Constrained dynamics in interphases of model filled elastomers - effect of interface chemistry on crosslinking, local stress distribution and mechanics (DINaFil)

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This proposal seeks to systematically elucidate the most important factors that govern the physical properties of filled elastomers, mainly contributing advanced NMR spectroscopy. The joint effort unites the competences of three groups which have all contributed significantly in the fields of synthesis, characterization, and modelling of (filled) elastomers, and sets out for a combined effort to now apply our knowledge to the development and thorough investigation of novel model systems that can mimic properties of filled elastomers that are relevant for applications. Our consortium combines the preparation of model-filled elastomers, the characterization of the dispersion state by scattering techniques, the molecular-scale study of chain dynamics and cross-link density by modern NMR spectroscopy and dielectric spectroscopy, sample characterization by mechanical spectroscopy, and finally theoretical studies based on novel models. Our emphasis is on as-perfect-aspossible control and systematic variation of the dispersion state of well-defined silica spheres, with additional control of the interaction between filler and elastomer matrix, either by chemical bonds or by adsorption. We build on preliminary work which has shown that our NMR techniques are able to specifically detect structure (cross-link density) and dynamics in the interphase between filler and elastomer matrix. Within this part of the joint proposal, we will also further develop and apply novel NMR methods for a spatially resolved analysis of interphase heterogeneity, and chain orientation effects in strained elastomers.