Selfsensitization of the Photopolymerization of Diacetylenes Studied in Multilayers

Abstract

Absorptionsspektren, sichtbar und ultraviolettThe photoreactivity of multimolecular Langmuir-Blodgett layers is studied with optical absorption spectroscopy. Whereas the polymerization of monomeric layers can be initiated by UV-irradiation only, irradiation of partially polymerized layers with visible light up to I 6 500 nm leads to a continuation of the reaction. The maximal polymer yield obtained with W-and visible light irradiation is the same. The action spectra of the chain growth of partially polymerized layers and of the photoconductivity correspond to each other. A new mechanism of the chain growth is proposed.

Self-Sensitization and Photo-Polymerization of Diacetylene Molecules Self-Assembled on a Hexagonal-Boron Nitride Nanosheet

“…This is attributed to the well-known effect of self-sensitization, which causes partially polymerized crystals to further polymerize slightly faster than pure monomer crystals. The mechanisms proposed to date include reactivation of the chain end [ 39 ], homogeneous self-sensitization [ 40 ], and phonon excitation from neighboring rows [ 41 ]. However, after the second irradiation, we do not observe enhanced PDA chain lengths, the polymerization pattern is clearly inhomogeneous, and the initial irradiation produced individual polymers.…”

Nanocomposites of Hairy‐Rod Macromolecules: Concepts, Constructs, and Materials

“…In contrast, the dimensionality of the reaction describes the tensorial character of the reaction. The polymerization of amphiphilic monomers within LB‐layered assemblies is a reaction that proceeds in one direction and gives polymeric chains as one‐dimensional products 52,53. Reactions with zero dimensionality, the type of reaction that takes place with individual molecules only, are exemplified by the reaction of pending olefinic side groups with osmium tetroxide (Figure 6).…”

Polydiacetylenes – recent molecular advances and applications

“…The unique feature of PDA systems has been the observation that the conjugated PDA networks oen absorb light in the visible spectral region, thereby exhibiting color, in most cases blue. [7][8][9] Beside the intriguing chromatic properties of PDA, the diverse physical congurations of the PDA have attracted broad research interest. 1).…”

“…Another attractive feature of PDA systems in the context of sensing applications has been the uorescence properties; blue phase PDA is non-uorescence while the red-phase conguration exhibits high uorescence with minimal bleaching. [7][8][9] Beside the intriguing chromatic properties of PDA, the diverse physical congurations of the PDA have attracted broad research interest. PDA systems have been shown to organize in vesicles, 10,11 Langmuir monolayers, [12][13][14] self-assembled lms, 15,16 and single crystals.…”