HOMOLEPTIC VS HETEROLEPTIC POSS® ADDITIVES

Heterolepetic cages (HC) are the third generation of POSS^® additives.  They are advantageous because they provide a statistically random distribution of two or more organic groups around the cage core. Especially unique to heteroleptics, is their ability to incorporate disparate organic functionalities together on the same cage.  This new versatility allows HC POSS  additive to serve as compatibilizers in addition to providing an envelope of effects.  The example shown below illustrates the combination of glycidyl and methacryl groups onto a heteroleptic cage. *Multiple primary reactive groups, can be combined with multiple secondary “effect” groups on heterocages.

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All HC POSS^® still retain the cage structure that enables them to be formulated in the same manner as organic-additives into thermoset, elastomer, and thermoplastic formulations.  The cage core size in HC POSS is a distribution of eight, ten and twelve which renders most HC POSS to be liquids as opposed to solids. The distribution of organic groups follows mathematical combinatorics.

ADVANTAGES:  Ideal for coatings that can benefit from primary reactivity  and  secondary effects (dispersion, gloss, leveling, compatibilization etc.). HC POSS eliminate the need for use of multiple additives thus simplifying formulations.

APPLICATIONS: Adhesives coatings, dispersion and reactive rheological diluents . Tie-layers, dual-uv cure (cationic + free radical) replacing oven processing, toughening at low loadings.

The suggested loading levels for HC POSS are 0.5-3 wt% relative to resin.

Primary Reactivity “R” group	Name	Effect
	Methacryloxypropyl	Fast UV, thermal, addition cure, vulcanization, rheological diluency, adhesion/reaction to coupling agents
	Acryloxypropyl	Faster UV, thermal, addition cure, vulcanization, rheological diluency, adhesion/reaction to coupling agents
	Alpha Acryloxy	Fastest UV, thermal, addition cure, vulcanization, adhesion to coupling agents
	Glycidyl	Cationic UV, thermal cure adhesion, coupling agent adhesion, modest dispersion
	Cyclohexylethylepoxy	Cationic UV, thermal cure, coupling agent adhesion, overall adhesion promoter
	Ethylnorbornene	ROMP, thermal cure, vulcanization, toughener for hydrosilylation cures relative to the vinyl functionality
	Vinyl	ADMET, thermal  cure, vulcanization, hydrosilylation cure

Secondary Effect “R” group	Name	Effect
	MethoxyPEG10	Wetting, dispersion, levelling, adhesion, gloss, water dispersion, bio-issue compatibilization
	Phenyl	Compatibilization with aromatics, high temp stability.
	Iso-octyl	Gloss, hydrophobicity, aliphatic compatibilization, rheological diluent, plasticization
	Iso-butyl	Hydrophobicity, aliphatic compatibilization, modest reinforcement, modest plasticization
	Trifluoropropyl	Similar to i-butyl, compatibilization of fluorinated additives.
	Methyl	Low carbon efficiency.