The liquid mixing process is an advantageous production method which has recently gained industrial interest for elaborating composites based on natural rubber (NR) and filler nanoparticles (NPs). Understanding how the relevant components such as polymer, fillers, as well as proteins and lipids coming from NR organize along the fabrication process is of importance for modulating material properties. Here, we successfully employed a combination of nano-imaging techniques to unravel the structure and evolution of hetero-aggregates formed by colloidal destabilization of a model NR latex - silica NPs liquid mixing process. First, field emission scanning electron microscopy (FESEM) was used to investigate the structures, from the early stage of contact between the particles until the formation of a composite. Results highlight an interaction in the liquid state between NR globules contained within the latex and silica NPs, hindering coalescence among globules. The latter can be achieved by applying shear in suspension or by solvent evaporation obtaining a dried composite. Atomic force microscopy coupled to infrared spectroscopy (AFM-IR) was employed to probe the in-depth nanoscopic distribution of silica NPs revealing a restricted mobility of the NPs during evaporation. Ultimately, the spatial distribution of proteins and lipids of NR, with respect to silica NPs, was investigated using dual color fluorescence images acquired with direct stochastic optical reconstruction microscopy (d-STORM) in a correlative light electron microscopy (CLEM) approach. The presence of silica NPs is found to influence the distribution of proteins and lipids in the composite; biomolecules form clusters of ~200 nm, which are partially colocalized with silica, highlighting an interaction between them. Our work provides comprehensive structural understanding of a model system undergoing liquid mixing, unlocking the potential of combining high-resolution imaging techniques to elucidate the structure of materials for tire applications.

Rubber-based nanocomposites prepared by solid-phase mixing with precipitated silica nanoparticlesare typically strongly aggregated systems with different levels of spatial organization. The strategy thatwe developed several years ago to investigate such systems is based on the study of simplifiedindustrial samples with ingredients limited to a strict minimum. On the scale of a micrometricsimulation box, tens of thousands of nanoparticles are embedded in the matrix, and their dispersionstrongly affects the mechanical properties of the material – and which is reflected in the scatteredintensity. A statistical method based on a reverse Monte Carlo solution of this many-parameterproblem will be presented, showing that some key features like percolation can be described. [1]Another key feature of rubber nanocomposites refers to the influence of the filler surfaces on thepolymer dynamics, and some recent progress – including incoherent neutron spin-echo measurements– will be discussed. [2] Such results may be confronted to dielectric spectroscopy measurements whichin some cases are not conclusive due the impossibility to correctly resolve the α-relaxation in presenceof strong interfacial polarization processes. An original application of dielectric spectroscopy with asurprising measurement of the adsorption isotherm of coating agents onto silica buried in the polymermatrix will also be discussed. [3][1] Musino D, Genix A-C, Chauveau E, Bizien T, Oberdisse J, Nanoscale 2020, 12:3907.[2] Musino D, Oberdisse J, Farago B, Alegria A, Genix A-C, ACS Macro Letters 2020, 9:910.[3] Musino D, Oberdisse J, Sztucki M, Alegria A, Genix A-C, Macromolecules 2020, 53:8083.

Polymerized ionic liquids (PolyILs) are an emerging class of polymer electrolytes which offer solutions to many problems in current battery technology. They combine the attractive features of ionic liquids with the mechanical strength of polymeric materials. However, a major obstacle in use of dry PolyILs is their low ionic conductivity at ambient temperature, which remains below the level required for many applications (ca. 10-3 S/cm). In this context, it has been shown that a significant enhancement of the ionic conductivity can be obtained by decoupling the ion motion from the segmental dynamics in polymers. We will review recent results obtained in this field using broadband dielectric spectroscopy, and discuss the microscopic parameters controlling ionic conductivity in PolyILs below Tg [1]. In particular, our detailed study of imidazolium-based PolyILs helped to unravel the interplay between nanostructure and ion conduction mechanism [2]. We also report first quasi-elastic neutron scattering experiments in these polymers suggesting the role of fast dynamics in assisting ion transport in the glassy state [3].[1] V. Bocharova and A.P. Sokolov, Macromolecules 2020, 53, 4141.[2] B. Doughty, A.C. Genix, I. Popov, B. Li, S. Zhao, T. Saito, D. Lutterman, R. Sacci, B.G. Sumpter, Z. Wojnarowska, V. Bocharova, Phys. Chem. Chem. Phys. 2019, 21, 14775.[3] V. Bocharova, A.C. Genix, A. Kisliuk, G. Sala, N.C. Osti, E. Mamontov, A. P. Sokolov, J. Phys. Chem. B 2020, 124, 10539.

The development of smart nanomaterials has attracted great attention in several fields like nanoscience, materials science,engineering and nanotechnology due to their unique response to external stimuli. Many of them are based on polymers thatcan exhibit great shape-changes when submitted to environmental modifications. Poly(N-isopropylacrylamide), PNIPAM, is sucha thermo-responsive polymer. It is water soluble at room temperature, forming gels by cross-linking but undergoes a reversiblecoil-to-globule volume phase transition (VPT) at a lower critical solution temperature (LCST) close to 32 °C due to thedehydration and subsequent collapse of its chains into compact globules.
Hybrid nanocomposite microgels associating PNIPAM and gold nanoparticles (GNP) have been designed in order to takeadvantage of the outstanding plasmonic and photo-thermal properties of GNP to promote the volume phase transition of themicrogels through an efficient photo-thermal conversion. With their strong diameter-dependent optical absorption in the nearinfrared (NIR) and their large surface area favoring photo-thermal transfer, semiconducting SWNT (s-SWNT) are goodcandidates for photo-thermal conversion in the NIR and may therefore be used to prepare multi-responsive hybrid microgels(Figure 1). However, to the best of our knowledge, no thorough studies of such nanomaterials have been reported so far.
Here we report the preparation of smart SWNT/PNIPAM nanocomposites through non-covalent functionalization techniques.These SWNT/PNIPAM hybrid microgels are stable in water and show a VPT, which can be promoted either by direct heating orby excitation of the resonant absorption of s-SWNT in the near infrared. Furthermore, the photoluminescence (PL) signal of s-SWNT is modulated at the phase transition and therefore, the PL signal can be used to monitor the VPT. This is illustrated inFigure 2, showing coupled Raman/PL measurements below and above the LCST, where a redshift of the PL bands is observedwhen crossing the LCST while the Raman signatures remain essentially the same.

Temperature is one of the basic parameters often required to characterize a system. A great demand has arisen for localmeasurements, especially in liquids or complex biological environments. Various approaches have been proposed to study thetemperature at the nano-scale level. Some of them are based on the spectroscopic properties of carbon nanotubes (CNT) usedas sensors.
Raman spectroscopy is indeed a powerful technique to identify single-walled carbon nanotubes (SWNT) and to study theirstructure, defects and electronic properties through the measurement of specific Raman signatures (RBM, D, G and 2D bands).On the other hand, individual SWNT or small bundles emit light in the near infrared and the photoluminescence (PL) spectra isvery sensitive to the quality of the dispersion and the dielectric environment of the nanotubes. In particular, when SWNT aredispersed in aqueous solutions, the PL energies are sensitive to the nature of the surfactants or polymers, to theirconcentration, and to the way they adsorb on/wrap around the nanotubes.
In this work we show that the PL/Raman spectra of SWNT dispersed with sodium dodecyl sulfate (SDS) is very sensitive to thetemperature (figure 1) in a large range of SDS concentrations. We discuss the influence of the chiral angle of the SWNT onthese PL changes, and the origin of the changes in terms of SDS reorganization at the surface of the nanotubes. Similarchanges are obtained with increasing laser power (figure 2), showing the local heating of the nanotubes. These results pavethe way for the development of SWNT-based nano-thermometers.

Polymer nanocomposites (PNCs) are made by the dispersion of hard fillers in a polymer matrix, where the fillers are usually added to enhance mechanical properties. Such materials attract industrial interest and their investigation is essential for the improvement of their performances. The latter are strongly related to the structural properties of PNCs: the dispersion state of nanoparticles (NPs) in the polymer melt is governed by the mixing protocols (e.g., solid phase mixing or solvent casting) and thermodynamics of the system (i.e., particle miscibility) which influence both filler-filler and filler-polymer interactions.The present study concerns nanocomposites obtained using hydrophilic silica NPs dispersed in two different polymer matrices: 1) poly(2-vinylpyridine) forming attractive NP/polymer interfaces or 2) a weakly interacting styrene-butadiene (SB) rubber. In the first system, the dynamical properties of the interfacial layer surrounding NPs are obtained using broadband dielectric spectroscopy (BDS). Moreover, we propose an original approach combining small-angle scattering experiments of X-rays and neutrons and simulations to investigate the static properties. Only in ideally well-dispersed systems using pre-adsorption of the polymer chains, a static interfacial layer with a gradient of density extending over a thickness of ca. 2 nm is evidenced based on the analysis with a form-free density profile. This gradient is found to be generated by out-of-equilibrium packing and folding of the preadsorbed layer.In the second polydisperse and disordered SB system, we recently proposed a reverse Monte-Carlo analysis of the scattering data giving access to NP aggregate mass distributions. In opposition to the previous system, BDS experiments are not conclusive regarding the impact of the industrial filler on the segmental relaxation. Therefore, we used neutron spin-echo spectroscopy (NSE) and demonstrate – here for the first time – that incoherent NSE based on fully hydrogenated compounds can be used to resolve small modifications of the segmental dynamics of PNCs.

Polymers with dynamic (transient) bonds, often called associating polymers, have been attracting significant attention in recent years due to their unique viscoelastic properties, self-healing ability, and recyclability. Nevertheless, understanding the mechanisms and the factors controlling their macroscopic properties remains limited due to the higher complexity introduced by the dynamic bonds. In this study, small-angle X-ray scattering (SAXS), broadband dielectric spectroscopy (BDS), and rheology were applied to unravel the structure and dynamics of telechelic associating polymers with different molecular weights. SAXS measurements revealed phase separation of the functional end groups with an average cluster size of ∼2–3 nm and the distance between clusters controlled by the chain length. Borrowing the interfacial layer model analysis of BDS data from the polymer nanocomposite field, we demonstrated the presence of an interfacial polymer layer with a thickness of ∼0.7–0.9 nm surrounding these clusters. Rheological measurements showed quantitatively that the presence of the interfacial layer significantly alters the viscoelastic behavior of these materials, indicating the crucial role of the interfacial layer in defining the macroscopic mechanical properties of the studied telechelic materials. The presented results emphasize that phase separation of the functional groups in associating polymers leads to very significant changes of the viscoelastic properties, opening a promising avenue in the design of novel functional materials.