Synthesis and Aggregation Behavior of Copolymer of Acrylamide with Pseudorotaxane Monomer by Threading Cucurbit[6]uril onto N′-(4-vinylbenzyl)-1,4-diaminobutane Dihydrochloride

Abstract

The novel side-chain copolymers of acrylamide (AM) and complex pseudorotaxane monomer N′-(4-vinylbenzyl)-1,4-diaminobutane dihydrochloride with cucurbit[6]uril (CB[6]) threading (4VBCB) were prepared via free-radical polymerization in aqueous solution. The copolymers with CB[6] (PAM4VBCB) were characterized by 1H NMR, FTIR, elemental analysis, and static light scattering. The thermodynamic properties of polypseudorotaxanes were studied by thermogravimetric analysis (TGA) and dynamic light scattering (DSC). The average hydrodynamic radius (Rh) of the polypseudorotaxanes was studied by DLS. At the same time, pH and conductivity of the polypseudorotaxanes was studied. The experiment data show that CB[6] beads are localized on 1,4-diaminobutane units in side chains of copolymer. TGA data show that thermal stability of the polypseudorotaxanes increases with the adding of the threading CB[6] because of the enhanced rigidity and the bulky steric hindrance of 4VBCB in side chains of PAM4VBCB. DLS data show that the average hydrodynamic radius of polypseudorotaxanes increases with the increase of the copolymer concentration and has a jump with increasing with increasing pH due to the existing of the small size CB[6] dethreading from the polypseudorotaxanes with increasing pH. Both pH and electrical conductivity curves of the solution of PAM4VBCB-4 have a jump because that CB[6] could dethread from the polypseudorotaxanes with the addition of NaOH.