-graining and backmapping approaches are addressed. For the concurrent strategy, we aimed to introduce the fundamentals and significant methods including the handshaking concept, energy-based, and force-based coupling approaches. Although such methods are very popular in metals and carbon nanomaterials, their use in polymeric materials is still limited. We have illustrated their applications in polymer science by several examples hoping for raising attention towards the existing possibilities. The relatively new adaptive resolution schemes are then covered including their advantages and shortcomings. Finally, some novel ideas in order to extend the reaches of atomistic techniques are reviewed. We conclude the review by outlining the existing challenges and possibilities for future research.

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The deformation of carbon nanotube (CNT)-filled PA6 droplets in PP matrix was examined under simple shear flows. The morphology of blends with various CNT contents in PA6 were probed by FE-SEM. Based on the wetting coefficient calculations and rheological measurements, it was noted that the majority of CNTs were selectively located in the PA6 phase for concentrations up to 2 wt%. TEM micrographs evidenced the results for a sample with 0.5 wt% CNT in PA6. Optical microscopy of the blends during simple shear flows revealed the reduced deformability and breakups for filled-droplets. Such observations were ascribed to the increased viscosity ratio and gradual formation of an elastic structure within the droplets. Maffetone-Minale transient droplet deformation model was coupled with a modified capillary number to account for the developed elastic forces. It was shown that the contribution of such forces to the total shape-conserving forces could arise up to 99% in comparison with the well-known interfacial forces. These resisting forces can be so strong that for blends with CNT concentrations above 0.5 wt% in PA6 almost no deformation was observed under the applied shear stresses in this work. POLYM. ENG. SCI., 55:1504-1519, 2015. FIG. 9. Optical micrographs of droplet deformation with time in PP/PA6 sample at a shear-rate of 2 s 21 . The micrographs are captured after startup of shear flow at (a) 0 s, (b) 1 s, (c) 2 s, (d) 5 s, (e) 10 s, (g) 20 s, (h) 50 s, and (k) 120 s. The arrow in (k) indicates the applied flow direction for all micrographs. FIG. 10. Optical micrographs of droplet deformation with time in PP/PA6-0.1 sample at a shear-rate of 2 s 21 . The micrographs are captured after startup of shear flow at (a) 0 s, (b) 1 s, (c) 2 s, (d) 5 s, (e) 10 s, (g) 20 s, (h) 50 s, and (k) 120 s. The arrow in (k) indicates the applied flow direction for all micrographs.

The orientation of a three‐layered silicate particle in uncompatibilized and compatibilized polymer melts is studied under shear flows utilizing dissipative particle dynamics (DPD). Based on trajectories, pair distribution functions are calculated in orthogonal planes. Regardless of the applied flow direction, it is shown that the layers rearrange themselves so that their surfaces would be normal to the velocity gradient direction. The maximum shear stress values fall in numerical uncertainties in uncompatibilized systems while they show a characteristic overshoot in compatibilized counterparts. This overshoot is shown to be a result of (i) the large interfaces between the silicate layers and the matrix due to the exfoliation, and (ii) the increased energy dissipation due to friction at the interface.

This study attempts to promote biobased polyamide 56 (PA56) as a sustainable candidate to replace commercial PA6 and PA66 when blended with polyethylene terephthalate (PET). Scanning and transmission electron microscopy of the blends with different PA56 contents reveals an immiscible morphology with an increase in the size of the dispersed domains by increasing PA56 content. The steady‐state mixing torque of the kneader is decreased to half by adding 10 wt% of PA56 to PET. Further addition of PA56 gradually increases this torque but does not surpass the neat PET sample up to 30 wt% of PA56. As revealed by microscopic dissipative particle dynamics (DPD) simulations, this gradual increase is ascribed to the difficulty to disperse larger domains of PA56 in the thermodynamically undesired PET. The results confirm that PA56 has a lubricating effect in PET. Using polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X‐ray diffraction (XRD) techniques, it is shown that PA56 acts as a nucleating agent in PET. This leads to the formation of numerous small crystals in the blends as opposed to several large crystals in the neat samples. The results encourage the use of PA56 biomaterial in combination with PET in products such as bicomponent segmented pie fibers.