Role of Ethylene Oxide and Propylene Oxide Groups of Pluronics in Binding of Fatty Acid to Pluronics in Microemulsions

Abstract

We investigated the drug and fatty acid binding capacity of Pluronic-based microemulsions through simple turbidity experiments. Pluronic-based oil-in-water microemulsions of various compositions were synthesized and titrated to turbidity with concentrated amitriptyline, an antidepressant drug. The BASF Pluronic grid was used to select two series of Pluronic surfactants: (1) those having the same number of ethylene oxide (EO) groups, with an increasing number of propylene oxide (PO) groups and (2) those having the same number of propylene oxide groups with an increasing number of ethylene oxide groups. We observed that the binding of sodium caprylate fatty acid and amitriptyline drug increases with increasing hydrophobicity (i.e., increasing number of PO groups). This is attributed to the greater number of binding sites for the sodium caprylate, which results in more charge on the microemulsion, subsequently leading to increased drug binding. We also determined that when the number of PO groups was held fixed and the number of EO groups was increased, there is no direct correlation to the binding behavior of fatty acid and drug. This is due to the fact that the hydrophilic groups (EO) do not play a direct role in the binding of fatty acid molecules. In fact, when there are a significantly large number of EO groups present, they can act to inhibit binding of fatty acid and hence, drug, to the microemulsion.

Friction and anti-wear property of aqueous tri-block copolymer solutions in metal forming

“…The other is reverse type comprised of poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) PPO m PEO n PPO m with propylene oxide end blocks. In aqueous form, copolymers are soluble non-ionic amphiphilic surfactants [1,2,[4][5][6][7][8][9].…”

Tribological Performance of Aqueous Copolymers Solutions in Metallic Contact

“…A difference solution states for normal and reverse copolymers may contributed to the higher COFs of the reverse copolymers 17R4 and 25R2. PEO m -PPO n -PEO m solutions are known to exist micelles phase [8][9][10]24] whereas PPO n -PEO m -PPO n solutions in unimer state [8].…”

“…Both copolymers structures have been reported to exist in an unimer phase at low concentration and low temperature for example PEO m -PPO n -PEO m at below 0.02g/ml [8]. The interaction between the unimer phase and the water is created by strong hydrogen bond resulting in soluble copolymer solutions [8][9][10]. When the concentration is increased up to the Critical Micelle Concentration (cmc) at a certain temperature known as Critical Micelle Temperature (cmt), the copolymers aggregate into nano-sized structures.…”

Thickness and scratch resistance of adsorbed film formed by triblock symmetrical copolymer solutions

“…for PEO m ‐PPO n ‐PEO m below 0.02 g ml −1 concentration . The unimer phase is attributed to strong hydrogen bond resulting in soluble copolymer . For a given solution temperature, when the concentration is increased up to critical micelle concentration, the copolymers phase changes to micellar phase with hydrophobic core and hydrophilic block corona extended towards the exterior water .…”

“…Typical water‐based strip rolling lubricants are oil‐in‐water ( o/w ) micro‐emulsions, which are known to have several drawbacks such as tendency to form phase segregation, significant disposal treatment and cost and bio‐instability . As alternative, using triblock copolymers, which adsorb on hydrophobic surface, water‐based solutions compose of water soluble non‐ionic amphiphilic triblock copolymers surfactant of varying hydrophobic poly(propylene oxide) ( PPO ) blocks and hydrophilic poly(ethylene oxide) ( PEO ) blocks have been considered as prospective rolling lubricants because of their tribological performance and surface cleaning properties …”