Simultaneous continuous, nonchromatographic monitoring and discrete chromatographic monitoring of polymerization reactions

Abstract

Automatic continuous nonchromatographic monitoring and discrete chromatographic monitoring were coupled together for the first time and used to monitor free radical and controlled-radical polymerization reactions. This was achieved by adding a multidetector Size Exclusion Chromatography (SEC) system (alternatively termed Gel Permeation Chromatography, GPC) to the ACOMP platform (Automatic Continuous Online Monitoring of Polymerization reactions). The fact that the reactor solution is already preconditioned in the ACOMP front-end to the concentration levels used in SEC makes direct coupling possible. Kinetics from two different types of reactions, Reversible Addition Fragmentation Transfer (RAFT) and free radical polymerization of butyl acrylate were studied, including the production of a bimodal population. Complementary and contrasting features from the continuous and SEC approaches are highlighted. The main advantage of the SEC detection is to follow the evolution of full molecular weight distributions (MWD), especially in 'living' type reactions, where polydispersity decreases with monomer conversion, whereas the continuous detection provides a much more detailed characterization of the reaction. Interestingly, in the case where a bimodal molecular weight distribution was produced, the continuous method automatically detected the onset of the second mode in a model independent fashion, whereas SEC could only discern the bimodality by applying preconceived models. The SEC approach will have valuable niche applications, however, such as when reactions are relatively slow, monitoring narrow polydispersity is of primary importance, and also in copolymerization and terpolymerization reactions where complex mixtures of reagents (e.g., RAFT agents, copper ions, etc.) make unfractionated spectroscopic resolution of comonomers difficult.

Living Radical Polymerization by the RAFT Process – A Third Update

“…[561] On-line monitoring of RAFT polymerization has been performed using ACOMP (automatic continuous online monitoring of polymerization reactions). [221,439,562] This technique [543] (EA) [543] (EA/MMA/Am) [543] 'R'-connected…”

“…The method has been applied to study the homopolymerization of BA in butyl acetate, [439] the copolymerization of BA with MMA, [562] and the copolymerization of DMAEMA with styrene in DMF [221] all with RAFT agent 155.…”

“…A* [435] St [221] CMS [436] (BD) [437] (Ip) [437] AA [438] BA [221,439] 348 [311] (DMAEA) [221] (DADMAC) [440] AN/BD [312] (AN/BD) [441] St/MAH [435] (AA-b-TFEMA) [438] AA-b-St [437] (AA-b-St-b-BD) [437] (AA-b-St-b-Ip) [437] (AA-b-St-b-Ip) [437] (AA-b-BA-b-St-b-BD) [437] 156…”

Fundamental Measurements in Online Polymerization Reaction Monitoring and Control with a Focus on ACOMP

“…A recent demonstration coupled the usual continuous non‐chromatographic detection of ACOMP with a multi‐detector SEC instrument fed by the continuous ACOMP waste stream 96. Figure 9 shows the combination of continuous and discrete SEC data obtained simultaneously.…”

Simultaneous Monitoring of the Effects of Multiple Ionic Strengths on Properties of Copolymeric Polyelectrolytes during Their Synthesis

“…Typical detectors include light scattering, UV/visible spectrophotometry, viscometry, refractivity, and polarimetry. While ACOMP is not inherently a chromatographic method, its continuous stream can be used in automatic conjunction with gel permeation and other separation techniques, as has been demonstrated [51].…”