Synthesis and distribution of structural units-Thermal property relationship of random and block butadiene-styrene copolymers with high trans 1,4 units content produced using an initiator composed of alkyl aluminum, n-butyl lithium, and barium alkoxide

• Published in: Journal of applied polymer science Vol. 116; no. 5; pp. 3103 - 3110
• Main Authors: Benvenuta-Tapia, Juan José, Tenorio-López, José Alfredo, Herrera-Nájera, Rafael, Ríos-Guerrero, Leonardo
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 05.06.2010; Wiley
• Subjects: 4 polybutadiene; Aluminum; anionic polymerization; Applied sciences; Block copolymers; Butadiene; Copolymerization; Copolymers; distribution of structural units; Exact sciences and technology; high trans 1; high trans 1,4 polybutadiene; Lithium; Organic polymers; Physicochemistry of polymers; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; Styrenes; Thermal properties; Butadiene copolymer; Molecular structure; high trans 1,4 polybutadiene; anicnic polymerization; Priming activity; Diene copolymer; Lithium Organic compounds; Barium Compounds; Butadiene-1,4 copolymer; Trans stereoisomer; thermal 'properties; Alkoxide; Anionic copolymerization; copolymerization; Diene polymer; Living polymer; distribution of structural units; Experimental study; Thermal properties; Random copolymer; Triblock copolymer; Preparation; Anionic catalyst; Diblock copolymer; Property structure relationship; Aluminium Organic compounds; Kinetics; Styrene copolymer
• ISSN: 0021-8995; 1097-4628; 1097-4628
• DOI: 10.1002/app.31853

Random, diblock, and triblock copolymers of butadiene and styrene, with a well‐defined, high number of 1,4‐trans units (c.a. 80%), were synthesized by anionic living polymerization using an initiator system composed of alkyl aluminum, n‐butyl lithium, and barium alkoxide. The thermal properties of the block copolymers obtained by sequential addition of monomers were basically determined by the 1,4‐trans units of the polybutadiene block. Kinetic data and 1H‐nuclear magnetic resonance analyses showed that simultaneous polymerization of butadiene and styrene provided copolymers with a predominantly random distribution. By increasing the styrene content, the thermal properties of these copolymers were modified; polymers with 80% content of 1,4‐trans units and 5% of styrene presented an endothermic transition at or slightly below room temperature (20°C), corresponding to the crystalline monoclinic form of high 1,4‐trans polybutadiene, whereas copolymers with 25–50% styrene content were amorphous. The glass transition temperature of these copolymers increased significantly as the styrene content was increased. Both the block and random copolymers have a sufficient number of 1,4‐trans units to display a regular distribution of structural units that makes them susceptible to strain‐induced crystallization, which is important for the manufacture of products such as high‐performance tires. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010