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Incorporating nanoparticles (NPs) into polymers is a practical method to tune the mechanical properties of the material. In such composite systems, it is well accepted that the interface properties...

We demonstrate that polymer number distribution (PND) for polymer grafted nanoparticles (NPs) fabricated via the grafting-to technique can be described, without any fitting parameters, as a function of the conversion of polymer chains. This distribution function is convenient to be applied since the variables in PND are directly linked to experimental measurements and easy to be obtained. As an independent validation, the molecular dynamics simulation in this study is important since the experimental approach may be prone to artifacts that result from the complex parameters. This distribution is further generalized to describe the PNDs for polymer grafted NPs fabricated via the grafting-from technique. Our study implies that the grafting process, no matter grafting-to or grafting-from, does not alter the heterogeneity. Our results also provide evidence that the Poisson model, often invoked to describe the PND in previous experiments, is not accurate. We also show that the binomial form function of PND wil...

The coassembly of block copolymers (BCPs) with nanoscale inorganic objects is an important route to fabricate nanostructured polymer composites. However, the immiscibility of inorganic/polymeric interface is a recurring challenge to overcome, particularly for inorganic clusters, such as the polyoxometalates (POMs)/BCPs system. In this paper, we present a general method to incorporate POMs into BCP matrices, in which a POM cluster is embedded as a core in a supramolecular star polymer (SSP) whose arms possess the same chemical composition as a BCP segment. Because of the enthalpic interaction between SSP arms and BCP segments, the SSP can carry POM into BCP matrices to realize their coassembly. By this way, we successfully localize a Keggin-type POM cluster [CoW12O40]6– modified with polystyrene (PS) arms into the PS domain of poly(styrene-b-ethylene oxide) micelles, which induces the formation of a series of hybrid micelles with spherical, toroidal, and bicontinuous structures. The morphological transitio...

Natural cellulose (NC) is the most abundant biomacromolecule. The fact that each pyranose ring of NC has three hydroxyl groups implies that NC should be highly hydrophilic. The paradoxical water insolubility of NC is usually explained by the strong tendency to form the hydrogen-bonding network by the high content of hydroxyl groups. In this study, we present the first experimental evidence that NC is rather hydrophobic, even if the chains are molecularly dispersed. By single-molecule force spectroscopy, the single-chain mechanics of NC has been studied in various liquid environments. In a common nonpolar solvent, octane, NC shows the elastic force–extension (F–E) curve. We find that this kind of F–E curve can be fitted well by the QM-FJC model, in which the single-chain elasticity obtained from quantum mechanical (QM) calculations is integrated into the freely jointed-chain (FJC) model. However, the result of NC obtained in water is different, which shows a long plateau in the F–E curve. Further study sho...

It is crucial to understand how much and how far the structure and dynamics properties of the polymer melt can be affected by incorporating nanoparticles (NPs) in the system. Here, we show that in an athermal all-polymer nanocomposites prepared from mixtures of linear polystyrene chains and cross-linked polystyrene NPs, the influence range of the NP on the melt polymer properties, namely interphase thickness, depends on the properties investigated. The local segment conformations can be affected in the range of an NP radius. However, if the interphase thickness is defined by the influence range of the NP on the radius of gyration (Rg) of the melt chain, it can be 1.5Rg for short-chain melts where the chain has a Rg smaller than particle radius Ra. For intermediate chain length polymer melts (Rg > Ra), the influence range of the NP does not change with the chain length. With the chain length further increasing, melt chains cannot feel the existence of the NP; the influence of the NP on the Rg tensors of th...

In this article, we present coarse-grained potentials of ethylbenzene developed at 298 K and of amorphous polystyrene developed at 500 K by the pressure-corrected iterative Boltzmann inversion method. The potentials are optimized against the fully atomistic simulations until the radial distribution functions generated from coarse-grained simulations are consistent with atomistic simulations. In the coarse-grained polystyrene melts of different chain lengths, the Flory exponent of 0.58 is obtained for chain statistics. Both potentials of polystyrene and ethylbenzene are transferable over a broad range of temperature. The thermal expansion coefficients of the fully atomistic simulations are well reproduced in the coarse-grained models for both systems. However, for the case of ethylbenzene, the coarse-grained potential is temperature-dependent. The potential needs to be modified by a temperature factor of T/T0 when it is transferred to other temperatures; T0 = 298 K is the temperature at which the coarse-gr...

The dissipative particle dynamics simulation technique is used to study the microphase transitions of perforated lamellae of cyclic diblock copolymers under steady shear. The perforated lamellae are transformed to perfect lamellae, and the layer normal is aligned to the direction parallel to the gradient of the velocity under weak shear, whereas they undergo a phase transition to form perfect lamellae whose normal is aligned to the direction perpendicular to the gradient of the velocity due to strong shear. Subjected to the moderate shear, the perforated lamellae are transformed to hexagonally ordered cylinders. By examining the microphase morphologies in the shearing process, we find shear thinning in general, which is reflected by the reorientation of the lamellae, and shear-induced thickening when hexagonally ordered cylinders appear. The calculated shear viscosity basically decreases with increasing shear rate but shows a local maximum at the shear rate that induces hexagonally ordered cylinders.

The dissipative particle dynamics (DPD) simulation method is applied to study the mesoscopic phase formation of cyclic diblock copolymer c-AmBn (m + n = 20). The phase diagram is constructed by simulating at different interaction parameters and composition fractions. The resulted phase diagram is similar to that of the linear diblock copolymer; i.e., the ordered structures such as lamellae, perforated lamellae, hexagonal cylinders, and body-centered-cubic spheres can be identified in the parameter space. Melted structures such as micelle-like, liquid rod, and random network phases have also been found in the phase diagram. The observed (χN)ODT is in agreement with the theoretical prediction, if a finite chain length mapping is applied. Cyclization of a linear block copolymer can induce remarkable changes in the morphology of the organized meso structure. This is attributed to the reduced chain length of the cyclic block copolymer. The existence of the melted structures between totally disordered and the o...