Synthesis and Characterization of Novel Thermoplastic Polyester Containing Blocks of Poly[(R)-3-hydroxyoctanoate] and Poly[(R)-3-hydroxybutyrate]

Abstract

Novel block copolyester containing biocompatible and biodegradable biopolyester blocks was prepared by polycondensation of telechelic hydroxylated poly[(R)-3-hydroxyoctanoate] (PHO-diol) and telechelic hydroxylated poly[(R)-3-hydroxybutyrate] (PHB-diol) with terephthaloyl chloride (TeCl). Reaction of PHO-diol (M p of 2100), PHB-diol (Mp of 3200), and TeCl at a ratio of 1.3:1:2.1 gave the block co-polyester PHOHBTe in 86% yield with a molecular weight Mp of 7200 (GPC). The chemical structure of the copolyester was confirmed by 1 H-, 13 C-, and COSY-NMR and IR spectra. On average, 2 PHO-diol, 1 PHBdiol, and 2 TeCl were incorporated in each molecule of the block copolyester PHOHBTe. For comparison, polyester PHOTe with a M p of 7100 (GPC) was prepared in 81% yield by reaction of PHO-diol and terephthaloyl chloride at a molar ratio of 1:1.2. NMR analysis suggested that PHOTe contains 3 PHO and 3 Te units on average. While PHOTe containing no PHB block is soft-sticky, PHOHBTe containing both soft PHO and hard PHB blocks showed good thermoplastic properties with T m of 129 and 140 °C and a Tg of -41 °C. Thus, for the first time, block copolyester containing PHO and PHB blocks has been prepared and demonstrated to be thermoplastic.

Polyhydroxyalkanoates: opening doors for a sustainable future

“…The presence of large crystals in PHB causes poor mechanical properties, which renders PHB unsuitable for various uses, including packaging film and biomedical applications such as heart valves and other vascular applications or controlled drug delivery systems. 6 In addition, the melting temperature (T m ) of PHB is similar to its thermal decomposition temperature. Its poor thermal stability renders PHB incompatible to conventional thermal processing techniques and susceptible to thermal degradation.…”

Synthetic routes to degradable copolymers deriving from the biosynthesized polyhydroxyalkanoates: A mini review

“…For example, a PHO-diol and a PHB-diol were chosen to produce block copolyesters with terephthaloyl chloride ( Figure 3), where a polycondensation reaction occurred between COCl and OH groups. Since water can inhibit the polymerization by reacting with TeCl to give the corresponding acid, the reaction must be carried out under an anhydrous condition and a nitrogen atmosphere [70]. …”

Particular thermal properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) oligomers

“…However, the commercial PHBV has some disadvantages including brittleness, high melting temperature, bad thermal stability, high crystallinity, and so on [7][8][9][10][11][12][13][14]. Various solutions have been used to solve the above problems, including physical blending [5][6][7][8][9][13][14][15], surface modification [16], grafting [17] and cross-linking copolymerization [18], block copolymerization [19][20][21][22][23][24][25][26][27][28] and biosynthesis [29]. Block copolymerization can be an effective way to modify PHBV because block copolymers has the potential Electronic supplementary material The online version of this article (doi:10.1007/s10965-011-9756-6) contains supplementary material, which is available to authorized users.…”