Aromatic polymers obtained by precipitation polycondensation: 4. Synthesis of poly(ether ketone ketone)s☆
Abstract High molecular weight aromatic poly(ether ketone ketone)s were synthesized by the Friedel-Crafts polyacylation condensation of iso- and terephthaloyl chlorides with diphenyl ether, 1,4- and 1,3-bis(4-phenoxybenzoyl)benzenes. Depending on the monomers used for polycondensation, polyketones of regular structure with different iso-/tereisomer repeating unit ratio ( 100 0 , 50 50 , 0 100 ) in the main chain were obtained. Polymers of each repeating isomer unit were prepared in two different ways. All the polymer syntheses were performed as precipitation polycondensations and the resulting polymers were obtained in particle form. The influence of reaction conditions and preparation route on the polymer properties were examined. The monomer concentration and monomer stoichiometric ratio were found to affect the polymer viscosity. The size and shape of the polyketone particles obtained were also found to be governed by reaction conditions and preparation route.
Poly(phthalidylidene arylene)s : synthesis of poly(3,3-phthalidylidene-4,4'-biphenylylene) by precipitative homopolycondensation of 3-(4-biphenylyl)-3-chlorophthalide
The synthesis of poly(3,3-phthalidylidene-4,4′ -biphenylylene) (PPB) by precipitative Friedel-Crafts homopolycondensation of 3-(4-biphenylyl)-3-chlorophthalide was studied. The polymer-catalyst complex precipitated from the initially homogeneous reaction mixture was shown to be active and providing the growth of macromolecular chains. The polymer obtained in the form of smooth, transparent glass-like particles, depending on the reaction parameters, may have either uni- or bimodal molecular weight distribution. Molecular characteristics were not found to depend on the size of the polymer particles. “Precipitative” PPB shows improved properties and higher crystallinity in comparison with “solution” PPB. 
 
 
 
Die Synthese von Poly(3,3-phthalidyliden-4,4′-biphenylylen) (PPB) durch eine Friedel-Crafts-Fallungspolykondensation von 3-(Biphenyl-4-yl)-3-chlorphthalid wurde untersucht. Der aus der ursprunglich homogenen Reaktionsmischung ausgefallte Polymer-Katalysator-Komplex erwies sich als aktiv und forderte das Wachstum der Polymerketten. Die in Form von glatten, tranparenten, glasartigen Partikeln erhaltenen Polymeren zeigen, abhangig von den Reaktionsparametern, entweder uni- oder bimodale Molekulargewichtsverteilung. Die Polymereigenschaften sind unabhangig von der Partikelgrose. Verglichen mit aus der Losungspolymerisation erhaltenem PPB zeigt das mittels Fallungspolykondensation hergestellte PPB verbesserte Eigenschaften und hohere Kristallinitat.
Evaluating Cultural Authenticity in Multicultural Picture Books: A Collaborative Analysis for Diversity Education
This study examines cultural authenticity reflected in multicultural picture books. Specifically, this study attempts to reframe issues surrounding the topic of cultural authenticity based on a systematic and empirical analysis of picture books that represent three different ethnic groups: African Americans, Asian Americans, and Hispanic Americans. A total of forty-five systematically selected picture books that represent fifteen books per ethnic group were selected and evaluated by multiple reviewers who were insiders of the culture. A coding scheme was developed to evaluate each book in terms of profile of major and minor characters, settings of the story, stereotypical features, and cultural authenticity. An in-depth evaluation of all selected books was added by a team of three reviewers in order to validate the results of the coded analysis. This study aims to shed light on library youth services and diversity education in a society with increasing ethnic diversity.