Modulation of the Optical Response of Polyethylene Films Containing Luminescent Perylene Chromophores

Abstract

In this work, two perylene derivatives containing different peripheral alkyl chains (i.e., N,N'-bis-(hexyl)perylene-3,4,9,10-tetracarboxyldiimide (ES-PTCDI) and N,N'-bis-(2'-ethylhexyl)perylene-3,4,9,10-tetracarboxyldiimide (EE-PTCDI)) were synthesized and efficiently dispersed at low loadings (from 0.01 to 0.1 wt %) into linear low-density polyethylene (LLDPE) by processing in the melt. Spectroscopic investigations (UV-vis and fluorescence) combined with quantum-mechanical studies demonstrated the ability of both chromophores to generate aggregates among the planar structure of dyes when dissolved in solution or dispersed into LLDPE above a certain concentration. The data acquired for dyes' dispersions into the polymer matrix reveal that the optical properties and responsiveness to mechanical stimuli are strongly dependent on the compactness of perylene aggregates provided by the different molecular structure of dyes. In particular, the strong intermolecular aggregates of ES-PTCDI resulted in being more resistant toward mechanical stress and less orientable by uniaxial drawing along the drawing direction of the film, whereas the less compact and distorted supramolecular architecture of EE-PTCDI chromophores provided composite films with a remarkable optical response to mechanical solicitations.

Luminescent Mechanochromic Sensors Based on Poly(vinylidene fluoride) and Excimer‐Forming p‐Phenylene Vinylene Dyes

“…We have shown that this general concept of stimulus-triggered dye (dis)assembly in polymer matrices allows for the design of a broad range of sensor materials, which are useful for the detection of temperature history, [13][14][15][16][17] exposure to chemicals, [18,19] and mechanical deformation, [20][21][22][23][24] as well as more complex combinations of stimuli, such as seen in shape-memory materials. [25] Others have adapted the concept and extended it to a range of dyes including cyano containing poly(phenylene ethynylenes), [26] perylenes, [27] CdS nanoparticles, [28] and bis(benzoxazolyl)stilbenes. [29] The temperature and humidity sensors based on such polymer/dye blends operate by kinetically trapping a thermodynamically unstable molecular mixture of the components by rapidly cooling a hot (and at this temperature miscible) mixture below its glass transition temperature (T g ).…”

Polymers and Dyes: Developments and Applications

“…The ability of the polymer matrix to break up these aggregates was found to be mainly determined by the dye aggregate size, the crystallinity of the polymer matrix, and the strain rate. Hydrophobically modified perylene derivatives were also found to be suitable candidates for forming aggregates in poly(ethylene) matrices that are responsive to mechanical stimuli [50].…”

Mechanochemistry in Polymers with Supramolecular Mechanophores

“…While the study did also not involve well-defined supramolecular assemblies, the results paved the way for subsequent work on mechanochromic polymers comprising assemblies of aggregachromic, excimer-forming cyano-substituted oligo(p-phenylene vinylene)s (cyano-OPVs, Figures 2-4). [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] Scanning confocal microscopy images of blend films of ultra-high-molecular-weight polyethylene and 10 -4 % w/w EHO-OPPE (Figure 1). a) As prepared film.…”

“…Similar changes in absorption have also been reported for a PETG-based polymer films in which a cyano-OPV dye was covalently introduced into polymer chain. [45] Pucci and coworkers have also reported LLDPE-based films containing perylene bisimide derivatives, [54] which have been intensively examined because of their attractive optoelectronic character and propensity to assemble into supramolecular architectures. Blend films comprising N,N'-bis-(2'-ethylhexyl)perylene-3,4,9,10-tetracarboxyldiimide (EE-PTCDI) in LLDPE were obtained by melt-mixing procedures and blend films with 0.1% w/w of the dye exhibited mechanoresponsive behavior as shown in Figure 10.…”