CHARACTERIZATION OF MORPHOLOGY IN MULTIPHASE MODIFIED POLYMERS BY SOLID STATE NMR Emilia P. Collara, Jesús Mª García-Martíneza, Leoncio Garridob aDepartamento de Física e Ingeniería, Instituto de Ciencia y Tecnología de Polímeros, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain. b firstname.lastname@example.org, Departamento de Química Física, Instituto de Ciencia y Tecnología de Polímeros, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
The modification of polymers is a very active area of research due to its significance to industrial polymers. These materials often include blends of two or more polymers and mixtures with inorganic components leading to multiphase structures. Since the physical and mechanical properties of the polymeric materials depend not only on the intrinsic properties of their components, but on how intimately they are mixed, numerous efforts to improve the compatibility between phases by chemical modification of the polymers of interest are ongoing. Moreover, the characterization of each phase by determining the critical dimensions of domains and interfacial regions, and how the chemical modification alters the polymer microstructure are paramount.
In this presentation, it will be described the characterization by 1H and 13C solid-state NMR of a multiphase triblock copolymer b-styrene-b-(ran-ethylene-butylene)-b-styrene (SEBS) chemically modified with maleic anhydride (MAH) in the presence of a radical initiator by reactive extrusion*. This thermoplastic elastomer consists of rigid domains (polystyrene) dispersed in a rubbery matrix (ethylene-butylene random copolymer). In the experiments performed, the concentration of MAH and the temperature profile in the extruder were varied while the concentration of initiator was kept constant. Samples with known degrees of grafting and crosslinking were analyzed with NMR by using techniques based on the spin-diffusion process1,2 to investigate the microphase structure of the modified copolymers. The results show that the rigid phase having domain sizes of ~17 nm and interdomain distances of ~31 nm is not significantly perturbed by the modification. Alterations in the rubbery phase are illustrated by measured changes in the proton T1 and T2 relaxation times and across the interface.
J. Clauss, K. Schmidt-Rohr, H.W. Spiess. Acta Polymer.1993, 44, 1-17.
*Samples analyzed on this research were obtained under the outsourcing contracted research works signed between Repsol-YPF and ICTP/CSIC (Ministerio de Educación y Ciencia). Kind support from Repsol-YPF to present work is acknowledged.