TY - JOUR A1 - Jäger, Christian A1 - Maltsev, Sergey A1 - Malz, Frank A1 - Karrasch, Andrea A1 - Altenburg, Wolfgang T1 - Nanoskalige Calciumphosphate, Oberflächenstrukturen und Wechselwirkung mit organischen Molekülen: Was kann die NMR? PY - 2005 SN - 1616-0177 SN - 0011-8656 VL - 6 IS - 3 SP - 232 PB - Verl. Neuer Merkur CY - München AN - OPUS4-11609 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jäger, Christian A1 - Maltsev, Sergey A1 - Karrasch, Andrea T1 - Progress of Structural Elucidation of Amorphous Calcium Phosphate (ACP) and Hydroxyapatite (HAp): Disorder and Surfaces as Seen by Solid State NMR KW - Hydroxyapatite KW - Amorphous calcium phosphate KW - Structural investigation KW - Surface KW - NMR PY - 2006 VL - 18 IS - 1 SP - 69 EP - 72 AN - OPUS4-11008 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karrasch, Andrea A1 - Jäger, Christian A1 - Karakawa, M. A1 - Nakatsubo, F. A1 - Potthast, A. A1 - Rosenau, T. T1 - Solid-state NMR studies of methyl celluloses. Part 1: regioselectively substituted celluloses as standards for establishing an NMR data basis N2 - Three methyl celluloses with completely uniform substitution pattern, 2-O-methyl cellulose (1), 3-O-methyl cellulose (2) and 6-O-methyl cellulose (3), were prepared according to the cationic ring opening polymerization approaches starting from substituted 1,2,4-orthopivalate derivatives of D-glucose. These samples allowed for the first time to sort out the methyl substitution effects on solid-state NMR chemical shifts and relaxation. Dipolar dephasing experiments allowed the detection and assignment (1H, 13C) of the methyl groups. In 1 and 2, these resonances overlapped with those of C-6, whereas in 3, the methyl signal experienced a low-field shift into the region of C-2,3,5. 13C T1 experiments were used to verify different relaxation behavior of the carbon sites, particularly the short relaxation time of at the carbon substitution site next to the methyl groups. This effect was used to unambiguously identify the 13C chemical shifts of the carbons carrying the methoxyl substituent, although they overlap with all resonances in the C-2,3,5 region. The data obtained for the standard samples with uniform substitution will now be used as the basis for determining methylation patterns and substitution degree in commercial methyl celluloses. KW - Methyl cellulose KW - Solid-state NMR KW - CPMAS NMR KW - Substituent distribution KW - Substitution pattern KW - Cationic ring opening polymerization KW - Methylation PY - 2009 DO - https://doi.org/10.1007/s10570-008-9247-z SN - 0969-0239 SN - 1572-882X VL - 16 SP - 129 EP - 137 PB - Chapman & Hall CY - London AN - OPUS4-18913 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karrasch, Andrea A1 - Jäger, Christian A1 - Rosenau, T. T1 - Solid-state NMR Studies of Methyl Celluloses T2 - The Alpine Conference on Solid-State NMR CY - Chamonix, France DA - 2009-09-13 PY - 2009 AN - OPUS4-19372 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karrasch, Andrea A1 - Jäger, Christian A1 - Saake, B. A1 - Potthast, A. A1 - Rosenau, T. T1 - Solid-state NMR studies of methyl celluloses. Part 2: Determination of degree of substitution and O-6 vs. O-2/O-3 substituent distribution in commercial methyl cellulose samples N2 - Solid state NMR spectroscopy was applied to determine the overall degree of substitution (DS) and the degrees of substitution at C-6 (DSC-6) and C-2/3 (DSC-2/3). Four commercial methyl cellulose samples were used, having a DS between 0.51 and 1.96 as determined by wet-chemical analysis. The strategy and optimization of the NMR data acquisition as well as the data evaluation procedures are explained in detail. Optimization of the approach mainly comprised (a) maximizing the signal by choice of NMR probe, MAS spinning frequency and B0 field, (b) minimizing the measurement time by a Torchia-type experiment and (c) suppressing probe background by rotor-synchronized echo detection. Data evaluation used simply the integration of three different spectral ranges in the 13C NMR spectrum. The results of the experiments were in good agreement with the wet-chemical data. The NMR approach takes about the same analysis time as the conventional hydrolysis/chromatography analysis. However, it is a generally applicable and simple alternative without need for an extended sample preparation which is most useful if wet-chemical/chromatographic analyses are undesired or unavailable. Further studies have to concentrate on the validation of the analytical method and application to a larger sample array. KW - Methyl cellulose KW - Solid-state NMR KW - 13C CPMAS NMR KW - Rotor-synchronized echo sequence KW - Substituent distribution KW - Substitution pattern KW - Degree of substitution PY - 2009 DO - https://doi.org/10.1007/s10570-009-9304-2 SN - 0969-0239 SN - 1572-882X VL - 16 IS - 6 SP - 1159 EP - 1166 PB - Chapman & Hall CY - London AN - OPUS4-21130 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karrasch, Andrea A1 - Jäger, Christian A1 - Braun, Ulrike A1 - Schartel, Bernhard T1 - Thermal decomposition of PDMS in flame-retarded bisphenol-A polycarbonate: A solid-state NMR investigation T2 - GDCh-Tagung Magnetische Resonanz 2008 CY - Regensburg, Germany DA - 2008-09-22 PY - 2008 AN - OPUS4-17831 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karrasch, Andrea A1 - Braun, Ulrike A1 - Schartel, Bernhard A1 - Jäger, Christian T1 - Festkörper-NMR Untersuchungen an flammgeschützten Polymeren T2 - Seminar "Festkörper-NMR-Methoden und Anwendungen in der Materialforschung", Universität Tübingen CY - Bad Hindelang, Germany DA - 2008-07-13 PY - 2008 AN - OPUS4-17899 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karrasch, Andrea A1 - Jäger, Christian A1 - Wawrzyn, Eliza A1 - Schartel, Bernhard T1 - Thermal decomposition behaviour of flame-retarded Bisphenol-a Polycarbonate: a solid-state NMR investigation T2 - Polydays 2008, Freie Universität Berlin CY - Berlin, Germany DA - 2008-10-01 PY - 2008 N1 - Geburtsname von Wawrzyn, Eliza: Pikacz, E. - Birth name of Wawrzyn, Eliza: Pikacz, E. AN - OPUS4-17960 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karrasch, Andrea A1 - Jäger, Christian A1 - Wawrzyn, Eliza A1 - Schartel, Bernhard T1 - Thermal decomposition of PDMS in flame-retarded Bisphenol-a Polycarbonate: a solid-state NMR investigation T2 - FRPM 09 12th European Conference on Fire Retardant Polymers CY - Poznan, Poland DA - 2009-08-31 PY - 2009 AN - OPUS4-19998 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karrasch, Andrea A1 - Jäger, Christian A1 - Wawrzyn, Eliza A1 - Schartel, Bernhard T1 - Thermal decomposition of PDMS in flame-retarded Bisphenol-a Polycarbonate: a solid-state NMR investigation T2 - GDCh Tagung Magnetische Resonanz 2009 CY - Dresden, Germany DA - 2009-09-21 PY - 2009 AN - OPUS4-20005 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -