Determining the exact polymerization structure of a copolymer containing multiple monomers can be a complex task. Since the methods you mentioned (DOSY, HPLC, GPC, DSC, and DMA) are not suitable in your case, here are a few alternative approaches you could consider:

Chapter Copolymerization

Distinction between true copolymers and polymer blends. Copolymers contain both monomer types within a single polymer chain (this occurs during synthesis), whereas polymer blends are made via mixing techniques (combination of multiple homopolymers, which generally occurs after synthesis).

Most step growth polymerizations require multiple monomer types during synthesis.

Comparison of polymer blends and copolymers by broadband dielectric analysis

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Abstract

Dielectric relaxation measurements on poly o-chlorostyrene (PoCS), polystyrene (PS), a 50 mol% PoCS/PS blend, and a 50 mol% P(oCS/S) random copolymer were made in the frequency range 1 mHz to 1 MHz as a function of temperature. The α-relaxation process associated with micro Brownian motion of the chain was observed in each sample. The shape of the absorption ϵ″(ω) of the copolymer was nearly the same as that of PS and of PoCS, and was considerably narrower than that of the blend. The broadened relaxation curve of the blend relative to the copolymer was well explained by a convolution of the individual relaxation processes, which were obtained in the copolymer by assuming equivalence to an ideal homogeneous mixture of two segments. The distribution, P(log τ), of the peak position was modeled by a Gaussian error function. To apply the Vogel–Fulcher equation, the distribution P(T0) of the Vogel–Fulcher temperature, T0, was calculated from P(log τ). To reflect the cooperative motion, T0 was distributed between the T0 of PoCS and that of PS. This is equivalent to assuming that the broadened loss peak in the blend is caused by localized concentration fluctuations on the scale of the segmental motion. The g-factor calculated from the relaxation strength of the polymer blend was nearly the same as that of PS and of PoCS, but was considerably smaller than that of the copolymer. This difference suggests that the local environment of the dipole moment of the chlorostyrene unit in the blend is similar to that of the homopolymer.

Introduction

The definition of miscibility generally satisfies the thermodynamic criteria for a single-phase system (see [1], [2], [3], [4]). However, miscibility in polymer blends is a relative term, and depends on the scale of homogeneity. It also depends, therefore, on the measurement technique employed. For example, if only one Tg is detected by DSC, the sample of a mixture of two constituents may be deemed miscible [1], [2], [3], [4]. However, it is possible to exhibit a minimum degree of homogeneity for both polymer blends and copolymers larger than the monomer unit scale.One reason for the apparent technique dependence of miscibility is the qualitative difference between the static structure and the dynamical property measured. Observation by a static method in the mixture will give information about the composition of the blend, such as how the polymer constituents interpenetrate each other [5]. On the other hand, dynamical properties such as the spin–lattice relaxation time T1 or spin–spin relaxation time T2 in NMR [6], [7], and the distribution of Tg[8] will yield information regarding the heterogeneity of molecular motions. The presence of a broad single Tg implies that the constituent polymers of the blend move together but the dynamics are not uniform. This cooperative motion is an important aspect of miscibility, but is not completely understood.Dielectric relaxation analysis can contribute to the understanding of the cooperative motion, because it is concerned with the movement of dipoles [9], [10]. In addition, because of the wide range of frequencies that can be covered, the relaxation spectrum can be obtained directly, rather than indirectly using time–temperature superposition. Such a spectrum reflects the state of the molecular dynamics of the segments, or group of segments, in the environment of other dipoles, or of nonpolar segments, in the heterogeneous or homogeneous domain [11], [12].Shears and Williams [13] were the first to observe the dielectric α relaxation, the relaxation associated with Tg, in mixtures of two glass-forming liquids. They found such mixtures to exhibit a broader loss peak than either of the pure components. They attributed this broadened distribution to variability in local dipole concentration. Their system was optically homogeneous, so the heterogeneities responsible for the broadening of the relaxation time spectrum were on a scale too small to scatter visible light.Wetton et al. developed a model based on the concentration fluctuation of dipoles for the analysis of the broadened distribution of relaxation times in blends [14], whereas Ngai and Roland introduced the concept of coupled relaxation modes, to analyze their stretched exponential function quantitatively [15], [16]. Fischer et al introduced a model based on concentration fluctuations of the Gaussian type that led to a broadening of the relaxation spectrum, and analyzed data obtained at various concentrations and temperatures. The results were found to be in agreement with light scattering data [17], [18]. Kumar et al. also utilized a concentration fluctuation model to explain the broadening of the relaxation peak [19]. We have previously investigated the dielectric relaxation of poly o-chlorostyrene (PoCS), polystyrene (PS), and their blends and copolymers [20]. The relaxation spectrum of the blend was found to be generally far broader than a random copolymer of the same composition.This study is an extension of our earlier work on the PoCS copolymers and their blends with PS. In the present work a wider frequency range from 10−3 to 106 Hz, and a wider temperature range 370–450 K were employed permitting a more definitive analysis. Utilizing these ranges of temperature and frequency it was possible to elucidate the nature of the molecular motions near to but above Tg.The cooperative nature of segmental relaxations characterizes the α relaxation [11], [12]. This is an intermolecular process, as opposed to the intramolecular cooperative relaxation typical of the β relaxation. When polymer molecules are in a ‘crowded’ environment, the motion of a segment is interfered due to the presence of its neighbor. Dissipation of energetic input, typically through a rotation of the segmental bond from one stable state to another, is then possible only through the cooperation of the neighbors. Such cooperation comes in the form of a simultaneous relaxation. For two segments to move cooperatively, the probability of relaxation is squared, since each relaxation is an independent event. Thus, the cooperative relaxation time is τ2, with τ as the relaxation time for a single segment in the absence of interference by neighbors.At progressively lower temperatures, the volume decrease causes greater interference among neighbors. At high temperatures the cooperative relaxation involves two segments, called conformers. At lower temperatures the number involved increases to three, and then four, etc. The number of cooperating segments is defined as the size of the cooperative domain, z. This quantity occurs in the exponent of the Boltzmann probability for the relaxation rate process of Arrhenius form, so the apparent activation energy Δμ for the single bond rotation is multiplied by z. As z increases with decreasing temperature, the apparent activation energy increases, transforming the Arrhenius form to the Vogel–Fulcher form. The temperature at which the latter diverges is T0, which is typically some 50 K below the empirical Tg obtained by DSC. At T0, z is supposed to approach infinity, but before this happens, the system will deviate from equilibrium, i.e. volume, entropy and enthalpy fail to keep up with the rate of cooling, and vitrification takes place.We have analyzed the concentration fluctuations in terms of the distribution of T0 at a given temperature. Such a distribution is a measure of the domain size distribution, again, at that temperature. From this, we describe the concentration fluctuations in segmental terms, i.e. the local or nanoscale heterogeneity.

like NMR,IR,XRD is better for to identify polymer contains which type of methacrylates

Since copolymers are having two or more type of monomers we can identify by analyzing peaks of IR, XRD etc

SEM and TEM can assist you as copolymers may display a more ordered and uniform structure compared to blends, which often have phase-separated domains.

Best way is to produce separately those different variations of copolymer blocks and then analyze them separately and mixed with the suggested methods and compare with your sample

XPS measurements are helpful to distinct the linking traduction the copolymerization process. Also this can be evidenced by TGA measurements.

Есть самый простой метод. Растворить образец в нескольких растворителях. Если полимерный материал растворяется только частично, то это смесь из двух полимеров. Если растворимость полная, то можно предположить, что это один сополимер. После растворения нужно провести дробное осаждение и тем самым можно проверить, насколько однородный образец. Соответственно проведя ИК-спектроскопию образцов на разных стадиях осаждения можно доказать однородность образца по химическому составу.