Degradable Polymers Prepared from Alkyl Sorbates and Oxygen under Atmospheric Conditions and Precise Evaluation of Their Thermal Properties

Abstract

ABSTRACT:We report here the alternating copolymers of diene monomers with oxygen as a new class of degradable polymer with great potential. The alternating copolymers of alkyl sorbates with oxygen are efficiently prepared without decomposition under atmospheric conditions in the presence of an azo initiator. The produced alternating copolymers exothermically decompose upon heating in a similar mechanism irrespective of the kind of the ester alkyl group of the sorbates; i.e., the methyl, ethyl, octadecyl, and trifluoroethyl esters. The initial and maximum decomposition temperatures (T init and T max ) are determined by differential thermal analysis (DTA) and thermogravimetric analysis (TG) in a nitrogen stream: T init = 106-112• C (DTA), T max = 147-152• C (DTA) or 144-148• C (TG). The TG curves obtained at a different heating rate are kinetically analyzed to evaluate an activation energy for decomposition by several methods. The decomposition rate constants, as well as overall activation energy, for the polymeric peroxide obtained from methyl sorbate are also precisely determined during the isothermal decomposition in a temperature range of 80-120• C by two different methods; E a = 86.7 and 84.7 kJ mol −1 on the basis of the weight loss of the polymer monitored by TG analysis, and the change in the molecular weight of the polymer determined by gel permeation chromatography, respectively. It has been revealed that the thermal cleavage of the peroxy linkage and the subsequent successive β-scission produce fumaraldehyde monoester and acetaldehyde during the thermal decomposition of the alternating copolymers as the polymeric peroxides.

Facile Synthesis of Main-Chain Degradable Block Copolymers for Performance Enhanced Dismantlable Adhesion

“…Both polymers showed twostep weight-loss and the first step was accompanied by the evolution of heat, which was typically observed for the thermal degradation of polyperoxide. 7 As inserted in Figure 6, the weight loss in the first degradation step of P2EHMA-b-PPMS5k (23.9 wt %) and P2EHMA-b-PPHD-5k (15.6 wt %) roughly agreed with the content of polyperoxide determined by 1 H NMR analysis (30.4 and 14.5 wt % for P2EHMA-b-PPMS-5k and P2EHMA-b-PPHD-5k, respectively). In order to analyze the residual after the first degradation step, P2EHMA-b-PPMS5k was isothermally heated for 5 h at 110°C, which is higher than the initial decomposition temperatures of PPMS (T init = 107.9°C).…”

In situ Collapse of Phase‐Separated Structure by Covalent Bond Cleavage at a Branching Point upon Heating

“…However, a preliminary GPC analysis suggests that the conversion of the macromonomers (PSt‐D and PIP‐D) to the branched copolymer is approximately 20–30% and the degree of polymerization of the branched copolymers is less than 10. The conversion will be increased by prolonging a reaction time with further addition of the radical initiator 11…”

“…In recent years, we have demonstrated a new kind of degradable polymer, a polyperoxide, which is readily prepared by the radical alternating copolymerization of diene monomers with molecular oxygen by a conventional radical polymerization procedure 10–14. Polyperoxides are more stable than typical organic peroxides with a low molecular weight and start to decompose by stimuli such as a heating at ca.…”

Kinetic and thermochemical study of the oxidative polymerization of α-substituted styrenes

“…Polyperoxides degrade highly exothermically in contrast to common polymers, and exhibit unusual phenomenon of auto-pyrolysis indicating its potential use as an autocombustible fuel [8]. Recently, degradable polyperoxides by the radical alternating copolymerization of 1,3-diene monomers with molecular oxygen at an atmospheric pressure are reported [9][10][11][12][13][14]. Application of polyperoxides from 1,3-diene monomers for dismantlable adhesion has been established [15].…”