Effects of Branches on the Isothermal Crystallization of Copolymers Based on Poly(ϵ‐caprolactone)

Abstract

A linear poly(ϵ‐caprolactone), PCL, and grafted copolymers based on poly(2‐hydroxyethylmethacrylate) and poly(ϵ‐caprolactone) are used to study the effect of branches on PCL crystallization process. Copolymers are synthetized by a combination of ring opening polymerization and reversible addition fragmentation chain transfer polymerization, showing molar masses between 32 000 and 46 000 g mol−1 with Mw/Mn lower than 1.19. Isothermal crystallization kinetic is performed by Differential Scanning Calorimetry combining Avrami and Hoffman‐Weeks theories. Regarding to Avrami parameters, copolymers exhibited half‐life crystallization times 42 times higher than PCL homopolymer and two‐dimensional crystallization growth. Copolymers’ growing rate values are 51 times higher than PCL values according to Hoffman‐Weeks equation. These results suggest that interaction of grafted chains could hinder the rearrangement of PCL by reducing their final crystallization capacity.

Photocrosslinked Poly(ϵ‐caprolactone) – Polydimethylsiloxane – Poly(ϵ‐caprolactone) Triblock Copolymeric Films: Structural, Thermal and Shape Memory Properties

“…reported that at a small degree of supercooling regime I kinetic is operative and primary nucleation as surface nucleation completed rapidly over the surface and dominated by secondary nucleation for crystal growth. Ninago et al [13] . are reported increase in K g and G 0 of 2 fold and 51 fold respectively for PCL‐g‐HEMA copolymer than pure PCL, indicating decrease in overall mobility of PCL chains due to major confinement, which reduces their final crystallization capacity.…”

“…Ninago et al . have studied that branches of poly(2‐ hydroxyethylmethacrylate) (PHEMA) hinder the formation of PCL crystallites by increasing final crystallization time in case of PCL/PHEMA graft copolymer [13] . In a study by Nie et al [21] .…”

“…Avrami model has been developed based on empirical concepts and it is widely described polymer crystallization kinetics. [13] In the conversion range up to the end of primary crystallization, the Avrami model provides a satisfactory fit for the experimental data. Crystal development in polymers can take the form of axialities, which are twodimensional lamellar aggregates, or spherulites, which are superstructural three-dimensional aggregates.…”

“…Ninago et al have studied that branches of poly(2-hydroxyethylmethacrylate) (PHEMA) hinder the formation of PCL crystallites by increasing final crystallization time in case of PCL/PHEMA graft copolymer. [13] In a study by Nie et al [21] on tetraethyl orthosilicate and PCL blends, the rate of crystallization decreases with decrease in ratio of PCL.…”

“…The energy barriers related to nucleation, crystal growth, and crystallization arrangement are measured using isothermal crystallization models. Avrami model has been developed based on empirical concepts and it is widely described polymer crystallization kinetics [13] . In the conversion range up to the end of primary crystallization, the Avrami model provides a satisfactory fit for the experimental data.…”