Single-step polymerization polyesters

Because of their uncomplicated syntheses, aromatic polyesters are the most widely studied class of highly branched polymers. The polyesters were prepared in a single step by condensation polymerization from aliphatic dihydroxy monoacids or by stepwise syntheses. 

In an attempt to apply this mechanism to a polyester formation and to investigate the single steps involved on a molecular basis one can for instance start with the CALB-phosphonate complex 1LBS [6] as the initial structure, as it is structurally close to the intermediate structure of an acylated Ser10s that certainly has to be passed through during an enzymatic polymerization process. In accordance with the accepted mechanism for serine hydrolases the enzymatic process consists of two mechanistically important steps. These are, in the case of for instance, a potential enzymatic esterification of adipic acid with 1,6-hexanediol ... 

Terminal-functionalized polymers such as macromonomers and telechelics are very important as prepolymers for the construction of functional materials. A single-step functionalization of the polymer terminal was achieved via lipase catalysis. Alcohols were able to initiate the ROP of lactones by a lipase catalyst. The lipase CA-catalyzed polymerization of DDL in the presence of 2-hydroxyethyl methacrylate, produced the methacryl-type polyester macromonomer, in which... 

Single-step synthesis of polyester macromonomers was achieved by lipase-catalyzed polymerization of lactones in the presence of vinyl esters acting as terminator ( terminator method ) (187,188). A methacryl-type poly(DDL) macromonomer was obtained using vinyl methacrylate (12.5 or 15 mol% based on DDL) and lipase PF as terminator and catalyst, respectively. By the addition of divinyl sebacate, the telechelic polyester having a carboxylic acid group at both ends was synthesized. 

AH step-growth polymerizations fall into two groups depending on the type of monomer(s) employed. The first one implies the use of at least two bifunctional and/or polyfunctional monomers, each one possessing a single type of active group. The monomers involved in this type of reaction are often represented as A-A and B-B, where A and B are the different reactive groups. An example of this reaction is the formation of polyesters from diols and diacids. 

In recent years, research on polymer-metal nanoeomposites and their properties has attracted considerable attention due to their potential applications in catalysts, electronics and non-linear optics. Polymer-metal composites consist of polymer and metal particles on the surface or interior (core) of the polymer matrix." They exhibit various properties depending on the type of metal and polymer, especially the former. These composites not only combine the advantageous properties of polymers and metals but also exhibit many new characteristics that single-phase materials do not have. Precious metals such as silver and gold have been studied most extensively among polymer-metal nanoeomposites." Many polymer-metal nanoeomposites have been prepared in one step with y-irradiation in an aqueous solution. Choi et al. reported on polyester-silver and nylon-silver nanoeomposites prepared by the dispersion of silver nanoparticles, which were prepared by y-irradiation, on to polyester and nylon during condensation polymerization to obtain antibacterial fibers." It was found that the silver nanoparticles aggregated in the polyester matrix, whereas the silver nanoparticles dramatically dispersed in the nylon matrix. 

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