Low molar mass polybutadiene made crosslinkable by the introduction of silane moities via urethane linkage: 1. Synthesis and kinetic study

• Published in: Polymer (Guilford) Vol. 39; no. 4; pp. 965 - 971
• Main Authors: Schapman, F., Couvercelle, J.P., Bunel, C.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1998; Elsevier
• Subjects: Applied sciences; Chemical modifications; Chemical reactions and properties; Exact sciences and technology; modification; Organic polymers; Physicochemistry of polymers; polybutadiene; silane; silane; polybutadiene; modification; Organic isocyanate; Catalytic reaction; End group; Telechelic polymer; Organic silane; Experimental study; Organic carbamate; Chemical modification; Butadiene polymer; Preparation; Kinetics; Tin Organic compounds; Butadiene(hydroxy) polymer; Activation energy
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/S0032-3861(97)00354-6

Polybutadiene crosslinkable under moisture was synthesised by modification of hydroxy telechelic functions of low molecular weight polybutadiene with isocyanato propyl triethoxy silane. At 50°C and with dibutyl tin dilaurate (DBTL) as catalyst, silane moities were introduced quantitatively at the rate of 1.2, 2 and 2.4 per polymer chain. Two analytical methods ( FTi.r. spectroscopy and volumetric titration) were used to follow isocyanate consumption. Two kinetic treatments were investigated (2nd and 3rd order) and influence of catalyst concentration and temperature were studied. A 2nd order kinetic seems to be better fitted for our experimental results. Nevertheless, in each case, Arrhenius law suggests an entropically controlled reaction with probably ethoxy silane groups participating in a transition state in the presence of DBTL.