About
Contributions
Activity
-
Together we can end #toxic leaders and workplace culture.
Together we can end #toxic leaders and workplace culture.
Liked by Mahdi Roohnikan
-
Evercloak Inc. has secured additional funding to accelerate the development of its membrane-based system for low carbon HVAC technology. The $1.1…
Evercloak Inc. has secured additional funding to accelerate the development of its membrane-based system for low carbon HVAC technology. The $1.1…
Liked by Mahdi Roohnikan
-
Excited to announce that following our successful first venture in the residential and commercial cleaning industry, we are now searching for our…
Excited to announce that following our successful first venture in the residential and commercial cleaning industry, we are now searching for our…
Liked by Mahdi Roohnikan
Experience & Education
Licenses & Certifications
Publications
-
Mechanochemical nanoparticle functionalization for liquid crystal nanocomposites based on COOH-pyridine heterosynthons
Royal Society of Chemistry
Nanoparticle/liquid crystal (NP/LC) composites can be stabilized by hydrogen bonding, a relatively strong, yet reversible interaction allowing for the annealing of defects. Previously, nanocomposites based on 4-hexylbenzoic acid (6BA) and ZrO2 NPs with pendant carboxylic acid groups were investigated, leading to problems of particle aggregation due to intra- and inter-particle hydrogen bonding. Here we report the synthesis of NP–LC composites based on different hydrogen bond acceptor and donor…
Nanoparticle/liquid crystal (NP/LC) composites can be stabilized by hydrogen bonding, a relatively strong, yet reversible interaction allowing for the annealing of defects. Previously, nanocomposites based on 4-hexylbenzoic acid (6BA) and ZrO2 NPs with pendant carboxylic acid groups were investigated, leading to problems of particle aggregation due to intra- and inter-particle hydrogen bonding. Here we report the synthesis of NP–LC composites based on different hydrogen bond acceptor and donor groups, promoting NP–LC coupling and reducing aggregation due to NP–NP interactions. Specifically, we developed a mechanochemical, solvent-free approach for efficient functionalization of ZrO2 NPs with (3-(pyridin-4-yl)propyl)phosphonic acid (3-PPA), leading to NPs with pendant pyridine groups that act as hydrogen bond acceptors only. This is the first example of using hydrogen bonded heterosynthons to tune the LC–NP interactions. The miscibility of the pyridine-functionalized NPs with 4-hexylbenzoic acid (6BA), a strong hydrogen bond donor, versus trans-4-butylcyclohexanecarboxylic acid (4-BCHA), a weaker hydrogen bond donor, was characterized by polarized optical and fluorescence microscopies. The specificity of the NP/LC acceptor/donor hydrogen bonds improves the miscibility over the NP/LC dispersions based on COOH dimer interactions only. The different effect of the NPs on the 4-BCHA properties as compared to 6BA can be related to the relative strengths of the COOH-pyridine hydrogen bonds.
Other authors -
-
Hydrogen Bond Stabilized Nanoparticle-Liquid Crystal Composites
Langmuir
Nanoparticle-liquid crystal (NP-LC) composites based on hydrogen bonding were explored using a model system. The ligand shells of 3 nm diameter zirconium dioxide nanoparticles (ZrO2 NPs) were varied to control their interaction with 4-n-hexylbenzoic acid (6BA). The miscibility and effect of the NPs on the nematic order as a function of particle concentration was characterized by polarized optical microscopy (POM), fluorescence microscopy and 2H NMR spectroscopy. Nonfunctionalized ZrO2 NPs have…
Nanoparticle-liquid crystal (NP-LC) composites based on hydrogen bonding were explored using a model system. The ligand shells of 3 nm diameter zirconium dioxide nanoparticles (ZrO2 NPs) were varied to control their interaction with 4-n-hexylbenzoic acid (6BA). The miscibility and effect of the NPs on the nematic order as a function of particle concentration was characterized by polarized optical microscopy (POM), fluorescence microscopy and 2H NMR spectroscopy. Nonfunctionalized ZrO2 NPs have the lowest miscibility and strongest effect on the LC matrix due to irreversible binding of 6BA to the NPs via a strong zirconium carboxylate bond. The ZrO2 NPs were functionalized with 6-phosphonohexanoic acid (6PHA) or 4-(6-phosphonohexyloxy)benzoic acid (6BPHA) which selectively bind to the ZrO2 NP surface via the phosphonic acid groups. The miscibility was increased by controlling the concentration of the pendant CO2H groups by adding hexylphosphonic acid (HPA) to act as a spacer group. Fluorescence microscopy of lanthanide doped ZrO2 NPs showed no aggregates in the nematic phase below the NP concentration where aggregates are observed in the isotropic phase. The functionalized NPs preferably concentrate into LC defects and any remaining isotropic liquid but are still present throughout the nematic liquid at a lower concentration.
Other authors -
-
Supramolecular self-assembly of a novel hydrogen-bonded cholesteric liquid crystal exhibiting macromolecular behavior
Liquid Crystal
The mesomorphic, thermoptic and glass-forming properties of 4-[6-((cholesteryloxy) carbonyl)oxy hexyloxy] benzoic acid (Ch-BA) have been investigated as a novel supramolecular hydrogen-bonded cholesteric mesogen. Fourier transform infrared and 1H nuclear magnetic resonance studies have confirmed the chemical structure and the hydrogen-bond formation between the mesogens. According to polarising optical microscope observations, the compound exhibited smectic and chiral nematic phases…
The mesomorphic, thermoptic and glass-forming properties of 4-[6-((cholesteryloxy) carbonyl)oxy hexyloxy] benzoic acid (Ch-BA) have been investigated as a novel supramolecular hydrogen-bonded cholesteric mesogen. Fourier transform infrared and 1H nuclear magnetic resonance studies have confirmed the chemical structure and the hydrogen-bond formation between the mesogens. According to polarising optical microscope observations, the compound exhibited smectic and chiral nematic phases. Differential scanning calorimetry indicated an unexpected glass transition (T g) around 32°C and a liquid crystalline region between 32 and 122°C, in which the cholesteric phase appeared at 80°C. As a result of the glass formation, samples of Ch-BA which were rapidly cooled below the T g were found to preserve the long-range ordering of the liquid crystalline state and retained the iridescent colours of the cholesteric phase. These results led to the conclusion that the formation of identical dimers by intermolecular hydrogen-bonding of the terminal carboxylic acids accompanying the lateral packing of the rigid cores, built a trimeric arrangement and this was responsible for the macromolecular behaviour of Ch-BA, despite its relatively simple structure and low molecular weight.
Other authors -
Honors & Awards
-
FRQS postdoctoral awardee
FRQS
-
Mitacs awardee
Mitacs
-
Institute Transmedtech awardee (Canada First)
-
-
Ulmer-Lamothe Graduate Award
Chemical Engineering Department
-
Graduate Research Enhancement and Travel Awards (GREAT)
Chemical Engineering department
-
CSACS travel award
CSACS center, Chemistry Department at McGill
-
Chemical Engineering Grad Excellence award
-
-
MEITA Award
McGill Faculty of Engineering
-
Ranked 1th among participants in nation-wide Polymer engineering Masters entrance exam
-
-
Mitacs Accelerate awardee
Mitacs
Languages
-
English
Full professional proficiency
-
French
Professional working proficiency
More activity by Mahdi
-
🚀 Exciting News from the Startup World! 🚀 Victoria-based startup VoxCell BioInnovation, winner of the YSpace, York University Technology…
🚀 Exciting News from the Startup World! 🚀 Victoria-based startup VoxCell BioInnovation, winner of the YSpace, York University Technology…
Liked by Mahdi Roohnikan
-
A great watch for anyone interested in the topic. Overpopulation comes up often, directly or indirectly. When we see such insights, one would think…
A great watch for anyone interested in the topic. Overpopulation comes up often, directly or indirectly. When we see such insights, one would think…
Shared by Mahdi Roohnikan
-
We've reached the final day of Startupfest, and what a journey it's been! 🎉 We've conducted series of incredible pitches, we will announce the…
We've reached the final day of Startupfest, and what a journey it's been! 🎉 We've conducted series of incredible pitches, we will announce the…
Liked by Mahdi Roohnikan
-
Setup for the super secret invite-only VC game taking place on day 3 of Startupfest 🏦💸 Great fun and an amazing game created by Raymond Luk…
Setup for the super secret invite-only VC game taking place on day 3 of Startupfest 🏦💸 Great fun and an amazing game created by Raymond Luk…
Liked by Mahdi Roohnikan
-
Milestone alert: The Product Market Fit Show hit 10,000 followers this week. Thank you for the support!
Milestone alert: The Product Market Fit Show hit 10,000 followers this week. Thank you for the support!
Liked by Mahdi Roohnikan
-
Break the cycle of burnout with expert advice from neuroscientist Alison Smith Ph.D., co-founder and chief science officer of Roga. Smith says the…
Break the cycle of burnout with expert advice from neuroscientist Alison Smith Ph.D., co-founder and chief science officer of Roga. Smith says the…
Liked by Mahdi Roohnikan
Other similar profiles
Explore collaborative articles
We’re unlocking community knowledge in a new way. Experts add insights directly into each article, started with the help of AI.
Explore More