Ödön Wagner

A new catalytic method for crosslinking of silicone polymers

The aim of our work was to develop a gelation process for polymerizing polydimethylsiloxane-α,ω-diols for pharmaceutical purposes. Three different gelling agents has been tried; among them, the prehydrolyzed tetraethoxysilane (TES 40) had the best performance. As initiators, several amines were investigated. The gelling time has been found to be correlated with the basicity, solubility, and diffusibility of the amines. The correlation between the thickness of the oligomer layer and the gelling time has also been investigated. The amount of the remaining initiator after the completion of the network formation has been determined, together with the time needed for its complete removal from the matrix. By using thermogravimetric methods it has been shown that no initiator is left in the matrix. The elastomers obtained by the present method were compared to those obtained by the usual catalysts, resulting in identical properties. The procedure developed is able to produce silicone oligomers for pharmaceutical purposes either in a continous or in a discontinous way. The procedure has several advantages in comparison with the conventional methods.

Synthesis and characterization of some bis(hydroxyalkyl)- and bis(hydroxyester)-functionalized disiloxanes

Abstract Novel hydroxyester disiloxanes (1,3-bis(6-hydroxyhexanoylmethyl)-1,1,3,3-tetramethyl disiloxane and 3-bis(2-hydroxypropanoylmethyl)tetramethyl disiloxane) were synthesized, and preparation of other known monomers, namely 1,3-bis(hydroxypropyl)-1,1,3,3-tetramethyl disiloxane, 1,3-bis(hydroxyethoxypropyl)-1,1,3,3-tetramethyl disiloxane and 1,3-bis(hydroxymethyl)-1,1,3,3-tetramethyl disiloxane was developed to obtain better yields and reduce production time and expense. All compounds were characterized by infrared spectroscopy, using 1H NMR, 13C NMR, and 29Si NMR and were reacted with diisocyanates, resulting in poly(siloxane-urethane) copolymers with unique properties.

Development of a new silicone base transdermal therapeutic system

The diffusion properties of L-deprenyl base and its hydrochloride salt were investigated in various silicone elastomers. The effect of liquid ingredients such as glycerol and propylene-glycol, together with trifunctional silicon compounds containing polar (basic) groups, were studied for drug delivery applications. On the basis of diffusion investigations and thermoanalytical testing, the silicone composition (R5 oligomer, propylene glycol, trifunctional silicon compound GF-91), having optimal properties for pharmaceutical delivery, was selected.