Complexing features and changes of the macromolecular conformations of poly-n-vinyl lactams in aqueous solutions

Energetics of Cooperative Transitions of N‐Vinylcaprolactam Polymers in Aqueous Solutions

“…This effect can indicate continuous changes in the hydration structure of the polymer. It can be related to the non-cooperative formation of the hydrophobic core in macromolecules of PNVCL [10,29] demonstrated by fluorescence measurements, viscometry, and dynamic lightscattering.…”

“…One believes that the folding of PNVCL in the pretransition range is caused by increasing hydrophobic interactions of apolar groups of the polymer upon heating. [10] Therefore, we can suppose that the obtained estimate of the enthalpy of non-cooperative hydration is a part of the contribution of apolar group to the total hydration enthalpy. The phase separation transition parameters obtained at different polymer concentrations: the cloud point temperature, transition temperature, transition enthalpy, and transition heat capacity increment, are listed in Table 1.…”

“…Upon further increase in surfactant concentration the amplitude of the low-temperature peak increases while that of the hightemperature peak vanishes. Phase separation transition in aqueous solutions of N-vinylcaprolactam-methacrylic acid copolymers of different compositions were studied at different polymer concentrations and pH (4)(5)(6)(7)(8)(9)(10)(11)(12). The transition parameters do not depend on polymer concentration and pH.…”

“…When the system approaches the binodal curve upon heating, macromolecules are found to be steadily collapsing with formation of an intramolecular hydrophobic core. [10] One believes that the further phase separation is caused by intermolecular hydrophobic interaction of partly collapsed macromolecules. According to Yanul' et al, [11] the phase separation is accompanied by a heat absorption effect of about 10 J Á g À1 .…”

Heterogeneous Morphology of Random Copolymer Microgels as Reflected in Temperature‐Induced Volume Transition and1H High‐Resolution Transverse Relaxation NMR

“…This polymer is soluble in water in temperature range between 0 and 30 ° C. The heating of the aqueous PVCL solution above LCST around 32 ° C leads to the phase separation and precipitation of the polymer. [4][5][6] PVCL is not only water soluble and thermally sensitive, but also biocompatible polymer. It contains hydrophilic amide group that is directly connected to the hydrophobic carboncarbon backbone chain so that its hydrolysis will not produce small amide compounds that are often bad for biomedical applications.…”