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Several ways using surface modification are commonly used to enhance thermal stability of polymer matrices. In this study, Continuous-Wave carbon dioxide (CW CO2) laser irradiation and atmospheric pressure non-thermal He plasma treatment on microporous poly(vinyl chlo-ride)/Silica composite have been investigated and compared. On one hand the alternative was based on the efficiency of the thermal energy afforded by CW CO2 laser irradiation and induced photodegradation processes to release HCl and form polyene sequences under well-controlled condition. On the other hand atmospheric plasma treatment involved surface modification by formation of unstable radicals, inducing crosslinking and dehydrochlorination. In both cases a global thermal stabilization of the composite was noticed by partial dehydrochlorination of PVC, even for short exposure time. The main effects observed after laser irradiation were related to the formation of a very dense structure on surface with very low chlorine content and an important chlorine atoms in-depth gradient on the cross section up to 150 μm in thickness; whereas atmospheric He plasma treatment led to a homogeneous decrease of the chlorine in-depth content due to the plasma interpenetration in the porous microstructure. Structural and chemical modifications both on extreme surface and in the thickness have been investigated respectively by Environmental Scanning Electron Microscope (ESEM) coupled with an Energy Dispersive X-ray analysis (EDX) and X-ray Photoelectron Spectroscopy (XPS). Composites thermal stability and investigation on chlorine release have been evaluated by Thermo Gravimetric Analysis (TGA) coupled with Mass Spectrometry (MS).

In this work, the use of Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) was explored as a technique for monitoring the interfacial retro Diels–Alder (retro DA) reaction occurring on well-controlled self-assembled monolayers (SAMs). A molecule containing a Diels–Alder (DA) adduct was grafted on to the monolayers, then the surface was heated at different temperatures to follow the reaction conversion. A TOF-SIMS analysis of the surface allowed the detection of a fragment from the molecule, which is released from the surface when retro DA reaction occurs. Hence, by monitoring the decay of this fragment’s peak integral, the reaction conversion could be determined in function of the time and for different temperatures. The viability of this method was then discussed in comparison with the results obtained by ¹H NMR spectroscopy.

This study reports the effect of pH (2, 7, 10) and heat treatment (80 °C for 30 min) on the oil–water (o/w) interfacial behavior of hemp seed protein isolate (HPI) aqueous dispersions. The physicochemical, interfacial adsorption, rheology, and emulsifying properties of protein dispersions were evaluated. HPI dispersions at pH 10 exhibited the highest water solubility (60%), the greatest net charge (−27 mV), and the lowest hydrophobicity (~5 a.u.), promoting o/w interfacial pressure (π) and interfacial viscoelasticity. Strong interfacial viscoelastic protein layers (E^* = 25 mN/m) were also observed under acidic conditions (pH 2), where proteins exhibited high solubility (40%), a high positive net charge (21 mV), and increased hydrophobicity (46 a.u.). HPI dispersions in their neutral state (pH 7) were not able to form stable o/w emulsions due to their poor physicochemical properties such as low solubility (18%), low surface charge (−18 mV), and hydrophobicity (~5 a.u.). Heat treatment significantly increased the charge and hydrophobicity of both neutral and alkaline proteins (~30 mV and ~10 a.u., respectively), increasing their particle size distribution and ultimately reducing their interfacial protein layer elasticity (E^* = 20 and 13 nM/m, respectively). While particles at acidic conditions showed high thermal resistance, heat treatment improved the emulsifying stability in alkaline conditions while further reducing it in the neutral state. Overall, HPI dispersions demonstrated the ability to form stable emulsions at both alkaline and acid pHs, with those formed at pH 2 exhibiting a lower droplet size and superior stability.