Confined Nucleation and Crystallization Kinetics in Lamellar Crystalline–Amorphous Diblock Copolymer Poly(ε-caprolactone)-b-poly(4-vinylpyridine)

Abstract

The nucleation and crystallization kinetics of lamellar crystalline−amorphous diblock copolymer poly(ε-caprolactone)-b-poly(4-vinylpyridine) (PCL−P4VP) was investigated by ultrafast differential scanning calorimetry (UFDSC) with temperature scanning rates up to 10 000 K/s and compared with that of poly(ε-caprolactone) (PCL) homopolymer. We found that the critical cooling rate (ccr) to get the fully amorphous PCL is 1 order of magnitude slower than that for PCL homopolymer with the similar molecular weight. Isothermal nucleation and crystallization of PCL block in the PCL−P4VP copolymer and PCL homopolymer were studied covering times from 10 −2 to 10 3 s and temperatures from 200 K (10 K below the glass transition temperature of PCL) to 300 K (about 40 K below the equilibrium melt temperature of PCL). It was found that the PCL block in PCL−P4VP copolymer experienced a slower homogeneous nucleation rate as well as crystallization rate than PCL homopolymer, indicating that even the local nucleation events of PCL chains is affected by the long-range glassy P4VP in copolymer. The confinement also hinders the long-range diffusion of PCL chains and becomes more effective once the chains get the mobility from the glassy state at crystallization temperatures above the T g . Another effect of the confinement is the lower Avrami index in copolymer than that in homopolymer attributed to the restricted growth dimension under confinement. The results reported here might enhance the understanding of confinement effect on crystallization and give new details on the nucleation kinetics under nanoscale confinement.

Crystallization of polymer chains confined in nanodomains

“…Consequently, the crystalline block crystallizes within hard (or glassy) nanodomains to form crystalline microdomain structures [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. It is generally observed for the crystallization in hard nanodomains that the melting temperature is considerably low and the final crystallinity is extremely small as compared with the case in the crystalline lamellar morphology formed by break-out crystallization (Fig.…”

Crystallization behaviors of poly(vinylidene fluoride) and poly(methyl methacrylate)-block-poly(2-vinyl pyridine) block copolymer blends

“…The parameter n of PVDF component in blends is almost the same as that in pure PVDF, suggesting that the PMMA-b-P2VP content has little influence on the crystallization mechanism of PVDF. What is more, it is found in Table 4 that the Z c value decreases with the increase of PMMA-b-P2VP content as the PMMA-b-P2VP concentration is below 50 mass%, indicating that the folding of PVDF chains is affected by the long-range glassy PMMA-b-P2VP in blends [52]. Meanwhile, the value of Z c almost remains unchanged as PMMA-b-P2VP concentration is over [53] found that the inclusion of amorphous polymer could reduce the crystallization rate of PVDF and make the spherulite less perfect, in agreement with our result.…”

Reorganization of Lamellar Diblock Copolymer Poly(ε‐caprolactone)‐block‐poly(4‐vinylpyridine) in the Melting Temperature Range

“…They detected the competing melting with reorganization in individual PEO domains . In our previous work, we demonstrated the confinement effect on the crystallization kinetics in a wide temperature range in lamellar amorphous‐crystalline poly(ε‐caprolactone)‐ block ‐poly(4‐vinylpyridine) (PCL‐P4VP) block copolymer and found that even the local nucleation kinetics was affected by the confinement . Here, we are interested in extending our investigation on the detailed reorganization processes in this confined system.…”

“…The PCL‐P4VP block copolymer was synthesized via living ring opening polymerization (ROP) and atom transfer radical polymerization (ATRP) in sequence . The samples used here were the same as in Chen et al The characterization of the PCL homopolymer and the PCL‐P4VP copolymer is listed in Table .…”