Functionalized polyesters polymerization

Parrish B, Quansah JK, Emrick T (2002) Functional polyesters prepared by polymerization of a-allyl(valerolactone) and its copolymerization with e-caprolactone and 5-valerolactone. J Polym Sci A Polym Chem 40 1983-1990... 

A second key factor in the lipase-catalyzed ROP of CL is the ability to controi the nature of the endgroups. This has important consequences in preparation of a, (o-functionalized polyesters, which are currently being explored in a variety of applications [111,112]. A systematic study by Heise and coworkers on the initiating efficiency of different initiators (1-3 in Fig. 5) in the CALB-catalyzed ROP of CL showed that three polymeric products were formed cyclic species, water-initiated... 

Other authors have described the lipase-catalyzed chemoselective acylation of alcohols in the presence of phenolic moities [14], the protease-catalyzed acylation of the 17-amino moiety of an estradiol derivative [15], the chemoselectivity in the aminolysis reaction of methyl acrylate (amide formation vs the favored Michael addition) catalyzed by Candida antarctica lipase (Novozym 435) [16], and the lipase preference for the O-esterification in the presence of thiol moieties, as, for instance, in 2-mercaptoethanol and dithiotreitol [17]. This last finding was recently exploited for the synthesis of thiol end-functionalized polyesters by enzymatic polymerization of e-caprolactone initiated by 2-mercaptoethanol (Figure 6.2)... 

Emulsion Polymerization in the Presence of functionalized Polyesters - Preparation of Latex... 

For polyester polymerization, it is necessary to have two functional groups on each monomer and to mix stoichiometric amounts of the reactants. 

Functional polyesters have been synthesized by utilizing characteristic catalysis of lipase. An optically pure polyester was synthesized by PPL-catalyzed enantioselective polymerization of bis(2,2,2-trichlo-roethyl) trans-3,4-epoxyadipate with 1,4-butanediol in diethyl ether (Scheme 26).212 The molar ratio of the diester to the diol was adjusted to 2 1 to produce the (-)-polymer with an enantiomeric purity of >96%. From end group analysis, the molecular weight was calculated to be 5.3 x 103. 

For instance an epoxy-functionalized polyester from the suberin monomer cis-9,10-epoxy-18-hydroxyoctadecanoic acid (see also Chapter 1) was synthesized by Olsson et al. [30]. The lipase-catalyzed polymerization was performed in toluene in the presence of 4A molecular sieves for 68 h and high molecular weight of epoxy-functionalized polyester was obtained (M , =20000 M JMn =2.2). 

Poly bd . [Atochem N. Am. Atochem UK] Butadiene polymer functional liq. polymers for elec, sqiplics., polyurethane and polyester polymerization, ester or ether derivatives. 

Scheme 2.8 Synthetic route to OH-functionalized polyesters by radical polymerization [43].

Functional polyesters were synthesized through the specific catalysis of lipase, and their properties and functions were evaluated. Enantio- and regioselec-tive polycondensations produced chiral and sugar-containing polyesters, respectively [20,23]. Using lipase catalyst reactive polyesters were conveniently obtained, some of which were crosslinked to biodegradable coatings. Recently, polyester-based biomaterials have been developed by lipase-catalyzed polymerizations. 

In the early distinction by Carrothers (1) between condensation and addition polymers, polyesters were uniformly considered as examples of the former. However it was soon appreciated that a large family of polymers could be made which were functionally "polyesters" but did not fall into the synthesis based definition of condensation polymers. This family of polymers are usually prepared by ionic routes, generally a ring opening polymerization, and are structurally different from the condensation polyesters by having a chain sense i.e. the crystalline chain conformation possesses an intrinsic dipole moment. Accordingly, a structurally based definition of polyesters in terms of "polar and non-polar" crystalline conformations will be used in this report. The non-polar molecules considered will be aromatic polyesters and the polar molecules will be polyalkanoates. 

Propen-3-ol and 3-methyl-3-butenol have been used to introduce an unsaturation in P-substituted p-lactones according to the aspartic route (Figure 2). These new malolactonic esters have been polymerized or copolymerized with benzyl malolactonate leading to high molecular weight functional polyesters. 

Figure II. PEG-grafting by post-polymerization click chemistry of acetylene functionalized polyesters...

In summary, aliphatic polyesters, already an important class of synthetic degradable polymeric biomaterials, have been taken to unprecedented levels of synthetic diversity and tailoring through the efforts of many research groups in the U.S. and abroad. Some of these have been described in this brief review, with a focus on pendent or graft functionality by polymerization of functionalized lactones, and post-polymerization modification. Future efforts in this area must attempt to connect these synthetic advances to specific applications, through the collaborative efforts of experts in the chemistry, biology, and clinical use of synthetic polymer materials. 

Besides polymeries and benzoates, there are several other important classes of specialty plasticizers. Citric acid esters form another such class, as well as those of adipates, trimellitates, specialty phthalates, epoxidized soybean oil, and phosphates. All of these add value to vinyl compositions that general pmpose plasticizers cannot. The focus for this chapter is on benzoates, polymeries and citrates. Not every benzoate, polyester polymeric plasticizer, and citrate ester will be catalogued in this chapter. An understanding of these plasticizers, how they function, and how to use them to advantage in formulation of flexible vinyl compositions is the desired outcome of the investment in reading time. 

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