Siloxane-Urethane Containing Block Copolymers

Oligomeric diisocyanate + Hydtoxy/amine tenninated siloxane Block copolymers 

Pofynrethane Modified with an Aminoetfaylaminopropyl-Substituted Pofydimethylsiloxane 

Fan et al. reported the syntheses and properties of a polyurethane-urea, copolymers 88 from a aminoethyl-aminopropyl poly(dimethylsiloxane) 86 (AEAPS), 

L Synthesis of Waterborne Potynrethane Modified with an Aminoethylaminopropyl-Snbstitnted Polydimetbylsiloxane 

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Hydrosilation reactions have been one of the earlier techniques utilized in the preparation of siloxane containing block copolymers 22,23). A major application of this method has been in the synthesis of polysiloxane-poly(alkylene oxide) block copolymers 23), which find extensive applications as emulsifiers and stabilizers, especially in the urethane foam formulations 23-43). These types of reactions are conducted between silane (Si H) terminated siloxane oligomers and olefinically terminated poly-(alkylene oxide) oligomers. Consequently the resulting system contains (Si—C) linkages between different segments. Earlier developments in the field have been reviewed 22, 23,43> Recently hydrosilation reactions have been used effectively by Ringsdorf 255) and Finkelmann 256) for the synthesis of various novel thermoplastic liquid crystalline copolymers where siloxanes have been utilized as flexible spacers. Introduction of flexible siloxanes also improved the processibility of these materials. 

One of the most important uses of end-functionalized polymers is the preparation of block copolymers.73,74 The reactions are identical to the chain extensions already mentioned, except that the sequences being joined are chemically different. In the case of the -OSilCR Y chain ends mentioned above, R is typically (CH2)3 5 and Y can be NH2, OH, COOH, CH=CH2, and so on The siloxane sequences containing these ends have been joined to other polymeric sequences such as carbonates, ureas, urethanes, amides, and imides. 

Similar enrichment of siloxane units occurs at the surfaces of block copolymers or even random copolymers containing PDMS sequences. Examples are poly(dimethylsiloxane-i-ethylene oxide) and poly(dimethylsiloxane-f)-imide) multi-block copolymers, poly(dimethylsiloxane)/imine copoly-mers, and poly(urethane-dimethylsiloxane) anionomers. Other materials, such as long-chain alkenes and highly branched polymer additives exhibit surface segregation. Much of the information on these changes in surface composition has been obtained by measurements of contact angles. 

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