Preparation of scratch- and abrasion-resistant polymeric nanocomposites by monomer grafting onto nanoparticles, 4 -: Application of MALDI-TOF mass spectrometry to the characterization of surface modified nanoparticles

被引:49
作者
Bauer, F
Sauerland, V
Ernst, H
Gläsel, HA
Naumov, S
Mehnert, R
机构
[1] Inst Oberflachenmodifizierung, D-04318 Leipzig, Germany
[2] Bruker Daltonik GmbH, D-04318 Leipzig, Germany
[3] Univ Leipzig, Inst Expt Phys 1, D-04103 Leipzig, Germany
关键词
coatings; fillers; MALDI; nanocomposites; polysiloxanes;
D O I
10.1002/macp.200390003
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
To obtain transparent, scratch- and abrasion-resistant coating materials a high content of nanosized silica and alumina filler was embedded in radiation-curable acrylate formulations by acid catalyzed silylation using trialkoxysilanes. Si-29 magic angle spinning (MAS) NMR spectroscopy and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) were used to elucidate the structure of the surface-grafted methacryloxypropyl-, vinyl-, and n-propyltrimethoxysilane. Si-29 MAS NMR measurements revealed a predominance of T-2 and T-3 structures of silicon atoms, i.e., silane oligomers have been formed by an extensive loss of water. For methacryloxypropyltrimethoxysilane, the proportion of the highly condensed T3 silicon atoms was estimated to be 75%. In accordance with these NMR findings, MALDI-TOF MS showed highly condensed oligomeric siloxanes of more than 20 monomeric silane units. The degree of silane condensation is higher on alumina than on silica, irrespective to the addition of maleic acid as catalyst. Moreover, completely condensed silsesquioxanes, e.g., octamers, decamers, and dodecamers, were detected. Based on the observed MS pattern, a ladder-like arrangement of two linked siloxane chains forming connected eight-membered rings is proposed, which is similar for all of the condensed organosilanes under study. The grafted polysiloxanes lead to an organophilation of inorganic nanofillers and improve their dispersibility in acrylate suspensions.
引用
收藏
页码:375 / 383
页数:9
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