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Full-Text Articles in Engineering

Emergence Of Non-Hexagonal Crystal Packing Of Deswollen And Deformed Ultra-Soft Microgels Under Osmotic Pressure Control, Molla R. Islam, Rachel Nguyen, L. Andrew Lyon Sep 2021

Emergence Of Non-Hexagonal Crystal Packing Of Deswollen And Deformed Ultra-Soft Microgels Under Osmotic Pressure Control, Molla R. Islam, Rachel Nguyen, L. Andrew Lyon

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Highly solvent swollen poly(N-isopropylacrylamide-co-acrylic acid) microgels are synthesized without exogenous crosslinker, making them extremely soft and deformable. These ultralow crosslinked microgels (ULC) are incubated under controlled osmotic pressure to provide a slow (and presumably thermodynamically controlled) approach to higher packing densities. It is found that ULC microgels show stable colloidal packing over a very wide range of osmotic pressures and thus packing densities. Surprising observation of co-existence between hexagonal and square lattices is also made over the lower range of studied osmotic pressures, with microgels apparently changing shape from spheres to cubes in defects or grain boundaries. It is proposed …


Enabling Method To Design Versatile Biomaterial Systems From Colloidal Building Blocks, Shalini Saxena, L. Andrew Lyon Jan 2016

Enabling Method To Design Versatile Biomaterial Systems From Colloidal Building Blocks, Shalini Saxena, L. Andrew Lyon

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Development of materials with fine spatial control over topographical, mechanical, or chemical features has been investigated for a variety of applications. Here we present a method to fabricate an array of polyelectrolyte constructs including two-dimensionally and three-dimensionally patterned assemblies using both compressible and incompressible colloidal building blocks. This method eliminates prior constraints associated with specific chemistries, and can be used to develop modular, multi-component, patterned assemblies. In particular, development of constructs were investigated using microgels, which are colloidally stable hydrogel microparticles, polystyrene (PS) beads, and PS-microgel core-shell building blocks in conjunction with the polycation poly(ethyleneimine) (PEI). The topography, mechanical properties, …