Self-assembly in aqueous block copolymer solutions

Abstract

The aggregation of EOgg-POes-EOge (EO and PO being ethylene oxide and propylene oxide, respectively) in water has been studied. By gel permeation chromatography (GPC) and self-diffusion studies, it was found that micelles are formed in dilute solutions, but only at higher temperatures. The micelles formed have a hydrodynamic radius of approximately 10 nm over a wide temperature range. The residence time of the polymer molecules in the micelles is extremely long (~hours). At higher polymer concentrations, a clear isotropic gel is formed at intermediate temperatures. The extension of the gel region depends strongly on the presence of cosolutes, such as inorganic salts and hydrocarbons; detailed phase diagrams are presented and discussed. Furthermore, the self-diffusion of the polymer and of solubilized oil was studied. The diffusion of the polymer molecules is slow (Dp ~10'n-10~12 m2/s), decreasing with increasing polymer concentration (roughly as Dp ~c*1) up to 20 wt %. In the gel region, the echo-amplitude decay curves reveal a distribution of diffusion coefficients, precluding detailed analyses. The self-diffusion of the oil is comparable to that of the polymer (D0ii ~DP), and several orders of magnitude slower than the diffusion of water (Dw = 10~9 m2/s).

Optimization and Physicochemical Characterization of Thermosensitive Poloxamer Gel Containing Puerarin for Ophthalmic Use

“…They pointed out the critical micelle concentration and the critical micelle temperature might decrease with some salts and the micelle would entangle and pack more tightly in the presence of some salts under the identical temperature. 37,38) These seem more reasonable to explain why NaCl can reduce the gelation temperature and enhance the gel strength of the poloxamer gels (21/5). Since the poloxamer with hydrophilic oxide group could bind to mucoproteins.…”

Development of tetracycline-serratiopeptidase-containing periodontal gel: Formulation and preliminary clinical study

“…If the hydrogen bonding is supplemented by adding compounds with a hydroxyl group, the gelation point decreases. 19 The gel structure was thought to remain unaltered with temperature until an excessively high temperature caused the destruction of the gel structure. At higher temperatures, the gel underwent dehydration, but excessive hydrogen bonding and closely packed micelles restricted the destruction of the gel structure.…”

“…Gelation of the thermoreversible gel is affected by a range of factors, such as temperature, polymer concentration, concentration of active ingredients, and electrolytes. 6,19 So, in the present study, to reduce polymer concentration and to obtain reasonable viscosity at a lower concentration of pluronic, the effect of Aerosil and tetracycline on gel properties was studied. Liquid crystalline gel was characterized using polarizing microscopy.…”

A Digital Microfluidic Approach to Proteomic Sample Processing

“…Additionally, F127 is known to form gels at high concentrations and temperatures [97][98][99] (i.e., 15-30% w/v, 37°C); thus, the parameters in our experiments were well below those required for gelation. Figure 2.2a shows typical images collected in a confocal microscopy assay for a surface exposed to labeled protein under the worst case scenario conditions.…”