Synthesis, crystallization, and morphology of star‐shaped poly(ε‐caprolactone)

Abstract

Six-arm star-shaped poly(e-caprolactone) (sPCL) was successfully synthesized via the ring-opening polymerization of e-caprolactone with a commercial dipentaerythritol as the initiator and stannous octoate (SnOct 2 ) as the catalyst in bulk at 120 8C. The effects of the molar ratios of both the monomer to the initiator and the monomer to the catalyst on the molecular weight of the polymer were investigated in detail. The molecular weight of the polymer linearly increased with the molar ratio of the monomer to the initiator, and the molecular weight distribution was very low (weight-average molecular weight/number-average molecular weight ¼ 1.05-1.24). However, the molar ratio of the monomer to the catalyst had no apparent influence on the molecular weight of the polymer. Differential scanning calorimetry analysis indicated that the maximal melting point, cold crystallization temperature, and degree of crystallinity of the sPCL polymers increased with increasing molecular weight, and crystallinities of different sizes and imperfect crystallization possibly did not exist in the sPCL polymers. Furthermore, polarized optical microscopy analysis indicated that the crystallization rate of the polymers was in the order of linear poly(e-caprolactone) (LPCL) > sPCL5 > sPCL1 (sPCL5 had a higher molecular weight than both sPCL1 and LPCL, which had similar molecular weights). Both LPCL and sPCL5 exhibited a good spherulitic morphology with apparent Maltese cross patterns, whereas sPCL1 showed a poor spherulitic morphology. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: [5449][5450][5451][5452][5453][5454][5455][5456][5457] 2005

Synthesis, Sequential Crystallization and Morphological Evolution of Well‐Defined Star‐Shaped Poly(ε‐caprolactone)‐b‐poly(L‐lactide) Block Copolymer

“…[13,14] Dong et al reported the synthesis of starshaped PCL and poly[(lactic acid)-alt-(glycolic acid)] having three, four and six arms using multifunctional initiators such as trimethylolpropane, pentaerythritol and dipentaerythritol, respectively. [15][16][17][18] As an extension, the synthesis and physical properties of linear PCL-b-PLLA diblock copolymer were further studied as follows. Jérôme et al investigated the sequential block copolymerization of CL and other lactones or lactides using aluminum alkoxide as an initiator.…”

Solution-based synthesis of a four-arm star-shaped poly(L-lactide)

“…Tam et al [30] considered the peak at 603 cm −1 as it corresponds to the lactide ring deformation. Degee et al [31] used the peak at 935 cm −1 that corresponds to COO ring breathing mode as the characteristic peak and the shared band at 1383 cm −1 corresponding to the CH 3 deformation mode [32] as reference for the calculation of the residual monomer. Braun et al [23] discussed the peak at 1383 cm −1 and showed that this peak was not isolated, but overlapped with the C-H bending vibration.…”

“…similar results for slow polymerization at lower catalyst concentration have been reported in the literature. [32] Thermal properties of the PLA products were evaluated using differential scanning calorimetry (DsC) as shown in Figure 9. A summery for the transitions is listed in Table 3.…”

Synthesis and characterization of novel β-cyclodextrin cored poly(α-caprolactone)s by anionic ring opening polymerization

“…Star-shaped polymers, because of their higher segment density within the distance of their radius of rotation compared to that of linear polymers under the same conditions, have gained much more attention in recent years [9][10][11][12][13][14]. The excluded volume effects are more pronounced in star-shaped polymers, causing them to have low melting points.…”