SPREADING OF POLY(BETA-HYDROXYLALKANOATE)S AT THE AIR-WATER-INTERFACE- A MODEL SYSTEM FOR THE NASCENT LYOTROPIC STATE OF BACTERIAL POLYESTERS

Bacterial poly(beta-hydroxybutyrate) aud bacterial copolyesters of bet a-hydroxybutyric acid with up to 29% of beta-hydroxyvaleric acid were shown to spread reproducibly from chloroform to give monolayers at the air-water interface. Typical limiting areas are 2.4 m(2) mg(-1), corr esponding to 0.35 nm(2) per repeating unit. Surface pressures of up to 36 mN m(-1) were reached, corresponding to packing densities of appro ximately 0.12 nm(2) per repeating unit. The spreading of chiral, water -insoluble biopolyesters to stable monolayers, in which a majority of the repeating units are in contact with the water subphase, has import ant implications for the structure of polyalkanoate inclusions.