Prepolymer

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]}

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]

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.

• Synthetic resin
• Resin