Poly(ethylene glycol)-poly(tetrahydrofuran)-poly(ethylene glycol) triblock copolymer : Synthesis, crystallization behavior and novel morphology

Abstract

Abstract. Poly(ethylene glycol)-poly(tetrahydrofuran)-poly(ethylene glycol) (PEG-PTHF-PEG) triblock copolymer was synthesized by ring-opening polymerization of ethylene oxide using sodium alcoholate of PTHF as the macroinitiator. Its crystallization behavior and formation mechanisms of different crystal structures were studied. The study showed that the molecular weight of PEG-PTHF-PEG exhibited a significant effect on its crystallization: that is, with the increase of the copolymer's molecular weight, the crystallizability of PTHF blocks decreased gradually, which led to the transition of copolymer from crystalline-crystalline to crystalline-amorphous. By adjusting the total molecular weight of triblock copolymer, the crystallization process can be effectively controlled, and as a result, different spherulite structures were obtained. Particularly, when PTHF blocks became amorphous, novel double concentric spherulites were observed. The morphological structures were studied by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), polarized optical microscopy (POM), and its crystalline process was investigated.

Differential analysis on precise determination of molecular weight of triblock copolymer using SEC/MALS and MALDI-TOF MS

“…M bias ¼ M n;SECÀMALLS À M n;MALDIÀTOF M n;SECÀMALLS ¼ 9:75% (16) As proved by titration, the chemical heterogeneity of PEG-PTHF-PEG triblock copolymer rarely affected the reliability of SEC/MALS measurement. Generally, the influence of chemical heterogeneity of copolymers on SEC/MALS measurement included two aspects.…”

“…However, data from neither SEC/ MALS nor titration was consistent with that of MALDI-TOF MS, suggesting that the molecular weight determined by SEC/MALS was reliable, but the result of MALDI-TOF MS was, indeed, smaller than the true value. With SEC/MALS as a reference method, the result of MALDI-TOF MS showed a deviation of 9.75%, according to Equation (16).…”

“…PEG-PTHF-PEG triblock copolymer was synthesized by the anionic ring-opening polymerization of ethylene oxide using sodium alcoholate of PTHF as the macroinitiator, based on our previous work [16], as shown in Fig. 1 …”

A New Strategy to Synthesize α,ω‐Dihydroxy Multiblock Copolymers via [CpRu(CH3CN)3]PF6/Quinaldic Acid Catalyst

“…Poly(1,5‐cyclooctadiene) (PCOD, M n = 3300 g mol −1 , M w / M n = 1.69) was synthesized via ring‐opening metathesis polymerization using cis‐1,4‐diacetoxy‐2‐butene as the chain transfer agent . Poly(ethylene glycol) (PEG, M n = 1500 g mol −1 , M w / M n = 1.24) was prepared via the modification of terminal groups . PEG‐PTHF‐PEG triblock polymer (M n = 2000 g mol −1 , M w / M n = 1.22) was prepared via anionic polymerization.…”

“…[45] Poly(ethylene glycol) (PEG, M n = 1500 g mol −1 , M w /M n = 1.24) was prepared via the modification of terminal groups. [46] PEG-PTHF-PEG triblock polymer (M n = 2000 g mol −1 , M w /M n = 1.22) was prepared via anionic polymerization. The detailed synthesis routes for the polymers and the structural characterization of macromonomers are described in the Supporting Information.…”