Small-angle X-ray scattering (SAXS) is a small-angle scattering technique by which nanoscale density differences in a sample can be quantified. This means that it can determine nanoparticle size distributions, resolve the size and shape of (monodisperse) macromolecules, determine pore sizes, characteristic distances of partially ordered materials, and much more. This is achieved by analyzing the elastic scattering behaviour of X-rays when travelling through the material, recording their scattering at small angles. It belongs to the family of small-angle scattering (SAS) techniques along with small-angle neutron scattering, and is typically done using hard X-rays with a wavelength of 0.07 – 0.2 nm.. Depending on the angular range in which a clear scattering signal can be recorded, SAXS is capable of delivering structural information of dimensions between 1 and 100 nm, and of repeat distances in partially ordered systems of up to 150 nm. USAXS can resolve even larger dimensions, as the smaller the recorded angle, the larger the object dimensions that are probed.
Dissipative particle dynamics (DPD) is an off-lattice mesoscopic simulation technique which involves a set of particles moving in continuous space and discrete time. Particles represent whole molecules or fluid regions, rather than single atoms, and atomistic details are not considered relevant to the processes addressed. The particles' internal degrees of freedom are integrated out and replaced by simplified pairwise dissipative and random forces, so as to conserve momentum locally and ensure correct hydrodynamic behaviour. The main advantage of this method is that it gives access to longer time and length scales than are possible using conventional MD simulations. Simulations of polymeric fluids in volumes up to 100 nm in linear dimension for tens of microseconds are now common.
Poly(N-isopropylacrylamide) (variously abbreviated PNIPA, PNIPAM, PNIPAAm, NIPA, PNIPAA or PNIPAm) is a temperature-responsive polymer that was first synthesized in the 1950s. It can be synthesized from N-isopropylacrylamide which is commercially available. It is synthesized via free-radical polymerization and is readily functionalized making it useful in a variety of applications.
Temperature-responsive polymers or thermoresponsive polymers are polymers that exhibit drastic and discontinuous changes in their physical properties with temperature. The term is commonly used when the property concerned is solubility in a given solvent, but it may also be used when other properties are affected. Thermoresponsive polymers belong to the class of stimuli-responsive materials, in contrast to temperature-sensitive materials, which change their properties continuously with environmental conditions. In a stricter sense, thermoresponsive polymers display a miscibility gap in their temperature-composition diagram. Depending on whether the miscibility gap is found at high or low temperatures, either an upper critical solution temperature (UCST) or a lower critical solution temperature (LCST) exists.
Michael Elmhirst Cates is a British physicist. He is the 19th Lucasian Professor of Mathematics at the University of Cambridge and has held this position since 1 July 2015. He was previously Professor of Natural Philosophy at the University of Edinburgh, and has held a Royal Society Research Professorship since 2007.
In chemistry, vinylene is a divalent functional group with formula −CH=CH−; namely, two carbons, each connected to the other by a double bond, to an hydrogen atom by a single bond, and to the rest of the molecule by another single bond.
Amit Chakrabarti is the former William and Joan Porter Chair in Physics at Kansas State University. He currently serves as the Dean of the College of Arts and Sciences at Kansas State University.
A sequence-controlled polymer is a macromolecule, in which the sequence of monomers is controlled to some degree. This control can be absolute but not necessarily. In other words, a sequence-controlled polymer can be uniform or non-uniform (Ð>1). For example, an alternating copolymer synthesized by radical polymerization is a sequence-controlled polymer, even if it is also a non-uniform polymer, in which chains have different chain-lengths and slightly different compositions. A biopolymer with a perfectly-defined primary structure is also a sequence-controlled polymer. However, in the case of uniform macromolecules, the term sequence-defined polymer can also be used.
Timothy P. Lodge is an American polymer scientist.
Polymerization-induced phase separation (PIPS) is the occurrence of phase separation in a multicomponent mixture induced by the polymerization of one or more components. The increase in molecular weight of the reactive component renders one or more components to be mutually immiscible in one another, resulting in spontaneous phase segregation.
Frank Steven Bates is an American chemical engineer and materials scientist. Bates is a Regent's Professor (2007–present), a Distinguished McKnight University Professor (1996–present), and department head (1999-2014) in the Department of Chemical Engineering and Materials Science at the University of Minnesota, where he has been a faculty member since 1989. Prior to his appointment at the University of Minnesota, Bates was a member of the technical staff at AT&T Bell Laboratories from 1982-1989.
Eilaf Egap is an Assistant Professor of Materials Science at Rice University. She works on imaging techniques and biomaterials for early diagnostics and drug delivery. She was a Massachusetts Institute of Technology MLK Visiting Scholar in 2011.
Macromolecular cages have three dimensional chambers surrounded by a molecular framework. Macromolecular cage architectures come in various sizes ranging from 1-50 nm and have varying topologies as well as functions. They can be synthesized through covalent bonding or self-assembly through non-covalent interactions. Most macromolecular cages that are formed through self-assembly are sensitive to pH, temperature, and solvent polarity.
Topological polymers may refer to a polymeric molecule that possesses unique spatial features, such as linear, branched, or cyclic architectures. It could also refer to polymer networks that exhibit distinct topologies owing to special crosslinkers. When self-assembling or crosslinking in a certain way, polymeric species with simple topological identity could also demonstrate complicated topological structures in a larger spatial scale. Topological structures, along with the chemical composition, determine the macroscopic physical properties of polymeric materials.
Matthias Ballauff is a German chemist and physicist, and is a professor of physics at the Free University of Berlin. His postdoctoral research and training was directed by Paul Flory. He contributed to various areas of physical chemistry, in particular to polymer science, colloidal chemistry and nanomaterials, as well as to soft matter physics. Ballauff is particularly known for having developed new catalyst materials in the form of functionalized metallic nanoparticles dispersed in liquid phase, which can greatly speed up the reaction kinetics of organic molecules.
Nico van der Vegt is a Dutch chemist and a professor for computational physical chemistry at Technische Universität Darmstadt.
Ronald G. Larson is George G. Brown Professor of Chemical Engineering and Alfred H. White Distinguished University Professor at the University of Michigan, where he holds joint appointments in Macromolecular Science and Engineering, Biomedical Engineering, and Mechanical Engineering. He is internationally recognized for his research contributions to the fields of polymer physics and complex fluid rheology, especially in the development of theory and computational simulations. Notably, Larson and collaborators discovered new types of viscoelastic instabilities for polymer molecules and developed predictive theories for their flow behavior. He has written numerous scientific papers and two books on these subjects, including a 1998 textbook, “The Structure and Rheology of Complex Fluids”.
Arthi Jayaraman is an Indian-American scientist who is the Centennial Term Professor for Excellence in Research and Education at the University of Delaware. Her research considers the development of computational models to better understand polymer nanocomposites and biomaterials. Jayaraman was elected Fellow of the American Physical Society in 2020.
Polysulfobetaines are zwitterionic polymers that contain a positively charged quaternary ammonium and a negatively charged sulfonate group within one constitutional repeat unit. In recent years, polysulfobetaines have received increasing attention owing to their good biotolerance and ultralow-fouling behavior towards surfaces. These properties are mainly referred to a tightly bound hydration layer around each zwitterionic group, which effectively suppresses protein adsorption and thus, improves anti-fouling behavior. Therefore, polysulfobetaines have been typically employed as ultrafiltration membranes, blood-contacting devices, and drug delivery materials.
Cononsolvency is a phenomenon where two solvents that can typically readily dissolve a polymer, when mixed, at certain ratios of these two solvents, are no longer able to dissolve the polymer. This phenomenon is in contrast to cosolvency where two solvents that are both poor at dissolving a material, but when the two poor solvents admixed, can form a mixed solvent capable of dissolving the material.
