High molecular weight poly(butylene
succinate-co-ethylene succinate)s, P(BS-co-ES)s,
were
obtained from succinic acid, 1,4-butanediol, and/or ethylene glycol
through a polycondensation process.
Enzymatic hydrolysis of hot-pressed copolyester films was carried
out by utilizing lipases derived from
a wide variety of microorganisms. The formation of water-soluble
total organic carbon (TOC) was
monitored to determine the effect of structure upon enzymatic
degradability. The P(BS-co-ES) copolyester
containing approximately 53 mol % ES exhibited a minimum in systemic
crystallinity and a maximum
in enzymatic degradation. These results suggest that the degree of
crystallinity may be the dominant
influence upon the rate of degradation. Furthermore, it appears
that the sequence distribution of BS
and ES subunits has little effect upon lipase activity.
Thermal curing of poly(4,4'-oxybis(phenylenepyromellitamic acid)) (PAA) films prepared from PAA solutions using a novel solvent system composed of tetrahydrofuran (THF) and methanol (MeOH) has been investigated. In the drying process of casted PAA films, MeOH was entirely evaporated, while a significant amount of THF remained in the dried film. The progress of thermal imidization was observed during the process of drying at 80 °C. NMR measurements for the dried film revealed that the thermal imidization of trans-amidized PAA predominated over that of cis-amidized PAA. Dynamic mechanical thermal analyses (DMTA) pointed out that the dried PAA film containing THF showed no significant plasticization during the thermal cure. This indicates the mobility of polymer chain would be low during the thermal cure so that the resulting polyimide film has a higher in-plane orientation. The coefficient of thermal expansion (CTE) of the polyimide film was found to be low compared with a film obtained from a PAA solution using NMP.
Telechelic polystyrene with glycylamino groups as active chain ends was prepared and used as initiator for the polymerization of the NCA of methyl D-glutamate [4-(2-meth-oxycarbony1)ethyl-1,3-oxazolidin-2,5-dione] (1). Using propionitrile or preferably ethyl acetate as solvent, the stepwise polymerization of the NCA 1 proceeded with a sufficiently high initiator efficiency, giving ABA-type block copolymers consisting of polystyrene and polypeptide segments.
ZUSAMMENFASSUNG:Telecheles Polystyrol mit Glycylamino-Gruppen als aktive Kettenenden wurde dargestellt und als Initiator zur Polymerisation des NCA von D-Glutamindure-methylester [4-(2-MethoxycarbonyI)athyl-1,3-oxazo1idin-2,5-dion] ( I ) verwendet. Mit Propionitril oder besser mit Athylacetat als Losungsmittel verlief die stufenweise Polymerisation von NCA 1 mit geniigend hoher Initiatorausbeute und fiihrte zu Blockpolymeren. des Typs ABA, die sich aus Polystyrol und Polypeptid-Segmenten zusammensetzen. *) Part 8: cf.".
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