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. [1]

Contents

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. [2] [3] [4] [5] [6] 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. [7]

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. [8]

Nowadays, lactic acid is used as a monomer for producing polylactic acid (PLA) which later has application as biodegradable plastic. [9] 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

Related Research Articles

<span class="mw-page-title-main">Polyurethane</span> Polymer composed of a chain of organic units joined by carbamate (urethane) links

Polyurethane refers to a class of polymers composed of organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane is produced from a wide range of starting materials. This chemical variety produces polyurethanes with different chemical structures leading to many different applications. These include rigid and flexible foams, and coatings, adhesives, electrical potting compounds, and fibers such as spandex and polyurethane laminate (PUL). Foams are the largest application accounting for 67% of all polyurethane produced in 2016.

<span class="mw-page-title-main">Petrochemical</span> Chemical product derived from petroleum

Petrochemicals are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sources such as maize, palm fruit or sugar cane.

<span class="mw-page-title-main">Epoxy</span> Type of material

Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also collectively called epoxy. The IUPAC name for an epoxide group is an oxirane.

<span class="mw-page-title-main">Thermosetting polymer</span> Polymer obtained by irreversibly hardening (curing) a resin

In materials science, a thermosetting polymer, often called a thermoset, is a polymer that is obtained by irreversibly hardening ("curing") a soft solid or viscous liquid prepolymer (resin). Curing is induced by heat or suitable radiation and may be promoted by high pressure or mixing with a catalyst. Heat is not necessarily applied externally, and is often generated by the reaction of the resin with a curing agent. Curing results in chemical reactions that create extensive cross-linking between polymer chains to produce an infusible and insoluble polymer network.

<span class="mw-page-title-main">Polyurea</span> Class of elastomers

Polyurea is a type of elastomer that is derived from the reaction product of an isocyanate component and an amine component. The isocyanate can be aromatic or aliphatic in nature. It can be monomer, polymer, or any variant reaction of isocyanates, quasi-prepolymer or a prepolymer. The prepolymer, or quasi-prepolymer, can be made of an amine-terminated polymer resin, or a hydroxyl-terminated polymer resin.

In organic chemistry, a polyol is an organic compound containing multiple hydroxyl groups. The term "polyol" can have slightly different meanings depending on whether it is used in food science or polymer chemistry. Polyols containing two, three and four hydroxyl groups are diols, triols, and tetrols, respectively.

Triethylamine is the chemical compound with the formula N(CH2CH3)3, commonly abbreviated Et3N. It is also abbreviated TEA, yet this abbreviation must be used carefully to avoid confusion with triethanolamine or tetraethylammonium, for which TEA is also a common abbreviation. It is a colourless volatile liquid with a strong fishy odor reminiscent of ammonia. Like diisopropylethylamine (Hünig's base), triethylamine is commonly employed in organic synthesis, usually as a base.

<span class="mw-page-title-main">Polylactic acid</span> Biodegradable polymer

Polylactic acid, also known as poly(lactic acid) or polylactide (PLA), is a thermoplastic polyester with backbone formula (C
3H
4O
2)
n or [–C(CH
3)HC(=O)O–]
n, formally obtained by condensation of lactic acid C(CH
3)(OH)HCOOH with loss of water. It can also be prepared by ring-opening polymerization of lactide [–C(CH
3)HC(=O)O–]
2, the cyclic dimer of the basic repeating unit.

<span class="mw-page-title-main">Polypropylene glycol</span> Chemical compound

Polypropylene glycol or polypropylene oxide is the polymer of propylene glycol. Chemically it is a polyether, and, more generally speaking, it's a polyalkylene glycol (PAG) H S Code 3907.2000. The term polypropylene glycol or PPG is reserved for polymer of low- to medium-range molar mass when the nature of the end-group, which is usually a hydroxyl group, still matters. The term "oxide" is used for high-molar-mass polymer when end-groups no longer affect polymer properties. Between 60 and 70% of propylene oxide is converted to polyether polyols by the process called alkoxylation.

<span class="mw-page-title-main">Alkyd</span> Polyester resin modified by the addition of fatty acids and other components

An alkyd is a polyester resin modified by the addition of fatty acids and other components. Alkyds are derived from polyols and organic acids including dicarboxylic acids or carboxylic acid anhydride and triglyceride oils. The term alkyd is a modification of the original name "alcid", reflecting the fact that they are derived from alcohol and organic acids. The inclusion of a fatty acid confers a tendency to form flexible coatings. Alkyds are used in paints, varnishes and in moulds for casting. They are the dominant resin or binder in most commercial oil-based coatings. Approximately 200,000 tons of alkyd resins are produced each year. The original alkyds were compounds of glycerol and phthalic acid sold under the name Glyptal. These were sold as substitutes for the darker-colored copal resins, thus creating alkyd varnishes that were much paler in colour. From these, the alkyds that are known today were developed.

Biodegradable polymers are a special class of polymer that breaks down after its intended purpose by bacterial decomposition process to result in natural byproducts such as gases (CO2, N2), water, biomass, and inorganic salts. These polymers are found both naturally and synthetically made, and largely consist of ester, amide, and ether functional groups. Their properties and breakdown mechanism are determined by their exact structure. These polymers are often synthesized by condensation reactions, ring opening polymerization, and metal catalysts. There are vast examples and applications of biodegradable polymers.

A thermoset polymer matrix is a synthetic polymer reinforcement where polymers act as binder or matrix to secure in place incorporated particulates, fibres or other reinforcements. They were first developed for structural applications, such as glass-reinforced plastic radar domes on aircraft and graphite-epoxy payload bay doors on the Space Shuttle.

Moisture-cure polyurethanes -- or polyurethane prepolymer -- are isocyanate-terminated prepolymers that are formulated to cure with ambient water. Cured PURs are segmented copolymer polyurethane-ureas exhibiting microphase-separated morphologies. One phase is derived from a typically flexible polyol that is generally referred to as the “soft phase”. Likewise the corresponding “hard phase” is born from the di- or polyisocyanates that through water reaction produce a highly crosslinked material with softening temperature well above room temperature.

Polyurethane dispersion, or PUD, is understood to be a polyurethane polymer resin dispersed in water, rather than a solvent, although some cosolvent maybe used. Its manufacture involves the synthesis of polyurethanes having carboxylic acid functionality or nonionic hydrophiles like PEG incorporated into, or pendant from, the polymer backbone. Two component polyurethane dispersions are also available.

<span class="mw-page-title-main">Dimethylolpropionic acid</span> Organic compound with one carboxyl and two hydroxyl groups

Dimethylolpropionic acid (DMPA) is a chemical compound that has the full IUPAC name of 2,2-bis(hydroxymethyl)propionic acid and is an organic compound with one carboxyl and two hydroxy groups. It has the CAS Registry Number of 4767-03-7.

Waterborne resins are sometimes called water-based resins. They are resins or polymeric resins that use water as the carrying medium as opposed to solvent or solvent-less. Resins are used in the production of coatings, adhesives, sealants, elastomers and composite materials. When the phrase waterborne resin is used, it usually describes all resins which have water as the main carrying solvent. The resin could be water-soluble, water reducible or water dispersed.

Hydrogenated MDI (H12MDI or 4,4′-diisocyanato dicyclohexylmethane) is an organic compound in the class known as isocyanates. More specifically, it is an aliphatic diisocyanate. It is a water white liquid at room temperature and is manufactured in relatively small quantities. It is also known as 4,4'-methylenedi(cyclohexyl isocyanate) or methylene bis(4-cyclohexylisocyanate) and has the formula CH2[(C6H10)NCO]2.

Blocked isocyanates are organic compounds that have their isocyanate functionality chemically blocked to control reactivity. They are the product of an isocyanate moiety and a suitable blocking agent. It may also be a polyurethane prepolymer that is NCO terminated but this functionality has also been chemically reacted with a blocking agent. They are usually used in polyurethane applications but not always. They are extensively used in industrial applications such as coatings, sealants and adhesives.

Neopentyl glycol diglycidyl ether (NPGDGE) is an organic chemical in the glycidyl ether family. It is aliphatic and a colorless liquid. It has the formula C11H20O4 and the CAS registry number of 17557-23-2. It has two oxirane groups per molecule. Its principle use is in modifying epoxy resins.

<span class="mw-page-title-main">Poly(propylene glycol) diglycidyl ether</span> Chemical compound

Poly(propylene glycol) diglycidyl ether (PPGDGE) is an organic chemical in the glycidyl ether family. There are a number of variations depending on the starting molecular weight of the polypropylene glycol. They have the formula (C3H6O)n.C6H10O3 and the IUPAC name is Poly[oxy(methyl-1,2-ethanediyl)],a-(2-oxiranylmethyl)-w-(2-oxiranylmethoxy)- A key use is as a modifier for epoxy resins as a reactive diluent and flexibilizer. It is REACH registered.

References

  1. ↑ "Prepolymer - an overview | ScienceDirect Topics". sciencedirect.com. Retrieved 2022-02-13.
  2. ↑ 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
  3. ↑ 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 . ISSN   1097-4628.
  4. ↑ Shi, Minxian; Zheng, Juanli; Huang, Zhixiong; Qin, Yan (2011-03-01). "Synthesis of Polyurethane Prepolymers and Damping Property of Polyurethane/Epoxy Composites". Advanced Science Letters. 4 (3): 740–744. doi:10.1166/asl.2011.1597.
  5. ↑ Pokharel, Pashupati; Lee, Dai Soo (2014-10-01). "High performance polyurethane nanocomposite films prepared from a masterbatch of graphene oxide in polyether polyol". Chemical Engineering Journal. 253: 356–365. doi:10.1016/j.cej.2014.05.046. ISSN   1385-8947.
  6. ↑ Wang, Lei; Shen, Yiding; Lai, Xiaojuan; Li, Zhongjin; Liu, Min (2011-05-01). "Synthesis and properties of crosslinked waterborne polyurethane". Journal of Polymer Research. 18 (3): 469–476. doi:10.1007/s10965-010-9438-9. ISSN   1572-8935. S2CID   56442579.
  7. ↑ Howarth, GA (2003-06-01). "Polyurethanes, polyurethane dispersions and polyureas: Past, present and future". Surface Coatings International Part B: Coatings Transactions. 86 (2): 111–118. doi:10.1007/BF02699621. ISSN   1476-4865. S2CID   93574741.
  8. ↑ Vacaras, Sergiu; Baciut, Mihaela; Lucaciu, Ondine; Dinu, Cristian; Baciut, Grigore; Crisan, Liana; Hedesiu, Mihaela; Crisan, Bogdan; Onisor, Florin; Armencea, Gabriel; Mitre, Ileana (November 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 (published 2019-07-24). 51 (4): 570–588. doi:10.1080/03602532.2019.1642911. ISSN   1097-9883. PMID   31296117. S2CID   195893132.
  9. ↑ DeStefano, Vincent; Khan, Salaar; Tabada, Alonzo (2020-01-01). "Applications of PLA in modern medicine". Engineered Regeneration. 1: 76–87. doi: 10.1016/j.engreg.2020.08.002 . ISSN   2666-1381. PMC   7474829 .
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