Dual Photosensitive Polymers with Wavelength‐Selective Photoresponse

Abstract

Polyurethane thin films that photopolymerize and photodegrade upon exposure to light of different wavelengths are presented. The chromic response is based on two caged monomers with the ability to be activated or photocleaved with different wavelengths under single and two‐photon excitation. This material represents a dual photoresist with “positive” and “negative” tone contained in a single resist formulation and with the ability to generate complex 2D and 3D patterns.

A new role of curcumin: as a multicolor photoinitiator for polymer fabrication under household UV to red LED bulbs

“…[3][4][5][6][7][8][9] Ultraviolet (UV) light has low penetration ability in photocurable formulations containing UV absorbing compounds; visible light, on the other hand, can easily penetrate such formulations, and visible light photoinitiation is expected to be safer and more efficient than UV. Recent efforts have been devoted to the development of new compounds with novel chemical structures and excellent light absorption properties for use as visible light sensitive PIs.…”

A Polyurethane‐Based Positive Photoresist

“…The photoactive monomer 1‐(2‐nitrophenyl)‐1,2‐ethanediol, NP(OH) 2 was purchased from Sigma–Aldrich and was used without purification. The monomer 2‐(4′‐(2‐hydroxyethoxy)‐4‐nitro‐[1,1′‐biphenyl]‐3‐yl)propan‐1‐ol, PMNB(OH) 2 , was synthesized as previously reported . The rest monomers were commercially available: isophorone diisocyanate (IPDI; Sigma–Aldrich), tryphenylmethane‐4,4′, 4′′‐triisocyanate (DRE, Bayer AG) and poly(propylene glycol) 1200 Mw (PPG; Dow Chemical).…”

“…A 780 nm laser was used to scan squares of 1 mm 2 area of the crosslinked PU film with 100% intensity (960 mW), a resolution of 2048 × 2048 (px per line) and a pixel time exposure of 51.7 μs. Under these conditions, three scans were enough for completion of photocleavage . The micropattern was developed in THF/EtOH (1:1).…”

Wavelength-Selective Sequential Polymer Network Formation Controlled with a Two-Color Responsive Initiation System

“…11 Del Campo and co-workers formed a polyurethane-based dual photoresist material based on a p -dialkylaminonitrobiphenyl caged molecule (cleaves at 520 nm) that was used to initiate polymerization and another methoxynitrobiphenyl-based caged molecule (cleaves at 397 nm) that would degrade the polymer network. 8 With the help of this dual wavelength control system, sequential polymer formation and degradation were achieved. Scott et al implemented a two-color irradiation scheme, whereby initiating species and inhibiting species generated at different wavelengths (480 and 365 nm) were used to achieve precise control on polymerization rate and thus facilitate enhanced spatial control over the photopolymerization.…”