Triblock copolymer P104 detailed behavior through a density, sound velocity and DLS study

Abstract

Pluronic triblock copolymers usually present complex phase behavior depending on the number of PEO and PPO blocks contained in the polymer. They have a great dependence to temperature and concentration, both considered as key factors in the pluronic phase behavior. The evaluation of physicochemical properties such as densimetry and sound velocity, as well as the determination of the size distribution profile of particles of P-104/water in solution allow obtaining a detailed temperatureconcentration behavior of the system. In this work we present a study of P104/water behavior through density, ultrasound velocity and dynamic slight scattering (DLS) measurements in a wide range of temperatures. The critical micellar temperature (CMT) and the sphere-to-rod micelle transition temperature (GMT) were determinate as a function of concentration.

Micellar Self-Assembly and Probe Exchange Dynamics of Triblock Copolymer Poly(ethylene oxide)–Poly(propylene oxide)–Poly(ethylene oxide) PEO57PPO45PEO57

“…Besides, k fusion also has a clear inflection point at which its slope changes to positive, making fusion an unfavorable process. Thus, for P103 and P104, the fragmentation becomes dominant close to equilibrium when rodlike micelles are formed as a result of instabilities along the rod surface. , …”

“…Thus, for P103 and P104, the fragmentation becomes dominant close to equilibrium when rodlike micelles are formed as a result of instabilities along the rod surface. 13,14 An alternative view of the observed k fragmentation , k fusion , and E a values can be considered on the basis of the copolymer hydrophile−lipophile balance value and the interfacial tension between the PO block and the solvent. At T < T t (formation of spherical micelles), the energetic cost for a copolymer with a PO/EO ratio >1 (considered as hydrophobic prone such as P103 or P104, e.g.)…”

“…The formed micelles in aqueous solution consist of a PO core surrounded by a more hydrophilic EO corona, becoming suitable nanocontainers for solubilization, for example, of poorly water-soluble hydrophobic compounds into the inner micellar core to enhance their solubilization and control their release, ,, hence, avoiding their unspecific absorption and favoring their extended circulation times while decreasing clearance from the body. Also, drug incorporation inside these polymeric nanocarriers can allow drug passive accumulation in solid tumors through the enhanced permeability and retention effect and overcoming the biological barriers, which increases the therapeutic efficacy of the bioactive cargo compound in diseases such as cancer. − The self-assembly properties of Pluronic-type block copolymers in aqueous solutions can be modified by, for example, modifying the PO/EO molar ratio or the copolymer’s molecular weight. , Moreover, this class of copolymers can also undergo morphological transitions from spherical micelles to, for example, rodlike structures upon temperature and/or concentration changes depending on the copolymer composition, structure, and block length, amongst other factors. − …”

Structural Behavior of Amphiphilic Triblock Copolymer P104/Water System

“…As soon as the sample temperature increases, the whiteness increases up to about 70 • C, when a separation phase is detected. This transition may be due the onset of the cloud point temperature (CPT) [70,74]. At higher concentrations, i.e., sample of 20 wt.% it exhibits a similar trend to the more diluted sample (see Figure S1b in Supplementary Materials), but some differences were detected; about 60 • C where the MGT appears the sample exhibits a gel-like behavior.…”