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.
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.12345 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.
References
References
- 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
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.