Thermogelling systems

Polymers Chitosan, poloxamer 407, liposomes thermogelling systems e.g. 

A poly(ethylene glycol)-poly(L-alanine-co-L-phenylalanine) (PEG-PAF) aqueous solution as a polypeptide-based thermogelling system and its... 

Feijen et al. have reported the thermogelling system using SC formation of star-shaped diblock copolymers, PEG- -(PLLA)8 and PEG- -(PDLA)8 [89,90]. They have investigated the effects of arm number of the branched architecture on their temperature-responsive gelation by comparing the PEG- -(PLLA)8/PEG-h-(PDLA)8 system with the... 

Pereswetoff-Morath, L., Bjurstrom, S., Khan, R., Dahlin, M., and Edman, P. (1995), Toxicological aspects of the use of dextran microspheres and thermogelling ethyl(hydroxyethyl) cellulose (EHEC) as nasal drug delivery systems, Int. J. Pharm., 128, 9-21. 

Three different techniques are used for the preparation of state of the art synthetic polymeric membranes by phase inversion 1. thermogelation of, a two or more component mixture, 2. evaporation of a volatile solvent from a two or more component mixture and 3. addition of a nonsolvent to a homogeneous polymer solution. All three procedures may result in symmetric microporous structures or in asymmetric structures with a more or less dense skin at one or both surfaces suitable for reverse osmosis, ultrafiltration or microfiltration. The only thermodynamic presumption for all three preparation procedures is that the free energy of mixing of the polymer system under certain conditions of temperature and composition is negative that is, the system must have a miscibility gap over a defined concentration and temperature range (4). 

Thermogelation of a Two-Component Mixture. The simplest procedure for obtaining a microporous system is the thermogelation of a two component mixture. At a specific temperature, the mixture forms a homogeneous solution for all compositions but at a tower temperature shows a miscibility gap over a wide range of compositions. This behaviour is illustrated schematically in Figure 1, which shows a phase diagram of a two component mixture of a polymer and a solvent as a function of temperature. 

The thermogelling PLGA is an amorphous polymer with a low glass transition temperature. Therefore, the PEG/PLGA copolymer systems of which... 

A pH/temperature sensitive system was also reported as an injectable system. The pH sensitive imits can complex with a protein drug with opposite charges to reduce the initial burst release of an incorporated drug. Thermogelling PEG/ PCGA, PEG/PCL, and PEG/PCLA were eoupled to pH sensitive amine containing blocks to prepare pH/temperature sensitive gelling system. ... 

Lindell, K. and Engstrom, S., Investigation of surfactant alkyl chain length and counterion effects on the thermogelling EHEC system, Int. J. Pharm., 124, 107-118 (1995). 

In this chapter, biodegradable IP systems that can form hydrogels after injection into the body are introduced. Especially, recent progress in biodegradable copolymer systems exhibiting temperature-responsive sol-gel transition (thermogelling polymer) is mainly introduced from the viewpoint of polymer nanoarchitectonics. 

One of the possible solutions to overcome low mechanical properties of thermogelling copolymer systems must be enlargement of their total molecular weights. But elongation of each segment (hydrophobic and hydrophilic) with keeping their hydrophobic/hydrophilic... 

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