Effect of Graft Length and Matrix Molecular Weight on String Assembly of Aligned Nanoplates in a Lamellar Diblock Copolymer

Abstract

Grafted nanoparticle polymer composites have been used to create a highly bespoke class of materials, with spherical nanoparticles serving as the gateway design into this class. Grafted nanoplates (nanoparticles where the radius is longer than the height of the particle) provide opportunities and pathways to control overall system properties through their anisotropic properties. Current research on addressing the challenges associated with assembly is quite limited and unexplored. Using hybrid particle/self-consistent field theory (hSCFT) simulations, we build upon our previous work examining polyethylene glycol (PEG) grafted nanoplates within a nearly symmetric (f ≈ 0.5) lamellar poly­(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymer (BCP) matrix. We examine the interplay between the nanoplate graft length and matrix molecular weight and their effect on the potential of mean force (PMF). Ultimately, we discover that the location and depth of both the energetic well (local minimum) and the energetic barrier (local maxima) of the PMF, as well as the existence of the local maxima, are dependent on the relative width of the nanoplates to the lamellar domain, with the longer grafts experiencing deeper energetic wells and further interplate separation distances. The results are driven by the interfacial tension due to the local domain bulging effects caused by the insertion of the nanoplates into the lamellar system. With experimental separation distances of a PEG-grafted gadolinium trifluoride doped with ytterbium and erbium, GdF3:Yb/Er (20/2 mol %) nanoplates corroborate the correlation found in the simulations between larger matrix domains and a widening of the energetic well. Additionally, the average separation distance follows a trend similar to the hSCFT data. We anticipate these results to help in the development and design of anisotropic nanoparticles within BCPs to create nanocomposites tailored for specific applications and properties.

Designed and tailor-made double hydrophilic block copolymer-graphene nanoplatelet hybrids for reinforcing epoxy thermosets

“…As mentioned before, the rGO-g-DHBC mixes well in the epoxy matrix due to the double exophilic nature of the double hydrophilic PVP-b-PEG block copolymer. Hence the grafting of the block copolymer to GO, helps it to disperse well in the epoxy matrix 53 , 54 . The HRTEM images of neat and rGO-g-DHBC toughened epoxy system show a similar appearance indicating better dispersion of the nanoplatelets in the epoxy matrix as shown in Figure S2.…”

Precise Control over Positioning and Orientation of Nanorods in Block Copolymer Nanocomposites via Regulation of Coassembly Pathways

“…Computational modeling is advantageous to provide valuable insights by isolating important control parameters and probe into the structure–property relationship over multiple scales. Due to the computational challenges associated with the nanoparticle-loaded block copolymers and their kinetics in particular, computational studies on the coassembly behaviors of block copolymer/nanorod mixtures are quite limited. − In earlier works, Sides et al proposed a hybrid particle/field (HPF) framework to investigate the coassembled morphologies of block copolymer nanocomposites consisting of spherical nanoparticles . Recently, our group developed a dynamic version of an HPF framework to probe into the morphological evolution of coassembled structures. , It should be emphasized that the anisotropic feature of nanoparticles is not introduced into the dynamic HPF model.…”