Thermoplastic elastomers with ABA-block structure, A representing the hard segment and B the soft segment, were prepared by ring-opening polymerization from 2,2-dirnethyltrimethylene carbonate (DTC, 1) and 8-caprolactone (ECL, 2) as monomers. Typical anionic initiators, viz. the dilithium salt of hydroxytelechelic poly(ethy1ene oxide) 200 (4) and of polytetrahydrofuran 1 OOO (5) and as an insertion initiator the bis(diethyla1uminium) salt of triethylene glycol were used. The soft block is formed by a sequence of random (or tapered) structure comprising equimolar amounts of the two monomers and obtained by simultaneous polymerization of DTC and ECL. The hard blocks consist of highly crystalline poly(2,2-dimethyltrimethylene carbonate) sequences. The thermal properties of the polymers depend on the sequence length, the content of heterodiads in the soft block and the thermal history of the samples. Copolymer films with short end blocks and high content of heterodiads show rubber-elastic properties at normal conditions. In t r o d u c t i o nThe ring-opening polymerization of 2,2-dimethyltrimethylene carbonate ( m C ) has been studied in our laboratory since 1984') and was recently reviewed2). Polymerization of c-caprolactone (ECL) has been studied in different laboratories. A recent review 3, on ring-opening polymerization of lactones summarizes the main aspects of ECL polymerization. The copolymerization of Dn= and ECL with a variety of initiators and reaction conditions has been studied in our laboratory since 19884-7). Depending on the reaction conditions, the structure of the copolymers can be varied from block copolymers to random copolymers. The living anionic polymerization technique is the method of choice for the synthesis of tailor-made copolymers'). The wide variety of copolymers which can be obtained from DTC and ECL originates from the fact that, from a mechanistic point of view, the active species in the polymerization of both monomers is the a l c~h o l a t e~, '~) .On the other hand a variation of the initiator, the solvent, and the reaction temperature may change the copolymerization parameters.Thus polymerization of a mixture of DTC and ECL in toluene as solvent and with sec-butyllithium (s-BuLi) or potassium dihydronaphthylide as initiator at 20 "C yields the tapered copolymer poly[(2,2-dimethyltrimethylene carbonate)-co-(c-caprolactone)] (p~ly(kYTC-tap-ECL)~). This is a polymer of the AXB-type where A represents the poly(DTC) block, B the poly(ECL) block and X stands for a tapered block containing both monomers with a compositional gradient. With dibutylmagnesium as initiator6) similar results were obtained; in addition it was shown that by raising the temperature from 0°C to 80 "C the length of the tapered block X increases, 0 1994, Huthig &

Die Dauerhaftigkeit eines Steinschutzstoffes auf Polyurethanbasis im Sander Schilfsandstein gegenüber chemischen Angriffen wurde nach verschieden langen Bewitterungszeiten in einer Versuchsanlage zur naturnahen Umweltsimulation untersucht. Dabei wurden sowohl die Gelpermeationschromatographie (GPC) als auch oberflächensensible Analysenmethoden (XPS und PAS‐FTIR) zur Untersuchung der Polyurethan‐Mikroschicht im Stein eingesetzt. Nur im Bereich der ersten vier Millimeter Gesteinstiefe konnten bewitterungsbedingte chemische Veränderungen des Polymeren festgestellt werden.

SUMMARY:The influence of extraction of reinforced fibres on surface properties and the curing reaction of epoxy resin matrix in composites were investigated. With increasing fibre surface polarity, as the result of the extraction, the resin wettability was improved and the reaction rate of curing of the epoxy resin matrix increased. The wettability and the reaction rate oppositely decreased with decreasing fibre surface polarity.