Siloxane-containing block copolymers

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. 

Dwight D, McGrath JE, Lawson G, Patel N,York G (1989) Surface and bulk microphase separation in siloxane-containing block copolymers and their blends The roles of composition and kinetics from multiphase macromolecular systems. BM Culbertson (ed) Plenum, pp 265-288... 

Siloxane-containing block copolymers are often prepared by step-growth or condensation polymerization of preformed diftmctionalized siloxane oligomers with other diftmctionalized monomers or oligomers. Our current work (3, 4, 6-8) on siloxane chemistry includes the preparation of a number of functionalized oligomers, with emphasis on equilibration processes with the commonly available cyclic tetramer, octamethylcyclotetrasiloxane (D4), in the presence of a functionalized disiloxane or end blocker. 

The properties of siloxane-containing block copolymers prepared from the functionally terminated siloxanes are influenced by the molecular weight distribution of the material which is typically Gaussian. The range of potential applications of the block copolymers can be extended if the molecular weight distributions of the siloxane blocks can be minimized. Thus, the impetus for evaluating supercritical fluid fractionation, aside from its utility as a characterization tool, as a means of improving end product performance is established. 

Using the same approach block lengths in siloxane containing block copolymers have been determined132,133... 

Gaines [13] has reported on dimethylsiloxane-containing block copolymers. Interestingly, if the organic block would not in itself spread, the area of the block polymer was simply proportional to the siloxane content, indicating that the organic blocks did not occupy any surface area. If the organic block was separately spreadable, then it contributed, but nonadditively, to the surface area of the block copolymer. 

Recently, as a further recognition of the importance of multiphase copolymers in specialty applications, siloxane containing block and segmented copolymers have received special attention for applications such as biomaterials, photoresists, gas separation membranes, protective coatings, elastomers and emulsifiers, as we shall... 

Morphology and Properties of Siloxane Containing Block and Segmented Copolymers... 

Siloxane containing block or segmented copolymers can be synthesized either by living anionic polymerization of the cyclic organosiloxane trimers with appropriate vinyl monomer(, 4 ) or by step-growth or condensation copolymerization of preformed a,w-difunctional siloxane oligomers with conventional difunctional... 

JP 05311144 (Japanese) 1993 Heat-resistant adhesive compositions containing polyimide-siloxane block copolymers Ube Industries, Japan H Inoe, S Takabayashi, T Funakoshi, K Sonoyana Useful for Cu-clad laminates of printed circuit boards and tape-automated bonding with good flexibility and heat resistance Formulated compositions containing siloxane-imide block copolymers made from aromatic tetracarboxylic acids and aromatic diamines and aminosiloxanes... 

Si NMR of siloxane systems has been used in studying organosilicone containing block copolymers to determine block length and chemical redistribution during polymerization. (85) Block copolymers of bisphenol A polycarbonate (BPAP) and polydimethyl-siloxane (PDMS) [20] were studied by both and Si NMR to determine a variety of structural parameters. 

Octadecyl group attachment to surface Silicon containing block copolymer additive Plasma fluoropolymer deposition Plasma siloxane polymer deposition Radiation-grafted hydrogels... 

FIGURE 9.16. General structure of the ferrocene containing siloxane random block copolymers used by Hale et al. in Ref. 103). 

Block copolymers containing polysiloxane segments are of great interest as polymeric surfactants and elastomers. Polycondensation and polyaddition reactions of functionally ended prepolymers are usually employed to prepare well-defined block copolymers. The living polystyrene anion reacts with a,co-dichloropoly(dimethyl-siloxane) to form multiblock copolymers398. ... 

Synthesis and characterization of ABA type copolymers containing polydimethyl-siloxane or poly(trifluoropropyl,methyl)siloxane middle blocks and aromatic ester based liquid crystalline end blocks were reported 252,253). These materials were synthesized in solution by the reaction of primary or secondary amine-terminated, di-... 

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