Two acid-labile, thermoresponsive poly(methacrylamide)s with the pendant cyclic orthoester moieties of trans and cis configurations, PtNEM and PcNEM, were synthesized via free radical polymerization of the corresponding trans and cis isomers of N-(2-ethoxy-1,3-dioxan-5-yl)methacrylamide (NEM). The thermally induced phase transition/separation behaviors of both polymers as well as the aqueous solution properties below and above their phase transition temperatures were investigated by means of turbidimetry, DSC, 1H NMR, microscopy, fluorescence probe, and dynamic light scattering. Both PtNEM and PcNEM showed aggregation behaviors below their respective LCSTs, and the former formed more hydrophobic microdomains which had greater capability to solvate pyrene molecules compared with PcNEM. These two polymers exhibited thermally induced sensitive and reversible phase transitions in aqueous solution. PtNEM showed a little lower cloud point but much greater phase transition enthalpy compared to PcNEM. The results...
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