The Effect of Added Gold Nanoparticles on the Volume Phase Transition Behavior for PVCL-Based Microgels


The volume phase transition (VPT) behavior of poly(N-vinylcaprolactam-co-4-vinylpyridine) P(VCL-co-4VP) microgels and their hybrid counterparts containing Au nanoparticles (AuNPs) is explored and compared by FTIR measurements in combination with the perturbation correlation moving window (PCMW) technique and two-dimensional correlation spectroscopy (2Dcos) analysis. It is demonstrated that the incorporation of AuNPs inside the microgels cause a slight dehydration effect on the microgels in the swollen state and an increase of the VPT temperature. Moreover, the interaction between C[double bond, length as m-dash]O and AuNPs can be confirmed by combining the conventional IR and 2Dcos analysis. It is with the help of the additional cross-links between AuNPs and the polymer chains (C[double bond, length as m-dash]O and pyridine groups) in the microgel network and the tendency of AuNPs to aggregate that the hybrid microgels exhibit a much greater dehydration during the VPT, as compared with the nonhybrid ones.