Low-bandgap organic polymers, poly[(4,4 bis(2 ethylhexyl)cyclopenta [2,1 b:3,4 b′]dithiophene) 2,6 diyl al (2,1,3 benzothiadiazole) 4,7 diyl](PCPDTBT), and poly [(4,4′ dioctyldithieno[3,2 b:2′,3′d] silol 2,6 diyl) alt (2,1,3 benzothiadiazole) 4,7 diyl)], (Si-PCPDTBT) were analyzed at the air-water interface forming a Langmuir monolayer. In order to form stable monolayers and to transfer to solid supports, amphiphilic molecules of stearic acid (SA) were mixed with them. For the pristine polymers, the floating monolayers were transferred onto solid substrates via the Langmuir-Schaefer (LS) technique. Surface pressure-area isotherms and compressibility modulus curves demonstrated that the SA incorporation to the polymers at the air-water interface modified the rheological properties of the Langmuir films, since the films became less compressible at higher pressures and there is clear conformational reorganization taking place at intermediary pressures. The UV-Vis absorption also depicted the changes on the overall film morphology by the shift on the maximum absorption bands, and along with cyclic voltammetry curves the absorption spectra made it possible to estimate the energy diagrams for the polymers. Photoconductivity effects were observed for all the sample, among which the pristine polymers fabricated by LS showed better results, suggesting that the organization provided by the Langmuir-Blodgett (LB) technique was not enough to overcome the insulating characteristic of the SA molecules in this specific configuration.

This paper presents the comparison between the numerical and analytical results of a spacecraft attitude propagation for a spin-stabilized satellite. Some external torques are introduced in the equations of the motion and the comparisons are done considering that these torques are acting together, which are: gravity gradient, aerodynamic, solar radiation, magnetic residual and eddy current. In the numerical approach it is used the quaternion to represent the attitude. This numerical approach can be applied for any kind of satellite. The analytical approach is applied directly for a spin-stabilized satellite and the equations of motion are described in terms of the spin velocity, spin axis right ascension and declination angles. An analytical solution of these equations is presented and valid for one orbit period. Applications are developed considering the Brazilian spin-stabilized satellites SCD1 and SCD2. The comparisons are important to validate some simplifications that are required in