The self-assembly of amphiphilic block copolymers in aqueous media is central to their applications in drug delivery and nanostructured materials. Poloxamer 10R5, a reverse nonionic triblock copolymer composed of poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEO-PPO), exhibits temperature-dependent micellization in water. In this work, we investigate the influence of the surface-active ionic liquid (SAIL), 1-butyl-3-methylimidazolium octyl sulfate ([BMIM][OSU]), on the temperature- and concentration-dependent aggregation behavior of Poloxamer 10R5 using nuclear magnetic resonance (NMR) spectroscopy and small-angle neutron scattering (SANS). NMR spin-relaxation reveals restricted mobility of [BMIM][OSU] with increasing concentration from 20 to 200 mM in the presence of 10R5 (200 mM). SANS results show temperature-induced transitions from unimers to prolate ellipsoidal micelles and demonstrate that [BMIM][OSU] induces aggregation below the critical micelle concentration and modifies micelle morphology at higher concentrations. These findings highlight the hydrophobic interactions between the SAIL and hydrophobic PPO blocks and provide insight into tuning block-copolymer self-assembly through SAIL additives. Overall, this study provides a detailed understanding of the influence of SAILs on the temperature- and concentration-dependent aggregation behavior of block copolymers, offering potential for tuning poloxamer 10R5-SAIL systems for applications in materials science and nanotechnology.

Periodically grafted amphiphilic polymers (PGAPs) belong to an interesting class of amphiphilic polymers that carry long hydrophobic alkylene segments along the backbone and periodically located hydrophilic pendant segments, such as polyethylene glycol monomethyl ether (MPEG). In earlier studies, we showed that such PGAPs undergo zigzag folding to segregate the backbone alkylene segments and the pendant MPEG segments; consequently, they organize in the solid state to yield a lamellar morphology with precisely tunable domain sizes. In the present study, two new periodically clickable polyesters were prepared; one bearing dodecyl (C12) segments between adjacent clickable propargyl units and the other carrying longer eicosyl (C20) segments. These were clicked with MPEG-azides of different molecular weights, namely 550, 750 and 2000, to generate a series of PGAPs with varying hydrophilic-lyophilic balance (hlb) and, consequently, different folding propensities. The collapse of these PGAP chains in solution was examined by pulse field gradient nuclear magnetic resonance (PFG NMR) diffusometry studies, in chloroform-methanol mixtures of varying composition; the diffusion constants, estimated from these measurements, underwent a sudden increase at a specific methanol content, which signified the chain-collapse transition. As expected, the collapse occurred at a lower methanol content in the polymers bearing smaller MPEG pendant segments. Additionally, the variation of the relative intensities of the proton peaks belonging to the central hydrophobic segment, that upon collapse becomes more solid-like, also exhibited a sudden drop at roughly the same solvent composition, reconfirming that the collapse occurs to generate a structure with a dense core and solvated shell.

Characterising drug-binding mechanisms, structural changes and dynamics at atomic resolution remains a challenge due to the dynamic and heterogeneous nature of surfactant supramolecular assemblies. In this context, nuclear magnetic resonance (NMR) is uniquely suited to overcome these complexities by offering precise information on binding, structure, dynamics and transport in native-like conditions. NMR spectroscopy, leveraging the nuclear Overhauser effect (NOE), spin-relaxometry and translational self-diffusometry, offers atomistic-level insights into drug-surfactant interactions. NOE measurements reveal spatial proximities between drug and surfactant molecules, while relaxometry captures local dynamics and facilitates the estimation of rotational correlation times for both free and bound drug species. Diffusometry probes global translational motion and geometric features, enabling quantification of the bound drug fraction (pb) and partition coefficient (K), both of which are pertinent to pharmaceutical and chromatographic contexts. Together, these NMR approaches provide an integrated view of structure, dynamics and transport, which is critical for understanding the physicochemical behaviour of drug-surfactant systems. This mini-review summarizes key solution-state NMR techniques, supported by theoretical models and selected applications, for incisive characterisation of these interactions.

Alternate copolymers of styrene and butadiene like styrene butadiene rubber (SBR) and the corresponding block copolymer polystyrene-block-polybutadiene-block-polystyrene (SBS) have different sets of applications either in making tire/conveyor belts or in coatings and adhesives. Although there are several reports of composites of SBR, there are only a handful of reports of composites of SBS with silica nanomaterials and detailed studies. In this paper, we report a detailed comparative study of composites of functionalized or nonfunctionalized SBS and silica nanoparticles. Functionalization involved polar groups in both SBS and silica in anticipation of better interactions leading to improvement of properties. Significant interactions were seen, as indicated by NMR spin-relaxation (T-2 and T-1) analysis and small-angle X-ray scattering experiments and further corroborated by electron microscopic data. Key mechanical properties like abrasion resistance and hardness improved substantially after composite formation.

The molecular dynamics study of thermotropic mesogens exhibiting the crystal phases is valuable in unraveling the complex global (collective) and local (noncollective) motions executed by liquid crystal molecules, which would further advance the existing knowledge on orientationally disordered crystalline (ODIC) phases. Toward the fulfillment of such a task, a combined nuclear magnetic resonance (NMR) relaxometry approach employing the fast field cycling (FFC) NMR (10 kHz-30 MHz) and high-field pulsed NMR (400 MHz) techniques is utilized to sample the broad frequency range offered by molecular motions in the crystal phase of 4-(trans-4'-n-hexylcyclohexyl)-isothiocyanatobenzene (6CHBT). The validity of the observed relaxation data is tested and interpreted by the Bloembergen-Purcell-Pound (BPP) model involving the superposition of four mutually independent Lorentzian spectral densities, reflecting molecular dynamical processes on different time scales. The salient feature of the detailed analysis reveals that the lengthening of temporal dynamics in the crystal phase due to molecular rotations by jumps, which are of intermolecular origin, is evident and further supports the presence of collective-like local dynamics. The analysis does permit decoupling of the molecular reorientations about their short axes (∼100 ns) as well as long axes (∼50 ns) and methyl group rotations (∼0.5 ns) on distinct time scales. The activation energies for reorientations about the short axes and methyl group rotations are found to be 27.3 ± 2.7 and 15.8 ± 1.1 kJ/mol, respectively. The fast methyl rotations in the crystal phase of 6CHBT obtained from FFC NMR are further well complemented by high-field NMR, where 1H NMR line shapes are relatively narrow when compared to those of the nematic phase.

Superhydrophobic coatings are essential to prepare water-repellent surfaces, self-cleaning materials, etc. Silica nano-materials are often immobilized to different surfaces for imparting super-hydrophobicity. Direct coating of silica-nanoparticles is often challenging since it can easily be peeled off under different environments. Herein, we reported the use of properly functionalized polyurethanes to facilitate the strong binding of silica-nanoparticles to surfaces. The alkyne terminal polyurethane was synthesized by step-growth polymerization while click-reactions facilitated to post-functionalization using phenyl moiety and were characterized by 1 H, 13 C nuclear magnetic resonance (NMR) spectroscopies, and 1 H spin-lattice relaxation times (T1 s). Upon functionalization, the glass transition temperature (Tg) increased due to enhanced interchain interactions. Moreover, additives like di(propyleneglycol)dibenzoate showed a substantial plasticizing effect to compensate for the increase in Tg, an important parameter for low-temperature applications. NMR signatures the spatial interactions between various protons of grafted silica-nanoparticles and phenyl triazole functionalized polyurethanes, thus indicating the usefulness of polyurethanes to bind silica-nanoparticles. After coating functionalized silica-nanoparticles to leather using functionalized polyurethanes, a contact angle value of more than 157° was observed with retention of grain patterns of leather due to transparency. We anticipate the results to help design varieties of materials with superhydrophobicity where the structural integrity of the surfaces is retained.

The influence of pH on the human serum albumin (HSA) interaction with ionic liquid (IL)1-butyl 3-methylimidazolium octyl sulfate ([BMIM][OSU]) at its sub-micellar concentration of 5 mM (well below CMC ∼31 mM at 25 °C) in aqueous solution has been monitored employing different methods, viz., circular dichroism (CD), fluorescence, electrokinetic determination of the zeta potential (ZP), nuclear magnetic resonance (NMR), small-angle neutron scattering (SANS), and molecular docking (MD). CD analysis indicated a noticeable reduction of the α-helical content of HSA by IL at pH 3. A significant interaction of the anionic part of IL with HSA was evident from the 1H chemical shifts and saturation transfer difference (STD) NMR. A strong binding between IL and HSA was observed at pH 3 relative to pH 5, revealing the importance of electrostatic and hydrophobic interactions assessed from global binding affinities and molecular correlation times derived from STD NMR and a combined selective/nonselective spin-relaxation analysis, respectively. ZP data supported the electrostatic interaction between HSA and the anionic part of IL. The nature of IL self-diffusion with HSA was assessed from the translational self-diffusion coefficients by pulse field gradient NMR. SANS results revealed the formation of prolate ellipsoidal geometry of the IL-HSA complex. MD identified the preferential binding sites of IL to the tryptophan centers on HSA. The association of IL with HSA was supported by fluorescence measurements, in addition to the structural changes that occurred in the protein by the interaction with IL. The anionic part of IL contributed a major interaction with HSA at the pH levels of study (3, 5, 8, and 11.4); at pH > 8 (effectively 11.4), the protein also interacted weakly with the cationic component of IL.

For the design of an efficient drug delivery system utilizing an ionic liquid (IL) as a carrier, it is prudent to gain molecular/atomistic level insights of a drug with IL in terms of binding and dynamics. In this scenario, the influence of anionic counterpart of imidazolium-based ILs, namely, 1-butyl-3-methyl-imidazolium octyl sulfate [BMIM][OSU] and 1-butyl-3-methyl-imidazolium chloride [BMIM][Cl] in their submicellar region ([IL] = 20 mM) on the model water-soluble anticancer drug doxorubicin hydrochloride (DOX) was probed by employing an arsenal of nuclear magnetic resonance (NMR) approaches. The salient feature of the present study includes the significant interaction of DOX with [BMIM][OSU], whereas the lack of such an interaction with [BMIM][Cl] is gauged by 1H NMR translation self-diffusometry and is further corroborated by 13C chemical shift perturbation. The two-step model was utilized to estimate the bound fraction (pb) and equivalent partition coefficient (K) of DOX with [BMIM][OSU]. A combination of selective and nonselective spin-lattice relaxation rates (R1SEL and R1NS, respectively) enables to gauze the significant interaction of DOX with [BMIM][OSU] over [BMIM][Cl]. Furthermore, 1D transient and truncated driven nuclear Overhauser enhancement (NOE) data analyses in the initial rate limit permits the evaluation of the cross-relaxation efficacy of DOX with the investigated ILs. An Arrhenius-type temperature dependence of the drug's self-diffusion was observed for DOX, DOX-[BMIM][OSU], and DOX-[BMIM][Cl] aqueous mixtures and the corresponding activation energies were evaluated.

Collagen-based materials have a wide range of applications in wound care, tendon repair, cartilage repair, etc. Improving certain properties such as hydrophobicity can diversify the application areas. In this work, we investigated the noncovalent interactions of suitably functionalized silica nanoparticles with collagen for the possibility of improving hydrophobicity. Functionalization on silica nanoparticles was achieved via Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) or "click" reaction using surface grafting methods. Furthermore, we synthesized two different silica nanoparticles (SiNPs) functionalized with the fluorine-containing substrate or only with an aryl moiety (silica-g-4EMB and silica-g-ETFMB) for comparison. The functionalized SiNPs immobilized along with the model system trans-4-hydroxy-l-proline (HPA) (usually present in abundant quantities in collagen) have been probed using nuclear magnetic resonance (NMR) spin relaxation to appreciate the influence of SiNPs on HPA. Furthermore, we effectively utilized a saturated transfer difference (STD) NMR experiment to measure the interaction parameters between judiciously functionalized silica nanoparticles and substrates of interest. In essence, such a detailed study on noncovalent interactions employing an arsenal of experimental approaches facilitated the immobilization of suitably functionalized silica nanoparticles to collagen and leather (where collagen is a major constituent), leading to improvements in hydrophobicity.

The nature of heterogeneity in maline deep eutectic system (DES) is characterised by inspecting the properties of the mixture at DES composition (1:1 choline chloride/malonic acid) and various mole fractions of the components at the vicinity of DES. Steady-state and time-resolved emission, and fluorescence anisotropy of suitable fluorescent probes in different choline chloride-malonic acid mixtures are used to describe the heterogeneity in various mixtures. Herein, we establish that nanodomains consisting of different molecule-ion clusters render DES' heterogeneous nature. The intermolecular interaction and the formation of molecule-ion structures are studied by spectroscopic technique including 1H NMR, 1H-1H-nuclear Overhauser effect, NMR diffusometry and mass spectrometry. It is demonstrated that the DES mixture comprises of a particular relative population of two different domains: a less polar domain (LP, 34%) and a more polar domain (MP, 66%). The physical properties of these domains strongly depend on the molar ratio of choline chloride and malonic acid. The experimental findings are further supported with theoretical predictions.

Amphiphiles aggregation in mixed aquo-organic solvent media has profound interest in the fields of chemistry, biology, pharmaceutics, and industry. Detailed fundamental understanding of the process in the bulk and at the interface is still remaining to be explored. In this report, the effect of two water miscible alkanols (ethanol (ET), and isopropanol (IP)) on the aggregation-behaviors of the surfactant sodium dioctylsulfosuccinate (Aerosol-OT or AOT) has been studied in a wide range of alcohol proportions (0 to 100 vol%) in water. Different physicochemical parameters like critical micelle concentration (CMC), counter-ion binding (13) and aggregation number (N-agg) of micelles, and the energetics of the AOT adsorption at the air/water interface, and its assembly formation in the bulk have been evaluated employing tensiometry and isothermal titration calorimetry (ITC) methods. The micelle forming region of AOT has been found to be 0-30 vol% for ET, and 0-20 vol% for IP. At [solvent] > 30 vol% the possibility of formation of "randomly arranged globular assembly" (RAGA) of the amphiphile [1] prevailed. Role of different solvent parameters have been attempted to explain the thermodynamics of the micellization process of AOT. SANS experiments have supported vesicle formation of concentrated solutions of AOT in 50 vol% ET or IP in water; with increasing alcohol vesicles transformed into micelles. DFT (density functional theory) calculations have been made for understanding the intermolecular interactions in AOT-H2O-ET or IP systems compared to their binary mixtures (AOT-H2O; AOT-ET; AOT-IP). NMR study has supported favorable interactions of the alkanols (ET and IP) with the head group of the AOT. Formation of micelles and reverse micelles by AOT in different composition of alcohols and pure alcohols reported by Michor and Berg [2] has been reasoned out to be incorrect. (C) 2022 Published by Elsevier B.V.

In the formulation of efficient drug delivery systems, it is essential to unravel the structural and dynamical aspects of the drug's interaction with biological membranes. This has been done for the anticancer drug-membrane system comprising doxorubicin hydrochloride (DOX), a water-soluble anticancer drug, and the micellar sodium dodecyl sulfate (SDS), the latter serving as a useful mimic for membrane proteins. Using a multimodal NMR approach involving 1H, 2H, and 13C as probe nuclei and through the determination of chemical shifts, spin-relaxation, nuclear Overhauser enhancements (NOE), and translational self-diffusion (SD), the binding characteristics of the DOX with SDS have been determined. The perturbation to 13C chemical shifts of SDS indicate the penetration of DOX into the SDS micelle, which is further revealed by 1H-1H NOESY and SD measurements. 2H spin-relaxation measurements and their analysis using a two-step model show DOX induced SDS micellar volume changes, which determine the correlation times involved in the DOX-SDS mobility.

The interaction of copolymer L61 i.e., (EO)2(PO)32(EO)2 (where EO and PO are ethylene and propylene oxides, respectively) with surfactant SDS (sodium dodecylsulfate) in relation to their self-aggregation, dynamics and microstructures has been physicochemically studied in detail employing the Nuclear Magnetic Resonance (NMR), Electron Paramagnetic Resonance (EPR), Small-Angle Neutron Scattering (SANS), and Freeze-Fracture Transmission Electron Microscopy (FF-TEM) methods. The NMR self-diffusion study indicated a synergistic interaction between SDS and L61 forming L61-SDS mixed complex aggregates, and deuterium (2H) NMR pointed out the nonspherical nature of these aggregates with increasing [L61]. EPR spectral analysis of the motional parameters of 5-doxyl steraric acid (5-DSA) as a spin probe provided information on the microviscosity of the local environment of the L61-SDS complex aggregates. SANS probed the geometrical aspects of the SDS-L61 assemblies as a function of both [L61] and [SDS]. Progressive evolution of the mixed-aggregate geometries from globular to prolate ellipsoids with axial ratios ranging from 2 to 10 with increasing [L61] was found. Such morphological changes were further corroborated with the results of 2H NMR and FF-TEM measurements. The strategy of the measurements, and data analysis for a concerted conclusion have been presented.

Ionic liquids (ILs) are considered as green solvents, and some ILs can stabilize proteins. ILs find significant importance from the perspectives of protein-ionic liquid (P-IL) interactions. An arsenal of nuclear magnetic resonance (NMR) methodologies can be employed to probe the differential binding and dynamics of cation and anion of ILs with the proteins of interest towards targeted functionalities. This chapter focusses on the recent developments of NMR spectroscopy on binding and dynamics of ILs as well as proteins, with a view to appreciate P-IL interactions. The favourable outcome of P-IL interactions can be exploited by employing various NMR approaches such as H-1 lineshapes, chemical shifts, spin-spin and spin-lattice relaxation (both selective and nonselective), translational self-diffusion, saturation transfer difference (STD), H-1-N-15 heteronuclear single-quantum correlation (HSQC) and High-resolution magic angle spinning (HRMAS). These experiments facilitate the extraction of fruitful information on mobility, size and spatial proximities, and preferential binding sites of ion species as well as proteins. In this scenario, we highlight here some of the recent NMR advances and future research directions in this important area.

The development of efficient, biodegradable and biocompatible surfactants has become a pressing need because of adverse effects of surface-active compounds on the aquatic environment and human health. Cleavable surfactants containing a labile functional group have the ability to eliminate some of these problems. Consequently, PEGylated amphiphiles have found widespread applications in pharmaceutics, household purposes, and drug delivery. Herein we report synthesis and characterization of two novel amphiphiles which to our knowledge are the first examples of double PEG-tailed amphiphiles with an anionic head group. Considering their chemical structure, they are expected to be biodegradable, biocompatible, milder and less irritant than conventional surfactants. The solution behavior of these newly developed amphiphiles was thoroughly investigated in aqueous buffer (pH 7.0) at 25 °C. The surface activity of the compounds in aqueous buffer was studied by surface tension measurements. The self-assembly properties were investigated by various techniques such as fluorescence and NMR spectroscopy, dynamic light scattering, transmission electron microscopy, atomic force microscopy, and isothermal titration calorimetry. Both molecules were found to be surface active in water and exhibit spontaneous vesicle formation in the absence of any additives at room temperature. As in the cases of conventional surfactants, the self-assembly is driven by the hydrophobic effect. The vesicles produced in aqueous media were shown to encapsulate hydrophobic dyes and exhibit structural transitions upon addition of salts. The sensitivity of the vesicles to change in environments qualifies them for potential use in drug delivery.

Correction for ‘Thermodynamically stable vesicle formation of biodegradable double mPEG-tailed amphiphiles with sulfonate head group’ by Rita Ghosh et al., RSC Adv., 2020, 10, 32522–32531, DOI: 10.1039/D0RA05613H

Molecular level insights on protein-ionic liquid (P-IL) interactions are beneficial for assessing protein stability, binding and dynamics. In the present work, interactions of ILs, namely, 1-butyl 3-methylimidazolium methyl sulfate (IL1), 1-butyl 3-methylimidazolium octyl sulfate (IL2) and 1-butyl 3-methylimidazolium chloride (IL3) with hen egg white lysozyme (HEWL) protein were investigated using solution-state nuclear magnetic resonance (NMR) spectroscopy. To ascertain the binding and dynamics from the perspective of both protein and IL, various ligand based NMR approaches such as selective and non-selective nuclear spin-relaxation (R1SEL and R1NS), saturation transfer difference (STD), difference of inversion recovery rate with and without target irradiation (DIRECTION), 35Cl line-shape and spin-relaxation, and protein back bone amide chemical shift perturbations (CSPs) from 1H-15N HSQC were utilized. Among the ILs investigated, IL2 experiences significant interaction relative to those of IL1 and IL3, as revealed by the combined R1SEL and R1NS analysis, which is further supported by STD NMR. CSP analyses of 1H-15N HSQC spectra of aqueous P-IL mixtures enabled to identify the potential binding sites of ILs with HEWL. Whereas, 15N longitudinal (R1) and transverse (R2) spin-relaxation rates and 15N{1H} heteronuclear nuclear Overhauser effect (hetNOE) data subjected to the model free analysis for IL2 yielded the rotational correlation times and order parameters of various residues of HEWL. Furthermore, the results could discern the nature of interactions between studied ILs and HEWL in terms of specific and non-specific interactions.

Associative block copolymers of the type (EO)(x)(PO)(y)(EO)(x) (where EO and PO represent ethylene and propylene oxides, respectively) in aqueous solution have far reaching commercial applications such as solubilization, controlled-drug delivery, etc. The molecular dynamics of a self-associating triblock copolymer (EO)(20)(PO)(70)(EO)(20) (known as P123 with a molecular weight of similar to 5800), in aqueous solution (D2O), consisting of various lyotropic liquid crystalline phases such as isotropic micellar, cubic, hexagonal, and lamellar phases, is investigated using the fast field cycling nuclear magnetic resonance (FFC NMR) relaxometry technique in the Larmor frequency range from 5 kHz to 30 MHz. A nuclear spin-relaxation model consisting of chain modes (Rouse modes) and order fluctuation (OF) modes typical for polymers and liquid crystals, respectively, is considered to explain the observed proton magnetic relaxation dispersion (PMRD) data in the lyophases under investigation. The PMRD analysis in both isotropic micellar and cubic phases revealed a Rouse frequency dependence of spin lattice relaxation rate (R-1), i.e., R-1 proportional to -tau(s) ln(omega tau(s)), in the entire frequency range of study. Hexagonal and lamellar phase data show Rouse modes as well as OF modes, leaving the signature of the latter as R-1 proportional to omega(-p), where p similar to 0.5 is typical for nematic mesogens. The activation energies were also determined from segmental correlation times in the lyophases of study. To the best of our knowledge, the present FFC NMR relaxometry study is unique and quantitative in unraveling molecular dynamics of the associative copolymer P123 in aqueous solution.

Electrolytic dissociation of lithium hexafluorophosphate (LiPF6) in the nonaqueous cyclic propylene carbonate (PC) has been investigated in the wide range of concentration (0.05-3.5 M) by Li-7 solution-state nuclear magnetic resonance (NMR) spectroscopy. Two-dimensional heteronuclear Overhauser enhancement spectroscopy NMR experiments have not only enabled the cation solvation and ion-pairing to be directly monitored but additionally evidence anion solvent interaction at higher concentrations (>1.2 M) of the PC electrolyte. Preliminary analysis of kinetic nOe data has been made to determine site-dependent cross-relaxation rates for the spatial interaction of the solvent with the Li+ cation and the PF6- anion. The concentration dependence of the Li-7 NMR self-diffusion coefficient (D-self), determined using very strong pulsed magnetic field gradients (similar to 1700 Gauss/cm), depicts two breaks to mark the solvation and ion-pairing events in a distinct manner. This in turn has aided the determination of solvent coordination number and average sizes of solvated and ion-paired clusters. Our results indicate that in the contact ion pair (CIP)-dominated electrolyte (>2 M), lithium-ion mobility across the solvated and ion-paired environments appears to be inhibited which makes the spectral distinction of solvated and ion-paired environments possible. The concentration dependence of the Li-7 NMR spectral and diffusometry data is in striking correspondence with that of bulk conductivity measurements and point to the detrimental effect of CIP aggregates in impeding the ionic conductivity at high salt concentrations. These results have significance in understanding the structure and dynamics of lithium-ion solvates that are ubiquitous in the working environment of a lithium-ion battery.

ABSTRACT We have explored two novel comonomers, namely, 4,16‐dicarboxyl[2.2]paracyclophane and 5,5′,6,6′‐tetraamino‐3,3,3′,3′‐tetramethyl‐1,1′‐spirobi[indane], for the synthesis of co‐polybenzimidazoles (co‐PBIs) with intrinsic porosity. Both these monomers possess twisted structures that can lead to “awkward” macromolecular shapes that cannot pack efficiently. The consequences of introducing these two monomers on the structure and properties of PBIs are reported. The random copolymers synthesized are amorphous and possess glass transition temperatures ( T g s) greater than 400 °C. T g decreases with increasing comonomer content indicating an increase in fractional free volume. The copolymers have low surface area. TEM and BET measurements show evidence of mesopore formation. The copolymers show significant carbon dioxide adsorption. Single chain molecular dynamics simulation of 24‐mer repeat units shows intramolecular void spaces arising as a result of distorted polymer chain with reduced conformational mobility. These studies define a new synthetic strategy for “bottoms‐up” synthesis of PBIs with intrinsic porosity. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56 , 1046–1057