Telechelic Polyesters Research Articles

Segmented block copolymers based on poly(butylene terephthalate) and telechelic polyesters and polyamides of dimerized fatty acids

Segmented block copolymers (SBCs) based on poly(butylene terephthalate) (PBT) and telechelics based on dimerized fatty acids have been synthesized in the melt. The dimerized fatty acids were coupled with diols or diamines to synthesize polyesters and polyamides of low molar mass. With these telechelic polyesters and polyamides we studied the influence of the different types of blocks and the block length on thermal transitions with differential scanning calorimetry and dynamic mechanical thermal analysis. The melting behaviour was compared to an SBC based on a dimerized fatty acid ( M n = 565 g mol −1) and PBT. Neither the compositions of the SBCs nor the block lengths of the telechelic polyesters and polyamides seemed to be of influence on the melting behaviour. The glass transition temperatures ( T g values) of the SBCs based on the telechelic polyester decreased, while the T g of the SBC based on the primary polyamide increased. Higher reaction temperatures and longer reaction times increased T g, owing to transesterification reactions in the melt.

Living polymerization and selective end functionalization of iε-caprolactone using zinc alkoxides as initiators

It is found that zinc alkoxides are effective initiators for the ring-opening polymerization of e-caprolactone under very mild conditions. Polymerization is living and the molecular weiht distribution is narrow. 1 H NMR data support the formation of asymmetric telechelic polyesters.

Aluminium alkoxides: A family of versatile initiators for the ring‐opening polymerization of lactones and lactides

AbstractAluminium alkoxides, such as Al(OiPr)3 or Et3‐pAl(O (CH2)2X)p with 1≤p≤3, are very effective in initiating the polymerization of lactones, e.g.ϵ ‐ca‐prolactone and δ ‐valerolactone, and lactides (D,L‐ or L,L‐ isomers). The ring‐opening polymerization proceeds through a “coordination‐insertion” mechanism that involves the selective rupture of the acyl‐oxygen bond of the monomer and its insertion into an Al‐O bond of the initiator. Polymerization is typically “living” and allows block copolyesters with perfectly controlled molecular weight and composition to be prepared. Aluminium alkoxides carrying functional alkoxy groups (X = ‐Br, ‐CH2‐NEt2, ‐CH2‐CH=CH2, ‐CH2‐OC(O)‐C(Me)=CH2…) provide asymmetric telechelic polyesters (end‐groups being ‐X and ‐OH, respectively) and very interesting polyester macromonomers. Coupling the asymmetric telechelic chains via the hydroxyl end‐group ‐ or better its A1 alkoxide precursor ‐ is a straightforward way to the symmetric telechelic polymer bearing the X functional group.

Macromolecular engineering of polylactones and polylactides

Aluminum alkoxides carrying functional alkoxy groups are effective initiators for theɛ-caprolactone polymerization in toluene and tetrahydrofuran. The coordination-insertion type of polymerization is living and yields exclusively linear polyesters of a predictable molecular weight with a narrow molecular weight distribution within the period of time required for the total monomer conversion. The functional group associated to the active alkoxy group of the initiator is selectively attached to one chain-end, and the second end-group is systematically a hydroxyl function resulting from the hydrolysis of the living growing site. Asymmetric telechelic polyesters are thus obtained in a perfectly controlled way, including macromonomers. Beside (meth)acrylic double bond, the functional end-group derived from the initiator can be, for instance, an unsaturation, a halogen and a tert-amine. Coupling the asymmetric telechelic polymer via the OH end-group (or the precursor Al alkoxide end-group) is a direct way to the related symmetric telechelic of a twofold increased molecular weight.