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EnglishRandom copolymers were prepared by Candida antarctica Lipase B (Novozyme-435) catalyzed copolymerization of omega-pentadecalactone (PDL) with epsilon-caprolactone (CL). Over the whole composition range PDL-CL copolymers are highly crystalline (melting enthalpy by DSC: above 100 J/g, crystallinity degree by WAXS: 60-70%). The copolymers melt at temperatures that linearly decrease with composition from that of poly(omega-pentadecalactone) PPDL (97°C) to that of poly(epsilon-caprolactone) PCL (59°C). The WAXS profile of PCL and PPDL homopolymers is very similar, except for the presence in PPDL of the (001) reflection at 2 theta = 4.58° that corresponds to a 19.3 Å periodicity in the chain direction. In PDL-CL copolymers the intensity of this reflection decreases with increasing content of CL units and vanishes at 50 mol% CL, as a result of randomization of the ester group alignment and loss of chain periodicity. PDL-CL copolymers crystallize in a lattice that gradually changes from that of one homopolymer to that of the other, owing to comonomer isomorphous substitution. Cocrystallization of comonomer units is also shown by a random PDL-CL copolymer obtained in a polymerization/transesterification reaction catalyzed by Candida antarctica Lipase B (Novozyme-435) starting from preformed poly(caprolactone) and PDL monomer.
| Titolo: | Cocrystallization of Random Copolymers of omega-Pentadecalactone and epsilon-Caprolactone Synthesized by Lipase Catalysis |
| Autore/i: | CECCORULLI, GIUSEPPINA; SCANDOLA, MARIASTELLA; A. Kumar; B. Kalra; R. A. Gross |
| Autore/i Unibo: | |
| Anno: | 2005 |
| Rivista: | |
| Digital Object Identifier (DOI): | http://dx.doi.org/10.1021/bm0493279 |
| Abstract: | Random copolymers were prepared by Candida antarctica Lipase B (Novozyme-435) catalyzed copolymerization of omega-pentadecalactone (PDL) with epsilon-caprolactone (CL). Over the whole composition range PDL-CL copolymers are highly crystalline (melting enthalpy by DSC: above 100 J/g, crystallinity degree by WAXS: 60-70%). The copolymers melt at temperatures that linearly decrease with composition from that of poly(omega-pentadecalactone) PPDL (97°C) to that of poly(epsilon-caprolactone) PCL (59°C). The WAXS profile of PCL and PPDL homopolymers is very similar, except for the presence in PPDL of the (001) reflection at 2 theta = 4.58° that corresponds to a 19.3 Å periodicity in the chain direction. In PDL-CL copolymers the intensity of this reflection decreases with increasing content of CL units and vanishes at 50 mol% CL, as a result of randomization of the ester group alignment and loss of chain periodicity. PDL-CL copolymers crystallize in a lattice that gradually changes from that of one homopolymer to that of the other, owing to comonomer isomorphous substitution. Cocrystallization of comonomer units is also shown by a random PDL-CL copolymer obtained in a polymerization/transesterification reaction catalyzed by Candida antarctica Lipase B (Novozyme-435) starting from preformed poly(caprolactone) and PDL monomer. |
| Data prodotto definitivo in UGOV: | 2006-01-24 11:43:50 |
| Appare nelle tipologie: | 1.01 Articolo in rivista |
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