Question

What is a Block Polymer?

Answer 1

Hint: A copolymer is a polymer made up of more than one monomer type. Copolymerization is the process of polymerizing monomers into copolymers. Bipolymers are copolymers formed by the copolymerization of two monomer types. Terpolymers and quaterpolymers are polymers made up of three and four monomers, respectively.

Complete answer:
Block copolymers are made up of two or more homopolymer subunits that are joined together by covalent connections. A junction block, a non-repeating intermediate component, may be required to join the homopolymer subunits. Triblock copolymers have three different blocks, whereas diblock copolymers have two separate blocks. A block is a section of a macromolecule that consists of several units and contains at least one characteristic that is not present in neighbouring areas. A possible sequence of repeat units A and B in a triblock copolymer might be ~A-A-A-A-A-A-A-B-B-B-B-B-B-B-A-A-A-A-A~.
Block copolymers are formed up of monomer blocks that have been polymerized. Polystyrene-b-poly(methyl methacrylate), also known as PS-b-PMMA (b = block), is typically produced by first polymerizing styrene and then polymerization methyl methacrylate from the polystyrene chains' reactive end. Because it comprises two distinct chemical blocks, this polymer is called a "diblock copolymer." It is possible to construct triblocks and multiblocks. Live polymerization methods such as atom transfer free radical polymerization, reversible addition fragmentation chain transfer, ring-opening metathesis polymerization (ROMP), and living cationic or living anionic polymerizations are used to make diblock copolymers.
Under the reaction conditions for the synthesis of block copolymers, both reactivity ratios must be substantially greater than unity, such that the terminal monomer unit of a growing chain tends to add a comparable unit most of the time. A copolymer's "blockiness" is a measure of comonomer adjacency vs. their statistical distribution.

Note:
Many, if not all, synthetic polymers are copolymers, comprising between 1 and 20% of a minority monomer. Blockiness is undesirable in these situations. As a quantitative measure of blockiness or departure from random monomer composition, a block index has been proposed.