Werner Mormann

Terminology of polymers and polymerization processes in dispersed systems (IUPAC Recommendations 2011)

A large group of industrially important polymerization processes is carried out in dispersed systems. These processes differ with respect to their physical nature, mechanism of particle formation, particle morphology, size, charge, types of interparticle interactions, and many other aspects. Polymer dispersions, and polymers derived from polymerization in dispersed systems, are used in diverse areas such as paints, adhesives, microelectronics, medicine, cosmetics, biotechnology, and others. Frequently, the same names are used for different processes and products or different names are used for the same processes and products. The document contains a list of recommended terms and definitions necessary for the unambiguous description of processes, products, parameters, and characteristic features relevant to polymers in dispersed systems.

DEFINITIONS OF TERMS RELATING TO REACTIONS OF POLYMERS AND TO FUNCTIONAL POLYMERIC MATERIALS (IUPAC Recommendations 2003)

The document defines the terms most commonly encountered in the field of polymer reactions and functional polymers. The scope has been limited to terms that are specific to polymer systems. The document is organized into three sections. The first defines the terms relating to reactions of polymers. Names of individual chemical reactions are omitted from the document, even in cases where the reactions are important in the field of polymer reactions. The second section defines the terms relating to polymer reactants and reactive polymeric materials. The third section defines the terms describing functional polymeric materials.

Terminology of polymers containing ionizable or ionic groups and of polymers containing ions (IUPAC Recommendations 2006)

This document defines the terms most commonly encountered in the field of polymers containing ionizable or ionic groups and polymers containing ions. The scope of the document has been limited to organic polymers. Inorganic materials, such as certain phosphates, silicates, etc., which also may be considered ionic polymers, are excluded from the present document. The terms selected are those that are widely used in the field of polymers containing ionizable or ionic groups and polymers containing ions. Only those terms that could be defined without ambiguity are considered. The terms are listed in alphabetical order, and cross-references to definitions given in other documents are provided.

Liquid crystalline thermosets by polymerization of mesogenic azomethine based diepoxides-influence of reaction rate on phase behaviour

Five azomethine linked triaromatic (triad) mesogenic diepoxides were used to study the phase behaviour during cross-linking anionic polymerization. Clearing points and phase transitions are lowered during polymerization hence, isotropic networks are obtained from non-catalyzed isothermal polymerization. A pronounced influence of the organization of diepoxides in a mesophase on the rate of polymerization was observed for diepoxide 3 which forms a smectic and a nematic mesophase. The reaction rate increases with the smectic/nematic/isotropic transitions of the melt. Increase of the reaction rate with ethyl-methylimidazol (EMI) allows liquid crystalline phases to fix in the resulting network. Organization of anisotropic networks depends on catalyst concentration and curing temperature (reaction rate).

Liquid crystalline cyanurate thermosets through cyclotrimerisation of novel triaromatic dicyanates

Three novel triaromatic dicyanates, hydroquinone bis(4-cyanatobenzoate) (1), methylhydroquinone bis(4-cyanatobenzoate) (2), and trimethylhydroquinone bis(4-cyanatobenzoate) (3) were synthesized and cyclotrimerised to form s-triazine thermoset networks. All monomers have a nematic mesophase. Networks with frozen nematic textures were obtained from 2 and 3 while 1 underwent a transition from the nematic melt to a smectic thermoset. The curing reactions were monitored by infrared spectroscopy and calorimetry. The final conversion of the rigid monomers was approximately 95% from dynamic DSC experiments. The nematic-isotropic transition and the glass transition temperature of 2 was measured as a function of conversion. The final glass transition temperature of the thermosets from the triaromatic dicyanates is 100°C and more below that of a diaromatic dicyanate, indicating that flexibility is increased with the number of ester groups between the branch points.

Definitions of terms relating to crystalline polymers (IUPAC Recommendations 2011)

Recommendations are given concerning the terminology relating to the structure and the morphology of crystalline polymers and the processes of polymer crystallization. They are applicable to cases where polymer crystals are a significant fraction of a system and primarily with crystal structures that are comprised of polymer chains with limited, static, or dynamic disorder. After some general definitions, terms pertaining to structural arrangements at subnanometric scales and to polymer crystal structures are defined. Terms relating to molecular conformation within polymer crystals, morphological aspects, and polymer crystallization are given in subsequent sections.

Partial silylation of cellulose with predictible degree of silylation – stoichiometric silylation with hexamethyldisilazane in ammonia

The silylation of cellulose with hexamethyldisilazane (HMDS) in liquid ammonia at elevated temperature has been extended to the synthesis of partly silylated trimethylsilylcellulose. Predictable degrees of silylation (DS) were obtained either with excess ammonia or in a nearly 1: 1 ratio of NH 3 /AGU (anhydroglucose unit) or with toluene as co-solvent. Complete reaction of the silylating agent allows to adjust the DS directly by simple variation of the ratio of OH groups to trimethylsilyl groups of the silylating agent. With chlorotrimethylsilane more than the stoichiometric amount of silylating agent is required to obtain a desired DS and the work up is more tedious. A simple method to determine the DS of trimethylsilylcellulose based on infrared spectroscopy is proposed. It is applicable to cellulose with a DS greater than 1.3.

Controlled desilylation of cellulose with stoichiometric amounts of water in the presence of ammonia

Desilylation of trimethylsilyl cellulose with stoichiometric amounts of water has been achieved in THF/ammonia in the presence of saccharin as catalyst. Experimental degrees of silylation are in close agreement with calculated ones. Deviations occur if the desired DS is near 1. These are due to the insolubility of silyl cellulose with DS 1 in THF/ammonia and to the heterogeneous character of the reaction at this point. Hydrolysis of 1,2-bis(trimethylsiloxy)propane in THF/ammonia showed that the secondary siloxy group is more readily cleaved than the primary. It also proved that the slow conversion of trimethylsilanol to hexamethyldisiloxane is responsible for the rather long reaction times required.

Synthesis and mesogenic properties of diaromatic cyanates and isocyanates-monomers for liquid crystalline thermosets

Abstract Five pairs of mesogens with identical cores having either a cyanate or an isocyanate reactive terminal group have been synthesized. The monofunctional mesogens have a n-butoxy or a methoxy substituent as the second terminal group. The influence of the two isomeric OCN moieties on the formation of a mesophase and on the thermal transitions has been investigated. The mesophases observed were identified as nematic. A tremendous difference in the mesogenic power (stabilizing effect on a mesophase) has been found for the two reactive terminal groups. The isocyanates have lower melting points than the isostructural cyanates and clearing points which are approximately 30°C higher per isocyanate group, as compared to a cyanate moiety.

Polymers from multifunctional isocyanates: 7. Synthesis and phase behaviour of liquid-crystalline triad ester-group-containing diisocyanates

Abstract A number of novel triaromatic diisocyanates based on para -linked ester mesogens (1,4-phenylene dibenzoate, diphenyl terephthalate, diphenyl trans -1,4-cyclohexanedicarboxylate and trans -dicyclohexyl trans -1,4-cyclohexanedicarboxylate) are described. One series was synthesized by reaction of 4-trimethylsiloxyphenyl or cyclohexyl isocyanate with terephthaloyl chloride or trans -1,4-cyclohexanedicarbonyl chloride, and the other from a 4-isocyanatobenzoyl chloride with a 1,4-bis(trimethylsiloxy)benzene (trimethylsilyl-protected hydroquinone). Acidic and basic catalysts were used in this reaction. The influence of substituents in various positions of the mesogenic cores on the phase transitions was also investigated. All liquid-crystalline diisocyanates have a nematic mesophase.