Syndiotactic polymerization of methyl methacrylate

Abstract

Typical Ziegler‐type catalysts derived from AIR3 and TiCl4 were found to be effective in the syndiotactic polymerization of methyl methacrylate at low temperatures. The influences of polymerization variables on the polymer yield, the molecular weight of the polymer produced, and the syndiotactic regulating capacity of the catalysts were investigated. In general AlEt3/TiCl4 molar ratios of 3:10 mixing of both the catalyst components and aging of the catalyst system in the temperature range of −30 to 30°C. using aromatic hydrocarbon solvents such as toluene as a polymerization medium, and low polymerization temperature, such as −78°C. are the preferred conditions for the formation of syndiotactic, high molecular weight poly(methyl methacrylate) in high yield. From the results of testing catalyst activities of the separated catalyst systems it was concluded that some cooperation between AIR3 and the insoluble Ti halide compound obtained by the reduction of TiCl4 with AIR3 is essential for the formation of syndiotactic poly(methyl methacrylate).

Synthesis of highly syndiotactic polymers by discrete catalysts or initiators

“…The same authors later investigated this polymerization system in more detail and observed the polymerization can also be mediated in a similar fashion by other trialkyl aluminum species such as triisobutylaluminum and trihexylaluminum, although there was a slight decrease in syndiotacticity (rr ¼ 87-90). 109 With AlEt 3 , the syndiotacticity of the resulting PMMA reported in this full paper was somewhat higher (94% rr) at T p of À78 C. Yasuda's seminal work developed the highly stereospecific polymerization of MMA by organolanthanide catalysts, leading to polymers with unprecedentedly high MW's and narrow MWD's. 110,111 In 1992, Yasuda and co-workers reported the use of neutral, single-component, trivalent lanthanocenes, such as dimeric samarocene hydride [Cp * 2 SmH] 2 (28,Chart 9), as catalysts for living polymerization of MMA in toluene.…”

Helix-Sense-Selective Encapsulation of Helical Poly(lactic acid)s within a Helical Cavity of Syndiotactic Poly(methyl methacrylate) with Helicity Memory

“…The st-PMMA was synthesized using the stereospecific polymerization technique (see SI). 90 The M n , its distribution (M w /M n ), and stereoregularities (mm:mr:rr) were as follows: M n = 616 kDa, M w /M n = 1.36, and mm:mr:rr = 0:4:96, in which m and r represent the isotactic (it) and st dyads of the meso and racemo sequences, respectively, and mm, mr, and rr are the corresponding triad sequences.…”

Influence of the Primary Structure of Syndiotactic Poly(Methyl Methacrylate) on the Inclusion Complex Formation with [60]Fullerene: Robustness of the Helix against Primary Structural Errors

“…The st-PMMAs with various rr contents ( rr = 85–94%) were synthesized by the syndiotactic-specific polymerization of MMA with a tert -butyllithium/(C 2 H 5 ) 3 Al initiator (85–130 k, 85–500 k, 89–170 k, 89–580 k, and 94–640 k) or a TiCl 4 /(C 2 H 5 ) 3 Al Ziegler-type catalyst (89–2 k; the 89 and 2 k values indicate the rr content and M n , respectively, 89–5 k, 89–8 k, 89–10 k, 89–20 k, 89–30 k, and 94–8 k) in toluene at varying polymerization temperatures from −95 to −60 °C . The polymers with rr contents of 85, 89, and 94 were obtained at the polymerization temperatures of −60, −78, and −95 °C, respectively.…”

“…Materials. The st-PMMAs with various rr contents (rr = 85−94%) were synthesized by the syndiotactic-specific polymerization of MMA with a tert-butyllithium/(C 2 H 5 ) 3 Al initiator 38 39 The polymers with rr contents of 85, 89, and 94 were obtained at the polymerization temperatures of −60, −78, and −95 °C, respectively. The st-PMMA with an rr content of 97% was prepared by the syndiotactic-specific polymerization of trimethylsilyl methacrylate in toluene at −78 °C with a tert-butyllithium/bis(2,6-ditert-butylphenoxy)methylaluminum initiator followed by hydrolysis of the pendent esters and methylation with diazomethane.…”