C1 polymerization: a unique tool towards polyethylene-based complex macromolecular architectures

Abstract

The recent developments in organoborane initiated C1 polymerization of ylides open unique horizons towards perfectly linear polymethylenes (equivalent to PE) and PE-based complex structures. This review summarizes research on conventional and newly discovered initiators/ylides, as well as initial efforts on C3 polymerization.

Tetracrystalline Tetrablock Quarterpolymers: Four Different Crystallites under the Same Roof

“…Solid-state NMR spectroscopy was also used to characterize the structure of PE-b-PEO-b-PCL-b-PLLA-2 (Table 1, entry 4). The 1 Ha nd 13 CC P-MAS spectra (Figures S10 and S11) show the chemical shifts of the -(CH 2 )-protons and carbon atoms of the PE block (e) at d = 0.68 ppm and d = 33.75 ppm, respectively.The 2D 1 H-13 Cshort-distance heteronuclear correlation (HECTOR) spectrum confirms the onebond correlation between the 1 Hs ignal at d = 0.68 ppm and the 13 Csignal at d = 31.84 ppm (Figure 2a). Asharp signal at d = 2.95 ppm is assigned as the -O À (CH 2 ) 2 À O-protons (g) of the PEO block and shows as trong correlation with the 13 C signal at d = 69.17 ppm.…”

“…Table 1, It is essential to assign the chemical shift of end-group protons of each block correctly because these protons are used to determine the M n value of the block. To support the 1D 1 HNMR assignment (Figure 1a), 2D 1 H-1 Hc orrelation spectroscopy (COSY,F igure 1b), total correlation spectroscopy (TOCSY,F igure S7), 1 H- 13 Ch eteronuclear single-bond correlation (HSQC,F igure S8), and heteronuclear multiplebond correlation (HMBC, Figure S9 Figure S8). The-CH 2 À OC end groups protons of PEO (b), PCL (c), and PLLA (d; Figure 1a)that overlap in the 1D 1 HNMR spectrum could be observed in separate positions by 2D NMR spectroscopy (Figure 1b and Figures S7-S9), thus ascertaining our assignment.…”

“…2D 1 H- 13 Cc ross-polarization (CP) magic angle spinning (MAS) wide-line separation (WISE) solid-state NMR spectroscopy is ap owerful technique to assess the relationship between the structure and segmental mobility of the polymer chain. [22] Thes tructure of the polymer is reflected in the chemical shifts of the 13 Cs ignals,w hereas the segmental mobility is reflected in the line width of the 1 Hs ignals.F or ag iven 13 Cr esonance,a na verage broad 1 Hl ine width (typically more than 50 kHz) [23] corresponds to low segmental mobility (rigid chain/crystalline domain), whereas an average narrow 1 Hline width corresponds to high segmental mobility (mobile chain/amorphous domain). TheWISE contour of PEb-PEO-b-PCL-b-PLLA-2 (Table 1, entry 4) is presented in Figure 5a.T ofind the segmental mobility of each block, four 1 Hs lices extracted from specific 13 Cc hemical shifts of each block: d = 33.7 ppm, -(CH 2 )-PE;6 9.17 ppm, -OÀ(CH 2 ) 2 ÀO-PEO;2 5.28 ppm, -CH 2 ÀCH 2 ÀCH 2 -P CL;a nd 16.33 ppm, -CHÀCH 3 PLLA, are analyzed and presented in Figure 5b.…”

“…[12] Thep olymerization is performed in two consecutive steps:1)formation of an "ate" complex between the ylide (monomer) and the alkylborane (initiator), followed by 2) intramolecular 1,2migration of the three alkyl branches of the borane with the simultaneous elimination of dimethyl sulfoxide.A fter quantitative consumption of the ylide,aboron-linked PE threearm star is generated, thereby giving three linear PE-OH chains by oxidation/hydrolysis.T his method enables the synthesis of perfectly linear PE-OH with acontrolled molecular weight. [13] ThePE-OH can be used as amacroinitiator to prepare various complex macromolecular architectures in combination with other living/controlled polymerization techniques. [13] Alimited number of reports are available in the literature on tricrystalline triblock terpolymers.A betz reported the synthesis of PB-b-PEO from aPB-OH macroinitiator.PB-b-PEO was used as the macroinitiator for the noncatalyzed thermal ROPo fC Lt oa fford PB-b-PEO-b-PCL.…”

“…[13] ThePE-OH can be used as amacroinitiator to prepare various complex macromolecular architectures in combination with other living/controlled polymerization techniques. [13] Alimited number of reports are available in the literature on tricrystalline triblock terpolymers.A betz reported the synthesis of PB-b-PEO from aPB-OH macroinitiator.PB-b-PEO was used as the macroinitiator for the noncatalyzed thermal ROPo fC Lt oa fford PB-b-PEO-b-PCL. [14] Hydrogenation of the PB block was then performed with the Wilkinson catalyst to yield PE-b-PEO-b-PCL triblock terpolymers.Side reactions led to the formation of undesired PCLb-PEO diblock copolymer, which was removed by several purification steps.Kuo and co-workers reported the synthesis of PEG-b-PCL-b-PLLA by at wo-pot ROP of CL and LLA from aP EG macroinitiator catalyzed by Sn(Oct) 2 .…”