Oligomer

In chemistry, an oligomer is a molecule derived from small-sized molecules and monomers, consisting of a few repeating units. The term oligomer is derived from the Greek words "oligo," meaning "few," and "mer," meaning "parts." Some biologically important oligomers are macromolecules such as proteins or nucleic acids; hemoglobin protein tetramer is an example of this. An oligomer of amino acids is called an oligopeptide or peptide. An oligosaccharide is an oligomer of monosaccharides (simple sugars). An oligonucleotide is a short, single-stranded fragment of nucleic acid such as DNA or RNA, or similar fragments of nucleic acid analogues such as peptide nucleic acid and morpholinos. The units of an oligomer may be linked by covalent bonds or weaker forces such as hydrogen bonds, which can be a product of bond rearrangement or condensation reactions. Oligomers comprise sub-units with a repeating structure that span a chemical gap region between small molecules and higher molecular weight polymers. This resulting class of material presents new aspects that are not found in the conventional classifications of either category and encompasses various research opportunities.

Difference Between Oligomer and Polymer

The fundamental difference between an oligomer and a polymer is that an oligomer is formed when a few monomers undergo polymerization, whereas a polymer is formed when a large number of monomers undergo polymerization. Polymers are large macromolecules containing many repeating units and are referred to as monomers. Monomers undergo a process called polymerization to create a polymer material. An oligomer is also a type of polymer, but by its nature contains fewer repeating units. Therefore, these two materials differ fundamentally depending on the number of monomers that have undergone the formation process. Additionally, the difference between oligomer and polymer can be defined based on chemical properties. Compared to oligomers, polymers have higher molecular masses and densities. If the number of monomers is two, a dimer is formed; when three monomers combine, a trimer is produced; four monomers form a tetramer. Consequently, oligomers can be named according to the number of monomers. There are two main forms of oligomers: homo-oligomers and hetero-oligomers. Homo-oligomers are formed when monomers of the same type undergo oligomerization, while hetero-oligomers are formed when monomers of different types undergo oligomerization. As for similarities, both oligomers and polymers consist of monomers. Therefore, both are polymeric structures and are based on chemical bonds between monomers. The combination of oligomers and catalytically active molecular species is an effective way to improve catalyst activity and selectivity. Since catalytic processes are often governed by the orientation of the catalyst and substrate, control over the nano-environment provided by discrete oligomers is quite beneficial for enhancing catalyst performance.

Applications

Many oils, such as liquid paraffin, are oligomeric. Plasticizers are typically oligomeric esters used to soften thermoplastics such as PVC. They can be produced by linking from monomers or by separation from higher fractions of crude oil. Polybutene is an oligomeric oil used in the manufacture of putty. The molecular recognition of oligomers is a research topic that draws significant inspiration from biological systems such as oligosaccharides. Elucidating and optimizing molecular recognition is a challenging effort, and the knowledge accumulated from saccharide and peptide-based recognition and related methods will be quite valuable at this point. In addition to the recognition of abiotic oligomers with biological systems, their role in small molecule substrate binding has tremendous potential in affecting catalytic reactions with superior selectivity. The significant impact that oligomer structure and sequence can have on catalytic properties has been demonstrated in recent research, and the development of more complex reactions and multifunctional oligomer designs is expected in the future. Sequence-defined oligomers are also estimated to be valuable in information storage, which requires well-defined oligomers to link molecular structure with information storage at ultra-high densities. When appropriately selected, oligomers provide superior performance in a wide range of applications such as adhesion, chemical resistance, substrate wetting, and resistance to weather conditions.   Sources https://onlinelibrary.wiley.com/doi/10.1002/pol.20200862 https://www.differencebetween.com/difference-between-oligomer-and-polymer/