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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 ...
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 three blocks, each of a different chemical species (e.g., A, B, and C) are termed triblock terpolymers.
Advanced polymerization techniques have been established for the preparation of covalent copolymers, however supramolecular copolymers are still in its infancy and is slowly progressing. In recent years, all plausible category of supramolecular copolymers such as random, alternating, block, blocky, or periodic has been demonstrated in a broad ...
In addition, block copolymers can exist as many types, including triblock (A-B-A), alternating block (A-B-A-B-A-B), etc. Of these three types, block and gradient copolymers are commonly synthesized through living polymerizations, due to the ease of control living polymerization provides.
If enough of the block copolymer molecules that make up a polymersome are cross-linked, the polymersome can be made into a transportable powder. [2] Polymersomes can be used to make an artificial cell if hemoglobin and other components are added. [13] [14] The first artificial cell was made by Thomas Chang. [15]
Block copolymers can be made this way. RDRP allows for control of molecular weight and dispersity. However, this is very difficult to achieve and instead a pseudo-living polymerization occurs with only partial control of molecular weight and dispersity. [15] ATRP and RAFT are the main types of complete radical polymerization.
The stiff homopolymer PVAc, but mostly the softer copolymer, a combination of vinyl acetate and ethylene, vinyl acetate ethylene (VAE), is also used in paper coatings, paint and other industrial coatings, as a binder in nonwovens in glass fibers, sanitary napkins, filter paper and in textile finishing.
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 ...