Photo-triggered redox frontal polymerization: A new tool for synthesizing thermally sensitive materials

Abstract

A novel approach of photo-triggered redox frontal polymerization (FP) by integrating photocaged superbase (QA-DBU) with a peroxide initiator (dibenzoyl peroxide, BPO) is presented for the synthesis of thermally sensitive materials. Under photo-irradiation at a localized region, the regenerated superbase can diffuse into unirradiated regions and effectively actuate redox FP in a diffusion-controlled manner. Moreover, the redox FP can be conducted at a much lower front temperature with enhanced front velocity. Astonishingly, the front temperature can be well-modulated by changing the concentration of latent superbase. The prepared thermally sensitive fluorescent polymer composites exhibit enhanced fluorescence emission intensity compared to that of conventional thermal FP. V C 2013

Efficient photopolymerization of thick pigmented systems using upconversion nanoparticles‐assisted photochemistry

“…After irradiation for 150 s, the peak temperature of 120.4 °C appeared and stayed stable, indicating that the polymerization became stable and therefore released less heat. The peak temperature during UCNPs‐assisted photopolymerization is comparable with or lower than that of some reported frontal photopolymerization applied to preparing functional composite polymeric materials . A similar trend was observed for other depths but with lower peak temperatures (Fig.…”

“…Such phototriggered thermal or redox polymerization has been applied in the synthesis of dental filling materials for a deep cavity and formation of opaque composites containing carbon nanotubes . However, since the propagation front is driven by the heat release of the exothermic polymerization, conventional FPP lacks sufficient control over the front temperature due to the intrinsically exothermic nature of polymerization . Hence, a complete spatial control of frontal polymerization is limited.…”

Development of New Photoinitiating Systems for Depth Curing of Thick Materials

“…Most of the papers deal with the use of type I photoinitiators which eventually lead to photobleaching during irradiation. In this case, a frontal photopolymerization propagates in depth, and curing thick samples appears to be possible [6,[16][17][18]. In this paper, polymethylmethacrylate (PMMA) was chosen as typical example of photocurable thermoplastic.…”

Photoinitiating systems and kinetics of frontal photopolymerization processes – the prospects for efficient preparation of composites and thick 3D structures

“…15 There is also an approach that combines the techniques of thermal and photo radical frontal polymerisation. [21][22][23][24][25] In thermal frontal polymerisation (TFP), after the initiation of the system, there is almost no option to control the process. 22 Additionally, the thermal propagating front temperature can rise to above 200°C, leading to bubble creation or even a "burnout" of the initiator.…”

“…[21][22][23][24][25] In thermal frontal polymerisation (TFP), after the initiation of the system, there is almost no option to control the process. 22 Additionally, the thermal propagating front temperature can rise to above 200°C, leading to bubble creation or even a "burnout" of the initiator. 26 The bubbles appearing in the reaction mixture can lead to a breakdown of the propagating front and "burnout" of the initiator due to very low monomer conversion.…”