Study of the Gelation Process of Polyethylene Oxidea–Polypropylene Oxideb–Polyethylene OxideaCopolymer (Poloxamer 407) Aqueous Solutions
✍ Scribed by Alain Cabana; Abdellatif Aı̈t-Kadi; Julianna Juhász
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 123 KB
- Volume
- 190
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
presumably caused by the penetration of liquid polymer solu-The gelation process of polyethylene oxide a -polypropylene oxtion into crevices of the tissue surface, resulting in mechaniide b -polyethylene oxide a copolymer (poloxamer 407) aqueous so-cal interaction (6).
lutions is studied by means of FTIR spectroscopy, rheology, and
In aqueous solution, with increasing temperature, poloxdifferential scanning calorimetry (DSC). The C-O-C stretching amers aggregate in micelles to minimize the free energy of bands of infrared spectra were found to shift toward higher wavethe solution. The micellar behavior of poloxamers was first numbers with sol-gel transition, indicating that hydrogen bonding assessed using differential ultrasonic velocity and light scatis not the driving force for gelation. Linear viscoelastic data protering (7). Since then, several studies (8-12) have been vide an alternative method for gel point determination of these devoted to the analysis of the poloxamer micellization prothermoreversible gels. The results obtained with this method are found to coincide with those obtained using DSC. Gel point tem-cess. In the low temperature region, poloxamers exist as peratures determined by these methods are close to 14ЊC for 25% unimers. Upon warming, an equilibrium between unimers (w/w) poloxamer 407 solutions and 10ЊC for 30% (w/w) solutions. and micelles is established, and finally aggregates are formed In gel state, the elastic modulus (G) and dynamic viscosity ( h*) at higher temperatures (8,9,12). It is generally accepted are found to be concentration and temperature independent for that these micelles are spherical and consist of a PPO core temperatures ranging from 20 to 35ЊC. In light of our results, we with a PEO water swollen shell. This conformation is attribsuggest a mechanism of gelation based on micelles packing and uted to the fact that PPO is poorly water soluble and PEO entanglements. ᭧ 1997 Academic Press is highly soluble in aqueous solvent (8-12).