Continuous reactors of frontal polymerization in flow for the synthesis of polyacrylamide hydrogels with prescribed properties

Abstract

<jats:title>Abstract</jats:title><jats:p>Taking into account the fact that since the 1970s frontal polymerization (FP) reactors in flow have been the subject of our study, the work gives a brief chronology of the development of FP reactors for the synthesis of high molecular polymers, polymeric hydrogels with cross-linked structure, their advantages and drawbacks. The reasons for the impossibility of the practical implementation of tubular FP reactors in flow for the synthesis of polymers are established. The possibility of implementation of tubular FP reactors for the synthesis of polyacrylamide hydrogels (PAH) capable of absorbing and releasing large amount of water is presented. The paper also presents some data on the methods for the synthesis of PAHs with prescribed properties in tubular continuous FP reactors by way of using nano-additives and regulating the kinetics of the synthesis process. As a result, the synthesis process of PAHs with the required properties both in the absorption and release of water, and in the physical-mechanical properties was carried out in frontal tubular-type reactors in flow, and the water absorption kinetic curves and physical-mechanical properties of the obtained hydrogels are presented.</jats:p>

Frontal Polymerizations: From Chemical Perspectives to Macroscopic Properties and Applications

“…Free-radical polymerizations are the most common type of frontal systems, with over 80 published reports as of 2022 (refs , , , , − , , − , , − , , − , , , , , , − ). Three distinct mechanistic regimes exist for chain growth radical polymerizations (see the simplified Scheme ).…”

“…The physical properties of hydrogels synthesized frontally are comparable, if not better than, traditional synthesized analogues. To date, more than 30 reports detailing the synthesis and properties of frontally prepared hydrogels exist (refs , − , − , , , , , , , , , , , , , , , , , , − , , , , ).…”

“…Future efforts to achieve large-scale FP extrusion, however, may benefit from earlier works described in this review. 32,157,162,243,374 In contrast to large-scale manufacturing processes, one may imagine possible industrial applications to fabricate small parts and components, such as those produced in the context of microfluidic devices (section 5.4.6). 278 In such cases, front initiation is less problematic than front-quenching associated with high surface area to volume ratios.…”

Front velocity dependence on vinyl ether and initiator concentration in radical‐induced cationic frontal polymerization of epoxies

“…[12][13][14][15] It was rediscovered by Pojman and studied in the 1990s [16][17][18] and has seen recent rapid growth through applications such as composites, 19,20 cure-on demand materials and adhesives, 21,22 deep-eutectic solvents 23 and hydrogels. [24][25][26][27][28] In a thermal frontal polymerization process, an input of thermal energy at a specific area initiates a propagating localized reaction zone that travels through the entire material, where monomer is converted into polymer as propagation occurs. 29 Typically, most monomers capable of supporting fronts proceed by free-radical mechanisms due to their high rate of reactivity and exothermicity.…”

“…Frontal polymerization (FP) was discovered by Chechilo and Enikolopyan 11 and studied in Russia by their group and others through the 1970s and 1980s 12–15 . It was rediscovered by Pojman and studied in the 1990s 16–18 and has seen recent rapid growth through applications such as composites, 19,20 cure‐on demand materials and adhesives, 21,22 deep‐eutectic solvents 23 and hydrogels 24–28 . In a thermal frontal polymerization process, an input of thermal energy at a specific area initiates a propagating localized reaction zone that travels through the entire material, where monomer is converted into polymer as propagation occurs 29 .…”