Automatic, simultaneous control of molar mass and composition in free radical copolymerization using ACOMP/CI

ACOMP/CI has progressed to the point where molar mass and composition can be automatically controlled during free radical copolymerization reactions. The topics covered will be: i) Automatic, simultaneous control of molar mass and composition in free radical copolymerization. The original strategy used to control only molar mass involved the use of two proportionality parameters, aA and p, without any detailed kinetic models. aA is monomer A conversion rate and p the link between instantaneous weight average molar mass Mw,inst and monomer concentration. aA and p can be re-measured during a reaction as frequently as needed and are used to control monomer feed from a reservoir into the reactor. Extending the method to simultaneous control of molar mass and composition requires only one additional, measurable proportionality parameter, the conversion rate of monomer B, aB. Figure 1 shows production of a copolymer with trimodal composition and constant Mw. The comonomers were Acrylamide and Styrene Sulfonate (SS). FSS is the instantaneous fraction of SS incorporated into chains. Please download the file below for full content

Label-Free Characterization of Organic Nanocarriers Reveals Persistent Single Molecule Cores For Hydrocarbon Sequestration

Self-assembled molecular nanostructures embody an enormous potential for new technologies, therapeutics, and understanding of molecular biofunctions. Their structure and function are dependent on local environments, necessitating in-situ/operando investigations for the biggest leaps in discovery and design. However, the most advanced of such investigations involve laborious labeling methods that can disrupt behavior or are not fast enough to capture stimuli-responsive phenomena. We utilize X-rays resonant with molecular bonds to demonstrate an in-situ nanoprobe that eliminates the need for labels and enables data collection times within seconds. Our analytical spectral model quantifies the structure, molecular composition, and dynamics of a copolymer micelle drug delivery platform using resonant soft X-rays. We additionally apply this technique to a hydrocarbon sequestrating polysoap micelle and discover that the critical organic-capturing domain does not coalesce upon aggregation but retains distinct single-molecule cores. This characteristic promotes its efficiency of hydrocarbon sequestration for applications like oil spill remediation and drug delivery. Such a technique enables operando, chemically sensitive investigations of any aqueous molecular nanostructure, label-free

Label-Free Characterization of Aqueous Micelle Nanostructures Via Novel Liquid In-Situ Resonant Soft X-Ray Scattering (RSoXS)

Micelles are fundamental to nanocarrier applications from drug delivery to environmental remediation. Their structure and dynamics are critical to their properties and functions but are challenging to measure. Here, we demonstrate a novel technique capable of such measurements based on resonant soft X-ray scattering (RSoXS). It uniquely probes organic materials using their intrinsic chemical bonds rather than laborious and disruptive labeling techniques. Our customized microfluidic cell enables RSoXS to be performed in liquid environments, allowing structure and dynamics to be measured in-situ. Using this technique in a multimodal approach, we investigated an amphiphilic polyelectrolyte copolymer micelle of three different molecular weights (Mw). Despite no measurable critical micelle concentration, structural analyses point towards multimeric structures for most Mw’s. The sizes of the micelle substructures are independent of both concentration and Mw. Combining these results with a Mw-invariant surface charge and zeta potential strengthens the link between nanoparticle size and ionic charge in solution that governs polysoap micelle structure. Such control would be critical for nanocarrier applications such as drug delivery and water remediation