Strength Improvement via Coating of a Cylindrical Hole by Layer-by-Layer Assembled Polymer Particles

Abstract

Negatively charged colloidal poly(methyl methacrylate-co-butyl acrylate) (P(MMA-BA)) particles and positively charged dissolved poly(ethyleneimine) (PEI) were adsorbed onto a cement block using a layer-by-layer (LBL) assembly technique. The block was fashioned so as to have a cylindrical hole running from one face to another along the long axis of the rectangular block, and a fluid containing either of the two charged materials was pumped through the block. The result was a film tens of micrometers thick, and the pressure required to crack the cement block was measured after one end of the hole was sealed. Latex particles with a T(g) near the use temperature showed the maximum improvement in the cracking stress of the blocks. In a multilayer coating with identically sized particles, the cracking stress of the blocks increased to an improvement of 25% and then dropped off with increasing number of layers, even though the relationship between film thickness and the number of layers was linear. An improvement of about 30% in the cracking stress of the coated blocks was obtained when using multiple layers with different particle sizes. The effects of the number of layers and particle size on the cracking stress suggest that both the morphology and the thickness of the film play a role in performance. Tests done under confinement, e.g., with an external stress applied to the outside of the blocks, suggest that not only does a film-forming mechanism contribute to performance but that filling of microcracks in the rock may also play a role.

Highly Stretchable Superhydrophobic Composite Coating Based on Self‐Adaptive Deformation of Hierarchical Structures

“…It indicates that the roughness of the composite coating can withstand the relatively small mechanical deformation and can keep its original superhydrophobic properties. However, at higher strain conditions (800% and 1000% as shown in Figure c,d,h), both surface and cross‐section morphologies of the composite coating greatly change due to the serious modulus mismatch between the composite coating and the rubber substrate . The micromastoids in the top layer are completely separated by very wide cracks along the stretching direction and the cracks further propagate into the bottom layer to generate many new micromastoids with different size.…”

Layer-by-Layer Assembly of Multifunctional Porous N-Doped Carbon Nanotube Hybrid Architectures for Flexible Conductors and Beyond

“…Layer-by-layer (LbL) assembly is a versatile and simple method to fabricate multifunctional, multilayer thin films on the surface, which involves the repeated, sequential immersion of substrates into desired solution. − Here, we report a simple and rapid method to incorporate diverse functional nanomaterials into 3D porous CHAs for flexible conductors on the basis of commercially available polyurethane (PU) sponge and LbL assembly. The key novelty to assemble such binary CHAs lies in selection of available PU sponges with macroscopically ordered 3D structure as the skeleton and synthesis of novel polyelectrolyte as surfactant and adhesion layer for immobilizing various nanostructured materials.…”