References of "Kurcok, Piotr"
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See detailMacromolecular engineering of lactones and lactides. 24. Controlled synthesis of (R,S)-β-butyrolactone-b-ε-caprolactone block copolymers by anionic and coordination polymerization
Kurcok, Piotr; Dubois, Philippe ULg; Sikorska, Wanda et al

in Macromolecules (1997), 30(19), 5591-5595

Block copolymers of (R,S)-β-butyrolactone and ε-caprolactone have been synthesized by combining the anionic polymerization of the first monomer with the coordinative ring-opening polymerization of the ... [more ▼]

Block copolymers of (R,S)-β-butyrolactone and ε-caprolactone have been synthesized by combining the anionic polymerization of the first monomer with the coordinative ring-opening polymerization of the second one. The copolymerization yield is close to 100% and the final molecular weight of each sequence can be predicted from the initial monomer-to-initiator molar ratio. The molecular weight distribution of copolymers obtained is quite narrow (Mw/Mn ≤ 1.3). According to NMR and DSC analysis, the polybutyrolactone block is atactic and totally amorphous, in contrast to the polycaprolactone block which is semicrystalline. A partial miscibility of the two blocks in the amorphous phase has however been detected. Thermal and enzymatic degradations of the block copolymers have been investigated. The enzymatic degradation rate promoted by the lipase form Rhizopus arrhizus strongly depends on the copolyester composition and increases with the β-butyrolactone content. [less ▲]

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See detailPolymerization of β-butyrolactone initiated with Al(OiPr)3
Kurcok, Piotr; Dubois, Philippe ULg; Jérôme, Robert ULg

in Polymer International (1996), 41(4), 479-485

Polymerization of gamma-butyrolactone has been studied in toluene with Al(OiPr)3 as an initiator. The ring-opening polyaddition proceeds through a coordination-insertion mechanism at a very low rate. Well ... [more ▼]

Polymerization of gamma-butyrolactone has been studied in toluene with Al(OiPr)3 as an initiator. The ring-opening polyaddition proceeds through a coordination-insertion mechanism at a very low rate. Well defined -isopropylester, -hydroxy poly(-butyrolactone)s (PBL) are formed with a narrow molecular weight distribution at low monomer-to-initiator molar ratios, When this ratio is higher (ca. 170), a competition occurs between propagation and side reactions, i.e. elimination, inter- and intra-molecular transesterifications and thermal degradation, which is responsible for a loss of control of the PBL molecular charcteristics. The addition of a Lewis base (1 equivalent of nicotine/Al) to the Al-alkoxide initiator has no significant effect on the polymerization rate, although the chain microstructure is deeply affected since predominantly syndiotactic PBL chains are formed (63% syndio-diads) in contrast to a completely atactic polymer in the absence of nicotine. [less ▲]

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See detailAnionic polymerization of pivalolactone initiated by alkali metal alkoxides
Jedlinski, Zbigniew; Kurcok, Piotr; Kowalczuk, Marek et al

in Macromolecules (1995), 28(21), 7276-7280

Polymerization of pivalolactone (alpha,alpha-dimethyl-beta-propiolactone) initiated with alkali metal alkoxides has been studied. It has been revealed that after addition of an alkoxide anion, from the ... [more ▼]

Polymerization of pivalolactone (alpha,alpha-dimethyl-beta-propiolactone) initiated with alkali metal alkoxides has been studied. It has been revealed that after addition of an alkoxide anion, from the initiator, onto the carbonyl carbon atom of the monomer the selective cleavage of the acyl-oxygen bond of the monomer leads to the formation of alkoxide propagating species. Thus, it has been demonstrated that, in contrast to alpha-unsubstituted beta-lactones and higher lactones, the anionic polymerization of pivalolactone proceeds through either alkoxide or carboxylate propagation centers, depending on the nature of initiator used, i.e. an alkoxide or a carboxylate, respectively. In the former case, however, cyclic oligomers are also formed which are unusual in the anionic polymerization of other beta-lactones. This indicates that, whatever the lactone ring size (four-, six-, or seven-membered lactones), intramolecular transesterification reactions can take place if alcoholate ions are propagating species. [less ▲]

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See detailSubstituent effect in anionic polymerization of β-lactones initiated by alkali metal alkoxides
Kurcok, Piotr; Matuszowicz, Andrzej; Jedlinski, Zbigniew et al

in Macromolecular Rapid Communications (1995), 16(7), 513-519

The influence of methyl substituent on the mechanism of the ring-opening polymerization of -lactones initiated by alkali metal alkoxides is discussed. Attention has been paid to the effect of the ... [more ▼]

The influence of methyl substituent on the mechanism of the ring-opening polymerization of -lactones initiated by alkali metal alkoxides is discussed. Attention has been paid to the effect of the substituent position in the monomer molecule on the ring-opening mechanism, the 3,3-dimethyl-2-oxetanone (pivalolactone), 4-methyl-2-oxetanone (beta-butyrolactone) and 2-oxetanone (beta-propiolactone) being chosen as model monomers. Moreover, it was found unexpectedly that in the case of pivalolactone polymerization, besides open-chain polymers, cyclic oligomers are produced. [less ▲]

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