Novel Surface-Attachable Multifunctional Initiators: Synthesis, Grafting, and Polymerization in Aprotic and Protic Solvents

• Published in: Macromolecules 2009-07, Vol.42 (13), p.4539-4546
• Main Authors: Czaun, Miklós, Hevesi, László, Takafuji, Makoto, Ihara, Hirotaka
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma900419q

Novel surface attachable AIBN type initiators involving mono-/di-/trichlorosilane anchoring groups have been successfully synthesized and grafted onto silica microspheres (average diameter, pore size and surface area are 5 μm, 12 nm, and 300 m2 g−1 respectively). Graft density of surface-tethered initiators was estimated on the basis of elemental analysis and thermogravimetric measurements giving 0.446, 0.705, and 0.819 group nm−2 respectively. Owing to the presence of two anchoring groups newly described initiators can attach to the surface through both ends avoiding the fragment-initiated polymerization in the solution that was considered as a main drawback of asymmetric AIBN-type initiators. Surface-initiated radical polymerization of styrene and N-vinyl pyrrolidone has been carried out in toluene and water solutions respectively, giving polymer-silica hybrids. Immobilized polystyrene chains were detached from the surface then the molecular weight and molecular weight distribution was determined by gel permeation chromatography giving 141 200 Da (5.58), 145 700 (5.72) and 149 100 Da (5.94), respectively. The connection between the initiator structure and average molecular weight of degrafted polymers furthermore the effect of possible radical−radical termination reaction on the molecular weight is also discussed.