Fully‐Biodegradable Poly(3‐hydroxybutyrate)/Poly(vinyl alcohol) Blend Films with Compositional Gradient

Abstract

Fully-biodegradable bacterial poly(3-hydroxybutyrate) (PHB)/chemosynthetic poly(vinyl alcohol) (PVA) blend films with compositional gradient from one surface to the other surface of the films were prepared by a dissolution-diffusion technique. Three kinds of PVA samples, high- and low-molecular weight atactic PVA and highly syndiotactic PVA (s-PVA), were used in order to investigate the effects of molecular weight and tactic structure on the generation of compositional gradient. The solution of PHB in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), which is also a good solvent for PVA, was cast on the PVA film and then the solvent HFIP was evaporated. By selecting the optimum volume of solvent and the evaporation rate, the PHB/PVA blend film with compositional gradient was obtained. The formation of compositional gradient was confirmed by FT-IR microscopy and ATR-FT-IR analysis. The 50%/50% PHB/s-PVA blend film with a nearly ideal compositional gradient, that is, the composition of PHB (or PVA) in the film changing gradually from 100% at one surface to 0% at the other surface of the film was obtained by casting PHB/HFIP solution on to the s-PVA film. Positional dependence of the absorbance of C==O and OH stretching bands along the film thickness direction for the PHB/S-PVA cast films.

A Tuneable Switch for Controlling Environmental Degradation of Bioplastics: Addition of Isothiazolinone to Polyhydroxyalkanoates

“…Increasing the antifoulant loading to 10% (w/w) DCOI prevented re-crystallisation (Figure 2b). This trend is consistent with reports of PHB blended with similar compounds such as poly(ethylene glycol) or poly(vinyl alcohol) where re-crystallisation is retarded [30], [31]; crystallisation temperatures for P(HB- co -8HV)-DCOI composites were seen, but up to 4°C lower (Figure 2d, Table 1). …”

Generation of Compositional‐Gradient Structures in Biodegradable, Immiscible, Polymer Blends by Intermolecular Hydrogen‐Bonding Interactions

“…[12] However, it is well known that most of the biodegradable polymer blends are immiscible because of their chemical structures and high molecular weights. [13] Previous research, [9,10] including our own, [11] on functionally graded polymeric materials have focused mainly on miscible blend systems and several preparation techniques have been developed, while only a few groups have reported on the gradient morphology being obtained in immiscible blend systems. Xie et al reported that a gradient structure was formed between an immiscible polymer blend of polypropylene-co-poly(ethylene vinylacetate) (weight ratio, 70/30) by making use of their segregation behavior in the annealing process.…”

Quantitative Analysis of Compositional Distribution in Biodegradable Poly(ethylene oxide)/Poly(3‐hydroxybutyrate) Blend Film with Compositional Gradient by FT‐IR Microspectroscopy

“…[13] First, 8 ml well mixed chloroform solution containing PEO/PHB20 was poured into a PTFE dish. The solution was evaporated at room temperature until the weight of the residual solution was 10% of the original solution weight, and then about 2 ml well mixed chloroform solution containing PEO/PHB50 was poured into the dish and evaporated.…”

“…In our previous work, [13] poly(3-hydroxybutyrate) (PHB)/poly(vinyl alcohol) (PVA) blend films with compositional gradient were analyzed by FT-IR microspectroscopy. Through the change of paired IR absorbance, we could monitor qualitatively the compositional distribution of PHB and PVA along the thickness direction of the blend films.…”