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

  • Effect of UV absorbers on the photofading of dyes in thermochromic systems
  • Analysis of polymer matrix polarity effect on polymer dispersions containing          thermochromic systems
  • Establishing of analysis methods for the study of thermochromic systems in polymeric dispersions with different polarities
  • Alternatives for obtaining of some encapsulated thermochromic systems
  • Alternatives for preparing thermotropic systems of hydrogel-type, based on aqueous solutions of thermosensitive polymers
  • Synthesis and characterization of thermosensitive polymer crosslinked microgels with the temperature of volume phase transition in the range 25-75°C
  • Alternatives for obtaining of some thermosensitive film building materials
  • Alternatives for obtaining of some thermochromic systems of donor-accepting type

 

Research works have been accomplished by the following results:

  • The functional model to obtain a blue thermochromic composite material
  • The functional model to encapsulate the blue thermochromic composite material
  • The functional model for obtaining thermochromic flame retardant coatings
  • The functional model for obtaining thermochromic nitrocellulose lacquers and washable film building materials 

      The study on the effect of several types of light stabilizers on the behavior of the thermochromic systems revealed the superiority of nickel quenchers over the classical UV absorbers and HALS without affecting essentially the thermochromic equilibrium the transition temperature or the contrast obtained. Regarding alternatives for color developers various biphenolic compounds were studied, including organic dyes containing phenolic groups, but the properties of the thermochromic mixtures were not remarkably improved.

     Different systems used for encapsulation were obtained and analyzed in relationship with the effect of the polymeric matrix polarity on the dispersion stability and on the thermochromic behavior. As an alternative to the systems studied, were obtained encapsulated mixtures by interfacial polycondensation. In order to ensure a good dispersion of the organic phase in the aqueous phase, are used different polymeric alcohols, non-ionic surfactants and copolymers with more hydrophilic monomers.

     The partner UPB conducted experiments in order to obtain different thermotropic systems based on polymers of N-isopropylacrylamide and N-vinylcaprolactam and copolymers with monomers more hydrophilic (acrylamide, acrylic acid) or more hydrophobic (N-t-butylacrylamide). The influence of different additives to the aqueous solutions of these polymers was studied with respect to the transition temperature. The study was completed with a series of cross-linked thermosensitive polymer microgels using different bifunctional monomers as cross-linking agents.

      Partner CHIMCOLOR conducted activities related to the identification, selection and physical-chemical characterization of the components necessary for the thermosensitive coating materials. Thus, during the experiments were obtained and characterized film building matrices based on: chlorinated rubber, nitrocellulose or hydroxyethylcellulose. Also, were carried out tests to obtain thermochromic coating materials by incorporating blue, red and yellow encapsulated thermochromic mixtures in the selected film building materials.