Synthesis and characterization of imidized poly(styrene‐maleic anhydride) nanoparticles in stable aqueous dispersion

Abstract

Organic nanoparticles are synthesized by partial imidization of high-molecular weight styrene(maleic-anhydride) with 26 to 34 mol% maleic anhydride, in aqueous environment and presence of ammonium hydroxide. The nanoparticle dispersions have a maximum solid content of 35 wt% and good stability that critically depends on the ratio of imidized and ammonolyzed maleic anhydride moieties. The deprotonated residual maleic anhydride moieties provide dispersion stability at pH > 4, while protonation at pH < 4 causes nanoparticle sedimentation. After presentation of the synthesis conditions, the imidization reaction is characterized by FT-IR and Raman spectroscopy, followed by thermal analysis (TGA, DSC), and morphological characterization (DLS, SEM, TEM, AFM). The reaction conditions were optimized by physical characterization of various dispersions, and finally nanoparticles could be obtained with a maximum degree of imidization of 77% in dispersed conditions, or 90 to 95% after drying that are favorable for coating applications.

Synthesis of imidized nanoparticles containing soy oil under various reaction conditions

“…After 4 h, the reaction mixture was cooled to room temperature and evacuated from the reactor. During the reaction, the torque for driving the stirrer at a constant speed was recorded as a measure for the evolution of the viscosity of the reaction mixture over time: typically starting from a high viscosity, the value drops after a reaction time of 3 h as an indication of successful imidization and formation of hybrid SMI/SO nanoparticles, in parallel with the evolution that was observed for synthesis of pure SMI nanoparticles [34].…”

“…The pure SMI nanoparticle dispersions could be synthesized with a maximum solid content of 35 wt.% as before [34], while the SMI/SO nanoparticle dispersions could be synthesized at maximum solid content of 50 wt.%. During synthesis, the MA is first converted into carboxylic groups by ammonolysis at 90-120°C, and consequently transformed into imide moieties during heating up to 160°C.…”

“…The SMA was previously used to form microcapsules from acetate or dodecanol by interfacial polyaddition with amines [31], by hydrolysis and surfactant synthesis with octadecane [32], or complex coacervation with gelatin [33]. On the other hand, the imidization of pure SMA results in nanosphere dispersions with good chemical stability and high glass transition temperatures of around 180°C [34]. In following experiments, the imidized nanospheres could be an excellent host for protecting soy oils as encapsulating agent and simultaneously provide a flexible way to form nanocapsules.…”

Bio-Based Coatings for Paper Applications

“…During transformation into nanoparticles, self-organization of monomers resulted into localization of hydrophobic sites at the surface that can be well controlled along with the wettability of nanoscale coated paper surfaces. First, the synthesis conditions were optimized to obtain stable particle dispersions with a maximum solid content and appropriate viscosity [148]. These materials were applied by a bar-coating process onto paper and paperboard surfaces to study the chemical and morphological properties in relation with printability [149].…”

Morphologies and Thermal Variability of Patterned Polymer Films with Poly(styrene-co-maleic anhydride)

“…While the composition with a nominal amount of 50 mol % MA has a fully alternating molecular structure, the alternating domains are separated by semi-or non-alternating domains as the nominal amount of MA decreases. This specific molecular structure allows for conversion of SMA into spherical nanoparticles during imidization [51].…”