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PHA polymers are thermoplastic, can be processed on conventional processing equipment, and are, depending on their composition, ductile and more or less elastic. [15] They differ in their properties according to their chemical composition (homo-or copolyester, contained hydroxy fatty acids).
Crystallization of polymers is a process associated with partial alignment of their molecular chains. These chains fold together and form ordered regions called lamellae, which compose larger spheroidal structures named spherulites. [1] [2] Polymers can crystallize upon cooling from melting, mechanical stretching or solvent evaporation ...
In 1996, Monsanto (who sold PHB as a copolymer with PHV) bought all patents for making the polymer from ICI/Zeneca including the trademark "Biopol". [5] However, Monsanto's rights to Biopol were sold to the American company Metabolix in 2001 and Monsanto's fermenters producing PHB from bacteria were closed down at the start of 2004.
Crystal structure of a first-generation polyphenylene dendrimer reported by Müllen et al [5] A first-generation "cyanostar" dendrimer and its STM image [6]. The first dendrimers were made by divergent synthesis approaches by Fritz Vögtle in 1978, [7] R.G. Denkewalter at Allied Corporation in 1981, [8] [9] Donald Tomalia at Dow Chemical in 1983 [10] and in 1985, [11] [12] and by George R ...
A more efficient analysis of copolymer molecular mass and composition is possible using GPC combined with a triple-detection system comprising multi-angle light scattering, UV absorption and differential refractometry, if the copolymer is composed of two base polymers that provide different responses to UV and/or refractive index.
Molecular structure of Kevlar Molecular structure of the LCP Vectran [5]. Liquid crystallinity in polymers may occur either by dissolving a polymer in a solvent (lyotropic liquid-crystal polymers) or by heating a polymer above its glass or melting transition point (thermotropic liquid-crystal polymers). [6]
The other strategy is to take advantage of the so-called "host-guest" assembly. In this case, the monomer is designed to link to a "host" molecule, while the host molecule is in charge of forming the ordered network. The host molecule stays intact during the polymerization. Such strategies simplify the synthesis of monomer. [16]
The newly formed nucleophile will then attack the atom X in another monomer molecule, and the sequence would repeat until the polymer is formed. [20] Anionic ring-opening polymerizations (AROP) involve nucleophilic reagents as initiators. Monomers with a three-member ring structure - such as epoxides, aziridines, and episulfides - undergo ...