A new tricrystalline triblock terpolymer by combining polyhomologation and ring‐opening polymerization. synthesis and thermal properties

New tricrystalline triblock terpolymers, polyethylene‐block‐poly(ε‐caprolactone)‐block‐poly(L‐lactide) (PE‐b‐PCL‐b‐PLLA), were synthesized by ROP of ε‐caprolactone (CL) and L‐lactide (LLA) from linear ω‐hydroxyl polyethylene (PE‐OH) macroinitiators. The linear PE‐OH macroinitiators were prepared by C1 polymerization of methylsulfoxonium methylide (polyhomologation). Tin(II) 2‐ethylhexanoate was used as the catalyst for the sequential ROP of CL and LLA in one‐pot polymerization at 85 °C in toluene (PE‐OH macroinitiators are soluble in toluene at 80 °C). ¹H NMR spectra confirmed the formation of PE‐b‐PCL‐b‐PLLA triblock terpolymers through the appearance of the characteristic proton peaks of each block. GPC traces showed the increase in the number average molecular weight from PE‐OH macroinitiator to PE‐b‐PCL, and PE‐b‐PCL‐b‐PLLA corroborating the successful synthesis. The existence of three crystalline blocks was proved by DSC and XRD spectroscopy. © 2019 The Authors. Journal of Polymer Science Part A: Polymer Chemistry published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2450–2456     

In-chain functionalized poly(ε-caprolactone): A valuable precursor towards the synthesis of 3-miktoarm star containing hyperbranched polyethylene

Well-defined 3-miktoarm star copolymer 3μ-HBPE(PCL)₂ (HBPE: hyperbranched polyethylene, PCL: poly[ε-caprolactone]) was synthesized by combining chain walking polymerization (CWP), ring-opening polymerization (ROP), and “click” chemistry. The synthetic methodology includes the following steps: (a) synthesis of in-chain ethynyl-functionalized PCL, (PCL)₂-C ≡ CH by ROP of ε-caprolactone (CL) with ethylene-functionalized solketal (3-[prop-2-yn-1-yloxy] propane-1,2-diol) as difunctional initiator and phosphazene superbase t-BuP₂ as catalyst; (b) synthesis of azido-functionalized hyperbranched PE (HBPE-N₃) by CWP of ethylene with α-diimine-Pd(II) catalyst, followed by quenching with excess 4-vinylbenzyl chloride and transformation of chloro to azide group with sodium azide; and (c) “clicking” HBPE-N₃ and (PCL)₂-C ≡ CH using copper(I)-catalyzed azide–alkyne cycloaddition. ¹H NMR spectroscopy, gel permeation chromatography, Fourier-transform infrared spectroscopy, and differential scanning calorimetry were used to determine the molecular characteristics and thermal properties of the polymers. Self-assembly behavior of 3μ-HBPE (PCL)₂ in petroleum ether, a selective solvent for HBPE, was investigated by dynamic light scattering, atomic force microscopy, and transmission electron microscopy. The in-chain alkyne-functionalized poly(ε-caprolactone) is a valuable precursor for PCL-based complex macromolecular architectures.     

Tetracrystalline Tetrablock Quarterpolymers: Four Different Crystallites under the Same Roof

Multicrystalline block polymers having three or more crystalline segments are essential materials for the advancement of physics in the field of crystallinity. The challenging synthesis of multicrystalline polymers has resulted in only a limited number of tricrystalline terpolymers having been reported to date. We report, for the first time, the synthesis of polyethylene‐b‐poly(ethylene oxide)‐b‐poly(?‐caprolactone)‐b‐poly(l ‐lactide) (PE‐b‐PEO‐b‐PCL‐b‐PLLA), a tetracrystalline tetrablock quarterpolymer, by combining polyhomologation, ring‐opening polymerization, and an organic/metal “catalyst switch” strategy. ¹H NMR spectroscopy and gel‐permeation chromatography confirmed the formation of the tetrablock quarterpolymer, while differential scanning calorimetry, X‐ray diffraction, and wide‐line separation solid‐state NMR spectroscopy revealed the existence of four different crystalline domains.