High-sensitivity Differential Scanning Calorimetry Research Articles

Protection of bovine serum albumin through encapsulation in hybrid vesicles

This study focuses on hybrid vesicles (HVs) formed through co-assembly of soy phosphatidylcholine (SPC) and a triblock copolymer (F127). After elucidating the superior stability of HVs over the assemblies of neat SPC and F127, these were encapsulated with bovine serum albumin (BSA), as model a thermolabile protein. Characterizations were performed using dynamic light scattering (DLS), electron microscopy, circular dichroism and high-sensitivity differential scanning calorimetry. The size of HVs increased slightly at higher proportion of F127 and upon encapsulation of BSA. In spite of this, vesicles remained spherical and displayed a smooth surface. They showed superior dilution stability in comparison to neat copolymer micelles and phospholipid vesicles. Their stability can be ascribed to hydrophobic association between the phospholipid and copolymer, and manifested into increase in phase transition temperature of the former. We found that HVs could protect BSA from denaturation and unfolding when challenged by high solution temperature, pH changes and salt incorporation.

Energetics of β-lactoglobulin–flavor compounds interactions

Interaction of bovine β-lactoglobulin (BLG) with several flavor compounds (FC) (2–methylpyrazine, vanillin, 2–acetylpyridine, 2– and 3–acetylthiophene, methyl isoamyl ketone, heptanone, octanone, and nonanone) was studied by high-sensitivity differential scanning calorimetry. The denaturation temperature, enthalpy, and heat capacity increment were determined at different FC concentrations. It was found that the denaturation temperature and heat capacity increment do not depend on the FC concentration, while the denaturation enthalpy decreases linearly with the FC concentration. These thermodynamic effects disclose the preferential FC binding to the unfolded form of BLG. By the obtained calorimetric data, the free energies of FC binding vs. the FC concentrations were calculated. These dependences were shown to be linear. Their slope relates closely to the overall FC affinity for the unfolded BLG in terms of the Langmuir binding model. The overall BLG affinity for FC varies from 20 M–1 (2-methylpyrazine) up to 360 M–1(nonanone). The maximal stoichiometry of the BLG–FC complexes was roughly estimated as a ratio of the length of the unfolded BLG to the molecular length of FC. Using these estimates, the apparent BLG–FC binding constants were determined. They are in the range of 0.3–8.0 M–1 and correlated strictly with the FC lipophilicity descriptor (logP).

CTAB induced growth and shrinkage of Pluronics® P103 micelles: Experimental and theoretical rationale

This study offers an insight into the concentration influence of a cationic surfactant- cetyltrimethylammonium bromide (CTAB) having a 16-carbon long alkyl side chain that influences the self-assembly and micellization behaviour of a linear triblock copolymer based on ethylene oxide (EO) and propylene oxide (PO) Pluronic® P103 in aqueous solution. The work makes an exclusive use of a variety of methodologies, such as high sensitivity differential scanning calorimetry (HSDSC), phase behaviour study, dynamic light scattering (DLS), and small-angle neutron scattering (SANS). The investigation on the clouding behaviour demonstrates that the cloud point value of 5 %w/v P103, which is typically in the vicinity of 90 °C, rises up to more than 100 °C with the addition on of very low concentration of CTAB. The DLS technique predicted the change in hydrodynamic diameter (Dh) of micelles with temperature and in varying CTAB concentration. The SANS results inferred the morphological changes in the micelles. A comprehensive approach revealing the relationship between the molecular orbital energies of the tested P103 and CTAB were assessed by utilising the computational simulation method with the Gaussian 09 calculation window and Gauss View 5.0.9 software. The perception of CTAB-stabilized Pluronics® micelles is predicted to be much improved from the evaluated optimised descriptors. Additionally, our examined micellar system revealed the solubilization enhancement of a model hydrophobic dye orange-OT utilizing UV–vis spectroscopy.

Cooperative interaction of a highly hydrophilic pluronic with bile salts of different hydrophobicity

In this study, we investigated the association of bile salts with pluronic F127 (F127) as a function of their hydrophobicity. Sodium cholate (NaC), sodium deoxycholate (NaDC) and sodium taurodeoxycholate (NaTDC) were used as bile salt. Our interpretations are based on the observations of isothermal titration calorimetry (ITC), high sensitivity differential scanning calorimetry (HSDSC), dynamic light scattering (DLS) and small angle neutron scattering (SANS) experiments. Bile salts affected the aggregation of F127 in accordance to their hydrophobicity, i.e. NaC<NaDC<NaTDC. Thermodynamically stable mixed aggregates were formed with NaC which remained confined at the interface even at high concentration (∼10 mM). On the contrary, hydrophobic NaTDC engaged more profoundly with F127 which manifested into dissociation of aggregates. With 4 mM NaTDC, the number density of aggregates increased more than ten-fold. We argue that dissociation would have occurred because of development of electrostatic repulsive forces in the presence of NaTDC molecules. This could be verified from bile salt driven changes in size distribution, aggregation number and thermodynamic parameters. For instance, upshift in critical micelle concentration and micellization temperature of F127 was recorded depending upon concentration of NaDC and NaTDC. Inspite of this, neutron scattering data ruled out the possibility of morphological transitions during these associations.

Thermo- and pH-Sensitive Behavior of Copolymers of N-Vinylcaprolactam with N-Vinylimidazole

Free-radical copolymerization in bulk has afforded copolymers of N-vinylcaprolactam and N‑vinylimidazole (40–60 mol %). Thermosensitive behavior of aqueous solutions of the copolymers has been probed over wide pH range by means of dynamic and static light scattering as well as high-sensitivity differential scanning calorimetry. Three regions of thermally induced conformational behavior have been observed with the change in the medium pH from the alkaline to acidic: phase separation region (I), region of the conformational transition into the mesoglobules state (II), and region of stable molecular solution of the poly-electrolyte (III). Significant polyelectrolyte effects have been revealed for the salt-free solutions of the copolymers, reflected in the presence of fast and slow diffusion modes in the relaxation time distributions. Moderate increase in the ionic strength with the addition of the low-molecular salt has led to shielding of the polyelectrolyte effects, yet the pH-dependent regions of the conformational behavior have not been affected much. The existence of different types of the thermally induced conformational behavior depending on pH has been explained by the balance between hydrophobic interactions involving the N-vinylcaprolactam units and electrostatic interactions of the weakly basic N-vinylimidazole units.

Soluble complexes of ovalbumin with fucoidan: Energetics of binding, protein stability and functional properties

The interaction between ovalbumin (OVA) and fucoidan (FVF), a branched sulfated polysaccharide of seaweeds, was studied by turbidimetry, velocity sedimentation, and high-sensitivity differential scanning calorimetry (HS-DSC). The boundary conditions of the existence of soluble OVA−FVF complexes were determined as a function of pH and/or OVA−FVF mixture composition. The yield of soluble OVA−FVF complexes was determined from the velocity sedimentation data at pH 4.0 and 5.0 in 5 mM NaCl. It achieved a maximal value of ∼90% at pH 5.0 and the OVA/FVF weight ratio of about 6. According to HS-DSC data, the denaturation behavior of OVA bound to FVF changed significantly as compared with that of the free protein. Depending on pH and OVA−FVF mixture composition, one or two heat capacity peaks were observed on the thermograms assigned either to the free or to bound protein. The denaturation temperature of the bound OVA was about 20 °C lower than that of the free OVA. Based on the HS-DSC results, the OVA to FVF binding curves were derived at pH 5.0 and 5.5. Both were well approximated by the Langmuir equation with n=66±3 and Kb=105.2±0.1 M−1 at pH 5.0, and n=1.1±0.2 and Kb=104.6±0.2 M−1 at pH 5.5. Some emulsifying and foaming properties of the OVA−FCD complexes were characterized and compared with those of OVA alone. The complexes showed a significantly lower emulsifying threshold. The foaming ability of the complexes could exceed that of OVA by more than twice. These results imply a high potential of the OVA−FCD complexes as emulsion and foam stabilizers.

β-Lactoglobulin–fucoidan nanocomplexes: Energetics of formation, stability, and oligomeric structure of the bound protein

Interaction of β-lactoglobulin (BLG) with a sulfated polysaccharide isolated from the brown alga Fucus vesiculosus (fucoidan, FVF), was studied by nephelometry, high-sensitivity differential scanning calorimetry, and sedimentation velocity as a function of pH and the polysaccharide/protein ratio. FVF–BLG complexes were found over the pH 2.5–6.0 range. The complexation was accompanied by the decrease in the conformational stability of BLG at pH < pI 5.2 of the protein where FVF and BLG were oppositely charged. Near pI of the protein and at the pH values larger a bit than pI, where BLG has a large dipole moment or carries a small negative charge, the complexation appeared as changes in the oligomeric state of the protein. Binding curves of BLG to FVF were obtained at pH 3.0 and 6.0 according to the DSC and sedimentation velocity data. Binding constants were evaluated: 3.6 × 103 M−1 at pH 3.0 and 2 × 104 M−1 at pH 6.0. Correlations between the denaturation enthalpy and temperature for the free and bound protein in terms of Kirchhoff's law indicated that the denaturation of both forms of the protein is associated with comparable changes in the accessible surface area of the BLG molecule. It means that the binding of BLG to FVF does not perturb the hydrophobic core of the protein.

Energetics and mechanism of β-lactoglobulin binding to dextran sulfate

Interactions of a major whey protein, β-lactoglobulin (BLG), with an anionic polysaccharide, dextran sulfate (DS), were investigated by nephelometric titration and high-sensitivity differential scanning calorimetry at pH 2.5–7.0 and NaCl concentrations of 0–500 mM. The pH-dependences of the light scattering of the BLG−DS system revealed a maximum. Its position was dependent on the polysaccharide/protein ratio and salt concentration. Thermodynamic parameters of the denaturation of BLG in mixtures with DS were determined at different pH and salt concentrations. Conformational stability of BLG in the BLG–DS complexes was shown to either increase or decrease depending on the solution conditions and complex composition. The binding curves of BLG to DS were calculated from the light scattering and calorimetric data and analyzed using various binding models including the Langmuir and McGhee–von Hippel models as well as a stoichiometric interpolyelectrolyte reaction. Mechanisms responsible for changes in the BLG oligomer structure and conformational stability induced by the complex formation with the polysaccharide were proposed.

Revisiting the salt-triggered self-assembly in very hydrophilic triblock copolymer Pluronic® F88 using multitechnique approach

An insight scrutiny into the micellization behavior of a linear triblock copolymer Pluronic® F88 in aqueous potassium chloride (KCl) solutions is put forth through various physicochemical techniques, viz. cloud point, tensiometric, microcalorimetry, fluorescence life-time decay, spectral, and scattering. Phase transitions of 5% w/v F88 in KCl electrolyte environment demonstrated the dehydration of copolymer coil; a decrease in the micellization temperature with increase in [KCl] due to salting out effect was configured with high sensitivity differential scanning calorimetry (HSDSC) and fluorescence spectroscopy conduct. Salting out effect exhibited by PEO and PPO blocks of F88 in the presence of KCl was measured by the variations in the bond stretching, intensity of vibrations, and change in chemical shifts using spectral (Fourier-transfer infrared (FT-IR) and 1H-nuclear magnetic resonance (1H-NMR) spectroscopy) techniques. The micellization that followed the double-relaxation process is further validated, employing ultrasonic absorption spectroscopy. The plausible unimers to spherical micelles transition induced by KCl are confirmed with the measured hydrodynamic diameter (Dh) of micelles using dynamic light scattering (DLS). Furthermore, UV-vis spectroscopy findings depicted the successive solubilization of water-insoluble organic dye (orange-OT) in the examined micellar solution which revealed the salient role of salt-water interaction in emboldening the micellization of F88.

Energetics and Mechanisms of poly(N-isopropylacrylamide) Phase Transitions in Water–Methanol Solutions

The phase transitions of poly(N-isopropylacrylamide) (PNIPAM) in water–methanol mixed solutions were studied in detail by high-sensitivity differential scanning calorimetry. From this study, the de...

Micellar characteristics of an amphiphilic star-block copolymer in DES-water mixture

Deep eutectic solvents (DES) have revealed the ability to promote the aggregation of amphiphiles in solution. With a brief overview on the self-assembly of amphiphilic substances in protic/aprotic, polar/non-polar solvents, ionic liquids (ILs), and deep eutectic solvents, we herein report the aggregation behavior of a star block (4-arm) ethylene oxide (EO)-propylene oxide (PO) block copolymer (5 %w/v) tetronic T1304 in the presence of different DESs [ChCl: urea, ChCl: ethylene glycol (EG), ChCl: glycerol (Gly), ChCl: malonic acid (MA), ChCl: glutaric acid (GA), and ChCl: oxalic acid (OA)] in varying aqueous molar ratio solution. From high-sensitivity differential scanning calorimetry (HSDSC), surface tension (S.T.), small-angle neutron scattering (SANS), and dynamic light scattering (DLS), we present for the first time the self-aggregation and size distribution profile of amphiphilic tetronic T1304 in DES-water mixture system. The solubility of poorly water-soluble drug, quercetin (QN), was also checked in 5 %w/v copolymeric micelles and in presence of different DESs using UV-Visible spectroscopy. The presence of various DESs alter the micellization and micellar characteristics and such observed behavior are due to the favorable interactions that support the self-assembly in DES-water solvent mixture which is further elucidated by the molecular simulation study using the Gauss View 5.0.9.

The Two Phase Transitions of Hydrophobically End-Capped Poly(N-isopropylacrylamide)s in Water.

High-sensitivity differential scanning calorimetry (HS-DSC) thermograms of aqueous poly(N-isopropylacrylamide) (PNIPAM) solutions present a sharp unimodal endotherm that signals the heat-induced dehydration/collapse of the PNIPAM chain. Similarly, α,ω-di-n-octadecyl-PNIPAM (C18-PN-C18) aqueous solutions exhibit a unimodal endotherm. In contrast, aqueous solutions of α,ω-hydrophobically modified PNIPAMs with polycyclic terminal groups, such as pyrenylbutyl (Py-PN-Py), adamantylethyl (Ad-PN-Ad), and azopyridine- (C12-PN-AzPy) moieties, exhibit bimodal thermograms. The origin of the two transitions was probed using microcalorimetry measurements, turbidity tests, variable temperature 1H NMR (VT-NMR) spectroscopy, and 2-dimensional NOESY experiments with solutions of polymers of molar mass (Mn) from 5 to 20 kDa and polymer concentrations of 0.1 to 3.0 mg/mL. The analysis outcome led us to conclude that the difference of the thermograms reflects the distinct self-assembly structures of the polymers. C18-PN-C18 assembles in water in the form of flower micelles held together by a core of tightly packed n-C18 chains. In contrast, polymers end-tagged with azopyridine, pyrenylbutyl, or adamantylethyl form a loose core that allows chain ends to escape from the micelles, to reinsert in them, or to dangle in surrounding water. The predominant low temperature (T1) endotherm, which is insensitive to polymer concentration, corresponds to the dehydration/collapse of PNIPAM chains within the micelles, while the higher temperature (T2) endotherm is attributed to the dehydration of dangling chains and intermicellar bridges. This study of the two phase transitions of telechelic PNIPAM homopolymer highlights the rich variety of morphologies attainable via responsive hydrophobically modified aqueous polymers and may open the way to a variety of practical applications.

Functionalized thermoresponsive microgels based on N-isopropylacrylamide: Energetics and mechanism of phase transitions

Nano- and micro-sized stimuli-responsive polymer containers capable of an effective controlled binding and release of ionic amphiphilic drugs are highly demanded in drug delivery. Thermoresponsive cross-linked microgels based on N-isopropylacrylamide (NIPAM) were synthesized by precipitation polymerization in aqueous media. The microgels were functionalized by the introduction of an ionic component (acrylic acid, AA, or vinyl sulfonate, VSA) either as a comonomer (NIPAM-co-AA and NIPAM-co-VSA microgels) or interpenetrating polymer network (PNIPAM-PAA microgel). The thermoresponsive behavior of the microgels was investigated by high-sensitivity differential scanning calorimetry. Thermodynamic parameters of the phase transitions (the transition temperature, enthalpy, and width) for the copolymer and interpenetrating microgels were determined. The copolymer microgels involving weak and strong ionogenic groups differ drastically by the transition energetics. This implies different types of their primary structures provided by either comonomer affinity or segregation in the reaction mixture under the polymerization conditions. The microgel functionalization via interpenetrating networks does not affect notably the transition temperature typical of the reference parent PNIPAM microgel but reduces the transition cooperativity. An analysis of the heat capacity profile of the microgel phase transition reveals some features of the mechanism of the thermoresponsivity in the microgels.

Interactions of alkyltriphenyl phosphonium based ionic liquids with block copolymer microstructures: A multitechnique study

Here we report comprehensive analysis on the influence of different alkyltriphenyl phosphonium (CnTPPBr) (with varying alkyl chain lengths) based cationic surfactants displaying analogical characteristics to ionic liquids (IL) on the physicochemical properties of an ethylene oxide–propylene oxide (EO–PO) triblock copolymer, Pluronic®, P103 (EO17-PO60-EO17; M. Wt-3250) using several techniques viz. cloud point (CP), viscosity, small angle neutron scattering (SANS), dynamic light scattering (DLS) and high sensitivity differential scanning calorimetry (HSDSC). The CP results indicate notable increase in values with the increase in alkyl chain length of IL. A significant decrease in the micelle size was witnessed from the DLS and SANS results. The presence of sodium bromide (NaBr), however, counteracted the disruptive effect of ILs and promoted micellar growth. The critical micelle temperature (CMT) results attained using HSDSC are also reported. The information acquired from the present study will be highly beneficial in understanding the behavior of Pluronic® micelles in the presence of CnTPPBr ILs and for their effective utilization in various industrial applications.

Binding Energetics of Charged Amphiphilic Ligands to Thermoresponsive Biodegradable Poly(methoxyethylaminophosphazene) Hydrogels.

Changes in the affinity of the swollen and collapsed forms of a thermoresponsive polymer gel for targeted ligands can be directly estimated using a thermodynamic approach based on high-sensitivity differential scanning calorimetry (HS-DSC). For macromolecular ligands (proteins) bound to the gel, this method provides information on changes in their conformational stability, which is of crucial importance for the biological or pharmaceutical activity of the protein. We used HS-DSC for the study of interactions of two widely administrated drugs-gemfibrozil and ibuprofen-and two globular proteins-α-lactalbumin and BSA-with hydrogels of the cross-linked poly(methoxyethylaminophosphazene). The gel collapse resulted in a substantial increase in the gel affinity for the drugs. We obtained quantitative estimations of the affinity of the collapsed gels depending on the gel structure, pH, concentration of NaCl, and phosphate buffer (an inductor of the thermoresponsivity). The gels retained a high affinity for the drugs in the near-physiological conditions (ionic composition and pH). The binding curves of globular proteins to the gels in the swollen and collapsed states were obtained. The different proteins demonstrated the preferential binding to the swollen or collapsed state of the gels, presumably depending on the protein surface hydrophobicity. The proteins bound to the gel subchains retain their native tertiary structure and, therefore, maintain their functionality when immobilized in the polyphosphazene hydrogels.

Thermodynamic insight into the thermoresponsive behavior of chitosan in aqueous solutions: A differential scanning calorimetry study

Thermoresponsivity of chitosan induced by β-glycerophosphate (GP) in diluted aqueous solutions has been first studied by high-sensitivity differential scanning calorimetry. It has been found that the GP solutions of chitosan undergo a first-order phase transition upon heating. The onset of this transition coincides with the cloud point of the system. This allows one to identify the thermoresponsivity of chitosan as a macroscopic demonstration of the phase separation transition. The transition temperature, enthalpy, heat capacity increment, and width were determined as functions of GP and chitosan concentrations, and the dielectric constant of the solvent. Based on this data, we suggested that GP binds cooperatively to the chitosan matrix at low temperatures. The standard free energy of GP binding (Δbgint= −6 ± 1 kJ mol−1) was estimated from the DSC data. It was shown that the Okada–Tanaka model of cooperative hydration of polymers adequately describes the thermogram of the GP induced phase transition of chitosan.

Poly(2-propyl-2-oxazoline)s in Aqueous Methanol: To Dissolve or not to Dissolve

At room temperature, poly(N-isopropylacrylamide) (PNIPAM) is soluble in water and methanol, but it is not soluble in certain water/methanol mixtures. This phenomenon, known as cononsolvency, has been explored in great detail experimentally and theoretically in an attempt to understand the complex interactions occurring in the ternary PNIPAM/water/co-nonsolvent system. Yet little is known about the effects of the polymer structure on cononsolvency. To address this point, we investigated the temperature-dependent solution properties in water, methanol, and mixtures of the two solvents of poly(2-cyclopropyl-2-oxazoline) (PcyPOx) and two structural isomers of PNIPAM (Mn ∼ 11 kg/mol): poly(2-isopropyl-2-oxazoline) (PiPOx) and poly(2-n-propyl-2-oxazoline) (PnPOx). The phase diagram of the ternary water/methanol/poly(2-propyl-2-oxazolines) (PPOx) systems, constructed based on cloud point (TCP) measurements, revealed that PnPOx exhibits cononsolvency in water/methanol mixtures. In contrast, methanol acts as a cosolvent for PiPOx and PcyPOx in water. The enthalpy, ΔH, and temperature, Tmax, of the coil-to-globule transition of the three polymers in various water/methanol mixtures were measured by high-sensitivity differential scanning calorimetry. Tmax follows the same trends as TCP, confirming the cononsolvency of PnPOx and the cosolvency of PiPOx and PcyPOx. ΔH decreases linearly as a function of the methanol content for all PPOx systems. Ancillary high-resolution 1H NMR spectroscopy studies of PPOx solutions in D2O and methanol-d4, coupled with DOSY and NOESY experiments revealed that the n-propyl group of PnPOx rotates freely in D2O, whereas the rotation of the isopropyl and cyclopropyl groups of PiPOx and PcyPOx, respectively, is limited due to steric restriction. This factor appears to play an important role in the case of the PPOxs/water/methanol ternary system.

Protein-like energetics of conformational transitions in a polyampholyte hydrogel

The volume phase transition of a hydrogel of the polyampholyte network N-isopropylacrylamide (6000) - N-(3-aminopropylmethacrylamide) (120) - Acrylic acid (120) - N,N′-Methylenebisacrylamide (40) was investigated by high-sensitivity differential scanning calorimetry in relation to pH, concentrations of NaCl and two oppositely charged drug ligands (ibuprofen and propranolol). The transition temperature, enthalpy, heat capacity increment and width against these thermodynamic variables were determined. The experimental data were used for calculation of the excess free energy functions of the phase transition which are measures of the relative stability of the dense (collapsed) state of the polyampholyte network under different conditions. By analogy with globular proteins, the stability of the network dense state is maximal at the isoelectric point of the polyampholyte and is increased by the kosmotropic salt and specific ligands. We demonstrate that the polyampholyte hydrogel consists of independent cooperative domains. The sizes of these domains in the hydrogel (9–15 kDa) are comparable with those in globular proteins.

A comparative study on the effect of structural variations of co-solvent on the Tetronic® micelles with widely different hydrophobicity

Here we report, a comparative study on the micellization and phase behavior of two commercially available ethylene oxide – propylene oxide (EO-PO) octablock copolymers, Tetronics® 1304 and 1307 (hereafter written as T1304 and T1307), in the presence of 2,2,2‑trifluoroethanol (TFE) and ethanol (EtOH) using cloud point (CP), dynamic light scattering (DLS), high sensitivity differential scanning calorimetry (HSDSC), relative viscosity and Langmuir film balance. These copolymers fabricated with almost the same PO block length vary in their EO chain lengths and hence display different characteristics. T1304 shows a more hydrophobic character and forms micelles at ambient temperature while T1307, due to longer EO chain length, exhibits high hydrophilicity and faces difficulty in forming micelles which results into high polydispersity in the aqueous system. In the presence of co-solvents TFE and EtOH, however a more interesting behavior is noted. T1304, as evident from DLS and viscosity measurements, displays micellar growth in the presence of TFE, while the presence of EtOH induces micellar breakdown. Though, in case of T1307, presence of TFE improves micellization and a single micellar peak becomes evident in the DLS stacks, no micellar growth can be noticed both through DLS and relative viscosity, which is possibly due to its highly hydrophilic character. Likewise, presence of TFE depresses the CMT in both the copolymers while EtOH increases it. A similar trend is also justified by π-A isotherms form Langmuir monolayers.

Controlled coagulation and redispersion of thermoresponsive poly di(ethylene oxide) methyl ether methacrylate grafted cellulose nanocrystals

HypothesisCellulose nanocrystals (CNCs) undergo precipitation in the presence of high concentrations of cationic surfactants in aqueous solutions. To avoid such behavior and/or to promote redispersion of CNC/surfactant mixtures, the CNC surface was grafted with poly di(ethylene oxide) methyl ether methacrylate, P(MEO2MA). ExperimentsCNC-g-P(MEO2MA) was characterized using the following techniques 13C solid-state nuclear magnetic resonance (13C SSNMR), Fourier-transform infrared spectroscopy – attenuated total reflection spectroscopy (FTIR-ATR) and thermal gravimetric analysis (TGA). Isothermal titration calorimetry (ITC), electrophoretic mobility, light scattering and high sensitivity differential scanning calorimetry (HSDSC) were used to study the interaction between CNC-g-P(MEO2MA) and ionic surfactants, dodecyltrimethylammonium bromide (C12TAB, cationic) and sodium dodecylsulfate (SDS, anionic) at temperatures below and above the LCST. FindingsCNC-g-P(MEO2MA) underwent phase separation above its lower critical solution temperature (LCST ∼ 25 °C) and precipitated from solution as seen by HSDSC and transmittance experiments. When C12TAB was added to CNC-g-P(MEO2MA) it induced the precipitation that prevented the redispersion due to strong electrostatic interactions with the negative charges on the CNC surface. With increasing concentrations of SDS, the polymer phase transition temperature was increased, which can be used to redisperse the CNC complexes. By removing SDS from the mixture via dialysis, the CNC-g-P(MEO2MA) underwent subsequent phase transition.