Design of Mixed-Matrix MOF Membranes with Asymmetric Filler Density and Intrinsic MOF/Polymer Compatibility for Enhanced Molecular Sieving.

The separation of high-value-added chemicals from organic solvents is important for many industries. Membrane-based nanofiltration offers a more energy-efficient separation than the conventional thermal processes. Conceivably, mixed-matrix membranes (MMMs), encompassing metal-organic frameworks (MOFs) as fillers, are poised to promote selective separation via molecular sieving, synergistically combining polymers flexibility and fine-tuned porosity of MOFs. Nevertheless, conventional direct mixing of MOFs with polymer solutions results in underutilization of the MOF fillers owing to their uniform cross-sectional distribution. Therefore, in this work, a multizoning technique is proposed to produce MMMs with an asymmetric-filler density, in which the MOF fillers are distributed only on the surface of the membrane, and a seamless interface at the nanoscale. The design strategy demonstrates five times higher MOF surface coverage, which results in a solvent permeance five times higher than that of conventional MMMs while maintaining high selectivity. Practically, MOFs are paired with polymers of similar chemical nature to enhance their adhesion without the need for surface modification. The approach offers permanently accessible MOF porosity, which translates to effective molecular sieving, as exemplified by the polybenzimidazole and Zr-BI-fcu-MOF system. The findings pave the way for the development of composite materials with a seamless interface.

Conductive nanofiltration membranes via in situ PEDOT-polymerization for electro-assisted membrane fouling mitigation.

Nanofiltration (NF) membranes play a pivotal role in water treatment; however, the persistent challenge of membrane fouling hampers their stable application. This study introduces a novel approach to address this issue through the creation of a poly(3,4-ethylenedioxythiophene) (PEDOT)-based conductive membrane, achieved by synergistically coupling interfacial polymerization (IP) with in situ self-polymerization of EDOT. During the IP reaction, the concurrent generation of HCl triggers the protonation of EDOT, activating its self-polymerization into PEDOT. This interwoven structure integrates with the polyamide network to establish a stable selective layer, yielding a remarkable 90 % increase in permeability to 20.4 L m-2 h-1 bar-1. Leveraging the conductivity conferred by PEDOT doping, an electro-assisted cleaning strategy is devised, rapidly restoring the flux to 98.3 % within 5 min, outperforming the 30-minute pure water cleaning approach. Through simulations in an 8040 spiral-wound module and the utilization of the permeated salt solution for cleaning, the electro-assisted cleaning strategy emerges as an eco-friendly solution, significantly reducing water consumption and incurring only a marginal electricity cost of 0.055 $ per day. This work presents an innovative avenue for constructing conductive membranes and introduces an efficient and cost-effective electro-assisted cleaning strategy to effectively combat membrane fouling.

Biobased Interpenetrating Polymer Network Membranes for Sustainable Molecular Sieving.

There is an urgent need for sustainable alternatives to fossil-based polymer materials. Through nanodomain engineering, we developed, without using toxic cross-linking agents, interpenetrating biopolymer network membranes from natural compounds that have opposing polarity in water. Agarose and natural rubber latex were consecutively self-assembled and self-cross-linked to form patchlike nanodomains. Both nano-Fourier transform infrared (nano-FTIR) spectroscopy and computational methods revealed the biopolymers' molecular-level entanglement. The membranes exhibited excellent solvent resistance and offered tunable molecular sieving. We demonstrated control over separation performance in the range of 227-623 g mol-1 via two methodologies: adjusting the molecular composition of the membranes and activating them in water. A carcinogenic impurity at a concentration of 5 ppm, which corresponds to the threshold of toxicological concern, was successfully purged at a negligible 0.56% pharmaceutical loss. The biodegradable nature of the membranes enables an environmentally friendly end-of-life phase; therefore, the membranes have a sustainable lifecycle from cradle to grave.

Multistep Transformation from Amorphous and Nonporous Fullerenols to Highly Crystalline Microporous Materials.

The structural and morphological properties of fullerenols upon exposure to heat treatment have yet to be understood. Herein, the temperature-driven structural and morphological evolutions of fullerenols C60 (OH) and C70 (OH) were investigated. In situ spectroscopic techniques, such as variable-temperature X-ray diffraction and coupled thermogravimetric Fourier-transform infrared analysis, were used to elucidate the structural transformation mechanism of fullerenols. Both fullerenols underwent four-step structural transformation upon heating and cooling, including amorphous-to-crystalline transition, thermal expansion, structural compression, and new crystal formation. Compared to the initially nonporous amorphous fullerenol, the crystalline product exhibited microporosity with a surface area of 114 m2 g-1 and demonstrated CO2 sorption capability. These findings show the potential of fullerene derivatives as adsorbents.

Norbornane-based covalent organic frameworks for gas separation.

Covalent organic frameworks (COFs) have emerged as a new class of crystalline porous materials with distinct structural features, such as uniform pore distribution, tunable architecture, and modifiable skeletons. COFs hold significant promise for application in gas separation because of their high Brunauer-Emmett-Teller surface area and narrow pore-size distribution, which enable selective separation. The porosity and separation performance of COFs have been finely tuned by structurally modifying the starting materials. Along this direction, for the first time, we prepared W-shaped diamines by catalytic arene-norbornene annulation (CANAL) and then treated them with trialdehyde (Tp) to synthesize novel ß-ketoenamine-linked norbornane-based COFs, i.e., ND-COF-1 and ND-COF-2, via a solvothermal Schiff-base condensation approach. The pore interior was decorated with methyl groups attached to the norbornane unit of the COF skeleton. Both COFs exhibited high chemical stability in different organic solvents and acidic media. Additionally, they showed high CO2/N2 selectivity compared with those of previously reported COFs. Moreover, their CH4/N2 separation efficiency was investigated, and the results revealed that ND-COF-1 is more selective than ND-COF-2, which could be attributed to the less hindered pathway offered to methane gas molecules by the framework pore.

Nanofibrous membranes comprising intrinsically microporous polyimides with embedded metal-organic frameworks for capturing volatile organic compounds.

Here, we report the fabrication of nanofibrous air-filtration membranes of intrinsically microporous polyimide with metal-organic frameworks (MOFs). The membranes successfully captured VOCs from air. Two polyimides with surface areas up to 500 m2 g-1 were synthesized, and the impact of the porosity on the sorption kinetics and capacity of the nanofibers were investigated. Two Zr-based MOFs, namely pristine UiO-66 (1071 m2 g-1) and defective UiO-66 (1582 m2 g-1), were embedded into the nanofibers to produce nanocomposite materials. The nanofibers could remove polar formaldehyde and non-polar toluene, xylene, and mesitylene from air. The highest sorption capacity with 214 mg g-1 was observed for xylene, followed by mesitylene (201 mg g-1), toluene (142 mg g-1), and formaldehyde (124 mg g-1). The incorporation of MOFs drastically improved the sorption performance of the fibers produced from low-surface-area polyimide. Time-dependent sorption tests revealed the rapid sequestration of air pollutants owing to the intrinsic porosity of the polyimides and the MOF fillers. The porosity allowed the rapid diffusion of pollutants into the inner fiber matrix. The molecular level interactions between VOCs and polymer/MOFs were clarified by molecular modeling studies. The practicality of material fabrication and the applicability of the material were assessed through the modification of industrial N95 dust masks. To the best of our knowledge, this is the first successful demonstration of the synergistic combination of intrinsically microporous polyimides and MOFs in the form of electrospun nanofibrous membranes and their application for VOC removal.

Fast-dissolving antibacterial nanofibers of cyclodextrin/antibiotic inclusion complexes for oral drug delivery.

HYPOTHESIS: The widespread use of antibacterial electrospun nanofibers is mostly restricted due to their low loading capacity to carry antibiotics and the need to use toxic organic solvents to boost the antibiotic loading capacity. Nanofibers based on natural excipients, such as cyclodextrin (CD)-based nanofibers, can carry larger amounts of antibiotics while achieving better stability via inclusion complexation. EXPERIMENTS: Nanofibers were produced by electrospinning and analyzed by electron microscopy to investigate the morphology of fibers. The formation of inclusion-complexation was analyzed by 1H NMR, FTIR, and XRD. Thermal analysis of the fibers was done using TGA. Ab initio modeling studies were done to calculate the complexation energies of antibiotics with CD. A disk-diffusion assay was used to test the antibacterial activity of the fibers. FINDINGS: Bead-free antibacterial nanofibers with mean diameters between 340 and 550 nm were produced. The formation of inclusion complexes (IC) between the CD and the antibiotics was confirmed by FTIR and 1H NMR, which was further verified by the disappearance of the crystalline peaks of antibiotics as determined by XRD analysis. Thermal analysis of the nanofibers revealed that the formulations showed good antibiotic encapsulation (45-90%). Ab initio simulations revealed that gentamicin had the highest complexation energy, followed by kanamycin, chloramphenicol, and ampicillin. The antibacterial nanofibers rapidly dissolved in water and artificial saliva, successfully releasing the CD antibiotic complexes. The nanofibers showed high antibacterial activity against Gram-negative Escherichia coli.

Asymmetric Membrane Capacitive Deionization Using Anion-Exchange Membranes Based on Quaternized Polymer Blends.

Membrane capacitive deionization (MCDI) for water desalination is an innovative technique that could help to solve the global water scarcity problem. However, the development of the MCDI field is hindered by the limited choice of ion-exchange membranes. Desalination by MCDI removes the salt (solute) from the water (solvent); this can drastically reduce energy consumption compared to traditional desalination practices such as distillation. Herein, we outline the fabrication and characterization of quaternized anion-exchange membranes (AEMs) based on polymer blends of polyethylenimine (PEI) and polybenzimidazole (PBI) that provides an efficient membrane for MCDI. Flat sheet polymer membranes were prepared by solution casting, heat treatment, and phase inversion, followed by modification to impart anion-exchange character. Scanning electron microscopy (SEM), atomic force microscopy (AFM), nuclear magnetic resonance (NMR), and Fourier-transform infrared (FTIR) spectroscopy were used to characterize the morphology and chemical composition of the membranes. The as-prepared membranes displayed high ion-exchange capacity (IEC), hydrophilicity, permselectivity and low area resistance. Due to the addition of PEI, the high density of quaternary ammonium groups increased the IEC and permselectivity of the membranes, while reducing the area resistance relative to pristine PBI AEMs. Our PEI/PBI membranes were successfully employed in asymmetric MCDI for brackish water desalination and exhibited an increase in both salt adsorption capacity (>3×) and charge efficiency (>2×) relative to membrane-free CDI. The use of quaternized polymer blend membranes could help to achieve greater realization of industrial scale MCDI.

Selective Electrocatalytic Oxidation of Biomass-Derived 5-Hydroxymethylfurfural to 2,5-Diformylfuran: from Mechanistic Investigations to Catalyst Recovery.

Invited for this month's cover is the group of Gyorgy Szekely at King Abdullah University of Science and Technology (KAUST). The image shows the efficient TEMPO-based electrocatalytic transformation of biomass-based C6 -platform chemical HMF to DFF using non-precious-metal-based electrodes in green solvents with nanofiltration-enabled catalyst recovery. The Full Paper itself is available at 10.1002/cssc.202000453.

Middle and Distal Common Carotid Artery Stenting: Long-Term Patency Rates and Risk Factors for In-Stent Restenosis.

PURPOSE: In the absence of literature data, we aimed to determine the long-term patency rates of middle/distal common carotid artery (CCA) stenting and to investigate predisposing factors in the development of in-stent restenosis (ISR). MATERIALS AND METHODS: Fifty-one patients (30 males, median age 63.5 years), who underwent stenting with 51 self-expandable stents for significant (≥ 60%) stenosis of the middle/distal CCA, were analyzed retrospectively. Patient (atherosclerotic risk factors, comorbidities, medications), vessel (elongation), lesion (stenosis grade, length, calcification, location), and stent characteristics (material, diameter, length, fracture) were examined. Duplex ultrasonography was used to monitor stent patency. The Mann-Whitney U and Fisher's exact tests, Kaplan-Meier analyses, and a log-rank test were used statistically. RESULTS: The median follow-up time was 35 months (interquartile range, 20-102 months). Significant (≥ 70%) ISR developed in 14 patients (27.5%; stenosis, N = 10; entire CCA occlusion, N = 4). Primary patency rates were 98%, 92%, 83%, 73%, and 61% at 6, 12, 24, 60, and 96 months, respectively. Reintervention was performed in six patients (11.8%) with nonocclusive ISR. Secondary patency rates were 100% at 6 and 12 months and 96% at 24, 60, and 96 months. In-stent restenosis developed more frequently (P < .001) in patients with hyperlipidemia; primary patency rates were also significantly worse (Chi-square, 11.08; degrees of freedom, 1; P < .001) in patients with hyperlipidemia compared to those without. CONCLUSION: Stenting of the middle/distal CCA can be performed with acceptable patency rates. If intervention is unequivocally needed, patients with hyperlipidemia will require closer follow-up care. LEVEL OF EVIDENCE: Level 3, Local non-random sample.

Selective Electrocatalytic Oxidation of Biomass-Derived 5-Hydroxymethylfurfural to 2,5-Diformylfuran: from Mechanistic Investigations to Catalyst Recovery.

The catalytic transformation of bio-derived compounds, specifically 5-hydroxymethylfurfural (HMF), into value-added chemicals may provide sustainable alternatives to crude oil and natural gas-based products. HMF can be obtained from fructose and successfully converted to 2,5-diformylfuran (DFF) by an environmentally friendly organic electrosynthesis performed in an ElectraSyn reactor, using cost-effective and sustainable graphite (anode) and stainless-steel (cathode) electrodes in an undivided cell, eliminating the need for conventional precious metal electrodes. In this work, the electrocatalysis of HMF is performed by using green solvents such as acetonitrile, γ-valerolactone, as well as PolarClean, which is used in electrocatalysis for the first time. The reaction parameters and the synergistic effects of the TEMPO catalyst and 2,6-lutidine base are explored both experimentally and through computation modeling. The molecular design and synthesis of a size-enlarged C3 -symmetric tris-TEMPO catalyst are also performed to facilitate a sustainable reaction work-up through nanofiltration. The obtained performance is then compared with those obtained by heterogeneous TEMPO alternatives recovered by using an external magnetic field and microfiltration. Results show that this new method of electrocatalytic oxidation of HMF to DFF can be achieved with excellent selectivity, good yield, and excellent catalyst recovery.

The incidence and risk factors of stent fracture in patients treated for proximal common carotid artery stenosis.

OBJECTIVE: Our aim was to identify the incidence of and predictors for common carotid artery (CCA) stent fractures (SFs) and to examine the effect of SFs on the development of in-stent restenosis (ISR). METHODS: Seventy patients (37 women; median age, 60.9 years) who were stented for significant (≥60%) proximal CCA stenosis from 2006 to 2016 and revisited us to determine SF using fluoroscopy in 2018 were evaluated. Seventy stents were deployed; among them 87.1% were balloon-expandable and 12.9% were self-expandable. SFs were classified as type I (fracture of one strut), type II (fracture of multiple struts without stent deformity), type III (fracture of multiple struts with stent deformity), type IV (complete fracture of the stent without a gap), and type V (complete fracture of the stent with a gap). Duplex ultrasound examination was used for monitoring stent patency. Mann-Whitney U and Fisher's exact tests, Kaplan-Meier and logistic regression analyses, and a log-rank test and a gamma correlation analysis were applied as statistical methods. RESULTS: The patients were followed for 75.5 months (range, 47-109 months). Significant (≥70%) ISR was observed in eight patients (11.4%). Reintervention was performed in four cases (5.7%). Twenty-seven SFs (38.6%; type I, 8; type II, 10; type III, 4; type IV, 2; and type V, 3) were found. Calcification was shown to be a significant predictor for SF (odds ratio, 13.2; 95% confidence interval, 3.9-45.1; P < .001). There was no significant difference between the fractured and the nonfractured group regarding the number of patients with ISR and reintervention (P = .701 and P = .636, respectively). Neither did the primary patency rates differ significantly (P = .372) in patients with and without SF. CONCLUSIONS: Fractures frequently occur in a wide variety of stent devices deployed in the proximal CCA, but SFs seem to have no effect on ISR and reintervention.

Bio-Inspired Robust Membranes Nanoengineered from Interpenetrating Polymer Networks of Polybenzimidazole/Polydopamine.

Marine mussel inspired polydopamine (PDA) has received increased attention due to its good thermal and chemical stability as well as strong adhesion on most materials. In this work, high-performance nanofiltration membranes based on interpenetrating polymer networks (IPN) incorporating PDA and polybenzimidazole (PBI) were developed for organic solvent nanofiltration (OSN). Generally, in order to obtain solvent stability, polymers need to be covalently cross-linked under harsh conditions, which inevitably leads to losses in permeability and mechanical flexibility. Surprisingly, by in situ polymerization of dopamine within a PBI support, excellent solvent resistance and permeance of polar aprotic solvents were obtained without covalent cross-linking of the PBI backbone due to the formation of an IPN. The molecular weight cutoff and permeance of the membranes can be fine-tuned by changing the polymerization time. Robust membrane performance was achieved in conventional and emerging green polar aprotic solvents (PAS) in a wide temperature range covering -10 °C to +100 °C. It was successfully demonstrated that the in situ polymerization of PDA-creating an IPN-can provide a simple and green alternative to covalent cross-linking of membranes. To elucidate the nature of the solvent stability, a detailed analysis was performed that revealed that physical entanglement along with strong secondary interaction synergistically enable solvent resistance with as low as 1-3% PDA content.

Tailoring the Performance of Organic Solvent Nanofiltration Membranes with Biophenol Coatings.

This study reports a systematic investigation of fine-tuning the filtration performance of nanofiltration membranes with biophenol coatings to produce solvent-resistant membranes with 390-1550 g mol-1 molecular weight cutoff (MWCO) and 0.5-40 L m-2 h-1 bar-1 permeance. Six kinds of inexpensive, commercial biophenols (dopamine, tannic acid, vanillyl alcohol, eugenol, morin, and quercetin) were subjected to identical oxidant-promoted polymerization to coat six kinds of loose asymmetric membrane supports: polyimide (PI), polyacrylonitrile (PAN), polysulfone (PSf), polyvinylidene difluoride (PVDF), polybenzimidazole (PBI), and polydimethylsiloxane (PDMS). The coatings were characterized by Fourier-transform infrared spectroscopy (FTIR), and the morphologies were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The long-term stability of 42 membranes were tested in 12 organic solvents, including emerging green solvents MeTHF and Cyrene. The biophenol coatings led to tighter membranes with a decrease in MWCO of 12-79% at a penalty of a 22-92% permeance decrease in acetone.

Robust Covalently Cross-linked Polybenzimidazole/Graphene Oxide Membranes for High-Flux Organic Solvent Nanofiltration.

Robust, readily scalable, high-flux graphene oxide (GO) mixed matrix composite membranes were developed for organic solvent nanofiltration. Hydroxylated polybenzimidazole was synthesized by N-benzylation of polybenzimidazole with 4-(chloromethyl)benzyl alcohol, which was confirmed by FTIR and NMR spectroscopy. Flat-sheet composite membranes comprising of polybenzimidazoles and 1 or 2 wt % GO were fabricated via conventional blade coating and phase inversion. Subsequently, GO was covalently anchored to the hydroxyl groups of the polymer using a diisocyanate cross-linking agent. The even distribution of GO in the membranes was mapped by visible-light microscopy. Hydroxylation and incorporation of GO in the polymer matrix increased the permeance up to 45.2 ± 1.6 L m-2 h-1 bar-1 in acetone, nearly 5 times higher than the unmodified benchmark membrane. The enhancement in permeance from the addition of GO did not compromise the solute rejection. The composite membranes were found to be tight in seven organic solvents, having molecular weight cut-offs (MWCO) as low as 140 g mol-1. Permeance increased with increasing solvent polarity, while rejection of a 420 g mol-1 pharmaceutical remained over 93%. The covalent anchoring resulted in robust composite membranes that maintained constant performance over 14 days in a continuous cross-flow configuration.

Nanofiltration-Enabled In†Situ Solvent and Reagent Recycle for Sustainable Continuous-Flow Synthesis.

Solvent usage in the pharmaceutical sector accounts for as much as 90 % of the overall mass during manufacturing processes. Consequently, solvent consumption poses significant costs and environmental burdens. Continuous processing, in particular continuous-flow reactors, have great potential for the sustainable production of pharmaceuticals but subsequent downstream processing remains challenging. Separation processes for concentrating and purifying chemicals can account for as much as 80 % of the total manufacturing costs. In this work, a nanofiltration unit was coupled to a continuous-flow rector for in situ solvent and reagent recycling. The nanofiltration unit is straightforward to implement and simple to control during continuous operation. The hybrid process operated continuously over six weeks, recycling about 90 % of the solvent and reagent. Consequently, the E-factor and the carbon footprint were reduced by 91 % and 19 %, respectively. Moreover, the nanofiltration unit led to a solution of the product eleven times more concentrated than the reaction mixture and increased the purity from 52.4 % to 91.5 %. The boundaries for process conditions were investigated to facilitate implementation of the methodology by the pharmaceutical sector.

Long-term stability and reusability of molecularly imprinted polymers.

Molecularly imprinted materials are man-made mimics of biological receptors. Their polymer network has recognition sites complementary to a substrate in terms of size, shape and chemical functionality. They have diverse applications in various chemical, biomedical and engineering fields such as solid phase extraction, catalysis, drug delivery, pharmaceutical purification, (bio)sensors, water treatment, membrane separations and proteomics. The stability and reusability of molecularly imprinted polymers (IPs) have crucial roles in developing applications that are reliable, economic and sustainable. In the present article the effect of crosslinkers, functional monomers and conditions for template extraction on the long-term stability and reusability of IPs was systematically investigated. Adsorption capacity, selectivity, morphology and thermal decomposition of eleven different l-phenylalanine methyl ester imprinted polymers were studied to reveal performance loss over 100 adsorption-regeneration cycles. Furthermore, crosslinker and functional monomer specific reversible and irreversible decomposition of imprinted polymers as a result of adsorbent regeneration were investigated through adsorption studies, electron microscopy, N2 adsorption and thermogravimetric analysis. A decomposition mechanism was proposed and revealed using NMR spectroscopy. Solutions to avoid or overcome the limitations of the most common crosslinkers, functional monomers and extraction techniques were proposed and experimentally validated.

Phospholipid imprinted polymers as selective endotoxin scavengers.

Herein we explore phospholipid imprinting as a means to design receptors for complex glycolipids comprising the toxic lipopolysaccharide endotoxin. A series of polymerizable bis-imidazolium and urea hosts were evaluated as cationic and neutral hosts for phosphates and phosphonates, the latter used as mimics of the phospholipid head groups. The bis-imidazolium hosts interacted with the guests in a cooperative manner leading to the presence of tight and well defined 1:2 ternary complexes. Optimized monomer combinations were subsequently used for imprinting of phosphatidic acid as an endotoxin dummy template. Presence of the aforementioned ternary complexes during polymerization resulted in imprinting of lipid dimers - the latter believed to crudely mimic the endotoxin Lipid A motif. The polymers were characterized with respect to template rebinding, binding affinity, capacity and common structural properties, leading to the identification of polymers which were thereafter subjected to an industrially validated endotoxin removal test. Two of the polymers were capable of removing endotoxin down to levels well below the accepted threshold (0.005 EU/mg API) in pharmaceutical production.

Exploring and Exploiting the Effect of Solvent Treatment in Membrane Separations.

It is well-known that solvent treatment and preconditioning play an important role in rejection and flux performance of membranes due to solvent-induced swelling and solvent adsorption. Investigations into the effect of solvent treatment are scarce and application specific, and were limited to a few solvents only. This study reveals the trend in solvent treatment based on solvent polarity in a systematic investigation with the aim to harness such effect for intensification of membrane processes. Nine solvents with polarity indices ranging from 0.1 to 5.8 (hexane to acetonitrile) were used as treatment and process solvents on commercial Borsig GMT-oNF-2, Evonik Duramem 300, and emerging tailor-made polybenzimidazole membranes. TGA-GCMS, HS-GC-FID, and NMR techniques were employed to better understand the effect of solvent treatment on the polymer matrix of membranes. In this work, apart from the solvent treatment's direct effect on the membrane performance, a subsequent indirect effect on the ultimate separation process was observed. Consequently, a pharmaceutical case study employing chlorhexidine disinfectant and antiseptic was used to demonstrate the effect of solvent treatment on the nanofiltration-based purification. It is shown that treatment of polybenzimidazole membranes with acetone resulted in a 25% increase in product recovery at 99% impurity removal. The cost of the process intensification is negligible in terms of solvent consumption, mass intensity, and processing time.

Experimental and theoretical investigation of the complexation of methacrylic acid and diisopropyl urea.

The present paper explores the complexation ability of methacrylic acid which is one of the most abundant functional monomer for the preparation of molecularly imprinted polymers. Host-guest interactions and the mechanism of complex formation between methacrylic acid and potentially genotoxic 1,3-diisopropylurea were investigated in the pre-polymerization solution featuring both experimental (NMR, IR) and in silico density functional theory (DFT) tools. The continuous variation method revealed the presence of higher-order complexes and the appearance of self-association which were both taken into account during the determination of the association constants. The quantum chemical calculations - performed at B3LYP 6-311++G(d,p) level with basis set superposition error (BSSE) corrections - are in agreement with the experimental observations, reaffirming the association constants and justifying the validity of computational investigation of such systems. Furthermore, natural bond orbital analysis was carried out to appraise the binding properties of the complexes.