Interactions and Dynamics in Aqueous Solutions of pH-Responsive Polymers: A Combined Fluorescence and Dielectric Relaxation Study.
J Phys Chem B
; 125(22): 6023-6035, 2021 06 10.
Article
en En
| MEDLINE
| ID: mdl-34057364
Interaction and dynamics of aqueous solutions of pH-responsive smart polymers are investigated via steady-state, time-resolved fluorescence emission spectroscopy with the help of external local reporter coumarin 153 (C153), while MHz to GHz dielectric relaxation spectroscopic (DRS) measurement reports the intrinsic medium relaxation features. A series of pH-responsive random copolymers (DPL-DP60) comprising of a pH-responsive moiety 2-((leucinyl)oxy)ethyl methacrylate (l-Leu-HEMA) and hydrophobic methyl methacrylate (MMA) are synthesized and characterized. A balance between the pH-responsive (l-Leu-HEMA) and the hydrophobic (MMA) content dictates the phase transition pH, which is found to be â¼5-7 for these aqueous copolymer solutions (1 mg/mL). Dynamic light scattering measurements in aqueous solutions of these polymers reflect a small particle size (â¼2-8 nm) at solution pH below their individual phase transition pH, while a large particle size (â¼140-340 nm) forms beyond their phase transition pH. No signature of a phase transition pH-driven abrupt change in static and dynamic properties of aqueous polymer solutions has been registered from pH-dependent dielectric relaxation as well as solute (C153)-centric fluorescence measurements. A significant impact of varying the l-Leu-HEMA/MMA segment ratio on steady-state fluorescence emission and rotational anisotropy decay of the fluorophore solute (C153) has been observed. MHz to GHz DRS in aqueous solutions of these pH-responsive polymers reflects bulk water-like dielectric features.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Polímeros
/
Metacrilatos
Idioma:
En
Revista:
J Phys Chem B
Asunto de la revista:
QUIMICA
Año:
2021
Tipo del documento:
Article
País de afiliación:
India