Simultaneous multiple sample light scattering detection of LCST during copolymer synthesis

This work has two objectives in the investigation of polymer solution lower critical solution temperature (LCST): First, to develop a new instrument to monitor LCST onset during copolymer synthesis by coupling several thermostatted light scattering flow cells to the output stream of an ACOMP system (Automatic Continuous Online Monitoring of Polymerization reactions). Second, to use this to investigate effects on LCST when N-isopropylacrylamide (NIPAM) is copolymerized with a charged comonomer, styrene sulfonate (SS). This comonomer pair has widely separated reactivity ratios. SS is rapidly consumed, yielding composition drift toward NIPAM rich polymer. High content SS chains inhibited LCST, and SS was dramatically effective at suppressing LCST down to copolymers of 5% molar SS in 10 mM NaCl aqueous solvent. LCST for higher content SS chains was elevated and required significant additional ionic strength to occur. It was determined that the suppression of the LCST by SS is chiefly an intramolecular effect.