Crosslinking of polydimethylsiloxane in heavy ion tracks

Gelation of polydimethylsiloxane irradiated with 256 MeV Ar ion was examine d. The insoluble residue of the irradiated polydimethylsiloxane was separat ed with membrane filters. The weight of the insoluble residue is proportion al to the number of irradiated ions. This result indicates that gelation oc curs in the high local dose region of the ion tracks. A gel string is gener ated in each ion track. The weight of a gel string increases in proportion to the initial molecular weight (M-n) of polydimethylsiloxane. It arises fr om an increase in the radius of the gel strings with increasing M-n The gel ation dose decreases with increasing M-n The region with a dose higher than the gelation dose is found in the ion tracks. The radius of the gel string s estimated using the G-value of crosslinking for low-LET radiation and wit h an appropriate dose distribution in the ion tracks explains the experimen tal results well. (C) 2001 Elsevier Science B.V. All rights reserved.