Does Plasticizer Penetrate Tightly Bound Polymer in Adsorbed Poly(vinyl acetate) on Silica?

Abstract

When only tightly bound poly­(vinyl acetate) (PVAc) was adsorbed on silica, the plasticizer, di­(propylene glycol) dibenzoate (DPGDB), was not effective in lowering its glass transition. To determine why the plasticizer was not effective, we probed the behavior of the deuterated plasticizer di­(propylene glycol) dibenzoate (DPGDB-d 10)/PVAc/silica system using deuterium (2H) solid state NMR and temperature-modulated differential scanning calorimetry (TMDSC). PVAc with 37% (w/w) of plasticizer/polymer was adsorbed on silica in adsorbed amounts of 2.60 and 0.76 mg PVAc/m2 silica. The dynamics of the plasticizer in the adsorbed PVAc was found to be more motionally heterogeneous than that observed in bulk samples. The NMR results provided firm evidence that when there is only a small amount of adsorbed polymer (e.g., only tightly bound polymer at less than 0.8 mg/m2), the plasticizer was effectively excluded from the polymer chains at the silica–polymer–air interface. When excluded from the tightly bound polymer, the plasticizer existed in an environment that was similar to that of pure plasticizer. At larger adsorbed amounts, the plasticizer was effective at lowering the T g of the adsorbed polymer.

Influence of PVAc/PVA Hydrolysis on Additive Surface Activity

“…The majority of mass loss occurs at an onset of~336 • C due to the deterioration of the acetate group leaving a percentage of residues of 30%, which is close to what was previously observed in the literature, where deterioration was shown to form C=C bonds [32]. This is followed by the decomposition of the polymer backbone at higher temperatures (452 • C) [33]. For pure sorbitol, the onset of complete deterioration occurs at 320 • C. For PVAc and sorbitol mixed samples, the thermal decomposition follows the pattern of PVAc and occurs in two stages, with a majority of weight loss occurring from~320 • C (temperature of deterioration of pure sorbitol) to~335 • C (temperature of deterioration of the acetate groups for pure PVAc) as the mass fraction of added sorbitol increases 5% < x < 15%.…”

“…The majority of mass loss occurs at an onset of ~336 °C due to the deterioration of the acetate group leaving a percentage of residues of 30%, which is close to what was previously observed in the literature, where deterioration was shown to form C=C bonds [32]. This is followed by the decomposition of the polymer backbone at higher temperatures (452 °C) [33]. For pure sorbitol, the onset of complete deterioration occurs at 320 °C.…”

Optically transparent, high-toughness elastomer using a polyrotaxane cross-linker as a molecular pulley

“…Even a cross-linked hard polymeric material will become supple with the addition of a plasticizer. However, over time, bleeding occurs in which the plasticizer melts, resulting in deterioration of the elastomer and contamination of the surface ( 16 ). Some plasticizers have adverse human health effects, and when elastomers containing these plasticizers are used in applications that require direct contact with people, the safety of the elastomers must be considered ( 17 ).…”

Experimental and Simulation Study on Glass Transition Temperatures of GAP with Ionic‐Liquid‐Based Energetic Plasticizers

“…However, the migration of plasticizers from polymer leading up weak interactions between polymeric chains and plasticizers . A covalent bond between the plasticizer and the polymeric chain is a solution to reduce migration .…”