Synthesis of Grafted Block Copolymers Based on e-Caprolactone: Influence of Branches on Their Thermal Behavior

MARIO D. NINAGO; AUGUSTO G.O. DE FREITAS; VIVINA HANAZUMI; PAULO I.R. MURARO; VANESA SCHMIDT; CRISTIANO C. GIACOMELLI; ANDRÉS E. CIOLINO; MARCELO A. VILLAR

MACROMOLECULAR CHEMISTRY AND PHYSICS

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2015 vol. 216 p. 2331 - 2343

1022-1352

Branched copolymers are a special class of polymeric materials in which are reflected the combinedeffects of polymer segments and architectural constraints of the branched architecture.This study employed two methodologies to obtain copolymers with different branching density.In the first case, poly(hydroxyethylmethacrylate-graft-poly(caprolactone)-block-poly(caprolactone), P(HEMA-g-PCL)-b-PCL, copolymers were synthesized by a grafting through method in a three-step reaction pathway involving ring opening polymerization (ROP) andradical addition fragmentation transfer (RAFT) polymerization. In the second case, a combinationof simultaneous grafting through and grafting from methods in a one-pot RAFT andROP reaction afforded P(HEMA-co-HEMA-g-PCL)-b-PCL comb-like copolymers with comparativelyless dense branching. Samples with molar masses between 5500 and 46 000 g mol−1and polydispersity indexes (Mw/Mn) lower than 1.3 were successfully obtained through bothapproaches.According to thermal analyses, the presence of branches reduces PCLmelting temperatureby as much as 20 ◦C, without affecting thermal stability. This fact was particularlyevident for the most densely branched copolymers with higher molar masses. Nonisothermalcrystallization process was successfully described using Ozawas method, which showed aclear dependence of crystallization rate and cooling on grafting density.