New heterobifunctional oligomeric energetic plasticizer with alkyne at one end and a hydroxyl group at the other end, was synthesized via ring opening polymerization of glycidyl nitrate monomer, propargyl alcohol as initiator and BF3 as a catalyst. The terminal hydroxyl group of plasticizer capped with methoxy and acetyl groups to generate two other types of reactive plasticizer. The chemical structure of plasticizers has characterized by FT‐IR and 1H NMR spectroscopy as well as DSC, and TGA methods. Also, plasticizers reactivity toward alkyne‐azide reaction, have evaluated through LUMO energy level calculation of reactive plasticizer that containing one and two repeating units in their structure. Moreover, the results show that grafting up to 10 % of the total amount of azide groups of GAP, reduces the viscosity and the glass transition temperature of GAP‐g‐PGN copolymer in comparison to glycidyl azide polymer.
This review is about the reactive plasticizer. Plasticizers are small molecules with low molecular weight. These compounds typically have an esteric structure. The plasticizers reduce the glass transition temperature, and the viscosity of the polymer also enhances the flexibility and processability of polymer materials. The main problem of these additives is that, over time, they migrate from the polymeric matrix and exude to the surface of polymeric matrix. As a result, the physical and mechanical properties of the polymer are affected. Various strategies, such as increasing molecular weight of plasticizer, selection of oligomeric structure for plasticizer, and adding nanoparticles of minerals, have been investigated to reduce and eliminate migration.An approach that has recently been of great interest to researchers is the use of reactive plasticizers. In this approach, plasticizers covalently bond to the polymeric chains and prevent migration.
Plasticizers are one of the additives that are added to polymers to increase the plasticity or decrease the viscosity of the material. Here, we have synthesized and characterized a new PGN-based reactive energetic plasticizer that has an oligomeric structure. The reactive energetic plasticizer can be grafted onto glycidyl azide polymer via a Cu-free Huisgen azide-alkyne 1,3-dipolar cycloaddition. The effect of the covalently bonded PGN-based plasticizer on the thermal properties of GAP-g-PGN copolymer has been investigated through thermogravimetric analysis and differential scanning calorimetry. The results indicate that the glass transition temperature of the prepolymer is decreased from-47.8 to-50.7 °C. Also, the kinetics of the thermal behaviour of GAP-g-PGN copolymer was determined by the application of the Kissinger and FWO kinetic models. The activation energies calculated by the Kissinger method were 165 and 188 kJ/mol for peak 1 and peak 2, respectively. Furthermore, the critical temperature (Tb) of thermal explosion for this energetic copolymer was estimated to be 182 °C.
Novel A2B2‐type energetic miktoarm star‐shaped copolymers composed of two PGN arms and two PCL arms was synthesized by the combination of ring‐opening polymerization (ROP) and “click” chemistry. Initially, diazido end‐functionalized two‐arm PGN, (PGN)2‐(N3)2, was synthesized by ROP of glycidyl nitrate monomers. Subsequently, (PGN)2‐(PCL)2 was obtained from the click reaction between diazido end‐functionalized (PGN)2‐(N3)2 polymers and propargyl‐terminated poly(ε‐caprolactone) (PTPCL). This star copolymer solves problems of PCL (lake of energy) and PGN (low Tg). The Fourier‐transform infrared (FT‐IR), 1H nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC) studies revealed that (PGN)2‐(PCL)2 was successfully obtained. The thermal behavior of star polymer was investigated by thermogravimetric analysis (TGA) and derivative thermogravimetry. The results show that (PGN)2‐(PCL)2 decomposed at two stages. The first stage is seen at 212.6°C which related to degradation of –ONO2 group and second stage attributed to degradation of PCL group which is seen at 346.1°C.
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