What is polymer???? poly meaning „many“ and meres meaning „parts“ is a large molecule (macromolecule) built up by the repetition of small chemical units Is a long molecule which contains a chain of atoms held together by covalent bonding Commonly people usually know polymer as plastic
Basic Concept [ ] repeating unit The structure of the repeating unit is not exactly the same as that of the monomer even though both possess identical atoms occupying The conversion of the similar relative monomer to the positions polymer involves a The residue from the rearrangement of monomer employed in electrons. the preparation of a polymer is referred to as the structural unitContains a double bond ... Opening so For homopolymer,that literally thousands of styrene repeating unit =molecules become linked together structural unitA monomer: any molecule that can beconverted to a polymer by combiningwith other molecules of the same ordifferent type
Polymer Architecture Based of their architecture polimer can be classified as linier, branched and cross-link
Linear Polymer Linear polymer have the structural units are arranged in a linear sequence
Branched Polymer Branched polymer have a branch in main chain. Branched polymer may have short and long branches Branched polymers include comblike and star polymers If the branch is extensive may lead to dendritic structure
Cross-linked polymers Crosslinked polymers are formed by polymer chains linked together forming a three dimensional network. They are characterized by crosslinking density
Chain Growth Polymerization In chain growth polymerization, monomers can only join active chain. Monomers usually contain carbon- carbon double bond.. The activity of the chains is generated by either a catalyst or an initiator.. Chain growth polymerization can be split into a few groups
Coordination Polymerization Coordination polymerization are carried out on a suitble catalyst and proceed by an insertion mechanism, in which the monomer units are inserted between the catalytic site and the growing polymer chain...
Free Radical Polymerization in free radical polymerization, the active center is a free radical (very reactive species that contain an unpaired electron) created from an initiator and polymerization proceed by addition of monomer units to the active end of the growing polymer chain that in the course of polymerization separates from the bound initiator fragment.
Step Growth Polymerization Condensation polymers were those polymers that were formed from polyfunctional monomers by the various condensation reactions of organic chemistry with the elimination of some small molecule such as water.
Step growth Polymerization All step growth polymerization fall into two groups depending on the type of monomer employed. The first one implies the use of at least two bifunctional and/or polyfunctional monomers, each one possesing a single type of active group. The monomers involved in this type of reaction are often represented as A-A and B-B, where A and B are the different reactive groups
Step Growth Polymerization the second type of step growth polymerization involves the use of monomers with different functional groups in the same molecule, are often represented as A-B type monomers.