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Prepolymer

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In polymer chemistry, the term prepolymer or pre-polymer, refers to a monomer or system of monomers that have been reacted to an intermediate-molecular mass state. This material is capable of further polymerization by reactive groups to a fully cured, high-molecular-mass state. As such, mixtures of reactive polymers with un-reacted monomers may also be referred to as pre-polymers. The term "pre-polymer" and "polymer precursor" may be interchanged.[ citation needed ]

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Polyurethane and polyurea prepolymers

In polyurethane chemistry, prepolymers and oligomers are frequently produced and then further formulated into CASE applications - Coatings, Adhesives, Sealants, and Elastomers. An isocyanate (usually a diisocyanate) is reacted with a polyol. All types of polyol may in theory be used to produce polyurethane prepolymers. [1] [2] [3] [4] [5] These then find use in CASE applications. When polyurethane dispersions are synthesized, a prepolymer is first produced usually modified with DMPA. In polyurea prepolymer production, instead of a polyol a polyamine is used. [6]

Lactic acid as a polymer precursor

Two molecules of lactic acid can be dehydrated to the cyclic molecule lactide, a lactone. A variety of catalysts can polymerise lactide to either heterotactic or syndiotactic polylactide, which as biodegradable polyesters with valuable (inter alia) medical properties are currently attracting much attention. [7]

Nowadays, lactic acid is used as a monomer for producing polylactic acid (PLA) which later has application as biodegradable plastic. [8] This kind of plastic is a good option for substituting conventional plastic produced from petrochemicals because of low emission of carbon dioxide. The commonly used process in producing lactic acid is via fermentation; to obtain the polylactic acid, the polymerization process follows.

See also

References

  1. ↑ Howarth G.A "Synthesis of a legislation compliant corrosion protection coating system based on urethane, oxazolidine and waterborne epoxy technology" page 40 Master of Science Thesis April 1997 Imperial College London
  2. ↑ Harani, H.; Fellahi, S.; Bakar, M. (1998). "Toughening of epoxy resin using synthesized polyurethane prepolymer based on hydroxyl-terminated polyesters". Journal of Applied Polymer Science. 70 (13): 2603–2618. doi: 10.1002/(SICI)1097-4628(19981226)70:13<2603::AID-APP6>3.0.CO;2-4 .
  3. ↑ Shi, Minxian; Zheng, Juanli; Huang, Zhixiong; Qin, Yan (March 2011). "Synthesis of Polyurethane Prepolymers and Damping Property of Polyurethane/Epoxy Composites". Advanced Science Letters. 4 (3): 740–744. doi:10.1166/asl.2011.1597.
  4. ↑ Pokharel, Pashupati; Lee, Dai Soo (October 2014). "High performance polyurethane nanocomposite films prepared from a masterbatch of graphene oxide in polyether polyol". Chemical Engineering Journal. 253: 356–365. Bibcode:2014ChEnJ.253..356P. doi:10.1016/j.cej.2014.05.046.
  5. ↑ Wang, Lei; Shen, Yiding; Lai, Xiaojuan; Li, Zhongjin; Liu, Min (May 2011). "Synthesis and properties of crosslinked waterborne polyurethane". Journal of Polymer Research. 18 (3): 469–476. doi:10.1007/s10965-010-9438-9.
  6. ↑ Howarth, Ga (June 2003). "Polyurethanes, polyurethane dispersions and polyureas: Past, present and future". Surface Coatings International Part B: Coatings Transactions. 86 (2): 111–118. doi:10.1007/BF02699621.
  7. ↑ Vacaras, Sergiu; Baciut, Mihaela; Lucaciu, Ondine; Dinu, Cristian; Baciut, Grigore; Crisan, Liana; Hedesiu, Mihaela; Crisan, Bogdan; Onisor, Florin; Armencea, Gabriel; Mitre, Ileana; Barbur, Ioan; Kretschmer, Winfried; Bran, Simion (2 October 2019). "Understanding the basis of medical use of poly-lactide-based resorbable polymers and composites – a review of the clinical and metabolic impact". Drug Metabolism Reviews. 51 (4): 570–588. doi:10.1080/03602532.2019.1642911. PMID   31296117.
  8. ↑ DeStefano, Vincent; Khan, Salaar; Tabada, Alonzo (2020). "Applications of PLA in modern medicine". Engineered Regeneration. 1: 76–87. doi: 10.1016/j.engreg.2020.08.002 . PMC   7474829 . PMID   38620328.
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