Static light scattering (SLS) determination of the parameters characteristic of microgel-containing
polysiloxaneurethane prepolymer solutions
Microgel-containing and microgel-free polysiloxaneurethane (PSU) prepolymers differing in chemical structure were prepared by reacting siloxane oligomers terminated with hydroxyalkyl groups and 20, 30, 40 or 72 -0 -Si(CH3)2- groups in the chain (KF-6001, KF-6002, KF-6003, Tegomer 2311) to react with isophorone diisocyanate (IPDI) or tetramethylxylilene diisocyanate (TMXDI) (Table 1). Theoretical principles are outlined how to determine the characteristics of the microgels occurring in the PSU examined, involving the use of the SLS method and Lange's procedure. Toluene solutions of PSU were studied by this method. Correlation is discussed between the synthesis conditions and microgel content in the PSU prepolymers (Table 2). The highest microgel content, 0.0010 wt. %, was found to occur in the prepolymer prepared from siloxane oligomer KF-6001 [terminated with hydroxyl groups connected to si with the radical -(СНгЬ-СЦСНгХэ- and having twenty -0 -Э1(СНз)2- groups in the oligomer chain] and TMXDI.
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