Energy dissipating poly(hydroxyurethane) elastomers – Synthesis, characterization and comparison with shear thickening fluid materials

Polymeric Materials Based on Carbon Dioxide: A Brief Review of Studies Carried out at the Faculty of Chemistry, Warsaw University of Technology

Carbon dioxide is an important raw material in many industrial technologies, but it is also one of the greenhouse gases that has to be effectively removed from the environment. This contribution provides a brief overview of carbon dioxide-based polymers developed in the laboratories of the Faculty of Chemistry at Warsaw University of Technology. We present some simple and versatile synthetic approaches that can be used to prepare a library of oligocarbonate diols, polycarbonates, poly(ester-carbonates), poly(ether-carbonates) and various types of polyurethanes, including the newly emerging family of environmentally friendly non-isocyanate polyurethanes. The main synthesis strategy involves the reaction of CO₂ with oxiranes to form five-membered cyclic carbonates, which can be utilized as a source of carbonate bonds in polymeric materials obtained by the ester exchange reactions and/or step-growth polyaddition. We also show that cyclic carbonates are valuable starting materials in the synthesis of hyperbranched polymers and polymer networks. The properties of several CO₂-based polymers are presented and their potential application as biomaterials, smart materials, and absorbers with a high CO₂ capture capacity is discussed.

Rheological and Technological Aspects in Designing the Properties of Shear Thickening Fluids

This work focuses on shear thickening fluids (STFs) as ceramic-polymer composites with outstanding protective properties. The investigation aims to determine the influence of raw material parameters on the functional properties of STFs. The following analyses were used to characterize both the raw materials and the STFs: scanning electron microscopy, dynamic light scattering, matrix-assisted laser desorption/ionization time-of-flight, chemical sorption analysis, rheological analysis, and kinetic energy dissipation tests. It was confirmed that the morphology of the solid particles plays a key role in designing the rheological and protective properties of STFs. In the case of irregular silica, shear thickening properties can be obtained from a solid content of 12.5 vol.%. For spherical silica, the limit for achieving shear thickening behavior is 40 vol.%. The viscosity curve analysis allowed for the introduction of a new parameter defining the functional properties of STFs: the technological critical shear rate. The ability of STFs to dissipate kinetic energy was determined using a unique device that allows pure fluids to be tested without prior encapsulation. Because of this, it was possible to observe even slight differences in the protective properties between different STFs, which has not been possible so far. During tests with an energy of 50 J, the dissipation factor was over 96%.