Rubber Colloquium Co- and Terpolymers of α-Methylstyrene with Conjugated Dienes above its ceiling Temperature Adel F. Halasa, Ph.D. College of Polymer Science Goodyear Polymer Center The University of Akron [email protected] Tire Properties Wear/Traction/RR These properties are always in compromise. LAP meets these challenges. Wear: Tg, Micro & macro molecular weight dependence and long chain branching each can be controlled By living anionic polymerization. Ex. Low Tg, vinyl, SBR narrow Mw/Mn styrene composition controlled 90% 1,4-structure,amine terminated excellent wear. As compared to emulsion SBR 2 Alpha-Methylstyrene (α-MeSt) Provides a different microstructure and macrostructure as compared to traditional SSBRs Additional -CH3 group should result in better wear properties Inability to homopolymerize above ceiling temperature - result no blockiness in the polymer backbone (only one or two units of αMS exist) 01/15/01 α-MeSt / Dienes The alpha-methyl styrene (α-MeSt) thermodynamically does not homopolymerize at elevated temperatures due to the low ceiling temperature of the monomer (61°C, neat monomer). alpha-methylstyrene does copolymerized with conjugated dienes at its ceiling temperature in Solution Anionic Polymerization if suitable monomers are used 4 Catalyst System • Catalyst Compostion . CsOR / TMEDA / Mg(Bu)2 2/2/1 . KOAm / TMEDA / Mg(Bu)2 2/2/1 . CsOR / TMEDA / n-BuLi 2/2/1 • Produces a random; . αMSBR . αMSSBR . αMSIBR . αMSSIBR • Linear polymer chains are achieved • Large molecular weight distribution - this could give better traction 01/15/01 Synthesis of αMeSBR - CsOR / TMEDA / Mg(Bu)2 system - α-MeSt 1,2-Bd 1,4-Bd Branch α-MeSt/Bd Ratio Tg (oC) ML-4 M M /M (%) (%) (%) w w n (%) 20/80 2/2/1 -53.0 35 21 32 47 386K 3.3 20/80 2/2/1 -53.9 68 20 34 46 - - 20/80 2/2/1 -54.1 108 20 31 49 520K 4.9 30/70 2/2/1 -42.0 74 31 30 39 461K 3.8 30/70 2/2/1 -44.0 77 33 27 40 481K 4.6 30/70 2/2/1 -44.4 88 30 28 42 492K 5.3 40/60 2/2/1 -32.0 96 42 26 32 512K 3.5 40/60 2/2/1 -32.0 - 43 22 35 430K 6.2 70 40/60 2/2/1 -36.0 81 42 24 34 472K 6.1 63 40/60 1/2/1 -33.5 - 43 23 34 430K 5.4 67 50/50 2/2/1 -27.9 52 52 19 29 270K 4.8 6 Synthesis of αMeSBR (30/70) - Time (min) vs. Conversion (%) - 100 Butadiene 80 α-MeSt 60 40 Conversion (%) 20 0 0 20 40 60 Time (Minutes) 7 o 30/70 a-MeSt SBR via 2/2/1 CsOR/TMEDA/MgR2 at 65 C Target Mn=225K Synthesis of αMeSBR (30/70) - Total Conversion (%) vs. Conversion (%) - 100 Butadiene α-MeSt 80 60 40 Conversion (%) 20 0 0 20 40 60 80 100 Total Convesion (%) 8 o 30/70 a-MeSt SBR via 2/2/1 CsOR/TMEDA/MgR2 at 65 C Target Mn=225K Synthesis of αMeSBR - KOAm / TMEDA / Mg(Bu)2 system - Tg α-MeSt 1,2-Bd 1,4-Bd Branch α-MeSt/Bd Ratio ML-4 M M /M (oC) (%) (%) (%) w w n (%) 10/90 2/2/1 -64.3 59 9 36 55 423K 3.9 15/85 2/2/1 -65.3 32 13 34 53 318K 4.0 20/80 2/2/1 -58.7 46 18 34 48 386K 4.4 20/80 2/2/1 -58.3 25 18 35 47 299K 4.7 20/80 4/2/1 -63.3 20 17 29 54 250K 4.6 20/80 2/2/1 -61.9 - 17 33 50 450K 5.4 45 9 Synthesis of αMeSBR (10/90) - Time (min) vs. Conversion (%) - 100 80 Butadiene α-MeSt 60 40 Conversion (%) 20 0 0 40 80 120 160 200 Time (Minutes) 10 o 10/90 a-MeSt SBR via 2/2/1 KOAm/TMEDA/MgR2 at 65 C Target Mn=350K Synthesis of αMeSBR (10/90) - Total Conversion (%) vs. Conversion (%) - 100 Butadiene α-MeSt 80 60 40 Conversion (%) 20 0 0 20 40 60 80 100 Total Conversion (%) 11 o 10/90 a-MeSt SBR via 2/2/1 KOAm/TMEDA/MgR2 at 65 C Target Mn=350K Synthesis of αMeSBR - CsOR / TMEDA / n-BuLi system - Tg α-MeSt 1,2-Bd 1,4-Bd Branch α-MeSt/Bd Ratio ML-4 M M /M (oC) (%) (%) (%) w w n (%) 15/85 2/2/1 -56.7 144 18 30 52 630 4.2 30/70 2/2/1 -41.2 100 31 28 41 485 6.0 40/60 4/2/1 -44.6 - - - - 300K 7.5 80 40/60 2/2/1 -30.0 - 45 22 33 450K 7.4 70 40/60 2/2/1 -29.8 - 42 23 35 - - 40/60 2/2/1 -31.5 - 43 23 34 - - 12 Terpolymers and Tetrapolymer PBd (%) PI (%) Tg α-MeSt CsOR/TMEDA/Mg(Bu) ML-4 St (%) 2 (oC) (%) 1,2 1,4 1,2 1,4 3,4 25/50/25 α-Methyl styrene / Isoprene / Butadiene (α-MeSIBR) 2 / 2 / 1 -39.0 18.5 25 13 11 0 34 17 - 2 / 2 / 1 -38.4 26 27 12 10 2 31 10 - 20/10/70 α-Methyl styrene / Styrene / Butadiene (α-MeSSBR) 2 / 2 / 1 -53.1 68 19 27 41 - - - 13 21/21/25/33 α-Methyl styrene / Styrene / Isoprene / Butadiene (α-MeSSIBR) 2 / 2 / 1 -37.0 0 21 15 18 0 16 9 21 13 Synthesis of α-MeSIBR (25/50/25) - Time (min) vs. Conversion (%) - 100 Butadiene 80 Isoprene α-MeSt 60 40 Conversion (%) 20 0 0 10 20 30 40 50 60 Time (Minutes) 25/50/25 a-MeSIBR via 2/2/1 CsOR/TMEDA/MgR2 at 65°C Synthesis of α-MeSIBR (25/50/25) - Total Conversion (%) vs. Conversion (%) - 100 Butadiene Isoprene α-MeSt 80 60 40 Conversion (%) 20 0 0 20 40 60 80 100 Total Conversion (%) 15 25/50/25 a-MeSIBR via 2/2/1 CsOR/TMEDA/MgR2 at 65°C Synthesis of α-MeSSBR (20/10/70) - Time (min) vs. Conversion (%) - 100 α−MeSt 80 Butadiene Styrene 60 40 Convesion (%) 20 0 0 10 20 30 40 Time (Minutes) o 16 2/2/1 of CsOR/TMEDA/Mg(Bu)2 at 56-77 C Synthesis of α-MeSSBR (20/10/70) - Total Conversion (%) vs. Conversion (%) - 100 80 60 α-MeSt 40 Butadiene Conversion (%) Styrene 20 0 0 20 40 60 80 100 Total Conversion (%) o 17 2/2/1 of CsOR/TMEDA/Mg(Bu)2 at 56-77 C Synthesis of α-MeSSIBR (21/21/25/33) - Time (min) vs. Conversion (%) - 100 80 60 40 Conversion (%) Isoprene α-MeSt 20 Butadiene Styrene 0 0 20 40 60 80 100 Time (Minutes) o 18 2/2/1 of CsOR/TMEDA/Mg(Bu)2 at 65 C Synthesis of α-MeSSIBR (21/21/25/33) - Total Conversion (%) vs. Conversion (%) - 100 80 60 40 Conversion (%) Isoprene 20 α-MeSt Butadiene Styrene 0 0 20 40 60 80 100 Total Conversion (%) o 19 2/2/1 of CsOR/TMEDA/Mg(Bu)2 at 65 C Reaction Mechanism 20 Summary Catalysts consisting of KOAm/TMEDA/Mg(Bu)2, CSOR/TMEDA/Mg(Bu)2 and CSOR/TMEDA/n-BuLi can successfully copolymerize α-methyl styrene, even at elevated temperatures. The CSOR/TMEDA/Mg(Bu)2 system has similar polymerization rates for α-methylene styrene and butadiene, resulting in the ability to incorporate higher α-methyl styrene amounts. Replacing the Mg(Bu)2 with n-BuLi results in a similar material. 21 Summary The similarity between polymers produced from Mg(Bu)2 or n-BuLi combined with the fact that n-BuLi cannot polymerize α-methyl styrene by itself would suggest that the active catalyst species is the cesium (or potassium) ion, while the Mg(Bu)2 and n-BuLi are acting more as reducing agents.. A fairly uniform distribution of α-methyl styrene is present along the polymer chain, with slightly more frequent α-methyl styrene incorporated at the end of the reaction when the butadiene is depleted. 22 Acknowledgement I’d like to acknowledge Goodyear Tire & Rubber Company. Dr. Kawg Su Seo College of Polymer science. 23 References 1. G. Odian ed. Principals of Polymerization. John Wiley & Sons, New York, 1995, p. 268-271. 2. H. 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