Thermal Latent Reductants for Controlled Degradation of Polyperoxides and Their Application to High Performance Dismantlable Adhesives

Abstract

1-Phenyl-3-pyrazolidone (PhP) having an active hydrogen was blocked by phenyl isocyanate derivatives to reduce its nucleophilicity, and the potential of the blocked PhP as a thermal latent reductant generating the organic reducing agent, PhP, was revealed for the first time. The degree of dissociation of the blocked PhP during heating in solution can be controlled by the steric hindrance of the isocyanate-blocking agents. The thermal latency of the blocked PhP for the sorbic ester-based polyperoxides, which undergo a serious reductive decomposition by PhP even at 30 °C, was investigated in order to accelerate the decomposition of the polyperoxides only at elevated temperatures. It was revealed that the stability of the polyperoxides was not significantly affected at 30 °C and marked reductive decomposition of the polyperoxides together with thermal decomposition took place at elevated temperatures. For the block PhPs, which are highly compatible with the polyperoxides, the decomposition promotion effect increased with increasing the steric hindrance of the blocking agents, and the controlled decomposition of the polyperoxides was successfully achieved. Moreover, the addition of the blocked PhP resulted in the complete solubilization of sorbic ester-based cross-linked polyperoxides by heating, which was not able to be achieved without the blocked PhP. The performance of the debondable adhesive using the sorbic ester-based cross-linked polyperoxides was improved by the addition of the blocked PhP, although hazardous isocyanate formation during the activation process may limit the practical application. Specifically, a faster decrease in the lap-shear adhesion strength by heating was accomplished. Furthermore, the same level of dismantlability was achieved in the wade range of heating temperatures and time, which is an 3 important requirement for polyperoxides undergoing significant exothermic decomposition bringing about undesired temperature rise.

Composition‐dependent crystallization behavior of copolyperoxides from methyl methacrylate and 4‐vinylbenzyl stearate

“…Recently, Sato and coworkers explored the thermal latent properties of 1‐phenyl‐3‐pyrazolidones (PhPs) with an active hydrogen towards their addition effect for sorbic ester‐based polyperoxides. The dismantlability of polyperoxide could be achieved in the wide range of temperatures …”

“…The dismantlability of polyperoxide could be achieved in the wide range of temperatures. [18] Various literature reports reveal semi-solidic or gummy type characteristics for the polyperoxide materials. [19] They will become solid material if the synthesized polyperoxide becomes crystalline in nature.…”

Polyperoxides from Cyclic Monomers: Synthesis, Characterization, and High-Pressure Kinetics Study

“…29 Very recently, the addition of the blocked 1phenyl-3-pyrazolidones to the sorbic ester-based polyperoxides that resulted in the dismantlability of polyperoxide at higher temperatures due to the thermal latent properties of PhP has been reported. 30 To date, a wide range of acyclic vinyl monomers were polymerized in the presence of different O 2 pressures to synthesize polyperoxide materials. Among these monomers, only two reports are there for the acyclic vinyl monomers [namely, α-methyl styrene (AMS) 31 and 9-vinyl anthracene 32 where the rate of oxidative polymerization (R p ) depends on the O 2 pressure.…”

“…In addition, polyperoxides and their several derivatives are able to find importance as dismantlable adhesives, coating for surface modifications, molding compositions, and biocompatible material . Very recently, the addition of the blocked 1-phenyl-3-pyrazolidones to the sorbic ester-based polyperoxides that resulted in the dismantlability of polyperoxide at higher temperatures due to the thermal latent properties of PhP has been reported …”

Controls and Effects of Monomer Junctions and Sequences in Curable and Degradable Polyarylate Containing Acrylate Moieties

“…In contrast, the latter, main chain scission changes macromolecules to their fragments of small molecules, leading to decrease or loss of glass transition temperature, improvement of solubility, and increase of loss elastic modulus. Materials capable of these opposite property changes are attractive for the design of dismantlable adhesions, [1,2] renewable elastomers, [3] and stimuli-responsive network polymers. [4][5][6] However, as curing and main chain scission are different chemical reactions, multi-functional monomers possessing two functional groups playing each role as well as reactive groups for polymerization are required.…”