Folded chain crystals as micro-phases

Summary A thermodynamic treatment of homo-polymer systems out of linear chains with folded chain crystals is developed outgoing from appropriate models for single component systems. An expansion of thermodynamics to multi-micro-phase systems the structure of which is partially or totaly frozen is indispensable. General properties of melt crystallized homopolymers with folded chain crystals can be recognized indeed when the thermodynamic formalisms developed are applied.

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Zusammenfassung Das Schmelzen in polymeren Einteilchensystemen mit Faltungskristallen einheitlicher Dicke kann thermodynamisch als Umwandlung 1. Ordnung in einer Richtung behandelt werden, wenn die Faltungslänge bis zur Umwandlungstemperatur konstant bleibt (Faltungslänge als innerer Zusatzparameter). Eine wesentliche begriffliche Erweiterung ist für eine phänomenologische Beschreibung mit den Mitteln der Thermodynamik unumgänglich, wenn eine Faltungskristallit-Dickenverteilung existiert, weil dann prinzipiell nur noch partielle Koexistenz bestimmter Fraktionen metastabiler autonomer Mikrophasen mit der Schmelze möglich ist. Partielles Aufschmelzen und Rektistallisation können so dann auch in Betracht genommen werden. Die entwickelten Konzeptionen bewähren sich in der Anwendung auf bekannte Experimente.

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Notation g ^c (y);g ^m (Y) molar Gibbs-free energy of a chain of a lengthy within an extended chain crystal and the melt rsp - g _o ^c ;g _o ^m molar free enthalpy of the unit in the crystal lattice and the melt rsp - g(y,y, f) molar Gibbs-function of an ideally folded chain crystal with the fold heighty _f - gco(y, y _ef,y _f) molar free enthalpy of the crystal corey _co - g ₀ ^ex ((y_ef) excess free enthalpy of the longitudinal layers of folded chain crystals - g ^f(y_ef,g _o ^ex ) molar free enthalpy of the longitudinal layers of the folded chain crystals - g ^tot molar free enthalpy of a chain of the lengthy within a folded chain crystal with longitudinal layers - h _o ^1c ,h _o ^m molar enthalpy of the chain unit within the crystal lattice and the melt rsp - h =h _o ^m -h _o ^c molar heat of fusion of the unit - C _p=C _p ^m -C _p ^c difference of the molar specific heat of a unit within the melt and within the chain crystal - h ^D molar defect enthalpy of local defects within the crystal lattice - h ^D molar defect enthalpy of the unit - s _o ^c ,s _o ^m molar entropy of the chain unit within the crystal lattice and the melt rsp - s _c ^m conformational entropy of a chain in the melt - s _gk conformational entropy of a chain of lengthy within a super-lattice as indicated in figure 5, - s molar entropy of fusion of the melt - s _n ^c nematic configurational entropy - T absolute temperature - T _M melting temperature of extended chain crystals of infinite size - T _M(y) melting temperature of extended chain crystals containing only chains of the lengthy - T _M (y, y _f) melting temperatureof folded chain crystals of the thicknessy _f composed of chains of the lengthy - T _M(y _f) melting temperature of folded chain crystals of the thicknessy _fy - _eh excess free enthalpy of the chain ends occupying crystallographic places - _ef excess free enthalpy of a single fold loop - z coordination number of the lattice - 7 Euler's constant - R Boltzmann's constant - y number of chain units - y _f height of lamelliform folded chain crystals - f=(y/y _f - 1) number of fold loops of a chain of a lengthy when being built into a folded chain crystal of the thicknessy _f - y _co thickness of the crystal core of the simplified twophase model - y _et average thickness of the surface layers of folded chain crystals - N _c number of crystallized units of a chain of the lengthy - x _c molar number of crystallized units of a chain of the lengthy - x _nc molar number of noncrystallized units - excess free enthalpy parameter - (y _f) thickness distribution of the fold heightsy _f With 15 figures and 2 tables     

Über 1-Alkyl-bzw. 1-Aryl-dihydro-6-methyl-2(1H)-pyrimidinthione

The title compounds7 are formed in a general reaction by heating β-isothiocyanoketones3 with primary amines in inert solvents, or by thermal elimination of water from tetrahydro-6-hydroxy-6-methyl-2(1H)-pyrimidinethiones5, also in inert solvents. The 1-alkyl compounds can also be prepared under similar conditions from α,β-unsaturated ketones by reaction with alkylammonium rhodanides. The NMR-spectra show that the 1-substituted dihydro-6-methyl-2(1H)-pyrimidinethiones are in tautomeric equilibrium with the tetrahydro-6-methylene-2(1H)-pyrimidinethiones13. The reactivity of 1-alkyl and 1-aryldihydro-6-methyl-2(1H)-pyrimidinethiones is similar to that of dihydro-4,4,6-trimethyl-2(1H)-pyrimidinethione7 j, although their ring stability is certainly less.     

Beiträge zur Chemie des Sulfamids, 1. Mitt.: Zur Konstitution des Disilber-sulfamids

According to spectroscopic (IR, broadline proton NMR) and chemical (alkylation) investigations of disilver sulphamide the following molecular structure is assumed: $$\begin{gathered} O \hfill \\ || \hfill \\ H_2 N\_\_S\_\_NAg| \hfill \\ OAg \hfill \\ \end{gathered}$$ From the IR and NMR data deduction concerning the nature of the chemical bonds in this compound is possible. The instability of the still unknown mono-and trisilver sulphamide is discussed with regard to the structure of disilver sulphamide.     

On the 6-exo-trig ring closure of substituted 5-hexen-1-oxyl radicals

Substituted 5-hexen-1-oxyl radicals have been generated from N-(5-hexen-1-oxy)-5-(p-methoxyphenyl)-4-methylthiazole-2(3H)-thiones under tin-free conditions and have been successfully applied as reactive intermediates in a mechanistic study on the formation of bromomethyl-substituted tetrahydropyrans via 6-exo-trig selective cyclizations.     

Über die Konfiguration des Prolins im Ergotamin

It is well known that in the ergot alkaloids of the peptide type the proline appears in thel-configuration. Different methods of acid hydrolysis may lead to various cleavage products; hydrolysis by HCl yieldsd-proline, on the other hand hydrolytic cleavage by means of strongly acid cation exchange resin preserved the orginall-configuration.

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Teilveröffentlichung der Dissertation vonH. Kolassa, Univ. Wien, 1973.     

Thermische Polymerisation von Acenaphthylen

Zusammenfassung Acenaphthylen wurde durch Anpolymerisation und zweifache Hochvakuumsublimation gereinigt. Die Reinigungsmethode wird ausführlich beschrieben.Bei verschiedenen Temperaturen wurde mit einer dilatometrischen Methode die thermische Bruttogeschwindigkeit gemessen. Zwischen 95 und 105 °C giltk _br=7,0₈·10¹⁰ exp (– 30,9 kcal/RT).Die beträchtliche Aktivierungsenergie der Bruttoreaktion ist sowohl auf eine große Aktivierungsenergie der thermischen Startreaktion als auch auf eine relativ hohe Wachstumsaktivierungsenergie zurückzuführen.Das Polymerisationsverhalten von Acenaphthylen kann vermutlich aufgrund seiner sterischen Eigenschaften erklärt werden.

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Summary Acenaphthylene was purified by partial polymerisation, followed by double stage high vacuum sublimation. The method of purification is described in detail.The thermal overall rate was measured at different temperatures by a dilatometric method. Between 95 and 105 °C the following relation holds:k _th=7,0₈ · 10¹⁰ exp (– 30,9 kcal/RT).The considerable energy of activation of the overall reaction depends on a relatively high energy of activation of both the thermal initiation and the propagation reaction.It is supposed, that the polymerisation behaviour of acenaphthylene depends mainly on its steric properties.

     

Size-selective organization of enthalpic compatibilized nanocrystals in ternary block copolymer/particle mixtures

Dependent on the relative particle core size, two distinct types of particle topologies in block copolymer/nanocrystal blends have been identified, that is, the localization of particles along the intermaterial dividing surface or at the center of the respective polymer domain. In ternary systems consisting of block copolymer and two different-sized nanocrystal species, the distinct morphological types are conserved, resulting in autonomous size-selective separation and organization of the respective nanocrystals within alternating arrays and sheets.     

Improved flask-combustion method for phosphorus in petroleum products

Summary An electrical assembly for the oxygen-flask combustion of lubricants and similar petroleum products is described. The pyrolysis is performed in two consecutive steps. After the ignition and burning of the sample (sorbed on sodium carbonate) the combustion is completed by further heating. The sample weight should not exceed 140 mg. In this way the sensitivity of phosphorus determination of the tentative IP standard procedure is enhanced from 0.01 to 0.001% phosphorus if the volume of solution for the final spectrophotometric measurement is reduced.

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Zusammenfassung Ein elektrisches Gerät für die Verbrennung von Schmierölen und ähnlichen Erdölprodukten im Schöniger-Kolben wurde beschrieben. Die Pyrolyse erfolgt in zwei aufeinander folgenden Schritten. Nach der Entflammung der an Natriumcarbonat adsorbierten Probe und nach Erlöschen der Flamme erfolgt die vollständige Verbrennung von Einwaagen, die 140 mg nicht überschreiten. So konnte die Empfindlichkeit der Phosphorbestimmung nach der tentativen IP-Standardmethode von 0,01% auf 0,001% Phosphor gesteigert werden, wenn man die spektrophotometrische Messung mit vermindertem Lösungsvolumen durchführt.

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Herrn Professor Dr. H. Lieb zum 90. Geburtstag gewidmet.