Green-blue luminescence dichroism of cyano-containing poly[(m-phenylene ethynylene)-alt-(p-phenylene ethynylene)] aggregates dispersed in oriented polyethylene

A new highly luminescent cyano-containing poly[(m-phenylene ethynylene)-alt-(p-phenylene ethynylene)] derivative (CN-PPE) has been prepared and blended in micro/nano-sized dispersions into linear low density polyethylene (LLDPE) films by melt-processing. CN-PPE macromolecules show pronounced tendency to form molecular aggregates in the excited state when dispersed in the polymer matrix with emission characteristics depending on the structural order of the luminescent chromophores. In CN-PPE/LLDPE films, the polymer matrix orientation induces effective anisotropic arrangements of the π-π staking interactions between luminescent guest aggregates, thereby generating a pronounced green-blue dichroic emission. The capability to easily modulate the luminescent properties of polyethylene films (from green to blue reversibly) simply by varying CN-PPE concentration or by stretching the polymer matrix, suggests various technological applications in the field of smart and intelligent films from thermoplastic materials.