A series of P(3HB-co-3MP)s with different 3MP unit content was biosynthesized by the fermentation of W. eutropha in a medium containing sodium gluconate and DTDP as carbon sources at different pH conditions ranging from pH 6.0 to 8.0. The P(3HB-co-3MP) samples were fractioned using the solvent/nonsolvent mixed solvent chloroform/heptane and the comonomer unit composition was investigated. It was found that W. eutropha produces P(3HB-co-3MP)s with extremely different 3MP unit content ranging from 3.6 to 70.0 mol-%, depending on the pH value of the fermentation medium. The copolyester samples produced in mild basic medium have a considerably narrower compositional distribution than the samples from acidic medium. The highest polymer yield was obtained at pH 8.0.DSC diagram for P(3HB-co-3MP)s biosynthesized in different pH medium. [graph: see text] DSC diagram for P(3HB-co-3MP)s biosynthesized in different pH medium.

The thin film stabilities of ω-N-(3-(dimethylamino)propyl)propylamide-terminated polystyrene (PS-N) and its blends with conventional polystyrene (PS-H) supported on silicon wafers with a native oxide layer were examined. Whereas a 20-nm-thick film of PS-H with a number-average molecular weight of ∼ 50k decomposed at 423 K, a comparable PS-N film and blended films containing a PS-N fraction of 440 wt% were stable. Although the local conformation of chains at the substrate interface was not the same for PS with and without the functional end group, the glass transition temperature at the interface was identical for both PS-H and PS-N. The residual adsorbed layer on the substrate after washing the films with a good solvent was thicker for PS-N than for PS-H. This implies that end functionalization, rather than segmental dynamics, affects chain movement on a large scale.

KEY WORDS: Polymer Blend / Nucleating Agent / Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) / Recently bacterial poly(3-hydroxybutyrate) (P(3HB)) has attracted much attention due to its inherent biodegradability. However, its brittleness and narrow processing temperature window limit its application. To overcome the inferior properties of P(3HB), a variety of P(3HB) copolymers such as, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HH)), have been bacterially synthesized.1 Especially, P(3HB-co-3HH)s with 3HH unit content of about 10-20 mol % have good mechanical properties.2 But the crystallization rate of P(3HB-co-3HH) compared with that of P(3HB) is too slow to use as molded products.In general, the addition of nucleating agents may be an effective method for acceleration of the crystallization of crystallizable polymers and the increase of the nucleation density, resulting in the reduction of the spherulite size. Boron nitride (BN) was found to be effective as the nucleating agent for the crystallization of P(3HB) and P(3HB-co-3HV). 3,4 But, it is found to be ineffective for P(3HB-co-3HH)s with relatively high 3HH unit content, as mentioned later in this article. Thus, it is in need of development of novel nucleating method effective for the crystallization of P(3HB-co-3HH)s.It is known that P(3HB-co-3HH) with 3HH composition higher than about 20 mol % is partially miscible with P(3HB) in the amorphous phase. 5As bacterially synthesized P(3HB) is a completely isotactic stereoregular polyester, it has higher tendency to crystallize than the 3HB-containing copolyesters.6 Bacterial P(3HB-co-3HH)s with high 3HB unit content form P(3HB) homopolymer type crystal, although the crystallization is very slow.7 In this study, we studied rapid crystallization of P(3HB-co-3HH) induced by in situ generated crystalline nuclei. EXPERIMENTALBacterial P(3HB-co-3HH) with 3HH unit content 18 mol % [P(3HB-co-18 mol %3HH)] was kindly supplied by Kaneka Corporation, Osaka, Japan.8 Because the comonomer-unit compositional distribution of bacterial P(3HB-co-18 mol %3HH) is very wide, as-produced P(3HB-co-18 mol %3HH) was fractionated with a chloroform(solvent)/n-heptane-(nonsolvent) mixed solvent systems at ambient temperature. 8 In this study, one of fractions with narrow comonomer-unit compositional distribution, that is, P(3HB-co-21 mol %3HH) (M n ¼ 1:15 Â 10 5 , M w =M n ¼ 1:42) was used. Bacterial P(3HB) sample (M n ¼ 1:55 Â 10 5 , M w =M n ¼ 2:56) provided by PHB Industrial S/A (Brazil) was used after purification. The BN fine powder was purchased from Nacalai Tesque, Inc (Kyoto, Japan). BN is known as nucleating agent for P(3HB). 9 The films of P(3HB-co-21 mol %3HH), P(3HB-co-21 mol %3HH)/P(3HB) (90 wt %/10 wt %) blend, P(3HB-co-21 mol %3HH)/BN (98 wt %/2 wt %) blend, P(3HB-co-21 mol %3HH)/P(3HB)/BN (88 wt %/10 wt %/2 wt %) blend (ternary blend), P(3HB) and P(3HB)/BN (98 wt %/2 wt %) blend were prepared by solution casting from chloroform solutions. The...

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Reactions of monoterpene hydrocarbons with alcohols (C1•`C4) were carried out in the presence of synthetic zeolites. The addition of (+)-limonene, 2-pinene, and 2 (10)-pinene to alcohols gave the corresponding terpenyl ethers as the major products. Some reaction products could be used as perfume bases.