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Chemistry classifies monomers by type, and two broad classes based on the type of polymer they form. By type: natural vs synthetic, e.g. glycine vs caprolactam, respectively; polar vs nonpolar, e.g. vinyl acetate vs ethylene, respectively; cyclic vs linear, e.g. ethylene oxide vs ethylene glycol, respectively; By type of polymer they form:
Monomers within a copolymer may be organized along the backbone in a variety of ways. A copolymer containing a controlled arrangement of monomers is called a sequence-controlled polymer. [44] Alternating, periodic and block copolymers are simple examples of sequence-controlled polymers.
When the polymer is formed, the C=C double bond in the monomer is replaced by a C-C single bond in the polymer repeat unit, which links by two new bonds to adjoining repeat units. In condensation polymers (see examples below), the repeat unit contains fewer atoms than the monomer or monomers from which it is formed.
Other monomer units, such as formaldehyde hydrates or simple aldehydes, are able to polymerize themselves at quite low temperatures (ca. −80 °C) to form trimers; [3] molecules consisting of 3 monomer units, which can cyclize to form ring cyclic structures, or undergo further reactions to form tetramers, [3] or 4 monomer-unit compounds. Such ...
Examples of monomer systems that undergo step-growth polymerisation. [5] The reactive functional groups are highlighted. Classes of step-growth polymers are: [6] [7] Polyester has high glass transition temperature T g and high melting point T m, good mechanical properties to about 175 °C, good resistance to solvent and chemicals. It can exist ...
Thus in the case of a functionality of f = 2 a linear polymer is formed by polymerizing (a thermoplastic). Monomers with a functionality f ≥ 3 lead to a branching point, which can lead to cross-linked polymers (a thermosetting polymer). Monofunctional monomers do not exist as such molecules lead to a chain termination. [6]
The degree of polymerization, or DP, is the number of monomeric units in a macromolecule or polymer or oligomer molecule. [1] [2] [3]For a homopolymer, there is only one type of monomeric unit and the number-average degree of polymerization is given by ¯ ¯ = ¯, where ¯ is the number-average molecular weight and is the molecular weight of the monomer unit.
Structure of an example polyphenylene dendrimer macromolecule. [14] Some examples of macromolecules are synthetic polymers (plastics, synthetic fibers, and synthetic rubber), graphene, and carbon nanotubes. Polymers may be prepared from inorganic matter as well as for instance in inorganic polymers and geopolymers.