星形磺化遥爪离子交联聚合物的力学性质

综述了分子结构、分子量、平衡离子的类型，过量中和剂，水分、离子增塑剂等诸因素对星形磺化遥爪离子交联聚合物的力学性质的影响，阐明三臂星形三官能度结构的遥爪离聚休整体母体，与适当的平衡离子、过量中和剂、离子增塑剂组成的遥爪离聚体体系可望可为一种热塑性弹性体材料。     

New polyisobutylene-based model elastomeric ionomers: RheoLogical behavior

The rheological behavior of sulfonated polyisobutylene based elastomeric ionomers has been studied. The effects of molecular architecture, type of cation, and addition of excess neutralization agent were investigated. The effect of temperature was studied to a limited extent. In a specific case, the influence of an ionic plasticizer, zinc stearate was also examined. It was found that in these telechelic ionomers where the ionic groups are located exclusively at the chain ends, significant Ionic interactions may persist even at 180°C. The zinc-neutralized ionomers had the lowest viscosity as compared to the corresponding potassium- or calcium-neutralized ionomers. The covalent character of zinc is believed responsible for this behavior. Other factors being constant, the triarm based ionomers are more viscous than the monofunctional ionomers. A mixture of monofunctional ionomers with the triarm, species is a model for dangling chain ends, and results in a slight lowering of the viscosity under the conditions studied. Zinc stearate acts as an ionic plasticizer. Upon the addition of 15 percent by weight of zinc-stearate to the ionomer, the low shear rate viscosity drops by several orders of magnitude and renders the ionomer thermally processable at moderate temperatures.     

New polyisobutylene-based model elastomeric ionomers. VIII. Thermal-mechanical analysis

A series of well-characterized telechelic polyisobutylene-based sulfonated metal-neutralized ionomers have been studied using thermal-mechanical analysis (TMA). These ionomers serve as models in the sense that the ionic groups are located exclusively at the chain ends and hence the ionomeric character is well defined. The chemical parameters varied are (i) molecular weight, (ii) molecular architecture (linear or triarm products), (iii) addition of excess neutralizing agent, and (iv) type of cation. The effect of the above parameters on the glass transition temperature and the softening temperature (after the rubbery plateau region) is presented. It is observed that the glass transition temperature is only slightly affected by the above parameters due to the very low ionic content in these ionomers (< 2 mol %). In the case of the triarm ionomer with excess neutralizing agent, the softening temperature following the rubbery plateau is much higher than that of the linear difunctional species. Linear monofunctional species do not show a rubbery plateau behavior and readily flow above their T_g in the absence or presence of excess neutralizing agent. The excess salt is most likely located at the ionic sites rather than being uniformly distributed throughout the matrix. Zinc-neutralized ionomers were found to have the lowest softening temperatures as compared to the corresponding calcium and potassium-neutralized ionomers. The covalent character of zinc is believed to be primarily responsible for this behavior. Thermal stability of these metalneutralized ionomers is not significantly different from the sulfonated hydrocarbon precursor polymer. However, the unneutralized acid precursor polymers start to discolor at relatively lower temperatures, thereby suggesting poorer thermal stability.     

Melt rheology of ion-containing polymers. I. Effect of molecular weight and excess neutralizing agent in model elastomeric sulfonated polyisobutylene-based ionomers

Melt rheology of elastomeric triarm sulfonated polyisobutylene model ionomers has been studied. The molecular weights (M _n) of the polymers have been varied from 8300 to 34,000. The sulfonated materials were neutralized with potassium hydroxide either to the exact stoichiometric equivalence point or to twice this amount, i.e., 100% excess neutralizing agent was added. For comparison one nonsulfonated precursor of M _n = 8300 was also studied. It was observed that the introduction of one sulfonate group at each chain end of the triarm poly-isobutylene molecule changes the state of matter at room temperature. Specifically, the unsulfonated materials are viscous liquids while the sulfonated ionomers are solid elastomers at room temperature. The zero-shear melt viscosity of the unsulfonated precursor is 900 poise (90 Pa·s), at room temperature while for those materials neutralized with potassium hydroxide to the exact stoichiometric point it is above 9 × 10³ poise (900 Pa·s) at 180°C. As expected, the zero shear viscosity increases with an increase in the molecular weight. Significant ionic interactions still persist at 180°C as evident by the high viscosity of the ionomers. However, at higher frequencies (～600 rad/s), the melt viscosity decreases to about 5 × 10³ poise for the different molecular weight materials. The melt viscosity of ionomers containing 100% excess neutralizing agent shows a dramatic increase. The excess KOH is speculated to be incorporated into the ionic domains rather than uniformly distributed throughout the matrix. This results in an increased strength of the ionic aggregates, thereby increasing the melt viscosities. Thus, due to the very pronounced effect on rheological properties it is important to know not only the extent of neutralization (up to full neutralization) but also the amount of excess neutralizing agent, if any, which is present in the sample.     

Sulfonated polyisobutylene telechelic ionomers. XIV. Viscoelastic behavior of concentrated solutions in nonpolar solvents

The effect of molecular variables upon the dynamic viscoelastic behavior of solutions of sulfonated polyisobutylene telechelic ionomers in nonpolar solvents has been investigated. Intermolecular association of the ionic end groups in nonpolar media results in the formation of a transient ionic network which displays a viscous response at low frequencies and an elastic response at high frequencies. The frequency of the transition from viscous behavior to elastic behavior, as well as the plateau storage modulus, is dependent upon molecular variables such as architecture, molecular weight, neutralizing cation, and extent of neutralization. Variables which affect the strength of the ionic interactions, such as temperature and the type of solvent, also influence the viscoelastic response. Solutions of ionomers neutralized with cations of Groups IA and IIA, such as potassium and calcium, behave elastically over most of the experimentally accessible frequency range, while those neutralized with transition metals, such as zinc, display viscous flow over a rather wide range at low frequencies. As in previous studies of dilute solution viscosity behavior, the threearm star trifunctional species was found to form a more extensive network in nonpolar solvents than the linear difunctional species at equivalent concentrations. The failure of time–temperature superposition indicates that these solutions are thermoheologically complex.     

Structure-property behavior of elastomeric segmented PTMO–ionene polymers. II

A series of segmented ionene polymers based on the reaction of α,ω-bis(dimethyl amino)polytetramethylene oxide with various dihalide compounds were investigated with respect to their structure–property behavior. The placement of quaternary ammonium ions and halide counterions along the polymer chains was varied by changing the molecular weight of the PTMO soft segment and the structure of the dihalide linking agent. The techniques of dynamic mechanical spectroscopy, thermal analysis, small angle X-ray scattering, and stress–strain behavior analysis were applied. For the case when the PTMO soft segment was amorphous, the ambient temperature properties of these materials displayed low modulus, high strength, and high elongation elastomeric behavior with tensile strength enhanced by the strain-induced crystallization of the PTMO. A high level of phase separation existed between the dihalide component relative to the PTMO soft segment. Due to the Coulombic association of the ionene species, these materials displayed many similarities to the segmented urethane ionomers. In particular, distinct domain structure was noted by SAXS, whose dimensional scale was similar to the segmented urethanes. It was also shown, however, that the driving forces for the microphase separation was caused by favorable electrostatic or Coulombic interactions in contrast to segment–segment incompatibility features as in the segmented urethanes.     

Plasticization effects on the mechanical properties and morphology of cobalt and sodium neutralized poly(ethyl acrylate-co-acrylate) ionomers

The present study aimed to investigate the effects of plasticization on the mechanical properties and morphology of poly(ethyl acrylate) ionomers neutralized with either Co²⁺ or Na⁺. In experiments, the dynamic mechanical properties of divalent Co²⁺-neutralized poly(ethyl acrylate) ionomers containing polar and non-polar plasticizers were compared with those of the monovalent Na⁺-neutralized ionomers. In the case of the ionomers plasticized with non-polar 4-decylaniline (4-DA), residing in non-ionic regions, the matrix and cluster T_gs of the ionomer decreased with increasing 4-DA contents. The decreasing rates of the matrix and cluster T_gs were found to be similar at 0.8 and 1.0 °C/(wt% of 4-DA) for the Co²⁺ and Na⁺ ionomers, respectively. The ionic modulus of the Co²⁺ ionomer changed only slightly with increasing 4-DA contents, but that of the Na⁺ ionomer decreased noticeably. In the SAXS study, it was observed that the un-plasticized Co²⁺ ionomer showed a strong small angle upturn and a very broad SAXS peak, indicating that the ionomer phase was compositionally heterogeneous. The plasticization of the Co²⁺ ionomer with 4-DA, however, induced a well-developed SAXS peak that was comparable to that of the un-plasticized Na⁺ ionomer. These results suggested that the addition of 4-DA to the Co²⁺ ionomer made the ionomer have more multiplets at a prevalent distance, leading to more clustering. In the case of the Co²⁺ ionomers plasticized with polar glycerol (Gly) that acted mainly as multiplet plasticizer, a very weak cluster glass transition, decreasing ionic modulus and only a well-developed small angle upturn were observed. These indicated that the addition of Gly to the Co²⁺ ionomer disrupted the multiplet formation, resulting in lower clustering.     

Zum kautschukelastischen verhalten von polyurethan-ionomeren

Dispersions of cationic and anionic ionomers of polyurethanes were prepared by the acetone method. Characteristic changes of the viscosity were observed during the addition of water. This change was studied with a cationic ionomer. The ionomers are mainly associated dimeric species in solution of acetone. During the addition of water the ions are solvated while the hydrophobic segments are increasingly associated. At the maximum of the observed viscosity the apparent molecular weight M_max ≈ 3 M_min. In the absence of solvents the ionomers behave like crosslinked materials even if no covalent crosslinks are present. The modulus at small elongations is a linear function of the square of the concentration of the cations. It is concluded that two ionic centers are required per crosslink. The anionic ionomers were also chemically crosslinked since an excess of isocyanate was used. A linear increase of the modulus was observed with increasing amount of chemical crosslinks, while the concentration of ions and hydrogen bonds was constant. The crosslinks formed by ions can be suspended by swelling with water. The portion of the modulus caused by ionic crosslinking can be computed from the difference of the moduli in the dry and swollen state.     

Synthesis and characterization of ionomeric poly(vinyl butyral)

A route to synthesizing novel poly(vinyl butyral) ionomers (IPVB), via a condensation polymerization process, has been developed. In the process, ionic groups were permanently incorporated into the poly(vinyl butyral) backbone by using an ion-containing aldehyde in addition to butyraldehyde during the acetalization of poly(vinyl alcohol). The resulting polymers demonstrated properties typical of ionomer systems, i.e., they behaved as “thermally reversible crosslinked thermoplastics” due to the presence of ionic associations present in the polymers. The ionic associations enabled the polymers to behave as crosslinked materials at ambient temperatures, whereas, at higher temperatures (processing temperatures), the ionic associations were lost, thus allowing the polymers to flow. Consequently, at ambient temperatures, the IPVBs demonstrated increased stiffness as determined from the storage modulus of the polymers, whereas, at higher temperatures, the IPVBs demonstrated moduli and stress-relaxation properties comparable to those of conventional poly(vinyl butyral). The IPVBs were characterized by a number of techniques including, high resolution NMR spectroscopy (¹H, ¹³C), dilute solution viscometry, dynamic mechanical analysis, and differential scanning calorimetry (DSC). Characterization was done on plasticized and unplasticized IPVBs.     

Selective plasticization of the ionic domains in a segmented thermoplastic ionene cationomer

The use of zinc stearate as an ionic plasticizer has been demonstrated to function effectively in a segmented ionene cationomer thereby permitting its melt processability. The ionene polymer is prepared by reacting dimethylamino-terminated polytetramethylene oxide (PTMO) oligomers with various benzyl dihalide compounds, leading to a segmented cationomer. Since the unplasticized ionene polymer undergoes degradation near the softening temperature (ca. 180°C), an ionic plasticizer was incorporated as a means of lowering the softening temperature to prevent degradation and permit melt processability. Zinc stearate was utilized in this study as it has been demonstrated to function well in other ionomers (essentially anionomers) in this capacity. Through the utilization of melt rheological and solid-state morphological investigations, it has been clearly shown that zinc stearate will function effectively as an ionic plasticizer in these quite different ionomer materials by lowering the softening temperature to ca. 120°C, thereby permitting melt processability. In addition, due to the crystallization of the zinc stearate following cooling, this same species also serves to enhance the mechanical properties in the solid state.     

Dynamic mechanical properties of polystyrene‐co‐styrenesulfonic acid copolymers neutralized with aliphatic diamines

In this article, we reported the effects of the addition of various aliphatic diamines (ADAs) on the dynamic mechanical properties of poly(styrene‐co‐styrenesulfonic acid) copolymers. It was found that the ionic modulus decreased with increasing chain length of ADAs but increased for the ADA12‐containing ionomers. Upon the neutralization of the copolymers with ADAs, a minor change in the size and position of the matrix loss tangent peak was observed. However, the position of the cluster loss tangent peaks shifted to lower temperatures, and the shift rate depended on the chain length of ADAs. Thus, it was suggested that the ADAs acted mainly as preferential plasticizer for the cluster regions. In addition, the effect of the amount of ADA on the difference between the matrix and cluster temperatures of the ionomers was strongest than that of the type of ADA or ion content. The X‐ray peak of ADA12 suggested that the ADA12 acted both as plasticizer and as filler. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Analysis of SAXS data from ionomer systems

A model was proposed earlier for the microstructure of ionomers which attributes the small-angle X-ray scattering (SAXS) peak observed in these materials to interparticle interference between small ionic domains arranged in the hydrocarbon matrix with a liquid-like degree of order. In this work, that model is used to interpret SAXS results obtained for a number of different ionomer systems. In addition, the effect of swelling of sulphonated polystyrene ionomers with water is investigated using this approach. Finally, the effect of temperature on the scattering was studied. The results reveal some interesting differences in domain size between different ionomer systems. The ethylene/methacrylic acid ionomers contain very small domains consistent with the concept of a multiplet, while the sulphonated EPDM rubbers have rather large domains. The results of the water absorption studies were inconsistent with the assumption that there is no change in the number of ionic domains upon swelling but if that assumption is not made, the data can be rationalized with the model. The elevated temperature measurements demonstrated the stability of the ionic domains even at temperatures well above those where the materials can be processed, leading to speculation regarding the mechanism of melt flow in ionomers.     

Characterization studies on aging properties of acetyl ferrocene containing HTPB‐based elastomers

In composite solid propellants, low‐molecular‐weight species such as burning rate catalysts, plasticizer, etc. which migrate into liner and thermal insulation layers during curing and storage invariably result in poor mechanical and ballistic properties of the propellants. In the present study, the migration of the burning rate catalyst, acetyl ferrocene, was investigated spectrophotometrically (UV–visible) by evaluating the extent of hindrance to such migration after applying a barrier (liner) of various crosslink densities between the additive (HTPB‐TDI‐plasticizer–acetyl ferrocene) and nonadditive (HTPB‐TDI) gumstocks replicating the propellant and insulating layer, respectively. Enhancing the crosslink densities of liner via a trifunctional aziridine crosslinking agent inhibited migration. The aging of additive gumstock was done at 60°C and its mechanical properties and extent of acetyl ferrocene migration were also evaluated and analyzed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2538–2545, 2006     

New polyisobutylene-based model elastomeric ionomers. VI. The effect of excess neutralizing agents on solid-state mechanical properties

The role of excess neutralizing agents on the mechanical properties of three-arm star polyisobutylene-based model ionomers is discussed. The stress level, particularly at high elongations, is significantly affected by the presence of excess neutralizing agents, and these effects are observed with different cations such as potassium, calcium, and zinc. A morphological model is proposed that can account for the observed mechanical behavior.     

Roles of mono- and di-functional organic salts as plasticizer and/or filler in styrene-based ionomers

The plasticization and/or filler effects of sodium salts of hexanoate (Na6), adipate (Na6Na), dodecanedioate (Na12Na), and dodecylbenzenesulfonate (Na12) on the dynamic mechanical properties of styrene-based ionomers were investigated. When a small amount of Na6, having one carboxylate ionic group at one end of alkyl chain, was added to a styrene-methacrylate ionomer, the salt acted as a very effective plasticizer for the ionomer cluster regions. With increasing salt contents, however, the salts became phase-separated and formed bilayer crystalline domains that acted as filler. In the case of the Na12Na and Na6Na salts, containing two carboxylate ionic groups, one at each end of alkyl chain, they formed phase-separated domains, acting as filler, in the methacrylate ionomers. Na12, possessing one sulfonate ionic group at only one end of a long alkyl chain, acted as a plasticizer in a sulfonated polystyrene ionomer. However, an excess amount of Na12 salt also formed phase-separated domains. It was also found that Na12 showed a filler effect only at much higher salt contents in comparison with Na6.     

Sulfonated polyisobutylene telechelic ionomers

The gelation of polyisobutylene-based model ionomers with-S0₃ ^–K⁺ terminal groups has been studied in hexane at 25°C. Both molecular architecture and molecular weight were found to significantly influence the concentration at which gelation occurs. Specifically, three-arm star trifunctional ionomers gel at lower concentrations than linear difunctional ionomers of similar molecular weight. In addition, the gelation concentration decreases with increasing molecular weight for the three-arm star trifunctional ionomer, but the results do not fit the relationship reported previously which relates gelation concentration and molecular weight for carboxylated linear telechelic polymers.     

Effects of the addition of LiCl and CsCl salts on the mechanical properties and morphology of poly(styrene‐co‐methacrylate) ionomers

The effects of the addition of LiCl and CsCl salts to Li‐ and Cs‐neutralized styrene‐co‐methacrylate ionomers, respectively, on the mechanical properties and morphology of the ionomers were studied. It was observed that with increasing inorganic salt contents, the ionic modulus increased, and this indicated that the inorganic salts in the ionomers acted as fillers. However, the type of salt did not affect the increase in the ionic modulus. It was also found that the addition of the inorganic salts did not change the matrix glass‐transition temperatures of the ionomers strongly but reduced the cluster glass‐transition temperature significantly and slowly for the LiCl‐ and CsCl‐containing ionomers, respectively. In addition, with increasing salt contents, a small‐angle X‐ray scattering peak shifted to slightly lower angles. These findings suggested that some of the inorganic salts resided in the multiplet with the ionic groups of the ionomers, acting as plasticizers. The presence of an X‐ray diffraction peak for the polymers containing a relatively large amount of CsCl indicated that the CsCl salt formed phase‐separated domains at sufficiently high salt contents. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of organic amine type on the structure and properties of the complex Zn(II) salts of ethylene–methacrylic acid copolymer with organic amines

The complex Zn(II) salts of ethylene–methacrylic acid copolymer (EMAA) were synthesized by using various organic amines from monoamines to polyamines, from primary amines to tertiary amines, and from molecular amines to polymer amines. Thermal analyses by differential scanning calorimetry (DSC), and the measurement of stiffness, melt flow rate (MFR), and dielectric properties were employed for the complex salts. It was found that the valence, strength of base, rigidity and flexibility, and bulkiness of the organic amines affect the degree of crystalline order of the ionic crystallites, which governs the stiffness of the complex ion ionomers. The stiffness is higher for the complex salts which form the higher orderliness in the ionic aggregates. The organic amines with two or more primary aliphatic amino groups and higher boiling temperatures from more rigid ionic crystallites in the complex ion ionomers leading to the enhanced modulus. Monoamines or polyamines with amino groups attached to flexible chains such as polyether and polysiloxane scarcely develop ionic crystallites and preferentially solvate the amorphous region including ionic groups leading to the decreased modulus. These results provide us with the fundamental information to control the modulus of ionomers.