Cocrystallization of random copolymers of omega-pentadecalactone and epsilon-caprolactone synthesized by lipase catalysis.
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 differential scanning calorimetry, above 100 J/g; crystallinity degree by wide-angle X-ray scattering, WAXS, 60-70%). The copolymers melt at temperatures that linearly decrease with composition from that of poly(omega-pentadecalactone) (PPDL; 97 degrees C) to that of poly(epsilon-caprolactone) (PCL; 59 degrees C). The WAXS profiles of PCL and PPDL homopolymers are very similar, except for the presence in PPDL of the (001) reflection at 2theta = 4.58 degrees that corresponds to a 19.3 angstroms 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 C. antarctica lipase B (Novozyme-435) starting from preformed PCL and PDL monomer.
Ceccorulli
Giuseppina
G
Department of Chemistry G. Ciamician and INSTM UdR Bologna, University of Bologna, via Selmi 2, 40126 Bologna, Italy.
Scandola
Mariastella
M
Kumar
Ajay
A
Kalra
Bhanu
B
Gross
Richard A
RA
D001426:Bacterial Proteins; D040761:Biomimetic Materials / Q000138:chemical synthesis* / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D002384:Catalysis; D003460:Crystallization; D005656:Fungal Proteins; D008049:Lipase / Q000378:metabolism*; D011091:Polyesters / Q000138:chemical synthesis* / Q000737:chemistry; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry; D014961:X-Ray Diffraction
D001426:Bacterial Proteins; D005656:Fungal Proteins; D011091:Polyesters; D011108:Polymers; C502910:poly(omega-pentadecalactone-co-epsilon-caprolactone); C016240:polycaprolactone; D008049:Lipase; C431349:lipase B, Candida antarctica