Method for preparing a siloxane based polymeric liquid material and materials made therefrom

A method for preparing a polymeric liquid material formed of molecular building blocks of core-shell type architecture, the method comprising:

• a) charging at least one silicon tetraalkoxide Si(OR)4, wherein R is an unbranched or branched alkyl group with up to four carbon atoms;
• and, optionally, a functional admixture of
• one R″-organofunctional trialkoxysilane R″—Si(OR)3 and, optionally, an R3,R4-organofunctional dialkoxysilane R3—Si(OR)2—R4;
• or
• a mixture of different R″-organofunctional trialkoxysilanes and, optionally, at least one R3,R4-organofunctional dialkoxysilane;
• in monomeric or in oligomeric form, into a reaction vessel together with a first stoichiometric amount of acetic anhydride selected according to the desired DPcore, in the presence of a catalyst;
• b) heating up the reaction mixture provided in a) in a water-free, inert atmosphere under stirring to reach a desired reaction temperature and distilling off resulting acetic acid ester reaction product until the reaction and the flow of distillate stop, thereby forming said hyperbranched polysiloxane core;
• c) adding
• one R′-organofunctional trialkoxysilane R′—Si(OR)3 and, optionally, an R1,R2-organofunctional dialkoxysilane R1—Si(OR)2—R2, or
• a mixture of different R′-organofunctional trialkoxysilanes and, optionally, at least one R1,R2-organofunctional dialkoxysilane,
• wherein:
• R′ and R″ are independently selected substituents each representable as L-Z, wherein
• L is a linker group selected from the group consisting of —C6H4—, —C6H4—CH2—, —CH2—CH2—C6H4—CH2— and —[(CH)2]n— with n=0, 1, 2, 3, 4;
• and
• is a terminal functional group selected from the following:
• wherein R* is selected from the group consisting of —H, —CH3, —C2H5, —C3H8, —C4H10 and —C6H5;
• or Z is —[(CH)2]m—CH3 with m=0, 1, 2, . . . , 11;
• and
• wherein R1, R2, R3 and R4 are substituents independently selected from the group consisting of —CH3, —C2H5, —C6H11, —CH═CH2, —CH2—CH2—Cl and —O5H5,
• with the provision that the triplets (R′, R1, R2) and (R″, R3, R4) are not identical;
• together with a second stoichiometric amount of acetic anhydride selected according to the desired DPshell, optionally in the presence of a catalyst, to the hot reaction mixture formed in b) with continuing stirring, thus initiating a selective build-up of said functional siloxane shell onto the core produced in b), whereby further acetic acid ester is formed and distilled over, and continuing the reaction until the distillate flow ceases again;
• d) optionally building additional functional layers in the shell by repeating the addition and reaction protocol described in c) at least once;
• e) optionally removing low-molecular reaction products and/or residual starting materials in the reaction mixture by vacuum distillation through gradually lowering the pressure inside the reaction vessel and holding a final pressure in the range of 5 to 250 mbar for a period of time between 10 and 120 minutes,
• f) cooling down and isolating the polymeric liquid material thus obtained;
• wherein a) through e) are carried out in one and the same reaction vessel.