Experts in Specialty Materials
Our chemistry group specializes in the design, synthesis, and formulation of ultra-pure organic materials including dichroic dyes, photochromic dyes, laser dyes, nematic liquid crystals, chiral dopants, mesogenic monomers, initiators, sol gels, and nanoparticles.
Liquid Crystal Formulations
Liquid crystal mixtures are a highly complex blend of several mesogenic and non-mesogneic LC molecules as well as chiral dopants, monomers, dyes, and other active dopants. There can be as many as 20 sub-components in any one LC mixture! Each subcomponent has to be specifically matched with other dopants in both chemical structure and concentration to provide the expected optical, thermal and electrical performance needed. Slight deviation or impurity can adverse the stability of the mixture and result in undesirable phase separation. The expertise in formulating liquid crystal mixtures comes only after years of experience and testing and is the prime reason why the suppliers of liquid crystalline material are limited.
AlphaMicron has spent over 20 years studying liquid crystal material and formulations. It has created a library of materials that can be used in various mixtures and catalogued their effects in guest-host systems. To meet the particular requirements needed for a final system, chemists and physicists at AlphaMicron formulate specific mixtures that will precisely meet each requirement to arrive at a final product.
Absorptive technologies like AlphaMicron’s e-Tint® technology is dependent on high order parameter dichroic dyes which are also soluble in the liquid crystal host. AlphaMicron has developed a variety of dichroic dyes with absorption spectrums that span the entire visible spectrum. They have been shown to have the highest recorded cichroic ratio. The dyes are used in both positive and negative hosts resulting in normally-dark or normally-clear systems. They can also be added to scattering or reflective technologies to enhance the performance. In addition, they can be used to create multi-color devices. for example, a 4-color system was designed and commercialized. Whether the system is activated with voltage (e-Tint®), temperature (thermochromics system), UV light (polarized photochormic), or visible light (configurational azo dyes), the presence of the high purity, high dichroic ratio dyes enhances the performance.
Optically Active Dopants
In addition to the liquid crystal and dichroic dyes, a formulation will include a number of dopants that provide functional capabilities to the liquid crystal host. These include chiral dopants, fluorescent dyes and stabilizers and other materials. Chiral dopants are used in many liquid crystal based devices to provide the material with a self-assembled pitch . Depending on this pitch, the optical properties of the system can be altered from a polarization rotator to a reflective polarizer and/or scatterer.
In addition to making chiral dopants, AlphaMicron synthesizes its own specialized dopants including liquid crystal compatible fluorescent dyes for CLC laser applications and stabilizers which help prolong the UV resistance and increase the lifetime of all its mixtures.
AlphaMicron has created UV activated chiral dopants which can alter their chirality upon light illumination. These unique materials are being provided to the Department of Defense for their unique optical requirements.
Addition of monomers to liquid crystal devices and subsequent polymerization increases the mechanical stability of liquid crystal systems. Creating polymer networks without effecting the phase of the liquid crystal host is a complex task and depends on both material and process-related parameters. AlphaMicron synthesizes polymerizable monomers which are mesogenic and compatible with liquid crystalline host. Once polymerized into main chain or side chains, these monomers provide a backbone which can help orient the liquid crystal as well as providing mechanical stability. More recently, AlphaMicron has synthesized liquid crystal compatible, polymerizable chiral dopants. This material imparts chirality to the polymer network during polymerization which is controllable by the processing conditions. This allows creation of unique structures such as a chirped twisted network used in broadband reflectors and CLC lasers. In addition to polymerizable chirals, AlphaMicron has created polymerizable photochromic/dichroic dyes which adhere to the network and can be activated by light or voltage.
Photonic Band Gap Materials
Photonic bandgap materials have become of significant importance in photonic and optical applications. One of the leading demonstrations has been photonic bandgap lasing in cholesteric liquid crystals. AlphaMicron scientists working alongside scientists from Kent State University’s Liquid Crystal Institute were pioneers in this field and have demonstrated lasing in a number of liquid crystal systems including pure liquid crystal, dyes doped liquid crystals, polymeric liquid crystals, elastomeric liquid crystals, and most recently in chirped chiral systems where continuous wave orCW lasing was observed. The system provides novel advantages to conventional photonic systems. These finding were reported in refereed journals and are routinely reference in scientific journals and optics book.
Report of the first observation of mirror-less lasing in three-dimensional photonic crystals in blue phase cholesteric liquid crystals. Lasing in a three-dimensional photonic crystal of the liquid crystal blue phase II, Nature Materials 1, 111–113 (2002)
These materials have potential as tunable seeds for CW and pulsed lasers, waveguiding, switching and sensing applications.
Technology evolves at an exponential rate. Humans, on the other hand, have hardly evolved in the past few thousand years. This discrepancy is not sustainable and is the fundamental driver for many of the advances in “smart” devices. There are two solutions. The first is to eliminate the human and create autonomous systems, self-driving cars, drones, etc. The second is to create technologies whose goal is to bridge the capability gap. Much like a shock absorber dampens the movement difference between the tire and the passenger.
The birthplace of liquid crystal displays, the Kent State University’s Liquid Crystal Institute is the world’s first research center focused on the basic and applied science of liquid crystals. Many AlphaMicron scientists studied at the LCI and the proximity of AlphaMicron to LCI has fostered a unique intellectual cross-pollination resulting in a flow of new ideas and spurred innovation!
Photonic-bandgap materials, with periodicity in one, two or three dimensions, offer control of spontaneous emission and photon localization. Low-threshold lasing has been demonstrated in two-dimensional photonic-bandgap materials, both with distributed feedback and defect modes. Liquid crystals with chiral constituents exhibit mesophases with modulated ground states. Helical cholesterics are one-dimensional, whereas blue phases are three-dimensional self-assembled photonic-bandgap structures. Although mirrorless lasing was predicted and observed in one-dimensional helical cholesteric materials and chiral ferroelectric smectic materials, it is of great interest to probe light confinement in three dimensions. Here, we report the first observations of lasing in three-dimensional photonic crystals, in the cholesteric blue phase II. Our results show that distributed feedback is realized in three dimensions, resulting in almost diffraction-limited lasing with significantly lower thresholds than in one dimension. In addition to mirrorless lasing, these self-assembled soft photonic-bandgap materials may also be useful for waveguiding, switching and sensing applications. ©2012 Macmillan Publishers Limited.
Introducing the concept of “Sentient” materials: a new way of looking at liquid crystals.
Everyone is familiar with “LCD”. They use it in their phones and TVs and computer monitors. But very few people know the material for which this acronym stands. As such, LCDs have become victims of their own success and like an actor who is type casted into a particular role, liquid crystals have found themselves pigeonholed as a medium for a display. In fact, they are much more than that. The role they played in catapulting smart phones into our society can be repeated for other industries.
The AlphaMicron team seeks to expose the hidden nature of this unique class of materials and tap into some of its yet unexplored potential – the potential to revolutionize a number of industries.