At this stage of the project the following activities were carried out related to the plan of the project:

  •  synthesis of some color formers of triphenylmethane dyes type  

  •  structurally accurate characterization of the compounds with the proposed structures

  •  study on the structural types of synthesized or commercially available color formers  (structural features required for the use of thermochromic mixtures to be encapsulated)

  •  study regarding encapsulation of thermochromic mixtures, in dispersed aqueous medium, by miniemulsion polymerization, in the presence of monomer mixtures or inorganic polymers

  • study of thermosensitive hydrogels obtained on the basis of cellulose derivatives (transparent-translucent transition temperature, gelation temperature and viscosity modification).

  • structurally characterization  of synthesized copolymers and their composition

  • study on structural types identification and physico-chemical characterization methods regarding components necessary to obtain the thermosensitive materials

  • obtaining and characterization of some film building matrices compatible with encapsulated thermochromic and thermotropic systems based on their fields of application. Research works have been accomplished by the following results:

  • the experimental model of thermochromic compositions

  • the experimental model of thermotropic hydrogels

  • the experimental model of encapsulated thermochromic compositions

  • film building matrices based on acrylic and epoxy resins

Dyes encapsulation in dispersed aqueous medium by miniemulsion polymerization was successfully achieved. To maintain the thermochromic effect of dyes, different conditioning mixtures were chosen to carry out miniemulsion polymerization. Different latexes were obtained depending on the dye nature and conditioning additives. The use of the anionic and nonionic surfactants mixture provides the conditions to obtain stable latexes.

 

UPB obtained thermosensitive hydrogels based on cellulose derivatives and studied methods to change the transparent - opaque transition temperature and viscosity of the aqueous solutions. Hydrogels based on block-copolymers of PEG and PPG type and thermosensitive hydrogels based on random copolymers were studied in order to establish the influence of the molecular weight of the polymer and the concentration of the aqueous solution, the influence of alcohol, the addition of salts, surfactants and organic solvents on the behavior of the thermosensitive polymer.

 

CHIMCOLOR conducted activities related to the identification of structural types and methods of physico-chemical characterization of acrylic and epoxy matrices compatible with encapsulated thermochromic and thermotropic systems.