Nuclear magnetic resonance studies on unusual bacterial copolyesters of 3-hydroxybutyrate and 4-hydroxybutyrate

Abstract

Unusual copolyesters of 3-hydroxybutyrate (3HB) and 4-hydroxybutyrate (4HB) with a range of compositions varying from 0 to 49 mol % 4HB were produced by Alcaligenes eutrophus in a nitrogen-free culture solution of 4-hydroxybutyric or 4-chlorobutyric acid. The copolyesters were characterized by solution NMR, solid-state 13C NMR, and differential scanning calorimetry. The compositions of the copolyesters were determined by 500-MHz NMR and two-dimensional homonuclear ( ) correlated spectroscopy. The copolymers were shown to have a random sequence distribution of 3HB and 4HB units by analysis of the 125-MHz 13C NMR spectra. The solid-state 13C NMR spectra and thermal analyses showed that the crystallinity of copolyester decreases with an increase in the fraction of 4HB units.

Poly(3-hydroxybutyrate)/multi-walled carbon nanotubes nanocomposites: preparation and characterizations

“…Figure 3(A) shows that carbon peaks appear in four places for the neat PHB (4: δ = 19.96 ppm; 3: δ = 67.46 ppm; 2: δ = 40.96 ppm; and 1: δ = 170.06 ppm). This result was similar to that reported by Doi et al [37] in which the 3-hydroxybutyrate and 4-hydroxybutyrate co-polyester was studied. A comparison of signals of PHB and PHB-g-AA, Figure 3(A) and 3(B), reveals that three extra peaks (C β : δ = 35.63 ppm; C α : δ = 42.19 ppm; and a: δ = 175.05 ppm) could be observed in the latter.…”

Performance of an acrylic-acid-grafted poly(3-hydroxybutyric acid)/starch bio-blend: characterization and physical properties

“…5A that carbon peaks occur in four places for PHB (C 4 = 19.96 ppm; C 3 = 67.46 ppm; C 2 = 40.96 ppm; C 1 = 170.06 ppm). This result of the 13 C-NMR spectrum of PHB was similar to that reported by Doi et al [28], in which the 3-hydroxybutyrate and 4-hydroxybutyrate co-polyester was studied. For the PHB/starch blend, the 13 C-NMR spectrum (Fig.…”

Bacterial polyhydroxyalkanoates-eco-friendly next generation plastic: Production, biocompatibility, biodegradation, physical properties and applications

“…In the presence of propionic or valeric acid, A. eutrophus (among other bacteria) also produces copolymers of 3-hydroxybutyric acid and 3-hydroxyvaleric acid (HV) P(HB-HV) (90). Copolymers of 3-hydroxybutyric acid with 4-hydroxybutyric acid can also be produced in A. eutrophus (91). The bacteria Rhodospirillum rubrum (59), Rhodocyclus gelatinosus (60) and Rhodococcus sp (59) produced terpolyesters consisting of 3HA units of C 4 , C 5 and C 6 from hexanoate.…”

“…Within the cell, PHAs exist as mobile liquid, amorphous (26,83,87,89,91) and water-insoluble inclusions (43,22). However, after extraction from the cell with organic solvents, PHAs become highly crystalline and show material properties that are similar to conventional commodity plastics such as polypropylene, polyethylene and polystyrene (Table 1) (22,(215)(216)(217).…”