Crystal habit modifiers

Exploiting ATRP as an enabling technology, we have recently synthesised a wide range of new, controlled-structure copolymers. These include (1) branched analogues of Pluronic non-ionic surfactants (2) schizophrenic polymeric surfactants which can form two types of micelles in aqueous solution (3) novel sulfate-based copolymers for use as crystal habit modifiers (4) zwitterionic diblock copolymers, which may prove to be interesting pigment dispersants. Each of these systems is discussed in turn below. 

Synthesis of Sulfate-based Block Copolymers as Crystal Habit Modifiers for BaS04... 

E.I. duPont de Nemours and Company Thickened Aqueous Inorganic Oxidizer Salt Blasting Compositions Containing Gas Bubbles and a Crystal Habit Modifier and Method of Preparation... 

The existing method for preparing crystalline zirconium phosphate is firstly to precipitate the amorphous form from a mixture of phosphonic acid and zirconyl chloride and secondly to reflux the amorphous form in 12M phosphoric acid for several days after washing the amorphous form free of chloride. This gives the a-form. Not only is this a time consuming process, but the amorphous form is difficult to filter. We aimed to develop a one step process to the crystalline material by using crystal habit modifiers. 

TTie above observations obey the Gay-Lussac Law which states that a compound that crystallises from a highly super-saturated solution first is the most soluble (from a saturated solution first it is the least soluble). In the above case, amorphous (2) is more soluble than (1). By choice of crystal habit modifier, it is possible to preferentially precipitate one form of the phosphate. 

The addition of crystal habit modifiers to the original phosphoric acid/zirconyl chloride solution gave catalysts which were mainly crystallinein less than one hour but still had some amorphous character (Figure 8). 

Table 5 - Phenol Hydroxylation Using Zirconium Phosphates Made with Crystal Habit Modifiers...

Crystal Habit Modifier % Phenol Conversion Selectivity Dihydroxy Ratio CAT.HO... 

Sarig, S., Glasner, A. and Epstein, J.A. (1975) Crystal habit modifiers the relationship between the structure of the additive and the crystal lattice. Journal of Crystal Growth, 28, 295-299. 

Once the ratio of sodium ultraphosphate to calcium polyphosphate had been more or less standardized, the game of adding crystal habit modifiers was undertaken in an attempt to determine the influence of modifiers. No reliable generalizations could ever be stated as to how foreign ions influenced these systems, but... 

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