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block copolymer: A copolymer that is a block polymer. In the constituent macromolecules of a block copolymer , adjacent blocks are constitutionally different, i.e. adjacent blocks comprise constitutional unit derived from different species of monomer or from the same species of monomer but with a different composition or sequence distribution ...
It can be used for example to synthesize block copolymers. By definition, a telechelic polymer is a di-end-functional polymer where both ends possess the same functionality. [2] Where the chain-ends of the polymer are not of the same functionality they are termed di-end-functional polymers.
In the case of triblock copolymers the membrane is a monolayer that mimics a bilayer, the central block filling the role of the two facing hydrophobic blocks of a bilayer. [7] In general they can be prepared by the methods used in the preparation of liposomes. Film rehydration, direct injection method or dissolution method.
Living polymerization is a popular method for synthesizing block copolymers since the polymer can be synthesized in stages, each stage containing a different monomer. Additional advantages are predetermined molar mass and control over end-groups .
[42] [43] For example, the chain-growth copolymer of vinyl chloride and vinyl acetate is random. [39] Block copolymers have long sequences of different monomer units. [39] [40] Polymers with two or three blocks of two distinct chemical species (e.g., A and B) are called diblock copolymers and triblock copolymers, respectively. Polymers with ...
TPU is a block copolymer consisting of alternating sequences of hard and soft segments or domains formed by the reaction of (1) diisocyanates with short-chain diols (so-called chain extenders) and (2) diisocyanates with long-chain diols. By varying the ratio, structure and/or molecular weight of the reaction compounds, an enormous variety of ...
Polyether block amide or PEBA is a thermoplastic elastomer (TPE). It is known under the tradename of PEBAX® ( Arkema ) and VESTAMID® E ( Evonik Industries ). It is a block copolymer obtained by polycondensation of a carboxylic acid polyamide ( PA6 , PA11 , PA12 ) with an alcohol termination polyether ( Polytetramethylene glycol PTMG), PEG ).
Synthesis of block copolymers is one of the most important applications of living polymerization as it offers the best control over structure. The nucleophilicity of the resulting carbanion will govern the order of monomer addition, as the monomer forming the less nucleophilic propagating species may inhibit the addition of the more ...