Cocrystallization of Random Copolymers of omega-Pentadecalactone and epsilon-Caprolactone Synthesized by Lipase Catalysis

• Published in: Biomacromolecules
• Main Authors: CECCORULLI, GIUSEPPINA, SCANDOLA, MARIASTELLA, A. Kumar, B. Kalra, R. A. Gross
• Other Authors: G. Ceccorulli, M. Scandola, A.Kumar, R.A. Gross
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2005
• Subjects: COPOLYMERS; COCRYSTALLIZATION; OMEGA-PENTADECALACTONE; EPSILON-CAPROLACTONE; TRANSESTERIFICATION; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/11585/17641; https://doi.org/10.1021/bm0493279

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.