N-isopropylacrylamide Copolymers Research Articles

Adaptable intelligent filters based on nanotextured nonwoven membranes containing water-insoluble hydrogels

The work demonstrates, for the first time, thermo-responsive, water-insoluble, hydrogel-based, nano-fibrous filter media comprised of copolymers of N-isopropylacrylamide (NIPAM) and methyl methacrylate formed by electrospinning. Moreover, a comprehensive novel physical explanation of all aspects responsible for the physical mechanisms resulting in the thermo-responsive regulation of the water flow rate and an enhanced interception of nanoparticles by such filter membranes is given. They are the wettable-non-wettable transition, pore, and fiber-size changes, as well as a diminishing filter thickness at the lower critical solution temperature (LCST) of the copolymers developed here, which interplay with a significant reduction in the water viscosity with temperature. Poly(N-isopropylacrylamide) (PNIPAM) hydrogel is an attractive material because of its thermo-responsive properties. Its wettability changes with water temperature. This characteristic holds great promise for the development of advanced filter media and related responsive materials. In this study, PNIPAM hydrogels were designed and transformed into filter membranes for applications in water filtration in biomedical and other related systems. These thermo-responsive filter membranes offer the potential for enhanced filtration efficiency, selectivity, and the overall system performance. Here, two different procedures were adopted to form water-insoluble thermo-responsive filter media based on PNIPAM hydrogels. The PNIPAM-based hydrogels were electrospun, resulting in the formation of thermo-responsive water-insoluble nanofiber membranes. These membranes underwent a series of comprehensive experiments to assess their performance and characteristics, including mass loss, water droplets for the wettability assessment, filtration tests, shrinkage measurements, and microscopic observations. These diverse experiments yield a full understanding of the PNIPAM-based nanofiber membranes’ properties and their potential applications.

Controlled Dissociation of Polymeric Micelles in Response to Oxidative Stress.

Nanoparticle-based drug carriers that can respond to oxidative stress in tumor tissue have attracted attention for site-specific drug release. Taking advantage of the characteristic microenvironment in tumors, one of the attractive directions in drug delivery research is to design drug carriers that release drugs upon oxidation. A strategy to incorporate oxidation-sensitive thioether motifs such as thiomorpholine acrylamide (TMAM) to drug carriers has been often used to achieve oxidation-induced dissociation, thereby targeted drug release. However, those delivery systems often suffer from a slow dissociation rate due to the intrinsic hydrophobicity of the thioether structures. In this study, we aimed to enhance the dissociation rate of TMAM-based micelles upon oxidation. The random copolymers of N-isopropylacrylamide and TMAM (P(NIPAM/TMAM)) were designed as an oxidation-sensitive segment that showed a fast response to oxidative stress. We first synthesized P(NIPAM/TMAM) copolymers with different NIPAM:TMAM molar ratios. Those copolymers exhibited low critical solution temperatures (LCSTs) below 32 °C, which shifted to higher temperatures after oxidation. The changes in LCSTs depend on the NIPAM:TMAM molar ratios. At the NIPAM:TMAM molar ratio of 82:18, the LCSTs before and after oxidation were 17 and 54 °C, respectively. We then prepared micelles from the diblock copolymers of poly(N-acryloyl morpholine) (PAM) and P(NIPAM/TMAM). The micelles showed an accelerated dissociation rate upon oxidation compared to the micelles without NIPAM units. Furthermore, the doxorubicin (Dox)-loaded micelles showed enhanced relative toxicity in human colorectal cancer (HT29) cells over human umbilical vein endothelial cells (HUVECs). Our novel strategy to design an oxidation-sensitive micellar core comprising a P(NIPAM/TMAM) segment can be used as a chemotherapeutic delivery system that responds to an oxidative tumor microenvironment in an appropriate time scale.

Nano-injectable pH/NIR-responsive hydrogel for chemo-photothermal synergistic drug delivery.

Conventional cancer treatments are highly toxic and ineffective; therefore, it is essential to develop less toxic and minimally invasive treatment methods. A pH/Near Infra-red (NIR) dual-responsive, nano-injectable smart hydrogel was fabricated by incorporating CuS nanoparticles into the hydrogel networks formed by a random copolymer of N-isopropylacrylamide (NIPAM) and double-bond functionalized uracil. Microstructural characterizations of synthesized polymer and hydrogels were carried out using transmission electron microscope (TEM), scanning electron microscope (SEM), nuclear magnetic resonance (NMR) and fourier transform infrared spectroscopy (FT-IR). Multiple hydrogen bonding interactions between uracils function as physical cross-linking points to construct the network structure of the polymeric nanogel without the addition of additional cross-linking agents, ensuring the material's safety. The amino group on the structure of uracil gives the uracil-modified polymeric hydrogel excellent pH responsiveness. Notably, as a temperature-responsive material, poly (N-isopropylacrylamide) (PNIPAM) nanogel solution can achieve in situ gel formation (within 100 s at 37°C) above its lower critical solution temperature (LCST), granting injectability to polymeric solutions. Moreover, using a hierarchical construction strategy, the variable loading of DOX and CuS was achieved. First, a heterogeneous system was created by encapsulating doxorubicin (DOX) inside the nanogel via hydrophobic and π-π stacking interactions, followed by the introduction of CuS nanoparticles as photosensitizers outside of the nanogels. Due to the presence of CuS nanoparticles, the gel is able to convert NIR light into local heat to enhance the destruction of tumor cells while simultaneously achieving rapid in situ gel formation. The in situ-forming hydrogel showed promising tissue biocompatibility. The in vitro antitumor test demonstrated the capacity of the nanocomposite hydrogel for chemo-photothermal synergistic therapy. Therefore, this prepared platform has the potential to become a safe and effective, smart-responsive drug carrier for chemotherapy and PTT synergy, a minimally invasive material for tumor treatment.

Reversible Thermo-Optical Response Nanocomposites Based on RAFT Symmetric Triblock Copolymers (ABA) of Acrylamide and N-Isopropylacrylamide and Gold Nanoparticles.

The development of composite materials with thermo-optical properties based on smart polymeric systems and nanostructures have been extensively studied. Due to the fact of its ability to self-assemble into a structure that generates a significant change in the refractive index, one of most attractive thermo-responsive polymers is poly(N-isopropylacrylamide) (PNIPAM), as well as its derivatives such as multiblock copolymers. In this work, symmetric triblock copolymers of polyacrylamide (PAM) and PNIPAM (PAMx-b-PNIPAMy-b-PAMx) with different block lengths were prepared by reversible addition-fragmentation chain-transfer polymerization (RAFT). The ABA sequence of these triblock copolymers was obtained in only two steps using a symmetrical trithiocarbonate as a transfer agent. The copolymers were combined with gold nanoparticles (AuNPs) to prepare nanocomposite materials with tunable optical properties. The results show that copolymers behave differently in solution due to the fact of variations in their composition. Therefore, they have a different impact on the nanoparticle formation process. Likewise, as expected, an increase in the length of the PNIPAM block promotes a better thermo-optical response.

Highly Sensitive Poly-N-isopropylacrylamide Microgel-based Electrochemical Biosensor for the Detection of SARS-COV-2 Spike Protein

ObjectiveLate 2019 witnessed the outbreak and widespread transmission of coronavirus disease 2019 (COVID-19), a new, highly contagious disease caused by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Consequently, considerable attention has been paid to the development of new diagnostic tools for the early detection of SARS-CoV-2. MethodsIn this study, a new poly-N-isopropylacrylamide microgel-based electrochemical sensor was explored to detect the SARS-CoV-2 spike protein (S protein) in human saliva. The microgel was composed of a copolymer of N-isopropylacrylamide and acrylic acid, and gold nanoparticles were encapsulated within the microgel through facile and economical fabrication. The electrochemical performance of the sensor was evaluated through differential pulse voltammetry. ResultsUnder optimal experimental conditions, the linear range of the sensor was 10−13–10−9 mg/mL, whereas the detection limit was 9.55 fg/mL. Furthermore, the S protein was instilled in artificial saliva as the infected human saliva model, and the sensing platform showed satisfactory detection capability. ConclusionThe sensing platform exhibited excellent specificity and sensitivity in detecting spike protein, indicating its potential application for the time-saving and inexpensive detection of SARS-CoV-2.

Synthesis and characterization of dual light/temperature-responsive supramolecular injectable hydrogel based on host-guest interaction between azobenzene and starch-grafted β-cyclodextrin: Melanoma therapy with paclitaxel

Injectable stimuli-responsive hydrogels could offer an opportunity for local administration at the tumor site and a sustained drug release. In this paper, a copolymer of azobenzene derivative and N-isopropyl acrylamide (NIPAM) was synthesized, which are performed as light- and thermo-sensitive parts, respectively. The DAS@SCD/NIPAZO hydrogel was prepared upon the establishment of host-guest interactions between the hydrophobic core of CD and azobenzene moiety. The LCST of the synthesized copolymer was modified from 31.3 °C to 36.5 °C by the incorporation of the hydrophilic host moieties of the modified starch into the NIPAM copolymer structure. The LCST-based property of the hydrogel made it syringable in low temperatures and switch to a gel state after local injection. The drug release profile of the hydrogel was explored in four different conditions involving two distinct temperatures combined with two different light wavelengths to examine the light- and thermo-sensitivity of the hydrogel. Moreover, a Paclitaxel-loaded hydrogel was prepared to study the in vitro efficiency of the sample and was investigated by MTT assay against the cancerous fibroblastic cells (A-431), which revealed a sharp decline in cell viability under 365 nm light irradiation; furthermore, to evaluate the in vivo effects of the PTX-loaded hydrogel, histological studies based on staining techniques were carried out.

Precision syntheses of poly(NIPAM-alt-HEMA) and effects of the alternating sequence on thermoresponsive behaviors in water

An alternating copolymer of 2-hydroxyethyl methacrylate and N-isopropylacrylamide was synthesized via cyclopolymerization of a divinyl monomer and aminolysis transformation for studies of the sequence-dependent thermal responsiveness in water.

The Diffusion of TEMPONE Radical in the Graft Copolymer of N-Isopropylacrylamide with Oligolactide in the Presence of Supercritical Carbon Dioxide by In Situ EPR Method

The Diffusion of TEMPONE Radical in the Graft Copolymer of N-Isopropylacrylamide with Oligolactide in the Presence of Supercritical Carbon Dioxide by In Situ EPR Method

Structure and Dynamics of Inhomogeneities in Aqueous Solutions of Graft Copolymers of N-Isopropylacrylamide with Lactide (P(NIPAM-graft-PLA)) by Spin Probe EPR Spectroscopy.

Coil-to-globule transition and dynamics of inhomogeneities in aqueous solutions of graft copolymers of NIPAM with different content of oligolactide groups were studied using spin probe continuous wave EPR spectroscopy. The technique of the suppressing of TEMPO as spin probe by spin exchange with Cu2+ ions was applied. This approach allowed us to detect individual EPR spectra of the probe in collapsed globules and estimate its magnetic and dynamic parameters reliably. The formation of inhomogeneities at temperatures lower than the volume phase transition temperature measured via transmission, and differential scanning calorimetry was fixed. An increase in oligolactide content in copolymers leads to the formation of looser globules, allowing for the exchange of the probe molecules between the globules and the external solution.

An injectable hyperthermic nanofiber mesh with switchable drug release to stimulate chemotherapy potency.

We developed a smart nanofiber mesh (SNM) with anticancer abilities as well as injectability and fast recovery from irregular to non-compressible shapes. The mesh can be injected at the tumor site to modulate and control anticancer effects by loading the chemotherapeutic drug, paclitaxel (PTX), as well as magnetic nanoparticles (MNPs). The storage modulus of the mesh decreases when applied with a certain shear strain, and the mesh can pass through a 14-gauge needle. Moreover, the fibrous morphology is maintained even after injection. In heat-generation measurements, the mesh achieved an effective temperature of mild hyperthermia (41-43°C) within 5min of exposure to alternating magnetic field (AMF) irradiation. An electrospinning method was employed to fabricate the mesh using a copolymer of N-isopropylacrylamide (NIPAAm) and N-hydroxyethyl acrylamide (HMAAm), whose phase transition temperature was adjusted to a mildly hyperthermic temperature range. Pplyvinyl alcohol (PVA) was also incorporated to add shear-thinning property to the interactions between polymer chains derived from hydrogen bonding, The "on-off" switchable release of PTX from the mesh was detected by the drug release test. Approximately 73% of loaded PTX was released from the mesh after eight cycles, whereas only a tiny amount of PTX was released during the cooling phase. Furthermore, hyperthermia combined with chemotherapy after exposure to an AMF showed significantly reduced cancer cell survival compared to the control group. Subsequent investigations have proven that a new injectable local hyperthermia chemotherapy platform could be developed for cancer treatment using this SNM.

Thermo-Responsive Polymer-siRNA Conjugates Enabling Artificial Control of Gene Silencing around Body Temperature.

Controlling small interfering RNA (siRNA) activity by external stimuli is useful to exert a selective therapeutic effect at the target site. This study aims to develop a technology to control siRNA activity in a thermo-responsive manner, which can be utilized even at temperatures close to body temperature. siRNA was conjugated with a thermo-responsive copolymer that was synthesized by copolymerization of N-isopropylacrylamide (NIPAAm) and hydrophilic N,N-dimethylacrylamide (DMAA) to permit thermally controlled interaction between siRNA and an intracellular gene silencing-related protein by utilizing the coil-to-globule phase transition of the copolymer. The composition of the copolymer was fine-tuned to obtain lower critical solution temperature (LCST) around body temperature, and the phase transition behavior was evaluated. The cellular uptake and gene silencing efficiency of the copolymer-siRNA conjugates were then investigated in cultured cells. The siRNA conjugated with the copolymer with LCST of 38.0°C exhibited ~ 11.5nm of the hydrodynamic diameter at 37°C and ~ 9.8nm of the diameter at 41°C, indicating the coil-globule transition above the LCST. In line with this LCST behavior, its cellular uptake and gene silencing efficiency were enhanced when the temperature was increased from 37°C to 41°C. By fine-tuning the LCST behavior of the copolymer that was conjugated with siRNA, siRNA activity could be controlled in a thermo-responsive manner around the body temperature. This technique may offer a promising approach to induce therapeutic effects of siRNA selectively in the target site even in the in vivo conditions.

Ionic coordination strengthening of temperature-driven gradient hydrogel actuators with rapid responsiveness

Emerging applications of stimuli-responsive hydrogels as soft actuators and robotics have attracted great attention, but they face challenges in practical applications due to their poor mechanical properties, low driving force, and low actuation speed. Herein, we presented tough hydrogel actuators composed of a copolymer of N-isopropylacrylamide (NIPAM) and 3-sulfopropyl methacrylate potassium salt (SPA) monomers, and tunicate cellulose nanocrystals (TCNCs). The negatively charged TCNCs as nanofillers were gradient arranged by a direct current electric field (DC-EF) via electrophoresis. After in situ polymerization, TCNCs gradient distributed across the thickness of hydrogel, resulting in the formation of gradient crosslinking density of networks. Hydrogel actuators with high strength were obtained via Zr4+/−SO3- ionic coordination, whose tensile strength was about 200 times of hydrogel without ionic coordination. These hydrogel actuators exhibited rapid bending velocity, excellent stability, and good cycling performance in response to temperature. Importantly, these hydrogel actuators could be designed as soft robots to lift and transport objects by changing environment temperature. This work provided a facile yet efficient strategy to fabricate soft actuators with high strength and rapid responsiveness.

Modelling and Optimization of Indigo Carmine Adsorption onto P(NIPAM-co-AN)/Clay Composite Using Response Surface Methodology

In the present work, a new polymeric adsorbent; Poly(NIPAM-co-AN)/clay composite was prepared via in-situ polymerization. The copolymerization of N-isopropylacrylamide, acrylonitrile and calculated clay (about 5% w/w) were carried out at 65°C in the presence of 10 mL 1,4-dioxane using AIBN as an initiator. Characterization of P(NIPAM-co-AN)/clay composite was determined by FT-IR techniques. NIPAM-AN/clay composite has been used as a novel adsorbent to remove indigo carmine dye from synthetic effluents. Three important process parameters i.e., initial IC concentration (5-30 mg/L), adsorbent dosage (0.01-0.08 g) and contact time (10–180 min) were modeled and optimized to get the best response of indigo carmine removal using a Central Composite Design assembled with Response Surface Methodology. The amount of indigo carmine in the solution was measured using a UV-visible spectrophotometer at a wavelength of 650 nm. Based on the ANOVA statistical value, the adsorption of indigo carmine onto P(NIPAM-co-AN)/clay composite is highly significant, with very low probability value (p

Molecular Transport within Polymer Brushes: A FRET View at Aqueous Interfaces.

Molecular permeability through polymer brush chains is implicated in surface lubrication, wettability, and solute capture and release. Probing molecular transport through polymer brushes can reveal information on the polymer nanostructure, with a permeability that is dependent on chain conformation and grafting density. Herein, we introduce a brush system to study the molecular transport of fluorophores from an aqueous droplet into the external “dry” polymer brush with the vapour phase above. The brushes consist of a random copolymer of N-isopropylacrylamide and a Förster resonance energy transfer (FRET) donor-labelled monomer, forming ultrathin brush architectures of about 35 nm in solvated height. Aqueous droplets containing a separate FRET acceptor are placed onto the surfaces, with FRET monitored spatially around the 3-phase contact line. FRET is used to monitor the transport from the droplet to the outside brush, and the changing internal distributions with time as the droplets prepare to recede. This reveals information on the dynamics and distances involved in the molecular transport of the FRET acceptor towards and away from the droplet contact line, which are strongly dependent on the relative humidity of the system. We anticipate our system to be extremely useful for studying lubrication dynamics and surface droplet wettability processes.

Multi-stimuli responsive poly(N-isopropyl-co-tetraphenylethene) acrylamide copolymer mediating AIEgens by controllable tannic acid

Copolymerization of N-isopropylacrylamide (NIPAM) and tetraphenylethene (TPE) acrylamide monomers produced aggregation-induced emission (AIE) active copolymers P1 , P2 , and P3 with relatively lower molecular weights (6000). Like poly-N-isopropylacrylamide (p-NIPAM), an aqueous solution of copolymers ( P1-P3 ) responds to temperature and undergoes a change in fluorescence intensity due to conformational transition (swelling/shrinking) below and above their lower critical solution temperature (LCST), respectively. The LCST of p-NIPAM (32 °C) shifted downward upon the incorporation of TPE in the copolymer chains depending on the concentration of TPE . Compared to P1 , the fluorescence response increased to a five-fold enhancement with increasing concentrations of tannic acid ( TA ) owe to the form of the P1-TA complex. Furthermore, the P1-TA complex showed a surprising change in fluorescence response under the effect of temperature and pH value. The conformational transitions of P1-TA were also studied by dynamic light scattering (DLS). DLS measurements for the P1-TA complex justified its fluorescence response based on particle size at different concentrations and pH value. Such stimuli-responsive AIE-active copolymers find potential applications in drug delivery systems for monitoring loading and release processes by fluorescence. • Compared to P1, the fluorescence intensity of AIE-active P1-TA complex increased to a five-fold enhancement. • A multi-stimuli response on temperature and pH value based on intermolecular hydrogen bonding interaction. • The interpenetrating networks can be formed without using two polymer chains or more.

Synthesis, characterization and application of dual thermo- and solvent-responsive double-hydrophilic diblock copolymers of N-acryloylmorpholine and N-isopropylacrylamide

A series of double-hydrophilic diblock copolymers of N-acryloylmorpholine (NAMO) and N-isopropylacrylamide (NIPAm) with varying degree of polymerization were synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization. Structures and average molecular weights of these diblock copolymers were determined through 1H NMR spectra and SEC methods. Thermo-sensitivities and solvent-responsiveness of these copolymers were studied at varying temperatures in ethanol/water mixtures with different ethanol content. Beyond that, thermal behaviors during phase transitions were monitored by means of transmittance methods and DSC measurements, and the variation of aggregating structures in the interim was deduced basing on the results from DLS and TEM tests. Due to the cononsolvency effect of PNIPAm block along with the alcohol-insolubility of PNAMO block, thermo-responsive behaviors of copolymer chains would keep changing with the gradual addition of ethanol. Considering the thermo-responsive and the polar solvent-sensitive properties, we introduced the copolymers into a heavy oil/water mixing system, which possessed both changes of temperature and the attendance of polar groups. Tests results showed that the copolymer solutions did a quite good job on heavy oil viscosity reduction at the target temperature. The stimuli-response behavior of these copolymers endowed the polymer solution with the ability to interact with polar groups in heavy oil and form heavy oil/water emulsions, and made it possible to be used as a novel heavy oil viscosity reducer.

TiO2 Nanoparticle-Loaded Poly(NIPA-co-NMA) Fiber Web for the Adsorption and Photocatalytic Degradation of 4-Isopropylphenol.

A TiO2 nanoparticle-loaded polymer fiber web was developed as a functional material with the ability to adsorb and photo-catalytically degrade organic pollutants in aquatic media. A linear copolymer of N-isopropylacrylamide (primary component) and N-methylol acrylamide (poly(NIPA-co-NMA)) was prepared, and composite fibers were fabricated by electrospinning a methanol suspension containing the copolymer and commercially available TiO2 nanoparticles. The crosslinking of the polymer via the formation of methylene bridges between NMA units was accomplished by heating, and the fiber morphology was analyzed by electron microscopy. 4-Isopropylphenol generated by the degradation of bisphenol A—one of the endocrine-disrupting chemicals—was used as the model organic pollutant. As poly(NIPA) is a thermosensitive polymer that undergoes hydrophilic/hydrophobic transition in water, the temperature-dependence of the adsorption and photocatalytic degradation of 4-isopropylphenol was investigated. The degradation rate was analyzed using a pseudo-first-order kinetic model to obtain the apparent reaction rate constant, kapp. The enhancement of the photocatalytic degradation rate owing to the adsorption of 4-isopropylphenol onto thermosensitive poly(NIPA)-based fibers is discussed in terms of the ratio of the kapp of the composite fiber to that of unsupported TiO2 nanoparticles. Based on the results, an eco-friendly wastewater treatment process involving periodically alternated adsorption and photocatalytic degradation is proposed.

Graft Copolymers of N-Isopropylacrylamide with Poly(d,l-lactide) or Poly(ε-caprolactone) Macromonomers: A Promising Class of Thermoresponsive Polymers with a Tunable LCST

Graft Copolymers of <i>N</i>-Isopropylacrylamide with Poly(<scp>d</scp>,<scp>l</scp>-lactide) or Poly(ε-caprolactone) Macromonomers: A Promising Class of Thermoresponsive Polymers with a Tunable LCST

Novel Thermosensitive-co-Zwitterionic Sulfobetaine Gels for Metal Ion Removal: Synthesis and Characterization.

Zwitterionic betaine polymers are promising adsorbents for the removal of heavy metal ions from industrial effluents. Although the presence of both negative and positively charged groups imparts them the ability to simultaneously remove cations and anions, intra- and/or inter-chain interactions can significantly reduce their adsorption efficiencies. Therefore, in this study, novel gels based on crosslinked co-polymers of thermosensitive N-isopropylacrylamide (NIPAAM) and zwitterionic sulfobetaine N,N-dimethylacrylamido propyl ammonium propane sulfonate (DMAAPS) were synthesized, characterized, and evaluated for ion removal. Fourier-transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) analyses confirmed the success of the co-polymerization of NIPAAM and DMAAPS to form poly(NIPAAM-co-DMAAPS). The phase transition temperature of the co-polymer increased with increasing DMAAPS content in the co-polymer, indicating temperature-dependent amphiphilic behavior, as evidenced by contact angle measurements. The ion adsorption analyses of the poly(NIPAAM-co-DMAAPS) gels indicated that co-polymerization increased the molecular distance and weakened the interaction between the DMAAPS-charged groups (SO3− and N+), thereby increasing the ion adsorption. The results confirmed that, with a low concentration of DMAAPS in the co-polymer gels (~10%), the maximum amount of Cr3+ ions adsorbed onto the gel was ~58.49% of the sulfonate content in the gel.

Determination of Reactivity Ratios from Binary Copolymerization Using the k-Nearest Neighbor Non-Parametric Regression.

This paper proposes a new method for calculating the monomer reactivity ratios for binary copolymerization based on the terminal model. The original optimization method involves a numerical integration algorithm and an optimization algorithm based on k-nearest neighbour non-parametric regression. The calculation method has been tested on simulated and experimental data sets, at low (<10%), medium (10–35%) and high conversions (>40%), yielding reactivity ratios in a good agreement with the usual methods such as intersection, Fineman–Ross, reverse Fineman–Ross, Kelen–Tüdös, extended Kelen–Tüdös and the error in variable method. The experimental data sets used in this comparative analysis are copolymerization of 2-(N-phthalimido) ethyl acrylate with 1-vinyl-2-pyrolidone for low conversion, copolymerization of isoprene with glycidyl methacrylate for medium conversion and copolymerization of N-isopropylacrylamide with N,N-dimethylacrylamide for high conversion. Also, the possibility to estimate experimental errors from a single experimental data set formed by n experimental data is shown.