In this work we present a dielectric relaxation study of Acrilyc/Polyurethane polymers synthesized via miniemulsion photo-polymerization. Three different samples, both parts of the synthesized hybrid latex (SOL and GEL fractions) and a full acrylic sample as reference have been considered. Besides dielectric experiments using broadband Dielectric Spectroscopy (BDS) technique, complementary Differential Scanning Calorimetry measurements have been performed. The thermodynamic characterization outcomes evidence very similar characteristics of the glass transition phenomena among the investigated samples without any signature of melting/crystallization. However BDS experiments show three well resolved dielectric relaxation processes above Tg, two of them evidence marked differences among the samples. A detail study allows us to provide a molecular origin for these three dielectric relaxation processes in connection with the sample characteristics. In particular, our results show that the characterization of these hybrid Acrylic/PU by BDS can provide access to some of the structural features that would ultimately influence the adhesives properties.

The supramolecular self-assembly of monocarboxydecyl-terminated dimethylsiloxane oligomer is investigated and characterized by combining different experimental methods. Thermodynamic properties were accessed by temperature-modulated differential scanning calorimetry, and two subambient phase transitions were identified. Fourier transform infrared spectroscopy gave access to the main molecular entities involved in these phase transitions. Diffraction experiments using small-angle X-ray scattering and wide-angle X-ray scattering evidenced the development of two distinct well-ordered sub-10 nm structures, each associated with one of the thermal transitions, without any indication of long-range atomic order. All the results point to the self-assembly of the oligomeric dimers below 230 K, giving rise to supramolecular structures involving new H-bonding interactions. A further structure is developed below 205 K by the assembly of the alkane part of the molecules in an arrangement of hexagonally packed cylinders. Dielectric relaxation experiments evidenced both the pronounced effect of the lowest temperature transition on the H-bond network fluctuations and the very effective segregation of dimethylsiloxane at lower temperatures. Moreover, we found that the structured liquid presents a rubber-like mechanical behavior in the temperature range 150–200 K, where dimethylsiloxane phase remains amorphous, and at lower temperatures a glassy nanostructured material is found.

In this paper we present a dielectric relaxation analysis of three Acrylic-Polyurethane gel samples in connection with their synthesis conditions. The dielectric analysis was carried out using Broadband Dielectric Spectroscopy (BDS). Additionally, Differential Scanning Calorimetry (DSC) and Small Angle X-ray Scattering (SAXS) measurements were performed. The thermodynamic characterization outcomes evidence very similar characteristics of the glass transition phenomena among the investigated samples without any signature of melting or crystallization. X-ray diffraction patterns evidence distinctive features for the three gel samples in two different regions, i.e., at high and low values of the scattering vector q. BDS measurements, identify three distinct dielectric relaxation processes above Tg. Particularly, differences in the dielectric parameters of the slowest relaxation process have been rationalized in connection with the synthesis method used. Our results show that the analysis of these Acrylic-Polyurethane gels by BDS-in combination with SAXS-provides access to characteristics of the network structure that would ultimately influence the properties of these materials.