## 3 Results and Discussion
### Commoner and Composition Sequence Distribution Analysis  
The molar HV content in PHBV was determined by \({}^{1}\)H-NMR spectroscopy (Table 1, Supplementary Material Figure S3). The molar HV content ranged between 0.16 and 0.24 which was in good agreement with those obtained by GC-MS (HV molar content 0.17 to 0.25, Table 1). To determine whether the PHBV samples were random or co-block-polymer a sequence distribution (CSD) was determined by \({}^{13}\)C-NMR spectroscopy (Figure 2) based on diad and triad sequence analysis [8]. The carbon resonances of HB and HV were split into multiplets due to diad and/or HV-centered triad comonomer sequences and assignments [8; 29] (Figure 2b, and Supplementary Material Table S1). The carbonyl area was composed of four peaks at \(\delta\) = 169.56, 169.38, 169.35, and 169.18 ppm attributed to different diad sequences of 3 HV*3 HV, 3 HB*3 HV, 3 HV*3 HB, and 3 HB*3 HB, respectively. The resonance of the 3 HV side-chain methylene C (V4 and V2) was split into four triad sequences peaks attributed to 3 HV-centered triads of 3 HB-3 HV*3 HB, 3 HV-3 HV*3 HB, 3 HB-3 HV*3 HV, and 3 HV-3 HV*3 HV. The chemical shifts observed (Supplementary Material Table S1) were in agreement with those reported previously [8; 29]. The relative peak intensities obtained for the carbonyl (V1 and B1) resonances and the methylene (V2, B2, and V4) resonances of PHBV samples were used to determine the mole, diad, and HV-centered triad sequence distributions (Table 5). In the PHBV-15, -32, and -39 samples some signals were assigned to carbonyl and methylene C (B2, V2, V4) and in the PHBV-71 a signal assigned to methylene C (B2) were not observed. Therefore, the calculation of moles for diad and HV-centered triad fractions of HB and HV monomers on these samples were not performed. The degree of randomness of copolymer based on experimental diad sequence distribution of the PHBV samples was determined by parameter \(D\) (Table 6), which is defined as  
\[D\ =\ \frac{F_{VV}F_{BB}}{F_{VB}F_{BV}} \tag{2}\]  
\(F_{XY}\) represents the mole fraction of \(XY\) sequence. The subscripts VV, BB, VB, and BV represent valerate-valerate, butyrate-butyrate, valerate-butyrate and butyrate-valerate of diad sequences, respectively. The statistically random copolymers have \(D\) value of 1.0. The \(D\) value for blocky and alternating copolymers are \(>\)1 and very close to 0, respectively. The term \"blocky\" means that the copolymer is a mixture of copolymers with different compositions or a mixture of PHB and PHY homopolymers. The parameter \(D\) is sensitive to the bimodal or multimodal (very large \(D\)) CSD, whereas it is not sensitive to the broadness of CSD [28]. A higher-order sequence distribution analysis such as the triad sequence distribution provides more accurate information on CSD. The degree of randomness in the PHBV copolymers based on the experimental triad sequence distribution was determined by the R parameter (Supplementary Material Equations (S1)-(S3). In the PHBV copolymers with a completely randomized distribution of HV and HB monomers, \(R\) has a value of 1 (Table 6) [28]. Figure 2: \({}^{13}\)C-NMR (**a**) full spectrum; (**b**) expanded region associating to the splitting of individual resonances of PHBV-61. * denotes linkage between units V and B.