No abstract

Automatic continuous online monitoring of polymerization reactions (ACOMP) was used to assess quantitatively the reactivity, average composition drift and distributions, as well as molar mass and intrinsic viscosity evolution of comonomers from the acrylate and methacrylate families during free radical copolymerization. In the latter case, N-methacryloxysuccinimide (MASI) was of chief interest because of its promise as a starting material from which highly tailored polymers can be produced by postpolymerization modifications. It was found that the reactivity ratios of MASI with an acrylate, such as butyl acrylate (BA), were widely separated and comparable to the case of methyl methacrylate (MMA) and BA. In contrast, reactivity ratios for MMA/MASI were closer together, consistent with general trends in the literature for MMA copolymerization with other methacrylates. While this is intuitively reasonable from a chemical point of view, this comprehensive online characterization confirms that at least some predictions about MASI copolymerization behavior can be made using the much wider knowledge base for MMA. The disparity between BA/MASI copolymerization compared to MMA/MASI is also seen in the unusual increase in weight-average molar mass and intrinsic viscosity as conversion increases. This work establishes the precedents and methodologies that can be used as a general tool in MASI-based developments and paves the way toward monitoring ATRP copolymerization of MASI, as well as postpolymerization modifications such as hydrolysis and derivitization.

The continuous record of monomer and polymer concentrations, C m and C p , and cumulative weight-average mass, M w , furnished by automatic continuous online monitoring of polymerization reactions (ACOMP) has been harnessed to provide feedback to control reactor monomer flow in order to follow a target trajectory M w,t (t) during linear chain growth free radical polymerization. This was achieved without a detailed kinetic model. Two proportionality parameters to pilot the controller, α and p, result from (i) reaction rate = αC m and (ii) M w,inst = pC m , where M w,inst is instantaneous M w . Using Ansatz values for α and p, the controller periodically recomputes these, based on the ACOMP data stream, in order to follow M w,t (t). A histogram of concentration vs M w,inst estimates the molecular weight distribution width. Invoking an instantaneous distribution provides polydispersities. Results are compared to GPC analysis on end products. The concept of "isomorphic reaction pair" is introduced: two reactions that follow the same trajectory under different reaction variables, e.g., varying T at constant [initiator] and varying [initiator] at T = constant. The controller can be used, as is, for high solids reactions, and extended to copolymerization, including for possible control of composition gradients in controlled radical polymerization.

Parallel temperature initial rates (PTIR) from chromatographic separation of aggregating protein solutions are combined with continuous simultaneous multiple sample light scattering (SMSLS) to make quantitative deductions about protein aggregation kinetics and mechanisms. PTIR determines the rates at which initially monomeric proteins are converted to aggregates over a range of temperatures, under initial-rate conditions. Using SMSLS for the same set of conditions provides time courses of the absolute Rayleigh scattering ratio, IR(t), from which a potentially different measure of aggregation rates can be quantified. The present report compares these measures of aggregation rates across a range of solution conditions that result in different aggregation mechanisms for anti-streptavidin (AS) immunoglobulin gamma-1 (IgG1). The results illustrate how the two methods provide complementary information when deducing aggregation mechanisms, as well as cases where they provide new mechanistic details that were not possible to deduce in previous work. Criteria are presented for when the two techniques are expected to give equivalent results for quantitative rates, the potential limitations when solution non-idealities are large, as well as a comparison of the temperature dependence of AS-IgG1 aggregation rates with published data for other antibodies.