Syndioselective coordination polymerization of unmasked polar methoxystyrenes using a pyridenylmethylene fluorenyl yttrium precursor

Abstract

A new family of syndiotactic polystyrene derivatives containing a methoxyl group was established successfully by employing a yttrium catalyst.

Stereoselective Copolymerization of Unprotected Polar and Nonpolar Styrenes by an Yttrium Precursor: Control of Polar‐Group Distribution and Mechanism

“…These results were quite different from those observed for the previously reported copolymerization of St with ap olar styrene masked by bulky groups or with pMOS in the presence of titanium-based catalysts,which gave only low-molecular-weight copolymers (M n = 0.8-2 10 4 gmol À1 ) [3a] or am ixture of two homopolymers,r espectively. Fore xample, the methylene-methine hydrogen atoms of St-oMOS copolymers gave triplet-quintet resonances centered at d = 1.52 (Ha) and 2.45 ppm (Hb) for sP(MOS) sequences [16] and at d = 1.28 (Hc) and 1.80 ppm (Hd) for sPS sequences.T he methylene and methine hydrogen atoms at junctions between sPS and sP(oMOS) units were identified at d = 1.40 (Hc')and 1.85 ppm (Hd')a nd d = 1.46 (Ha')a nd 2.40 ppm (Hb'), Figure S4). Fore xample, the methylene-methine hydrogen atoms of St-oMOS copolymers gave triplet-quintet resonances centered at d = 1.52 (Ha) and 2.45 ppm (Hb) for sP(MOS) sequences [16] and at d = 1.28 (Hc) and 1.80 ppm (Hd) for sPS sequences.T he methylene and methine hydrogen atoms at junctions between sPS and sP(oMOS) units were identified at d = 1.40 (Hc')and 1.85 ppm (Hd')a nd d = 1.46 (Ha')a nd 2.40 ppm (Hb'), Figure S4).…”

“…More strikingly,t he copolymerization of mMOS with St not only occurred successfully (1.26 10 6 gmol Y À1 h À1 ), but also with more uniformly controlled mMOS incorporation (Table 1, entries 6-10). Thea ctivity dropped dramatically as the pMOS loading increased (Table 1, entries [11][12][13][14][15][16][17]. Thea ctivity dropped dramatically as the pMOS loading increased (Table 1, entries [11][12][13][14][15][16][17].…”

Coordination‐Insertion Copolymerization of Norbornene and p‐Substituted Styrenes Using Anilinonaphthoquinone‐Ligated Nickel Complexes

“…Typical 13 C NMR spectra of the N/MeOS, N/MeS, and N/ClS copolymers (Run 2, 9, and 18) are shown in Figures 1b, 2b, and 3b. Each signal of the N/MeOS copolymer was assigned as follows in reference to those of N/S copolymer obtained by the same catalyst23 and S/MeOS copolymer obtained by an yttrium‐based catalyst24,25: 137.0 ppm for C 1 , 112.9 ppm for C 2 , 128.1 ppm for C 3 , 157.5 for C 4 , 54.9 for C 5 , 47.0 and 39.3 ppm for C 6 and C 7 of the MeOS segment; 49–52.7 ppm for C 8 , 36.5–38.8 ppm for C 9 , 33.8–36 ppm for C 10 , and 28.0–31.9 ppm for C 11 of the N unit. The phenyl carbons of the MeOS units in the regions of 113–157 ppm and methoxy carbon in the regions of 55 ppm indicate the presence of the MeOS units in the N/MeOS copolymer (Figure 1b).…”

Syndiospecific Coordination Polymerization of Si‐H‐Containing Styrenes Catalyzed by Scandium Complex and Synthesis of Styrene‐Based Triblock Copolymers

“…One involves functionalized styrene containing polar group, the other involves functionalized styrene containing reactive group. To date, through the direct polymerization, some polar functional groups such as amino, silyloxy, methoxy, methylthio, and halogen groups have been successfully introduced into sPS to improve its properties. But the direct polymerization of such styrene derivatives is still limited to the combination of polar groups with specific catalyst systems, because the strong Lewis acid–base interaction between polar groups and catalyst centers extremely restricted polymerization stereoselectivity and activity.…”