This research explored the impact of temperature on the mechanical properties of poly(n-butyl acrylate-co-Na methacrylate) (PBA) ionomers, as an elastomeric ionomer, with an emphasis on their ion content. The PBA ionomers were found to exhibit dual glass transition temperatures (Tgs) and ionic plateaus, characteristics typically observed in other amorphous ionomers. Significantly, in PBA ionomers, ionic aggregates (i.e., multiplets) functioned like chemical cross-linking points in addition to their conventional role as physical cross-links. This dual functionality resulted in an upward shift of the rubbery plateau and a consequent enhancement of storage moduli. In a comparative analysis of the mechanical properties of PBA, poly(ethyl acrylate) (PEA), and poly(styrene-methacrylate) (PSMA) ionomers, it was determined that the extent of ionomer clustering increased progressively from PBA ionomer to PEA ionomer to PSMA ionomer. The mechanical properties of these three ionomer systems were interpreted through the lens of multiplet formation mechanisms, with a particular focus on the quantity of multiplets and the number of ion pairs per multiplet, both of which were modulated by the matrix Tgs of each ionomer.

The plasticization effect by the addition of nonpolar bis(2-ethylhexyl) phthalate (dioctyl phthalate) (DOP) on the glass transition temperatures (T(g)s) of poly(styrene-Na methacrylate) (PSMANa) ionomers was investigated. The matrix T-g (T-g,T-m) and cluster T-g (T-g,T-c) of the ionomers dropped linearly as the DOP content in the PSMANa ionomers enhanced, only when the phase separation of DOP did not occur. Since the T-g,T-m and T-g,T-c of the ionomer increased somewhat linearly with increasing ion content of the ionomer, simple equations were obtained to express the T(g)s of the ionomers using the ion contents (x mol%) and the DOP contents (y wt%) of the ionomers; T-g,T-m (degrees C) = 121 + 3.0x + 2.8y and T-g,T-c (degrees C) = 171 + 6.3x + 2.6y. According to the x-ray scattering results, for the ionomer containing 6.4 mol% of ions, the distance between scattering centers increased from 21 to 22 angstrom when ca. 40 wt% of DOP was added. This suggested that the DOP promoted the mobility of the styrene chains, enhancing the formation of multiplets. On the other hand, for the ionomer containing 22.4 mol% of ions, when ca. 40 wt% was added, the distance between multiplets widened from 18 to 21 angstrom.

In this study, the water absorption of poly(styrene-co-itaconate) PSITNa ionomers, having two ion pairs in an ionic repeat unit, was investigated. Plotting the water absorption data as a function of the ionic repeat unit content revealed that the PSITNa ionomer exhibited more water uptake than the poly(styrene-co-methacrylate) PSMANa ionomer, having one Na–carboxylate ion pair per ionic repeat unit. On the other hand, when the water absorption data were simply expressed as a function of the ion content, it was found that the PSMANa ionomer showed more water absorption than the PSITNa ionomer. These results and the SAXS results suggested that to increase the degree of water absorption of the ionomer, it would be better for the ion pairs of the ionomer to form aggregates with other ion pairs rather than to exist alone in the matrix. In addition, it was observed that the degree of water absorption of the ionomer gradually improved as the size of the cation used for neutralization of the ionomer increased. These results and morphological results indicated that when the strength of interaction between ion pairs was weakened, the number of ionic aggregates decreased, and, at the same time, the ionic aggregates readily absorbed water due to weak interaction between ion pairs in the aggregates. The water absorption of poly(styrene-co-itaconate) PSITNa ionomers was investigated. It was found that to increase the degree of water absorption of the ionomer, it would be better for the ion pairs of the ionomer to form ionic aggregates with other ion pairs rather than to exist alone in the matrix. In addition, when the strength of interaction between ion pairs was weakened, the ionic aggregates readily absorbed water due to weak interaction between ion pairs in the ionic aggregates.

In this study, after blending with ionomer to expand the use of PA11, the stress-stain properties of these blends were investigated. In particular, the ionomers blended with PA11 differed in polarities, T(g)s, and types of ionic groups, and the effects of these variables on the mechanical properties of the blends were studied. First, it was found that the relatively non-polar ionomer seemed to have stronger interactions between ionic groups and polar functional groups with non-polar PA11 than the polar ionomer. Second, the ion pairs of the ionomer tended to form ionic aggregates when the strength of interaction between ion pairs increased, so the ionomer did not interact with PA11 effectively rather phase-separated. Third, when the T-g of the ionomer was relatively low, the ionomer seemed to act as a softening agent and help the PA11 chains move easily while molding the samples at high temperatures. In addition, the high T-g ionomers were found to behave as hard fillers in the PA11 blends. It was also suggested that the interfacial adhesion between PA11 and the ionomer was good when the strength of ionic interaction was relatively weak and the T-g of the ionomer was not too low.

In this work we prepared poly(styrene-co-methacrylate) ionomers neutralized with three different monovalent cations and added these ionomers to heavy oil to determine how the ionomer affected asphaltenes dispersion in the heavy oil. First, it was found that ionomers neutralized with smaller-sized cations led to better dispersion of asphaltenes in heavy oil. Second, ionomers neutralized with smaller-sized cations were observed to slow the asphaltene aggregation process. Third, it was found that the concentration of the ionomer exhibiting the best asphaltene dispersibility depended on which cation neutralized the ionomer. The above results suggested that the strength of the interactions between the ions of the ionomer and the strength of the interactions between the cations of the ionomer and the functional groups of the asphaltenes were very important factors for the ionomers to act as effective asphaltene dispersants. The SAXS results also showed that the ionomer neutralized with smaller-sized cations induced asphaltene dispersion in heavy oil relatively well. The addition of poly(styrene-co-methacrylate) ionomers further improved the dispersion of asphaltenes in heavy oil as the size of the monovalent cation neutralizing the ionomer decreased. In addition, ionomers neutralized with smaller sized cations resulted in slower asphaltene aggregation. Also, the concentration of the ionomer in the heavy oil for the best asphaltene dispersion depended on the cation type of the ionomers. The above results indicated that the strength of the interactions between the ions of the ionomer and the strength of the interactions between the cations of the ionomer and the functional groups of the asphaltenes were very important factors for the ionomers to act as effective asphaltene dispersants.

The effects of the cation type and under-neutralization on the scratch healing of poly(methyl methacrylate-co-methacrylate) ionomers by heat treatment were investigated as a function of time. The scratch healing efficiency of the ionomer was found to reach 84‒98% within 10 min at a temperature at which logE’ (Pa) = ca. 6.6, regardless of the type of cations of the neutralizing agents or the under-neutralization or the multiplet plasticization. From the results of this study and previous study, it was concluded that a significant level of scratch healing effect without sample deformation could be obtained in a fairly short time at a temperature at which the logE’ (Pa) of the ionomers was maintained at ca. 6.5 ± 0.1, regardless of the polarity of the ionomers, type of neutralizing agents, and degree of under-neutralization of the ionomers. Furthermore, we propose that the above results can be extended to optimal thermal scratch healing conditions for some of amorphous polymers, and are also useful when only small damaged areas of polymer materials are needed to be healed thermally.

In this study, the relation between the amount of a polar plasticizer, i.e. glycerol, and the glass transition temperature (T-g) and ion content of the poly(styrene-Na methacrylate) (PSMANa) ionomers was investigated dynamic mechanically. Since glycerol affected the formation of ionic aggregates due to its polarity, the T-g of ion poor matrix regions decreased slightly. On the other hand, the cluster T-g (T-g,T-c) was influenced by the amount of glycerol, the ion content of the ionomer, and the phase separation of glycerol in the ionomer matrix. Furthermore, the T-g,T-c of plasticized ionomers was estimated by a simple equation as follows: 1/(T-g,T-c (degrees C) - 7.1 x (15.7 - ion content (mol%))) (degrees C) = 1/(166 + 7.1 x ion content (mol%)) + 0.00025 x (wt% of plasticizer). In addition, the maximum amount of glycerol (wt%) before phase separation was simply expressed as 0.124 x (ion content (mol%))(2). The above results revealed that the T-g,T-c of PSMANa ionomers could be controlled from above 300 degrees C to below 100 degrees C by changing the ion content of the ionomers and the amount of glycerol in the ionomers.

The purpose of this work was to investigate the effects of polystyrene-based acidic copolymers and ionomers on the dispersion of asphaltenes in heavy oil. In the first part of the work, we studied the effect of the addition of sulfonated polystyrene acidic copolymers (SSA) and Na-neutralized ionomers (SSNa) on asphaltene dispersion. It was found that the SSA copolymers and the low ion content SSNa ionomers did not show asphaltene dispersion enhancement. However, high ion content SSNa ionomers improved asphaltene dispersion. In the second part of the work, styrene-methacrylate ionomers (SMANa) were used as dispersants. It was observed that the SMANa ionomers improved asphaltene dispersion significantly as the ion content increased and the molecular weight of the SMANa ionomer decreased. Finally, it was found that asphaltene dispersion was more effective when SMANa ionomers were used as asphaltene dispersants, compared to SSNa ionomers. Therefore, it can be concluded that to improve asphaltene dispersion, the acidic copolymers must first be converted to ionomers by neutralization. In addition, when using the ionomer as an asphaltene dispersant, it should be noted that the type of ionic group of the ionomer was more important to control asphaltene dispersion than the MW of the ionomer.

In this study, the effects of the degree of neutralization and cation type on water absorption of poly(styrene-co-methacrylate) ionomers were investigated. It was found that the water absorption of the ionomer increased as the degree of neutralization increased. It was also observed that for the same ion content, fully neutralized ionomers had less water absorption than partially neutralized ionomers. In the case of ionomers neutralized with various cations, water absorption increased when the type of cation was changed from Li+ to Na+, whereas the water absorption decreased when the type of cation was changed from Na+ to Cs+. Ba2+-neutralized ionomers absorbed less water than K+-neutralized ionomers with a cation size similar to Ba2+. Based on the above findings, it was concluded that the water absorption of ionomers could be understood only by simultaneously considering the number and size of multiplets, the plasticization of multiplets, and the contact surface area occupied by the polymer chains emanating from the multiplets.

In this work, we studied the effects of storage moduli on thermal healing of poly(styrene-co-methacrylate) and poly(styrene-co-itaconate) ionomers. It was found that as the ion content and neutralization degree of the ionomers increased, the healing efficiencies decreased. This was due to the fact that the ionic aggregates, acting as physical cross-links, and the clustered regions of the ionomers, reducing polymer chain mobility, interrupted the relaxation of the polymer chains near the damaged site, slowing the recovery. The most important finding in this work was that, to heal the ionomer without severe sample deformation, the optimal healing temperature should be the temperature where the storage modulus of the ionomer was similar to 10(6.6) Pa. Obviously, the healing rate and healing efficiency were mainly influenced by the healing temperature, related directly to the storage modulus of the polymer, and the maximum healing efficiency was strongly affected by healing time.

The active water absorption behavior of poly(styrene-co-methacrylate] PSMANa and sulfonated polystyrene PSSNa ionomers was studied. On one hand, the acidic copolymers did not absorb water noticeably. On the other hand, the amount of water absorbed by the ionomer increased with increasing ion content. Especially when the ion contents of the PSMANa and PSSNa ionomers exceeded 6 and 10 mol%, respectively, the maximum amount of the water absorbed by the ionomers increased rapidly as the ion content increased. This indicated that the cluster-dominant ionomers exhibited stronger water absorption behavior, compared to the matrix-dominant ionomers. In addition, when the ion contents of the PSMANa and PSSNa ionomers were less than 6 and 10 mol%, respectively, the volume and shape of the bulk ionomers did not change significantly by the water absorption. Morphological studies on the soaked ionomers showed that the SAXS peak shifted to lower angles as the water uptake increased with increasing ion content of the ionomers, which was consistent with the results obtained by the swelling method.

The dynamic mechanical properties of newly-made poly(methyl methacrylate-co-3-sulfopropyl sodium methacrylate) (M-SPMA) ionomers were measured and compared with those of methyl methacrylate ionomers having sodium methacrylate units (M-MA) and styrene ionomers having SPMA or MA units (S-SPMA or SMA). It was observed that the position of the matrix loss tangent peak of M-SPMA ionomers was not changed by the ion content, but the size of the peak was decreased. At high ion contents, however, the ionomers showed a cluster loss tangent peak and a very weak SAXS peak. These results were quite different from those obtained from the styrene ionomers. Thus, it was concluded that this dissimilarity was due to the differences in the polarity and persistence length of PS and PMMA. When the mechanical data of M-SPMA ionomers were compared with those of M-MA ionomers, M-SPMA and M-MA ionomers were found to behave like a filled system and a cross-linked system, respectively. This was due to the fact that M-SPMA ionomers had propyl groups and sodium sulfonate ion pairs, and thus the ionic groups formed fewer and larger ionic aggregates than M-MA ionomers.

In this work, the effect of low-temperature dehydration of a poly(styrene-co-styrenesulfonic acid) (PSSA) membrane was investigated by differential scanning calorimetry, fourier transform infrared spectroscopy (FT-IR), electron magnetic resonancespectroscopy (EMR), and H-1-and C-13 solid-state nuclear magnetic resonance spectroscopy. These analyses were performed at room temperature for powdered PSSA specimens with and without dehydration and the following key observations were made. First, FT-IR analysis showed that low-temperature dehydration not only transformed the [SO3- center dot center dot center dot H+] ionic pair in the non-hydrated PSSA to an SO3H group, but also induced the formation of -C=C- double bonds in the dehydrated PSSA. Second, the -SO3 center dot radical was unambiguously identified by EMR spectroscopy. Third, H-abstraction was detected by H-1 magic-angle spinning spectroscopy. Finally, an unexpected color shift from white for the non-hydrated PSSA to a yellowish brown for the dehydrated sample was observed. In order to explain these experimental results, it was proposed that the formation of the intermediate hydrogen (H-center dot) or hydroxyl radical (HO center dot) species was initiated by the dehydration process. The sespecies attacked the SO3H group and the tertiary proton at the alpha-carbon, resulting in the formation of -SO center dot radicals and -C=C- double bonds, which correlated with the color shift in the dehydrated PSSA sample. The semechanisms are useful for understanding the simultaneous loss of an aromatic ring and -SO- groups in the PSSA fuel cell membrane.

The dynamic mechanical properties of styrene-co-styrenesulfonate (SA) and styrene-co-methacrylate (MA) ionomers containing 30 wt% of fatty acid salts obtained from either soybean oil or lard oil were investigated. It was observed that when the fatty acid salts were added to the SA ionomers (2.7 or 6.3 mol% of ionic groups), the ionic modulus increased, but the cluster T (g) decreased strongly. In the case of the MA ionomer at 2.4 mol% of ion content, the addition of the fatty acid salts also increased the ionic modulus, but decreased the cluster T (g) slowly. On the other hand, for the MA ionomer at 6.9 mol% of ion content, the ionic modulus was not changed much by the addition of acid salts, but the cluster T (g) was decreased significantly. The above findings indicated that the roles of the fatty acid salts in the styrene-based ionomers were changed by the types and amounts of ionic groups of the ionomers. The SAXS results were also consistent with this conclusion. Finally, it was suggested that the fatty acid salts could be used as both eco-friendly plasticizer and filler for the ionomers.

In this work, two sets of dispersants based on poly(butylene succinic anhydride) reacted with various alkylamines and poly(ethyleneamine)s were prepared to enhance the dispersion properties of asphaltenes in heavy crude oil. It was found that the dispersants containing poly(ethyleneamine) moieties showed better dispersion properties than those containing alkylamine moieties. In addition, it was also observed that the dispersion of the asphaltenes was improved by the increase in the length of the ethyleneamine chain. Thus, it was proposed that the functional groups of the dispersant interacted with those of the asphaltenes to form complexes, by which the asphaltene aggregation would be interrupted. Furthermore, the dispersants containing comparable amounts of amide and imide forms exhibited better dispersion, but the dispersants containing salt form showed less effective dispersion. This might be possibly due to the ionic interactions between the salt form dispersants.

The document gives definitions of terms met in the conventional thermal and thermomechanical characterisation of polymeric materials.

ABSTRACT The dynamic mechanical properties and morphology of poly(styrene‐ co −3‐sulfopropyl sodium‐methacrylate) SSPMANa ionomers were investigated. It was found the increasing rate of ionic moduli of the SSPMANa ionomer was very low, and the cluster T g of the ionomers remained more or less constant with increasing ion content. A well‐developed SAXS peak was seen for low ion content SSPMANa ionomers and the peak position changed slightly with ion content. Thus, it was suggested that the presence of the alkyl ester side chains made the ion pairs form multiplets more easily at their prevalent distances, and the small‐agglomerated multiplets were dispersed in the polymer matrix relatively evenly. The interpretation of ionic moduli using a number of theories implied that the multiplets and clusters acted as effective crosslinks and filler particles, respectively, and the size and shape of the clusters were irregular. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54 , 1043–1053