Copolymers alternating segmented synthesis

Scheme 7. Synthesis of perfectly alternating segmented engineering thermoplastics (ETP)-polydimethylsiloxane copolymers [44]...

Smith S D (1991) MS thesis. Synthesis and characterization of perfectly alternating segmented copolymers comprised of poly(dimethylsiloxane)s and engineering thermoplastics. Virginia Polytechnic Institute and State University, Blacksburg... 

Synthesis and Characterization of Perfectly Alternating Segmented Fully Cyclized Poiyimide Siloxane Copolymers... 

Scheme 3. Perfectly Alternating Segmented Copolymer Synthesis by the Transimidization Route Table 2 shows that high molecular weight is achieved within 10 minutes and increases slightly after 2 hours.

Scheme 3. Perfectly Alternating Segmented Copolymer Synthesis by the Transimidization Route...

Three major topics of research which are based on phase transfer catalyzed reactions will be presented with examples. These refer to the synthesis of functional polymers containing functional groups (i.e., cyclic imino ethers) sensitive both to electrophilic and nucleophilic reagents a novel method for the preparation of regular, segmented, ABA triblock and (A-B)n alternating block copolymers, and the development of a novel class of main chain thermotropic liquid-crystalline polymers, i.e., polyethers. 

The comonomer distribution can be alternated by controlling the synthesis conditions, such as the copolymerization at different reaction temperatures at which the thermally sensitive chain backbone has different conformations (extended coil or collapsed globule). In this way, hydrophilic comonomers can be incorporated into the thermally sensitive chain backbone in a more random or more segmented (protein-like) fashion. On the other hand, short segments made of hydrophobic comonomers can be inserted into a hydrophilic chain backbone by micelle polymerization. One of the most convenient ways to control and alternate the degree of amphiphilicity of a copolymer chain, i.e., the solubility difference of different comonomers in a selective solvent, is to use a thermally sensitive polymer as the chain backbone, such as poly(N-isopropylacrylamidc) (PNIPAM) and Poly(N,N-diethylacrylamide) (PDEA). In this way, the incorporation of a hydrophilic or hydrophobic comonomer into a thermally sensitive chain backbone allows us to adjust the degree of amphiphilicity by a temperature variation. 

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