Synthesis and characterization of graft copolymers of syndiotactic polystyrene with polybutadiene and 4‐methylstyrene

Abstract

The basic method for synthesizing syndiotactic polystyrene-g-polybutadiene graft copolymers was investigated. First, the syndiotactic polystyrene copolymer, poly(styrene-co-4-methylstyrene), was prepared by the copolymerization of styrene and 4-methylstyrene monomer with a trichloro(pentamethyl cyclopentadienyl) titanium(IV)/modified methylaluminoxane system as a metallocene catalyst at 50 C. Then, the polymerization proceeded in an argon atmosphere at the ambient pressure, and after purification by extraction, the copolymer structure was confirmed with 1 H-NMR. Lastly, the copolymer was grafted with polybutadiene (a ready-made commercialized unsaturated elastomer) by anionic grafting reactions with a metallation reagent. In this step, poly(styreneco-4-methylstyrene) was deprotonated at the methyl group of 4-methylstyrene by butyl lithium and further reacted with polybutadiene to graft polybutadiene onto the deprotonated methyl of the poly(styrene-co-4-methylstyrene) backbone. After purification of the graft copolymer by Soxhlet extraction, the grafting reaction copolymer structure was confirmed with 1 H-NMR. These graft copolymers showed high melting temperatures (240-250 C) and were different from normal anionic styrene-butadiene copolymers because of the presence of crystalline syndiotactic polystyrene segments. Usually, highly syndiotactic polystyrene has a glass-transition temperature of 100 C and behaves like a glassy polymer (possessing brittle mechanical properties) at room temperature. Thus, the graft copolymer can be used as a compatibilizer in syndiotactic polystyrene blends to modify the mechanical properties to compensate for the glassy properties of pure syndiotactic polystyrene at room temperature.

Preparation of Tethered Half-Titanocene Complex on Syndiotactic Poly(styrene-co-p-methylstyrene) for Using in Syndiospecific Polymerization of Styrene

“…2, the characteristic peak (phenyl C-1 carbon at 144.3 ppm) in spectrum is strong and sharp confirming that the obtained copolymer is syndiotactic. Figure 2 shows the peak at 20.1 ppm derived from methyl carbon in p-methylstyrene units and the entire spectrum matches with those of sPSMS in previous reports [33,34].…”

Grafted polydimethylsiloxane onto syndiotactic poly(styrene-co-p-methylstyrene): Synthesis and characterization

“…Figure 4(a) shows the peak at 20.1 ppm derived from methyl carbon in p-methylstyrene units and the entire spectrum matches with those of sPSMS in previous reports. 21,22 Characterization of sPSMS-graft-PDMS and Solvent Effect on the Degree of Graft. In order to investigate the effect of solvent on the degree of graft, the grafting reaction with hexamethylcyclotrisiloxane was carried out in two different solvents (THF and cyclohexane) under the same reaction condition.…”

“…E-mail: aaentezami@yahoo.com or aentezami@tabrizu.ac.ir blended with sPS. 22 Silicons of various microstructure and architecture are widely used in industry mainly because of their absence of toxicity, high chain flexibility and low surface energy. There are only a few reports concerning the synthesis of graft copolymers having polydimethylsiloxane and sPS by anionic ring-opening polymerization of hexamethylcyclotrisiloxane (D 3 ) from a side chain functionalized syndiotactic polystyrene.…”

Novel monocyclopentadienyl zirconium and hafnium trialkoxide complexes: Syntheses and catalytic properties for olefin polymerization

“…6) reveal that EPs prepared using monoCp Zr alkoxide have a very low level of propylenepropylene repeating units (S aa ) comparing with EPs prepared using other metallocene catalysts. 16 The extremely low level of propylene-propylene repeating units indicates that EPs prepared by these new catalyst systems have a unique microstructure, which is characterized by its highly random EP distribution. This unique microstructure is highly desirable for EP rubber.…”

“…[1][2][3] Utilization of various structures of Group 4 metal catalysts to provide effective polymer architectural control (e.g., molecular weight, 4,5 molecular weight distribution, 6,7 regiochemistry, [8][9][10] stereochemistry, [11][12][13][14] branching, [15][16][17] and chain end functionalization [18][19][20][21][22][23] ) has led to significant advancement in polymer chemistry. Studies have demonstrated that employing different structures of Group 4 metal catalysts in olefin polymerizations drastically affects the chain reaction pathways; 24,25 thus, specific polymer architectures can be obtained by the proper selection of Group 4 metal catalysts.…”