Free Polymer Research Articles

Synthesis of Multiresponsive Gold@Polymer‐Nanohybrid Materials Using Polymer Precursors Obtained by Photoiniferter RAFT Polymerization

AbstractCombining gold nanoparticles (GNP) with stimuli‐responsive polymers is a fascinating field for applications as sensor materials or in biomedical applications. The synthesis of multiresponsive Au@Polymer hybrid systems in an in situ approach using tailor‐made poly(2‐(dimethylamino)ethyl methacrylate) (P(DMAEMA)) precursor synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization is introduced. In particular, because of its multiresponsive behavior, P(DMAEMA) is of great interest and is used as the precursor for the synthesis. For the polymerization of the precursor, an approach is introduced that applies the photoiniferter RAFT (photoRAFT) mechanism applicable for tertiary amine‐bearing methacrylic monomers like DMAEMA. By varying the chain transfer agents (CTA), the influence of different RAFT Z‐groups on the solubility of the Au‐hybrids is studied. Aging effects are observed by transmission electron microscopy (TEM) analyses. A comprehensive dynamic light scattering (DLS) study reveals the thermoresponsive behavior of the Au‐hybrids in an aqueous solution. The influence of free polymer in solution on the suspension stability is observed. The capability of crosslinking using 1,5‐dibromopentane (DBP) and the CO2 sensitivity of the synthesized hybrids expands the area of their potential application.

Mechanical Behavior of Polymer Nanocomposites via Atomistic Simulations: Conformational Heterogeneity and the Role of Strain Rate.

Polymer nanohybrids with a high fraction of nanofillers have been found to exhibit improved mechanical properties compared to the neat polymer homogeneous systems. Since polymer-based materials are characterized by a broad range of relaxation times, it is expected that their response under external load would depend on the actual rate of the applied deformation. In this work, we investigate the heterogeneous mechanical behavior in glassy poly(ethylene oxide)/silica nanoparticles (PEO/SiO2) nanocomposites via detailed atomistic molecular dynamics simulations. Our goal is to unravel the effect of strain rate on the mechanism of polymer nanocomposite reinforcement, within the glassy state, by directly probing the mechanical properties at the molecular level. By applying tensile deformations with various strain rates we clearly demonstrate that the value of the applied strain rate strongly affects the mechanical properties of the PEO/SiO2 model systems, inducing a transition from a rubber-like behavior, at low strain rate, to a more brittle one, at high strain rates. Then, we further investigate the mechanical heterogeneity in glassy PEO/SiO2 systems by probing directly the stress and strain fields for various conformations of adsorbed (trains, tails, loops, and bridges), and free polymer chains. Our data emphasize the importance of both train and bridge conformations on the mechanical reinforcement of the polymer nanocomposites. Last, we also probe the mobility of various chain conformations, under different applied strain rates, and their contribution to the overall mechanical behavior of the nanocomposite, during the deformation process.

Gamma irradiation-induced pH-responsive poly(methyl methacrylate- acrylic acid-divinyl benzene) hybrid polymer particles for dye treatment

ABSTRACT The environmentally friendly method is used to fabricate spherical poly(methyl methacrylate-methyl acrylate-divinylbenzene) (P(MMA-MA-DVB)) hybrid particles by gamma irradiation-induced suspension polymerization without an initiator. The MMA: MA: DVB of 60: 20: 20 was used to encapsulate 10 wt% oleic coated-magnetic nanoparticles using ultrasonication for monomer droplet preparation. A stable suspension with approximately 90% monomer conversion was produced using 5 kGy gamma-ray to initiate the polymerization. A large quantity of submicrometer-sized free polymer particles as a by-product was formed in an aqueous medium where the radicals were generated by gamma irradiation of water. However, the number of free polymer particles decreased with the decrease in monomer droplet size. The obtained particles were hydrolyzed to form P(MMA-AA-DVB) particles presenting a negative surface charge (> −30 mV) in an alkaline condition. It was found that the prepared particles presented dye adsorption efficiency as the methylene blue (MB) concentration reduced with adsorption time. The MB adsorption efficiency also increased with pH due to the presence of PAA as a pH-responsive material. Moreover, the hybrid polymer particles were easily separated by the application of an external magnet. Therefore, the fabricated pH-responsive hybrid polymer particles would be served as an alternative dye adsorbent for wastewater treatment.

Polythiophene enveloped tungsten-oxide hybrid nanofillers dispersed oleo (Pithecellobium Dulce seed oil) polyurethane bi-functional nanocomposite coatings

Sustainable resource-based oleo-polyurethanes with low viscosity, superior fluidity, and good ability to spread on the surface of the substrate without involving any organic solvents, led to the formulation of volatile organic compounds (VOCs) free polymer coatings. Here, work reports the use of Pithecellobium Dulce seed oil (PDO), an eco-friendly, abundantly available, and sustainable resource for the synthesis of oleo-polyurethane (PDPU) and formulation of its nanocomposites coatings. To enhance their physicomechanical, anticorrosive, and antimicrobial properties, the tungsten oxide (WO), polythiophene (PTH), and polythiophene enveloped tungsten oxide (PTH/WO) hybrid nanofillers were dispersed in the proposed oleo-PDPU matrix. The physicochemical properties of PDPU and their nanocomposites along with the physicomechanical characterization of their coatings were conducted using standard laboratory/American Standard Testing Methods (ASTMs), spectroscopic methods (FTIR, XRD, NMR), microscopic techniques (SEM and TEM), and thermo-gravimetric analysis (TGA) techniques were used for structural, morphological, and thermal characterization. Their corrosion protective performances were analyzed using salt mist chamber, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Their microbial resistance performance against the S. aureus, E. coli, and P. aeruginosa bacteria was also investigated using the well diffusion method. These studies revealed that the hybrid nanofillers (PTH/WO) dispersed PDPU coatings possess highest antibacterial and anticorrosive activity as compared to plain PDO-based polyurethanes (PDPU) and other such systems reported in the literature.

Matrix free polymer nanocomposites from amphiphilic hairy nanoparticles: Solvent selectivity and mechanical properties

Matrix free polymer nanocomposite of spherical nanoparticles with shells made of amphiphilic homopolymer was studied in molecular dynamics experiments. The amphiphilic homopolymer was presented as sequence of identical monomer units, each containing two beads having different affinity to solvent. The self-assembly in solution of such hairy nanoparticles was studied depending on solvent quality and selectivity for different polymer concentrations. Two of the most characteristic morphologies were identified and described. The first one is a structure resembling a mixture of sea hedgehogs. There is a nanoparticle in the core of a hedgehog, and the spines consist of several grafted chains. Hedgehogs float freely, do not aggregate with other nanoparticles, their solutions have a low moduli of elasticity and viscosity up to a fairly high polymer concentration. The second morphology is thin membrane lamellae assembled from amphiphilic homopolymers. In this case, the nanoparticles are joined into a single network-like aggregate at very low polymer concentrations. Such networks possess a unique porous structure and demonstrate high elasticity and viscosity moduli. These findings could be useful for molecular design of smart materials, that are able to reversibly assemble, disintegrate on request and repair damage by self-healing mechanism. • Nanoparticles, coated with amphiphilic homopolymers, are studied. • Such nanoparticles can self-assemble either into gels or into “hedgehogs” mixture. • Gels have membrane-like, porous structure, and demonstrate elastic and viscous response. • Core-shell filaments preserve aggregation and favor uniform distribution of “hedgehogs”. • Structure type is determined by solvent quality and selectivity.

Preparation of coumarin polymer grafted nanocellulose films to form high performance, photoresponsive barrier layers

AbstractHydrophobically modified cellulose is prepared in this research by conducting atom transfer radical polymerization (ATRP) of methacrylate substituted coumarin monomer on initiator grafted cellulose. The photocrosslinking of uniformly grafted coumarin on cellulose surface is applied to improve the water vapor barrier property of the film. The water vapor transmission rate (WVTR) of films prepared from modified cellulose with varying grafting density, grammage, and photocrosslinking time is studied. By increasing the amount of crosslinking within the grafted cellulose film, we succeeded in reducing WVTR. The WVTR is reduced from 160 to 20 g/m2/day using a sheet of 60 g/m2 after crosslinking. The effect of grafting density on WVTR is also analyzed to observe that the higher the grafting density, lower the WVTR of the sheet both before and after crosslinking. Furthermore, free ATRP polymerization (without cellulose) and polymerization using a sacrificial initiator of the monomer are conducted to estimate the dispersity of the polymer on cellulose. The monomer, free polymer and cellulose grafted polymers are analyzed for the composition, thermal, morphology, photoresponsive behavior, and polymerization quantification using NMR, FTIR, UV–Vis, TGA DSC, GPC, SEM, ICP‐MS. It is concluded that the inter and intramolecular photo dimerization of coumarin molecules forms a hydrophobic crosslinked hyper network in the polymer sheet, which improves its barrier property.

Accelerating Discovery of High Fractional Free Volume Polymers from a Data-Driven Approach

As a fundamental structure characteristic in polymers, fractional free volume (FFV) plays an indispensable role in governing polymer properties and performance. However, the design of new high-FFV polymers is challenging. In this study, we report a data-driven approach and aim to accelerate the discovery of high-FFV polymers. First, a computational method is proposed to calculate FFV, and a two-step fragmentation method is developed to construct a fragment library for digital representation of polymer structures. Data mining is employed to identify promising fragments for high FFV. Subsequently, machine learning (ML) models are trained using a data set with 1683 polymers and their excellent transferability is demonstrated by out-of-sample predictions in another data set with 11,479 polymers. Finally, the ML models are used to screen ∼1 million hypothetical polymers, and 29,482 polymers with FFV > 0.2 are shortlisted; representative high-FFV polymers are validated by molecular simulations, and design strategies are highlighted. To further facilitate the discovery of new high-FFV polymers, we develop an online interactive platform https://ffv-prediction.herokuapp.com, which allows for rapid FFV predictions, given polymer structures. The data-driven approach in this study might advance the development of new high-FFV polymers and further explore quantitative structure-property relationships for polymers.

Hyaluronan in pathophysiology of vascular diseases: specific roles in smooth muscle cells, endothelial cells, and macrophages.

One of the main components of the extracellular matrix (ECM) of blood vessels is hyaluronic acid or hyaluronan (HA). It is a ubiquitous polysaccharide belonging to the family of glycosaminoglycans, but, differently from other proteoglycan-associated glycosaminoglycans, it is synthesized on the plasma membrane by a family of three HA synthases (HAS). HA can be released as a free polymer in the extracellular space or remain associated with the plasma membrane in the pericellular space via HAS or HA-binding proteins. Several cell surface proteins can interact with HA working as HA receptors, like CD44, RHAMM, and LYVE-1. In physiological conditions, HA is localized in the glycocalyx and the adventitia where it is responsible for the loose and hydrated vascular structure favoring flexibility and allowing the stretching of vessels in response to mechanical forces. During atherogenesis, ECM undergoes dramatic alterations that have a crucial role in lipoprotein retention and in triggering multiple signaling cascades that induce the cells to exit from their quiescent status. HA becomes highly present in the media and neointima favoring smooth muscle cells dedifferentiation, migration, and proliferation that strongly contribute to vessel wall thickening. Furthermore, HA is able to modulate immune cell recruitment both within the vessel wall and on the endothelial cell layer. This review is focused on deeply analyzing the effects of HA on vascular cell behavior.

Delayed collapse transitions in a pinned polymer system.

Employing Langevin dynamics simulations, we investigated the kinetics of the collapse transition for a polymer of length N when a particular monomer at a position 1≤X≤N is pinned. The results are compared with the kinetics of a free polymer. The equilibrium θ-point separating the coil from the globule phase is located by a crossover in 〈R_{g}^{2}〉/N plots of different chain lengths. Our simulation supports a three-stage mechanism for free and pinned polymer collapse: the formation of pearls, the coarsening of pearls, and the formation of a compact globule. Pinning the central monomer has negligible effects on the kinetics as it does not break the symmetry. However, pinning a monomer elsewhere causes the process to be delayed by a constant factor ϕ_{X} depending linearly upon X. The total collapse time scales with N as τ_{c}∼ϕ_{X}N^{1.60±0.03}, which implies τ_{c} is maximum when an end monomer is pinned (X=1 or N), while when pinning the central monomer (X=N/2) it is minimum and identical to that of a free polymer. The average cluster size N_{c}(t) grows in time as t^{z}, where z=1.00±0.04 for a free particle, whereas we identify two time regimes separated by a plateau for pinned polymers. At longer times, z=1.00±0.04, while it deviates in early time regimes significantly, depending on the value of X.

Biocompatible Chemically Fueled Transient Polymer Nanoparticles for Temporally Programmable in Vivo Imaging

Biocompatible Chemically Fueled Transient Polymer Nanoparticles for Temporally Programmable in Vivo Imaging

Versatile strategy for homogeneous drying patterns of dispersed particles

After spilling coffee, a tell-tale stain is left by the drying droplet. This universal phenomenon, known as the coffee ring effect, is observed independent of the dispersed material. However, for many technological processes such as coating techniques and ink-jet printing a uniform particle deposition is required and the coffee ring effect is a major drawback. Here, we present a simple and versatile strategy to achieve homogeneous drying patterns using surface-modified particle dispersions. High-molecular weight surface-active polymers that physisorb onto the particle surfaces provide enhanced steric stabilization and prevent accumulation and pinning at the droplet edge. In addition, in the absence of free polymer in the dispersion, the surface modification strongly enhances the particle adsorption to the air/liquid interface, where they experience a thermal Marangoni backflow towards the apex of the drop, leading to uniform particle deposition after drying. The method is independent of particle shape and applicable to a variety of commercial pigment particles and different dispersion media, demonstrating the practicality of this work for everyday processes.

Polymer Grafting to Polydopamine Free Radicals for Universal Surface Functionalization

Modifying surfaces using free radical polymerization (FRP) offers a means to incorporate the diverse physicochemical properties of vinyl polymers onto new materials. Here, we harness the universal surface attachment of polydopamine (PDA) to "prime" a range of different surfaces for free radical polymer attachment, including glass, cotton, paper, sponge, and stainless steel. We show that the intrinsic free radical species present in PDA can serve as an anchor point for subsequent attachment of propagating vinyl polymer macroradicals through radical-radical coupling. Leveraging a straightforward, twofold soak-wash protocol, FRP over the PDA-functionalized surfaces results in covalent polymer attachment on both porous and nonporous substrates, imparting new properties to the functionalized materials, including enhanced hydrophobicity, fluorescence, or temperature responsiveness. Our strategy is then extended to covalently incorporate PDA nanoparticles into organo-/hydrogels via radical cross-linking, yielding tunable PDA-polymer composite networks. The propensity of PDA free radicals to quench FRP is studied using in situ 1H nuclear magnetic resonance and electron paramagnetic resonance spectroscopy, revealing a surface area-dependent macroradical scavenging mechanism that underpins PDA-polymer conjugation. By combining the arbitrary surface attachment of PDA with the broad physicochemical properties of vinyl polymers, our strategy provides a straightforward route for imparting unlimited new functionality to practically any surface.

High Free Volume Polymeric Membranes for CO2 Capture: Stateof- the-art

Abstract: Carbon dioxide (CO2) capture has been widely accepted to be a prerequisite strategy to mitigate the increase of CO2 concentration in the atmosphere. Membrane separation has been envisaged to be one of the most promising technologies for CO2 capture due to its small footprint, simple up- and down-scaling, and low impact on the environment. Owing to their extraordinary high CO2 permeability and moderate CO2 selectivity over other gases, high free volume polymeric membrane materials have been intensively studied for CO2 capture. In the past few years, abundant high free volume polymers have been developed and big progress has been made in this field. Therefore, in this review, starting from CO2 emissions and sources, followed by CO2 transport mechanisms in polymeric membranes, this paper emphasizes reviewing recent research progress in high free volume membrane materials, collecting and analyzing CO2 separation data, as well as discussing the challenges of high free volume polymeric membranes. Furthermore, perspectives on future directions of high free volume polymeric membranes were also proposed.

Crosslinked poly(m-terphenyl N-methyl piperidinium)-SEBS membranes with aryl-ether free and kinked backbones as highly stable and conductive anion exchange membranes

The aryl-ether free polymer backbones containing ion-conducting head groups have drawn recent interest as high-performance anion exchange membrane (AEM) materials because of their excellent chemical stability against hydroxide ions. However, a relatively high ion exchange capacity (IEC) is required to ensure high ion conductivity and cell performance. In this study, new AEMs based on crosslinked poly(m-terphenyl N-methyl piperidinium)- poly(styrene-b-ethylene-co-butylene-b-styrene), x-PmTP-SEBS, were developed by crosslinking two aryl-ether free polymers with different structures: poly(m-terphenyl N-methyl piperidine) (PmTP) and SEBS. The crosslinked x-PmTP-SEBS membranes showed excellent mechanical properties (tensile strength of 28.5 MPa and elongation of break of 170.3% for the sample with 50% crosslinking degree, 50xPmTP-SEBS), as well as high dimensional stability (swelling ratio of around 30%) despite its high water uptake. In addition, despite its relatively low IEC value (1.68 meq g−1), this membrane also exhibited excellent ionic conductivity (116 mS cm−1 at 80 °C) and hydration number (λ = 42), which are higher than representative AEMs. This is due to the high content of bound water, which originates from the excellent phase separation of the SEBS unit and the kinked structure of the m-terphenyl unit. The AEM fuel cell using this membrane had a peak power density of 642 mW cm−2 with H2/O2 gas flow at 60 °C and 95% room humidity (RH). Moreover, the 50x-PmTP-SEBS membrane retained around 99% of its original conductivity and IEC after immersion in 2 M KOH solution at 80 °C for 600 h, exceeding the alkaline stability of most reported AEMs.

Heating cement to slow down its hydration: The unexpected role of PCE interpolymer bridge formation

PCEs with specific polymer structures at dosages over 1% were shown to delay cement hydration as temperature increased. The present work investigates this unexpected phenomenon, reporting hydration kinetics of chemically admixed cement pastes at different temperatures, mineralogical changes, chemical composition of the pore solution and rheological properties.At 23 °C, a significant increase of Si, Al, Mg and Fe in pore solution of admixed samples was measured and nano-particles (polymer aggregates and/or organo-aluminates) were detected. In contrast, these nano-particles were not present at higher temperature, 70 °C, when a dramatic hydration delay was observed. This could increase the amount of free polymer available to delay silicate hydration. Molecular dynamics simulations confirmed the formation of polymer aggregates via interpolymer bridges in presence of both calcium and aluminum at room temperature, while the ability of aluminum to bridge the polymers was reduced with the increase of the temperature.

Synthesis, structure, and properties of catechol functionalized tripodal chelate and its radical complex of strontium

A new tripodal chelate ligand (NaH3L·1.5H2O) was synthesized via Mannich reaction from iminodiacetic acid and t-butyl-catechol in MeOH/H2O in the presence of polyformaldehyde and NaOH. Colorless NaH3L·1.5H2O react with Sr(OH)2 affords a deep-blue 2D-coordination polymer [Sr3L̇2·8H2O]·10.5H2O in aqueous solution. Crystal structure shows [Sr3L̇2·8H2O]·10.5H2O is a free radical 2D coordination polymer with g = 2.004 and guest accessible cavity 35.6% after removal water molecules in solid state. N2 adsorption indicates [Sr3L̇2·8H2O]·10.5H2O has specific surface area 5.4561 m2 g−1, average pore diameter is 18.48 nm, maximum N2 adsorption capacity is 18.05 cm3·g−1. [Sr3L̇2·8H2O]·10.5H2O is relatively stable in DMSO, with absorbance maximum at 259(7095), 305(6940) and 623 nm (4495 M−1 ·cm−1), but will decompose in the presence of HCl, citric acid and ascorbic acid. Stronger acid decomposes faster. Large excess H2O2 can also decompose [Sr3L̇2·8H2O]·10.5H2O. The decomposition reaction is first-order to concentration of H+/H2O2 and [Sr3L̇2·8H2O]·10.5H2O. The second-order rate constants at room temperature DMSO solution are 6.86 × 10−4 and 15.5 s−1·M−1 for H2O2 and H+ respectively.

Preparation of poly(acrylamide‐co‐acrylonitrile) grafted glass and thermal stimulated detachment of surface‐attached human immortalized mesenchymal stem cells

AbstractNovel cell culture substrates for non‐invasive‐targeted cell recovery were developed by grafting an upper‐critical‐solution‐temperature (UCST)‐type poly(acrylamide‐co‐acrylonitrile) (PAA) onto a glass substrate as a cell attachment scaffold by surface‐initiated reversible addition‐fragmentation chain‐transfer (Si‐RAFT) polymerization. To optimize the UCST of PAA, the cloud point of the free polymer was first determined. Varying the chain lengths of PAA with an optimized AN‐compositions of 31 mol% followed by Si‐RAFT produced immobilized glass substrate (PAA‐g). The PAA‐g surface became hydrophilic, and the polymer brushes swelled as the temperature increased from 30 to 38°C. In addition, the viscoelasticity of PAA‐g was increased by the polymer brushes swelled. Thermal detachment of PAA‐g attached human immortalized mesenchymal stem cells (hiMSC) was observed by raising the temperature from 30 to 38°C. The polymer brushes length of PAA‐g affects the degree of hiMSC detachment, likely due to the change in viscoelasticity with the polymer brushes length.

Thermoresponsive Poly(N-isopropylacrylamide) Grafted from Cellulose Nanofibers via Silver-Promoted Decarboxylative Radical Polymerization.

A family of thermoresponsive poly(N-isopropylacrylamide) [PNIPAM]-grafted cellulose nanofibers (CNFs) was synthesized via a novel silver-promoted decarboxylative polymerization approach. This method relies on the oxidative decarboxylation of carboxylic acid groups to initiate free radicals on the surface of CNFs. The polymerization reaction employs relatively mild reaction conditions and can be performed in a one-step, one-pot fashion. This rapid reaction forms a C─C bond between CNF and PNIPAM, along with the formation of free polymer in solution. The degree of functionalization (DF) and the amount of PNIPAM grafted can be controlled by the Ag concentration in the reaction. Similar to native bulk PNIPAM, PNIPAM-grafted CNFs (PNIPAM-g-CNFs) show remarkable thermoresponsive properties, albeit exhibiting a slight hysteresis between the heating and cooling stages. Grafting PNIPAM from CNFs changes its cloud point from about 32 to 36 °C, influenced by the hydrophilic nature of CNFs. Unlike physical blending, covalently tethering PNIPAM transforms the originally inert CNFs into thermosensitive biomaterials. The Ag concentration used does not significantly change the cloud point of PNIPAM-g-CNFs, while the cloud point slightly decreases with fiber concentration. Rheological studies demonstrated the sol-gel transition of PNIPAM-g-CNFs and revealed that the storage modulus (G') above cloud point increases with the amount of PNIPAM grafted. The novel chemistry developed paves the way for the polymerization of any vinyl monomer from the surface of CNFs and carbohydrates. This study validates a novel approach to graft PNIPAM from CNFs for the synthesis of new thermoresponsive and transparent hydrogels for a wide range of applications.

Charge Carrier Molecular Sieve (CCMS) Membranes with Anti-aging Effect for Long-Life Vanadium Redox Flow Batteries

Vanadium crossover hinders widespread commercial adoption of vanadium redox flow batteries (VRFBs). Superglassy polymers have the potential to offer high selectivity needed to control the crossover but as yet do not possess the requisite proton conductivity and stability. Here, we explore nanocomposite separators that can improve this selectivity. We report a dual-function charge carrier molecular sieve (CCMS) membrane, consisting of a high free volume microporous glassy polymer, poly[1-(trimethylsilyl)-1-propyne] (PTMSP)/sulfonated PAF (PAF-1-SO3H), that effectively hinders the migration of hydrated vanadium ions. Furthermore, ideally placed PAF-1-SO3H pores not only proved excellent for developing proton conductive channels but also suppressed physical aging within the separator. Experiments then linked this to an increased battery cycle life. As a consequence of achieving higher and more stable VRFB performance compared to benchmarked Nafion (Coulombic efficiencies of 97 vs 87% and capacity retention values of 85 vs 58% at a current density of 60 mA cm–2, respectively), our integrated design heralds a class of stable separators for hydrogen-based energy technologies.

Facile Method to Determine the Molecular Weight of Polymer Grafts Grown from Cellulose Nanocrystals.

One of the main challenges associated with the modification of cellulose nanocrystals (CNCs) with polymers by surface-initiated polymerization is the characterization of the resulting products, notably the molecular weight of the grafts. The solid nature of the (modified) CNC nanoparticles limits the possibility to apply solution-based characterization techniques, and the cleavage of the macromolecules from the surface of the CNCs to enable their characterization using solution-based techniques is intricate. Here, we report that 1H NMR spectroscopy of the supernatant of the heterogeneous reaction mixture can be used to approximate the molecular weight of poly(hexyl methacrylate) grafts grown from the surface of CNCs via surface-initiated atom transfer radical polymerization. This was achieved using 1H NMR spectra to determine the monomer conversion from the change of the relative ratio of monomer and solvent signals in the 1H NMR spectra, which in turn allowed determining the weight of PHMA produced. The number-average molecular weight of the grafted polymer was then estimated by assuming that standard atom transfer radical polymerization kinetics are at play and using the initiator concentration on the CNC surface determined by elemental analysis. The method was validated by comparing the results with the gravimetric data and the data of free polymers that were synthesized with a sacrificial initiator.