Detail of "28084-48-2"

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Thermotropic homopolyesters - VI

Thermotropic homopolyesters - VI. A study of polymers based on 4'-hydroxyphenyl 4-hydroxybenzoate. Krigbaum, W. R.Several substances are used for example 89298-36-2 and 99-96-7 which are their cas registry numbers.; Kotek, R.; Ishikawa, T.; Hakemi, H.; Preston, J. (Gross Chem. Lab., Duke Univ., Durham, NC 27706, USA). Eur. Polym. J., 20(3), 225-35 (English) 1984. CODEN: EUPJAG. ISSN: 0014-3057. DOCUMENT TYPE: Journal CA Section: 36 (Physical Properties of Synthetic High Polymers) Section cross-reference(s): 25, 35, 75 Polyesters were synthesized from 4-acetoxyphenyl 4-acetoxybenzoate (I) [74774-65-5] and dibasic acids having 6-12 methylene units using the transesterification procedure described by D. Luyen and L. Strzelecki (1980). The transition temps. were in reasonable agreement with those reported by L. Strzelecki and L. Liebert (1981). The nematic phase extended over a broad temp. range (70-100°), and the biphasic region spanned an addnl. 50°. The texture of the nematic phase was normal for I-azelaic acid copolymer (II) [81546-31-8] having inherent viscosities (hinh) = 0.30 dL/g (0.5 g/dL, phenol-tetrachloroethane mixt., 25°), but the other polymers showed bright nematic droplets on a darker background. The d. of the droplets decreased with increasing hinh for II, and with increasing methylene-unit no. for the other polymer homologs. Only II having hinh = 0.30 dL/g exhibited Williams domains on application of an elec. field. Quite different properties were found for polymer (III) [89298-37-3] having hinh = 0.80 dL/g and prepd. from 4-hydroxyphenyl 4-hydroxybenzoate [28084-48-2] and azelaoyl chloride. III melted sharply 24° higher, and its nematic phase showed a normal texture. Moreover, the nematic-isotropic transition of III appeared in the DSC as a sharp peak, and the biphasic region spanned only 9°. These data were explained by the transesterification reaction occasionally involving the internal ester linkage in the monomer unit, producing a polymer with no definite repeating unit structure and a distribution of hard segment lengths. .

Synthesis of main chain liquid crystalline polyesters based on mesogenic monomers with controlled transition temperatures

Synthesis of main chain liquid crystalline polyesters based on mesogenic monomers with controlled transition temperatures. Jannesari, Ali; Ghaffarian, S. Reza; Abdouss, Majid; Taromi, Faramarz Afshar; Mohammadi, Naser; Ranjbarfar, Behrouz; Ranjbar, Zahra ( Department of Polymer Engineering, Amir Kabir University of Technology, Tehran, Iran). Iranian Polymer Journal, 13(2), 121-130 (English) 2004 Iran Polymer and Petrochemical Institute. CODEN: IPJOFF. ISSN: 1026-1265. DOCUMENT TYPE: Journal CA Section: 35 (Chemistry of Synthetic High Polymers) Section cross-reference(s): 75 The structure-property relationships in segmented-chain liq. cryst. polyesters based upon diphenols and aliph. dibasic acid chloride was studied by differential scanning calorimetry and polarizing optical microscopy. Two mesogenic monomers were synthesized by direct esterification of hydroquinone with p-hydroxybenzoic acid in a convenient method. The well-characterized mesogenic monomers incorporated into segmented liq. 99-96-7 and 28084-48-2 are cas registry numbers of chemicals which are used as reagents here. cryst. polyesters with short linear chain and COOH- end groups. The structure of the monomers and the polymers was studied by FTIR, 1H NMR, MS. The temp. of transition between the phases and, as a consequence, the range of mesomorphism is highly dependent upon the mol. wt. of the polyesters and the length of the mesogenic monomers. .