Masao Murano

Sequence distribution of segmented polyurethane-urea.

Segmented polyurethane-urea (SPU) elastomer was prepared from poly-tetramethyleneglycol (PTMG), 4,4′-diphenylmethane diisocyanate (MDI), and ethylenediamine (EDA). The SPU is a kind of block copolymer composed of soft and hard segments. 13C NMR spectra of the SPU were measured and the mean sequence lengths of polyurethane block and polyurea block were estimated from the signals of aromatic carbons. The mean polyurea sequence length was shorter than the hard segment as estimated by X-ray diffraction (Kimura et al.) or by other methods (Suzuki et al.). This polymer was found to be almost a random copolymer. The reactivity of the isocyanate group in MDI decreases slightly when the other side of isocyanate has reacted. The hard segment observed by X-ray diffraction or by other methods might only be the longer fraction of polyurea sequences.

Studies on the Tacticity of Polyacrylonitrile by the High Resolution Nuclear Magnetic Resonance Spectrum

重合条件の異なる16種類のポリアクリロニトリル (PAN), およびポリ-α-重水素化アクリロニトリル (PAN-αd1) について, NaCNSの重水溶液を溶媒として高分解能核磁気共鳴スペクトルを測定した。PANのメチレン基プロトンの共鳴スペクトルはSyndiotactic部分とIsotactic部分とによる二つのTripletの重なりと考えられ, それらの面積強度を別々に算出することによって各試料の立体規則性を推定することができた。ラジカル重合および常温のアニオン重合でつくったPANは約75%のSyndiotactic部分を含み, 低温アニオン重合, 固相放射線重合, Mg分子線法および尿素包接化合物の放射線重合により得たPANではSyndiotactic部分がやや少ないが, いずれも顕著な立体特異性は示していない。