Origin of catalytic activity differences between phosphine and phosphine oxide-based structures in the water-crosslinkable polyalkoxysilane composition

Document Type : Original research


1 Department of Chemistry, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, 753-8512, Japan

2 Kuriyama R&D Inc., Sayama, Yamaguchi, 747-0849, Japan

3 Opto-Energy Research Center, Yamaguchi University, Yamaguchi, 753-8511, Japan


Organocatalysts have attracted enormous interest in the water-crosslinking reaction in silane-grafted polyolefins (SGPOs) system owing to their simplicity, low toxicity and environmentally benign nature compared to organotin catalysts, which are most used in SGPOs system. We focus on organophosphorus compounds including four structure types as organocatalysts; phosphoric acids, phosphoric esters, phosphine oxides and phosphine. The catalytic activities of them for the water-crosslinking reaction in 3-methacryloxypropyltrimethoxysilane grafted ethylene-propylene copolymer (EPR-g-MTMS) system were evaluated using the ATR-FTIR technique and gel-fraction method. The phosphine oxides, phosphoric acids, and phosphoric esters possessing an O=PR3 or O=P(OR)3 unit were found to be an excellent catalyst for the water-crosslinking reaction in EPR-g-MTMS system, while phosphine (PR3) showed no catalytic activity on water-crosslinking reaction in this system, indicating the phosphoryl (P=O) moiety played the important role on catalytic performance of these compounds. In comparison, phosphine oxides showed considerably higher catalytic activities than phosphoric acids / esters. Density functional theory (DFT) calculations demonstrated that the difference of catalytic activity could be attributed to an electron density at P=O moiety making the activation for water through hydrogen-bonding. Finally, the possible catalytic mechanism for the phosphoryl compounds in the EPR-g-MTMS system was proposed on the basis of these results and the SN2-Si pathway in silicate sol-gel chemistry.


Main Subjects

  1. Boaen NK, Hillmyer MA (2005) Post-polymerization functionalization of polyolefins. Chem Soc Rev 34: 267-275
  2. Scott HG (1972 Feb 29) Crosslinking of a Polyolefin with a Silane, U.S. Patent 3, 646, 155
  3. Sirisinha K, Chimdist S (2008) Silane-crosslinked ethylene–octene copolymer blends: Thermal aging and crystallization study. J Appl Polym Sci 109: 2522-2528
  4. Sirisinha K, Boonkongkaew M, Kositchaiyong S (2010) The effect of silane carriers on silane grafting of high-density polyethylene and properties of crosslinked products. Polym Test 29: 958-965
  5. Han C, Bian J, Liu H, Han L, Wang S, Dong L, Chen S (2010) An investigation of the effect of silane water-crosslinking on the properties of poly(L-lactide). Polym Inter 59: 695-703
  6. Qiao J, Guo M, Wang L, Liu D, Zhang X, Yu L, Song W, Liu Y (2011) Recent advances in polyolefin technology. Polym Chem 2: 1611-1623
  7. Hanifpour A, Bahri-Laleh N, NekoomaneshHaghighi M (2020) Preparation of novel, liquid, solvent-free polyplefin-based adhesives. Polym Adv Technol 31: 922-931
  8. Hanifpour A, Bahri-Laleh N, NekoomaneshHaghighi M (2020) Methacrylate-functionalized POSS as an efficient adhesion promoter in olefinbased adhesives. Polym Eng Sci 60: 2991-3000
  9. Adachi K, Hirano T (2009) The utility of sulfonic acid catalysts for silane water-crosslinked network formation in the ethylene–propylene copolymer system. J Sol-Gel Sci Technol 49: 186- 195
  10. Wang D, Klein J, Mejia E (2017) Catalytic systems for the cross-linking of organosilicon polymers. Chem Asian J 12: 1180-1197
  11. Cervantes J, Zarraga R, Salazar-Hernandez C (2012) Organotin catalysts in organosilicon chemistry. Appl Organometal Chem 26: 157-163
  12. Cypryk M, Gostyruski B, Pokora M, (2019) Hydrolysis of trialkoxysilanes catalysed by the fluoride anion. Nucleophilic vs. basic catalysis. New J Chem 43: 15222-15232
  13. Valliant EM, Jones JR (2011) Softening bioactive glass for bone regeneration: sol–gel hybrid materials. Soft Matter 7: 5083-5095
  14. Brinker CJ, Scherer GW (1990) Sol–gel science the physics and chemistry of sol–gel processing. Academic Press Inc., New York
  15. Sardon H, Engler AC, Chan JMW, Garcia JM, Coady DJ, Pascual A, Mecerreyes D, Jones GO, Rice JE, Horn HW, Hedrick JL (2013) Organic acid-catalyzed polyurethane formation via a dual-activated mechanism: Unexpected preference of N-activation over O-activation of isocyanates. J Am Chem Soc 135: 16235-16241
  16. Ignatyev IS, Montejo M, Gonzalez JJL (2009) Role of structures with penta- and hexacoordinate silicon in the nucleophile-catalyzed hydrolysis of tetramethoxysilane. Phys Chem Chem Phys 11: 841-847
  17. Bassindale AR, Liu Z, Mackinnon IA, Taylor PG, Yang Y, Light ME, Horton PN, Hursthouse MB (2003) A higher yielding route for T8 silsesquioxane cages and X-ray crystal structures of some novel spherosilicates. Dalton Trans 14: 2945-2949
  18. Fuchise K, Igarashi M, Sato K, Shimada S (2018) Organocatalytic controlled/living ring-opening polymerization of cyclotrisiloxanes initiated by water with strong organic base catalysts. Chem Sci 9: 2879-2891
  19. Kobayashi K, Ueno M, Kondo Y (2006) Phosphazene base-catalyzed condensation of trimethylsilylacetate with carbonyl compounds. Chem Commun 3128-3130
  20. Saito T, Aizawa Y, Tajima K, Isono T, Satoh T (2015) Organophosphate-catalyzed bulk ringopening polymerization as an environmentally benign route leading to block copolyesters, endfunctionalized polyesters, and polyester-based polyurethane. Polym Chem 6: 4374-4384
  21. Delgove MAF, Wroblewska AA, Stouten J, van Slagmaat CAMR, Noordijk J, De Wildeman SMA, Bernaerts KV (2020) Organocatalyzed ring opening polymerization of regio-isomeric lactones: Reactivity and thermodynamics considerations. Polym Chem 11: 3573-3584
  22. Chen S, Wang H, Li Z, Wei F, Zhu H, Xu S, Xu J, Liu J, Gebru H, Guo K (2018) Metallic organophosphate catalyzed bulk ring-opening polymerization. Polym Chem 9: 732-742
  23. Gal JF, Maria PC, Yanez M, Mo O (2019) On the lewis basicity of phosphoramides: A critical examination of their donor number through comparison of enthalpies of adduct formation with SbCl5 and BF3. Chem Phys Chem 20: 2566- 2576
  24. Tupikina EY, Bondensteiner M, Tolstoy PM, Denisov GS, Shenderovich LG (2018) P═O moiety as an ambidextrous hydrogen bond acceptor. J Phys Chem C 122: 1711-1720
  25. Liu X, Verkada JG (2001) Electron-rich O = PR3 compounds: Catalysts for alcohol silylation. Heteroat Chem 12: 21-26
  26. Huang T, Saga Y, Guo H, Yoshimura A, Ogawa A, Han LB (2018) Radical hydrophosphorylation of alkynes with R2P(O)H generating alkenylphosphine oxides: Scope and limitations. J Org Chem 83: 8743-8749
  27. Makiguchi K, Satoh T, Kakuchi T (2011) Diphenyl phosphate as an efficient cationic organocatalyst for controlled/living ring-opening polymerization of δ-valerolactone and ε-caprolactone. Macromolecules 44: 1999-2005
  28. Krasovec F, Jan J (1963) Investigation on the extraction of metal ions with different organophosphorus compounds. I. The dissociation, distribution and dimerization of some di-aryl esters of orthophosphoric acid. Croat Chem Acta 35: 183- 193
  29. Tanaka S, Adachi K (2019) A novel efficient catalyst for water-crosslinking reaction of silanegrafted polyolefin system: Specific influence of axially coordinated n-alkylamine ligand on catalytic abilities of metal acetylacetonate complex. Mater Today Commun 21: 100584
  30. Bartob AFM (1983) Handbook of Solubility Parameters and Other Cohesion Parameters. Boca Raton
  31. Barton AFM (1985) Applications of solubility parameters and other cohesion parameters in polymer science and technology. Pure Appl Chem 57: 905-912
  32. Frisch M J, Trucks G, Schlegel H, Scuseria G, Cheeseman J, Scalmani G, Barone V, Mennucci B, Petersson G (2009) Gaussian 09 Revision D. 01. Gaussian. Inc., Wallingford CT
  33. Lee C, Yang W, Parr RG (1987) Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Phys Rev B 37: 785-789
  34. Mclean AD, Chandler CS (1980) Contracted Gaussian basis sets for molecular calculations. I. Second row atoms, Z=11-18. J Chem Phys 72: 5639-5648
  35. West JK (1997) Theoretical analysis of hydrolysis of polydimethylsilozane (PDMS). J Biomed Mater Res 35: 505-511
  36. West JK, Hench LL (1994) Silica fracture Part I. A ring contraction mode. J Mater Sci 29: 3601- 3606
  37. Shieh YT, Liu CM (1999) Silane grafting reactions of LDPE, HDPE, and LLDPE. J Appl Polym Sci 74: 3404-3411
  38. Zhao Q, Liu Q, Xu H, Bei Y, Feng S (2016) Preparation and characterization of room temperature vulcanized silicone rubber using α-amine ketoximesilanes as auto-catalyzed cross-linkers. RSC Adv 6: 38447-38453
  39. Adachi K, Hirano T (2008) Good linear relationship between logarithms of Eigen’s water exchange constants for several divalent metal ions and activation energies of corresponding metalcatalyzed alkoxysilane hydrolysis in ethylene– propylene copolymer system. Eur Polym J 44: 542-549
  40. Adachi K, Hirano T (2008) Controllable silane water-cross-linking kinetics and curability of ethylene−propylene copolymer by amine compounds. Ind Eng Chem Res 47: 1812-1819
  41. Tan YC, Zeng HC (2018) Lewis basicity generated by localised charge imbalance in noble metal nanoparticle-embedded defective metal–organic frameworks. Nature Com 9: 4326
  42. Giba IS, Mulloyarova VV, Denisov GS, Tolstoy PM (2019) Influence of hydrogen bonds in 1:1 complexes of phosphinic acids with substituted pyridines on 1H and 31P NMR chemical shifts. J Phys Chem A 123: 2252-2260
  43. Tanaka F, Edwards SF (1992) Viscoelastic properties of physically crosslinked networks. 1. Transient network theory. Macromolecules 25: 1516-1523
  44. Aelion R, Loebel A, Eirich F (1950) Hydrolysis of ethyl silicate. J Am Chem Soc 72: 5705-5712
  45. Grubb WT (1954) A rate study of the silanol condensation reaction at 25° in alcoholic solvents. J Am Chem Soc 76: 3408-3414
  46. Bassindale AR, Chen H, Liu Z, Mackinnon A, Parker DJ, Taylor PG, Yang Y, Light ME, Horton PN, Hursthouse MB (2004) A higher yielding route to octasilsesquioxane cages using tetrabutylammonium fluoride, Part 2: Further synthetic advances, mechanistic investigations and X-ray crystal structure studies into the factors that determine cage geometry in the solid state. J Organomet Chem 689: 3287-3300
  47. Mulloyarova VV, Giba IS, Denisov GS, Ostras AS, Tolstoy PM (2019) Conformational mobility and proton transfer in hydrogen-bonded dimers and trimers of phosphinic and phosphoric acids. J Phys Chem A 123: 6761-6771
  48. Styskalik A, Babiak M, Machac P, Relichova B, Pinkas J (2017) New adamantane-like silicophosphate cage and its reactivity toward tris(pentafluorophenyl)borane. Inorg Chem 56: 10699-10705
  49. Styskalik A, Skoda D, Moravec Z, Babiak M, Barenes CE, Pinkas J (2015) Control of micro/ mesoporosity in non-hydrolytic hybrid silicophosphate xerogels. J Mater Chem A 3: 7477- 7487
  50. Weinberger C, Heckel T, Schnippering P, Schmitz M, Guo A, Keil W, Marsmann HC, Schmidt C, Tiemann M, Wihelm R (2019) Straightforward immobilization of phosphonic acids and phosphoric acid esters on mesoporous silica and their application in an asymmetric aldol reaction. Nanomaterials 9: 249