Acrylic acid aac

Example 1

N-Isopropylacrylamide (NIPAm) (Sigma) was recrystallized with hexanes heated to 60° C. for 1 hr and 0.22 μm filtered after cooling. NIPAm (95% of a 140 mM monomer solution by weight) was dissolved completely with agitation (1 hr) then filtered in ultrapure water into a 3-neck reaction vessel heated in silicon oil, stirred at 450 rpm, and fluxed at 70° C. A condenser with running cold water was attached to the middle neck, nitrogen was bubbled through the monomer solution via a side neck, and a temperature probe connected to a hot plate through a feedback loop was in the 3^rd neck. NIPAm was fluxed 50 min before adding co-monomer Acrylic acid (AAc) (Sigma) (5% by weight) to flux an additional 10 minutes prior to initiation. The nitrogen was removed to add 1 mM ammonium persulfate (APS) to initiate the reaction and the nitrogen was then gently blown over the surface of the solution. The reaction proceeded for 6 hours, while stirring, with water flow through condenser. The reaction vessel was removed from the oil and stirred to cool overnight. Microgels were purified by filtering over glass wool to remove large aggregates and by dialysis to remove excess monomers in 1000 kDa MWCO cellulose ester dialysis tubing (spectrum) against ultrapure water (40× volume with 2 water changes over 48 hr).