Surlyn®/silicate hybrid materials. I. Polymer in situ sol–gel process and structure characterization

We report the creation of a new organic/inorganic hybrid material that results from sol–gel reactions for tetraethylorthosilicate (TEOS) within poly[ethylene‐co‐methacrylic acid], as well as within a Zn⁺² partially neutralized form of this copolymer (Surlyn®). FTIR and ²⁹Si solid‐state NMR spectroscopic probes yield information regarding molecular connectivity within the in situ grown silicate structures. FTIR analyses of Surlyn® matrix bands suggest that strong molecular level interactions between the organic and inorganic phases are not present, although there is other evidence that these phases are mechanically coupled on a larger dimensional scale. The ²⁹Si solid‐state NMR analyses indicate mainly Q₃ and Q₄ coordination states about the SiO₄ substructures, regardless of silicate content, which is in general agreement with the interpretation of the FTIR results that show incomplete condensation. Environmental scanning electron microscopy and energy dispersive X‐ray analysis results reinforce the conclusion that a significant silicate component is incorporated deep within TEOS‐treated films. Differential scanning calorimetry studies of Surlyn®‐Zn⁺²/silicate hybrids suggest that silicate incorporation essentially does not disrupt crystallinity. Thermogravimetric analyses show practically no change in the degradation onset temperature, which is consistent with organic/inorganic phase separation. The general conclusion is that a silicate phase can indeed be incorporated within this acid copolymer, as well as its Zn⁺² ionomeric form, via in situ sol–gel processes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2832–2844, 2000     

Effects of Difference in Ionic Radii on Chemical Ordering in Mixed‐Cation Silicate Glasses: Insights from Solid‐State 17O and 7Li NMR of Li–Ba Silicate Glasses

Understanding of the extent of cation disorder and its effect on the properties in glasses and melts is among the fundamental puzzles in glass sciences, materials sciences, physical chemistry, and geochemistry. Particularly, the nature of chemical ordering in mixed‐cation silicate glasses is not fully understood. The Li–Ba silicate glass with significant difference in the ionic radii of network‐modifying cations (~0.59 Å) is an ideal system for revealing unknown details of the effect of network modifiers on the extent of mixing and their contribution to the cation mobility. These glasses also find potential application as energy and battery materials. Here, we report the detailed atomic environments and the extent of cation mixing in Li–Ba silicate glasses with varying X_BaO [BaO/(Li₂O + BaO)] using high‐resolution solid‐state nuclear magnetic resonance (NMR) spectroscopy. The first ¹⁷O MAS and 3QMAS NMR spectra for Li–Ba silicate glasses reveal the well‐resolved peaks due to bridging oxygen (Si–O–Si) and those of the nonbridging oxygens including Li–O–Si and mixed {Li, Ba}–O–Si. The fraction of Li–O–Si decreases with an increase in X_BaO and is less than that predicted by a random Li–Ba distribution. The result demonstrates a nonrandom distribution of Li⁺ and Ba⁺ around NBOs characterized by a prevalence of the dissimilar Li–Ba pair. Considering the previously reported experimental results on chemical ordering in other mixed‐cation silicate glasses, the current results reveal a hierarchy in the degree of chemical order that increases with an increase in difference in ionic radius of the cation in the glasses [e.g., K–Mg (~0.66 Å) ≈Ba–Mg (~0.63 Å) ≈Li–Ba (~0.59 Å) > Na–Ba (~0.33 Å) > Na–Ca (~0.02 Å)]. The ⁷Li MAS NMR spectra of the Li–Ba silicate glasses show that the peak maximum increases with increasing X_BaO, suggesting that the average Li coordination number and thus Li–O distance decrease slightly with increasing X_BaO, potentially leading to an increased activation energy barrier for Li diffusion. Current experimental results confirm that the degree of chemical ordering due to a large difference in ionic radii controls the transport properties of the mixed‐cation silicate glasses.     

Synthesis,physical properties,and crystallization of optically active poly(L‐phenyllactic acid) and poly(L‐phenyllactic acid‐co‐L‐lactic acid)

Optically active poly(L ‐phenyllactic acid) (Ph‐PLLA), poly(L ‐lactic acid) (PLLA), and poly(L ‐phenyllactic acid‐co‐L ‐lactic acid) with weight‐average molecular weight exceeding 6 × 10³ g mol^?1 were successfully synthesized by acid catalyzed direct polycondensation of L ‐phenyllactic acid and/or L ‐lactic acid in the presence of 2.5–10 wt % of p‐toluenesulfonic acid. Their physical properties and crystallization behavior were investigated by differential scanning calorimetry, thermogravimetry, and polarimetry. The absolute value of specific optical rotation ([α]) for Ph‐PLLA (?38 deg dm^?1 g^?1 cm³) was much lower than that of [α] for PLLA (?150 deg dm^?1 g^?1 cm³), suggesting that the helical nature was reduced by incorporation of bulky phenyl group. PLLA was crystallizable during solvent evaporation, heating from room temperature, and cooling from the melt. Incorporation of a very low content of bulky phenyllactyl units even at 4 mol % suppressed the crystallization of L ‐lactyl unit sequences during heating and cooling, though the copolymers were crystallizable for L ‐phenylactyl units up to 6 mol % during solvent evaporation. The activation energy of thermal degradation (ΔE_td) for Ph‐PLLA (200 kJ mol^?1) was higher than that for PLLA (158 kJ mol^?1). The ΔE_td for the copolymers increased with an increase in L ‐phenyllactyl unit content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Physicomechanical and dielectric properties of magnesium and barium ionomers based on sulfonated maleated styrene‐ethylene/butylene‐styrene block copolymer

Ionomers, containing both carboxylate and sulfonate anions on the polymer backbone, based on metal cations like Mg⁺² and Ba⁺² were prepared by sulfonating maleated styrene‐ethylene/butylene‐styrene block copolymer, hereafter referred to as m‐SEBS, followed by its neutralization by metal acetates. Infrared spectroscopic studies reveal that sulfonation reaction takes place in the para position of the benzene rings of polystyrene blocks and metal salts are formed on neutralization of the precursor acids. Dynamic mechanical thermal analyses show that sulfonation causes increase in T_g of the rubbery phase of m‐SEBS and decrease in tan δ at T_g of the hard phase, along with formation of a rubbery plateau. The changes become more pronounced on neutralization of the sulfonated maleated SEBS, and the effect is greater in the case of Ba salt. Dielectric thermal analyses (DETA) show that incorporation of ionic groups causes profound changes in the dielectric constant (ϵ′) of m‐SEBS. In addition to the low temperature glass–rubber transition, the plot of ϵ′ vs. temperature shows occurrence of a high‐temperature transition, also known as the ionic transition. Activation energy for the dielectric relaxation could be determined on the basis of frequency dependence of the ionic transition temperature. Two values of the activation energy for the dielectric relaxation refer to the presence of two types of ionic aggregates, namely multiplets and clusters. Incorporation of the ionic groups causes enhancement in stress–strain properties as well as retention of the properties at elevated temperatures (50° and 75°C), and the effect is more pronounced in the case of Ba ionomer. Although sulfonated ionomers show greater strength than the carboxylated ionomers, the sulfonated maleated ionomers show higher stress–strain properties in comparison to both sulfonated and carboxylated ionomers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 816–825, 2000     

Influence of calix[2]‐p‐benzo[4]pyrrole on the electrochemical properties of poly(ethylene oxide)‐based electrolytes for lithium batteries

Poly(ethylene oxide) based electrolytes comprising LiCF₃SO₃ and calix[2]‐p‐benzo[4]pyrrole (CBP) as anion binder were prepared and subjected to DSC, ionic conductivity, cationic transport number and FTIR analyses. Symmetric cells of the type Li/PEO+LiCF₃SO₃+CBP/Li were assembled with these electrolytes and evolution of interfacial resistance as a function of time was analyzed. The cationic transference number, t, was found to increase from 0.23 to 0.78 on incorporation of CBP in the polymer electrolyte (PE). The incorporation of CBP as an anion trap does not enhance ionic conductivity below 60°C although it improves the interfacial properties. FTIR study revealed the formation of Li–C compounds on the lithium surface upon contact with the CBP added membranes. The CBP added PE was found to be optimal in terms of ionic conductivity and transport number, t, above 70°C, which were found to be higher for a system previously reported with calix[6]pyrrole. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Characterization and properties of sPS/PET/SsPS‐K engineering plastic alloys

The compatibility, crystallization behavior, and mechanical properties of syndiotactic polystyrene (sPS)/polyester (PET)/potassium salt of sulfonated syndiotactic polystyrene (SsPS‐K) were investigated. DMA results showed that all the alloys showed one T_g and the half‐peak width of the sPS/PET/SsPS‐K alloys became narrower compared with that of sPS/PET alloys, which decreased with an increasing content of the SsPS‐K ionomer. The results of DSC showed that the T_m of sPS and PET of the alloys was similar to those of the pure materials and did not change with the content of the SsPS‐K ionomer, while the initial crystallization temperature (T₀) and crystallization temperature at peak (T_p) increased. The crystallization velocity of PET increased with an increasing content of SsPS‐K. The TMA results showed that the alloys could retain the perfect heat proof property of sPS. SEM micrographs showed that the addition of SsPS‐K could reduce the PET domain dimension and enhance the adhesion between the PET domains and the matrix. With an increasing content of SsPS‐K, the PET domain dimension was reduced continuously and dispersed more evenly. The ternary alloys had better mechanical properties and significantly higher unnotched Izod impact strength than those of the alloys without SsPS‐K. When the weight ratio of sPS/PET/SsPS‐K was 85/15/4, the impact strength reached a maximum of 11.5 kJ/m², which was about three times that of pure sPS, and still had a higher tensile strength, flexural strength, and storage modulus, which were 38.8, 54.2, and 1.55 × 10⁴ MPa, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 656–661, 2002     

Synthesis of sulfonated rubber ionomers by the ring‐opening reaction of epoxidized styrene–butadiene rubber,their characterization,and their properties

A novel method for the synthesis of the sulfonate ionomer of styrene‐co‐butadiene rubber (SBR) was developed. SBR was first epoxidized by performic acid formed from hydrogen peroxide and formic acid in situ in solution, and this was followed by a ring‐opening reaction with an aqueous solution of NaHSO₃. The optimum conditions for the epoxidation of SBR in the presence of a phase‐transfer catalyst and for the ring‐opening reaction of epoxidized SBR with an aqueous solution of NaHSO₃ were studied. During the epoxidation of SBR, a phase‐transfer catalyst, such as poly(ethylene glycol), could enhance the conversion of double bonds to epoxy groups. During the ring‐opening reaction, both the phase‐transfer catalyst and ring‐opening catalyst were necessary to enhance the conversion of the epoxy groups to ionic groups. The addition of Na₂SO₃ to the reaction mixture was important to obtain 100% conversion. The products were characterized with Fourier transform infrared spectrophotometry, ¹H‐NMR spectroscopy, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). DSC showed that the sodium sulfonate SBR ionomer possessed a dissociation temperature of ionic domains at 110°C, which appeared as black spots under TEM, after the sodium ions of the ionomer were substituted by lead ions. Some properties of the sodium ionomer, such as the water absorbency, oil absorbency, and dilute solution behavior, were studied. With increasing ionic groups, the water absorbency of the ionomer increased, whereas the oil absorbency decreased. The dilute solution viscosity of the ionomer increased abruptly with increasing ionic group content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3090–3096, 2006     

Influence of ionic groups on the crystallization and melting behavior of segmented polyurethane ionomers

The isothermal crystallization kinetics and melting behavior of the soft segment in polyurethane (PU) ionomer/nonionomer based on PCL‐4000 (poly(ε‐caprolactone)) were investigated using polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). In general, the presence of ionic groups in PU ionomers can promote the formation of a more stable crystalline structure and lower the equilibrium melting temperature of the crystallizable phase. Comparison between the crystallization characteristics of PU nonionomers and ionomers suggests that the Coulombic Forces between ionic groups within hard segment can increase the crystallization rate and decrease the crystal size of soft segment when the total molecular weight (M_w) of PU ionomer is higher than ～71,000. On the other hand, the opposite effect of ionic groups on the crystallization rate is observed in PU ionomers with M_w below ～20,000. The DSC thermograms illustrate that the ionic groups can significantly enhance the microphase separation in PU ionomers with higher M_w values. By the control and manipulation of crystallization and microstructure formation in PU ionomer, it is possible to achieve shape memory PUs with superior physical property. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4603–4613, 2006     

Poly(styrene-b-isobutylene-b-styrene) block copolymer ionomers (BCPI) and BCPI/silicate nanocomposites. 2. NaBCPI sol-gel polymerization templates

Polystyrene (PS) blocks in poly(styrene-b-isobutylene-b-styrene) (PS-PIB-PS) block copolymers were partially sulfonated and the acid groups converted to Na⁺SO₃⁻ groups to create ionomers. Then, dimethylacetamide was used to selectively swell the ionic PS domains and the swollen films were exposed to sol-gel reactive tetraethylorthosilicate solutions. (EtO)_4−xSi(OH)_x monomers then permeated films so that sol-gel reactions occurred within/around the ionic PS domains. Environmental scanning electron microscopy/energy dispersive X-ray spectroscopy investigations showed that silicate structures can be incorporated within the interior of the ionomer films. Differential scanning calorimetry studies indicated that there is no variance in the PIB block T_g with respect to ionomer formation, or with respect to silicate loading of the ionomer at low levels, which suggests that the silicate component does not reside in the PIB phase. ²³Na solid state NMR spectroscopy detected isolated Na⁺SO₃⁻ groups as well as aggregated SO₃⁻Na⁺ ion pairs for ‘as cast’ and ‘dry’ non-silicate containing ionomer samples. In a hydrated sample, almost all Na⁺ ions were solvent-separated. AFM analysis showed that phase separation exists, but that the degree of order is significantly less than that for hybrids based on the corresponding benzyltrimethylammonium ionomer. This frustrated morphology was also seen in the results of small angle X-ray scattering experiments. Given the scale of organic/inorganic heterogeneity, these hybrids are properly classified as nanocomposites.     

Using 1H‐NMR spectroscopy for the kinetic study of the in situ solution free‐radical copolymerization of styrene and ethyl acrylate

The free‐radical copolymerization of styrene and ethyl acrylate in benzene‐d₆ as the solvent in the presence of benzoyl peroxide as an initiator at 70°C was studied by online ¹H‐NMR spectroscopy. The chemical composition of the copolymer at different reaction times was calculated from the conversion of the monomers to the copolymer, and then the reactivity ratios of styrene and ethyl acrylate were determined at both low and high conversions. Data for the overall monomer conversion versus the time were used to estimate the ratio k_pk_t^?0.5 for different compositions of the initial feed (k_p is the propagation rate constant, and k_t is the termination rate constant). k_pk increased with an increasing molar fraction of ethyl acrylate in the initial feed. The monomer mixture and copolymer compositions versus the overall monomer conversion were calculated with the data of ¹H‐NMR spectra. The incorporation of the styrene monomer into the copolymer structure was more favored than that of the ethyl acrylate monomer. Reducing the molar fraction of styrene in the initial feed intensified this. Drawing the molar fraction of styrene (or ethyl acrylate) in the copolymer chains versus that in the initial feed showed a tendency of the system toward random copolymerization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Poly(styrene-b-isobutylene-b-styrene) block copolymer ionomers (BCPI), and BCPI/silicate nanocomposites. 1. Organic counterion: BCPI sol-gel reaction template

Silicate structures were inserted along the cylindrical polystyrene (PS) domains in an ionomer form of elastomeric poly(styrene-b-isobutylene-b-styrene) tri-block copolymers, via in situ sol-gel reactions. Environmental scanning electron microscopy/energy dispersive X-ray spectroscopy studies indicated that silicate structures do in fact grow within the interior of ca. 0.8 mm thick films rather than forming undesirable silica precipitates on the surface. The combination of a domain-selective swelling solvent (DMAc) and the attachment of large organic counterions (benzyltrimethylammonium) along the styrene blocks facilitated the preferential migration of hydrolyzed Si(OEt)₄ monomers to these ionic domains where the sol-gel reactions are apparently seeded. Differential scanning calorimetry and dynamic mechanical studies indicated that T_g for the polyisobutylene (PIB) phase is essentially unaffected, but the PS phase T_g shifts to higher values with ionomer formation, and to even higher values with subsequent silicate phase insertion. These two methods provide indirect evidence that the silicate component is mainly incorporated in the PS rather than PIB domains. Combined with the results of earlier atomic force microscopy studies that demonstrated that the basic morphology of the unmodified block copolymer is unchanged despite the insertion of a silicate phase, the data presented here reinforce the concept of a robust sol-gel reaction template. Also, the rubbery plateau storage modulus was elevated as a result of ionomer formation and more so after the ionomer was imparted with a silicate phase, which illustrates mechanical reinforcement.     

The Effect of Alkali Ions on the Incorporation of Aluminum in the Calcium Silicate Hydrate (C–S–H) Phase Resulting from Portland Cement Hydration Studied by 29Si MAS NMR

The incorporation of aluminum in the calcium–silicate–hydrate (C–S–H) phases formed by hydration of three different white Portland cements has been investigated by ²⁹Si MAS NMR. The principal difference between the three cements is their bulk Al₂O₃ contents and quantities of alkali (Na⁺ and K⁺) ions. ²⁹Si MAS NMR allows indirect detection of tetrahedral Al incorporated in the silicate chains of the C–S–H structure by the resonance from Q²(1Al) sites. Analysis of the relative ²⁹Si NMR intensities for this site, following the hydration for the three cements from 0.5 d to 30 weeks, clearly reveals that the alkali ions promote the incorporation of Al in the bridging sites of the dreierketten structure of SiO₄ tetrahedra in the C–S–H phase. The increased incorporation of Al in the C–S–H phase with increasing alkali content in the anhydrous cement is in accord with a proposed substitution mechanism where the charge deficit, obtained by the replacement of Si⁴⁺ by Al³⁺ ions in the bridging sites, is balanced by adsorption/binding of alkali ions in the interlayer region most likely in the near vicinity of the AlO₄ tetrahedra. This result is further supported by similar ²⁹Si MAS NMR experiments performed for the white Portland cements hydrated in 0.30M NaOH and NaAlO₂ solutions.     

Effect of different anchor groups on adsorption behavior and effectiveness of poly(N,N‐dimethylacrylamide‐co‐Ca 2‐acrylamido‐2‐methylpropanesulfonate) as cement fluid loss additive in presence of acetone–formaldehyde–sulfite dispersant

The impact of various anchor groups on adsorption behavior of AMPS® copolymers was studied. The anchor groups differ in anionic charge density. Copolymer adsorption and water retention of oil well cement slurries achieved from CaAMPS®‐co‐NNDMA in the presence of an acetone–formaldehyde–sulfite (AFS) dispersant were improved by incorporation of minor amounts (～ 1% by weight of polymer) of acrylic acid (CaAMPS®‐co‐NNDMA‐co‐AA), maleic acid anhydride (CaAMPS®‐co‐NNDMA‐co‐MAA), or vinyl phosphonic acid (CaAMPS®‐co‐NNDMA‐co‐VPA), respectively. Performance of these terpolymers was studied by measuring static filtration properties of oil well cement slurries at 27°C and 70 bar pressure. All fluid loss additives possess comparable molar masses and show the same adsorption behavior and effectiveness when no other admixture is present. In the presence of AFS dispersant, however, adsorption of CaAMPS®‐co‐NNDMA and hence fluid loss control is dramatically reduced, whereas effectiveness of CaAMPS®‐co‐NNDMA‐co‐AA is less influenced because of acrylic acid incorporated as additional anchor group. Even more, CaAMPS®‐co‐NNDMA‐co‐MAA combined with AFS allows simultaneous adsorption of both polymers and thus produces good fluid loss control. CaAMPS®‐co‐NNDMA‐co‐VPA no longer allows adsorption of AFS dispersant. This was also confirmed by rheological measurements. The results show that, in a binary admixture system, adsorption of the anionic polymer with anchor groups possessing higher charge density is preferred. Surface affinity of the anchor groups studied increase in the order ? SO → ? COO^? → vic‐(? COO^?)₂→ ? PO. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Surface activity and micellar behavior of dimethylamino‐ and trimethylammonium‐ tipped oxyethylene–oxybutylene diblock copolymers in aqueous media

Surface activity and micellar behavior in aqueous media in the temperature range 20–50°C of the two block copolymers, Me₂N(CH₂)₂OE₃₉B₁₈, (DE₄₀B₁₈) and I^?Me₃N⁺(CH₂)₂OE₃₉B₁₈, (TE₄₀B₁₈) in the premicellar and postmicellar regions have been studied by surface tensiometry, viscometry, and densitometry. Where E represents an oxyethylene unit while B an oxybutylene unit. Various fundamental parameters such as, surface excess concentrations (Γ_m), area per molecule (a) at air/water interface and standard Gibbs free energy for adsorption, ΔG have been investigated for the premicellar region at several temperatures. The thermodynamic parameters of micellization such as, critical micelle concentrations, CMC, enthalpy of micellization, ΔH, standard free energy of micellization ΔG, and entropy of micellization ΔS have also been calculated from surface tension measurements. Dilute solution viscosities have been used to estimate the intrinsic viscosities, solute‐solvent interaction parameter and hydration of micelle. Partial specific volume and density of the micelle were obtained from the density measurements at various temperatures. The effect of modifying the end group of the hydrophilic block was investigated by comparing the behavior of trimethylammonium‐ and dimethylamino‐tipped copolymers, designated TE₄₀B₁₈, and DE₄₀B₁₈, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Organic–inorganic composite materials from acrylonitrile–butadiene–styrene copolymers (ABS) and silica through an in situ sol‐gel process

Nonbonded and chemically bonded organic–inorganic composite materials, ABS/SiO₂ and ABS Si(OCH₃)₃/SiO₂, were prepared by the sol‐gel processing of tetraethoxysilane (TEOS) in the presence of ABS and trimethoxysilyl functionalized ABS, ABS Si(OCH₃)₃, under the catalization of NH₄F. The ABS Si(OCH₃)₃ was obtained by oxidizing the cyano group in ABS with hydrogen peroxide, then subsequently underwent ring‐opening reaction with 3‐glycidoxypropyltrimethoxysilane (GPTS). The ABS Si(OCH₃)₃/TEOS sol‐gel liquid solution system, in which the ABS chains formed the covalent bonds with silica network and helped fix the polymer chains in the silica network, had a shorter gelation time than that of the ABS/TEOS system, which linked ABS chains to the silica network only by hydrogen bonding the cyano groups in ABS to the silanol groups. The morphology and properties of composite were characterized by scanning electron microscopy (SEM), differential scanning calorimeter (DSC), tensile tests, and thermogravimetry. It was found that the composite prepared from ABS Si(OCH₃)₃ had higher tensile strength, glass transition point (T_g), thermal stability, and more homogeneous morphology because of the existence of the covalent bond between ABS chains and silica network that increased the compatibility between the organic and inorganic phases. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 275–283, 2000     

Synthesis,characterization, and thermodynamic properties of poly(3‐mesityl‐2‐hydroxypropyl methacrylate)

Poly(3‐mesityl‐2‐hydroxypropyl methacrylate) (PMHPMA) was synthesized in a 1,4‐dioxane solution with 2,2′‐azobisisobutyronitrile as the initiator at 60°C. The homopolymer and its monomer were characterized with ¹H‐ and ¹³C‐NMR, Fourier transform infrared, differential scanning calorimetry, thermogravimetric analysis, size exclusion chromatography, and elemental analysis techniques. According to size exclusion chromatography analysis, the number‐average molecular weight, weight‐average molecular weight, and polydispersity index of PMHPMA were 65,864 g/mol, 215,375 g/mol, and 3.275, respectively. According to thermogravimetric analysis, the carbonaceous residue value of PMHPMA was 14% at 500°C. The values of the specific retention volume, adsorption enthalpy, sorption enthalpy, sorption free energy, sorption entropy, partial molar free energy, partial molar heat of mixing, weight fraction activity coefficient of solute probes at infinite dilution (Ω), and Flory–Huggins interaction parameter (χ) were calculated for the interactions of PMHPMA with selected alcohols and alkanes by the inverse gas chromatography method at various temperatures. According to Ω and χ, selected alcohols and alkanes were nonsolvents for PMHPMA at 423–453 K. Also, the solubility parameter of PMHPMA (δ₂) was found to be 24.24 and 26.33 (J/cm³)^0.5 from the slope and intercept of (δ/RT) ? χ/V₁ = (2δ₂/RT)δ₁ ? δ/RT at 443 K, respectively [where δ₁ is the solubility parameter of the probe, V₁ is the molar volume of the solute, T is the column temperature (K), and R is the universal gas constant]. The glass‐transition temperature of PMHPMA was found to be 386 and 385 K by inverse gas chromatography and differential scanning calorimetry techniques, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 101–109, 2006     

The effect of SiO2 porosity on activity profiles and comonomer incorporation in slurry ethylene/butene‐1 polymerization by (SiO2/MgCl2/TEOS/TiCl4) catalyst system

To investigate the influence of support porosity parameters e.g., average pore volume (APV), pore diameter (PD), and pore surface area distribution (PSAD) on activity‐profile of catalyst and comonomer incorporation, a series of silica‐supports with different porosity were prepared through sol–gel method and used to synthesize corresponding (SiO₂/MgCl₂/TEOS/TiCl₄) catalysts. Polymerization of ethylene/butene‐1 showed that increasing of APV from 0.75 to 2.2 cm³ g increase initial activity from 120 to 400 (g_poly/g_cat.bar.hr) followed by appearance of secondary peaks in activity‐profile which could be attributed to the variation of PSAD. It is found that the effect of support in polymerization is a complicated issue which depends not only on the porosity parameters also on the comonomer concentration. The catalyst with PD of 300 Å gives higher comonomer incorporation and polymers with 15–20% lower crystallinity in contrast to catalyst with PD of 100 Å. Porosity effect was quantitatively studied by modifying of conventional Z‐N catalyst polymerization mechanism through introducing fragmentation term to achieve a new tool in designing and developing of polyolefin catalysts. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Incorporation of Al and Na in Hydrothermally Synthesized Tobermorite

Calcium silicate hydrate and its Al‐substituted form synthesized by a hydrothermal process were investigated by X‐ray diffraction, compositional analysis, and magic‐angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, in order to determine the mechanism of Al and Na incorporation in the tobermorite structure with varying molar ratios of Ca/Si and Al/Si. At a high molar ratio of Ca/Si, the silicate chains of tobermorite are ruptured, the degree of polymerization of the silicate chains is lowered, and the high calcium concentration lowers the content of Na₂O in the structure. Solid‐state ²⁹Si and ²⁷Al MAS NMR spectroscopy confirm that all Al atoms were incorporated in the silicate chains of tobermorite. The tetrahedrally coordinated Al (Al(IV)) could either act as the bridging tetrahedron () for the dreierketten chain of tobermorite, or be present in Q³ sites that link two dreierketten chains together. Therefore, the degree of polymerization of the silicate chains of tobermorite is increased at high molar ratio of Al/Si. Furthermore, the greater charge deficit due to the replacement of Si⁴⁺ by Al³⁺ ions is compensated by increased adsorption or binding of Na⁺.     

Synthesis and characterization of maleated ionomers via ring‐opening reaction of epoxidized styrene‐butadiene rubber with potassium hydrogen maleate and study of their behavior as compatibilizer

A novel method for synthesizing maleate ionomer of (styrene‐co‐butadiene) rubber (SBR) from epoxidized SBR was developed. The epoxidized SBR was prepared via epoxidation of SBR with performic acid formed in situ by H₂O₂ and formic acid in cyclohexane. The maleated ionomer was obtained by ring‐opening reaction of the epoxidized SBR solution with an aqueous solution of potassium hydrogen maleate. The optimum conditions were studied. It was found that it is necessary to use phase transfer catalyst and ring‐opening catalyst for enhancing the epoxy group conversion. To obtain 100% conversion addition of dipotassium maleate is important. The product was characterized by FTIR spectrophotometry and transmission electron microcroscopy (TEM). The results showed that the product was really an ionomer with domains of maleate ionic groups. Some properties of the ionomer, such as water absorbency, oil absorbency and dilute solution behavior were studied. With increasing ionic groups, the water absorbency of the ionomer increases, whereas the oil absorbency decreases. The dilute solution viscosity of the ionomer increases abruptly with increasing ionic group content. The ionomer can be used as a compatibilizer for the blends of SBS and chlorosulfonated polyethylene (CSPE). Addition of a small amount of the ionomer to the blend can enhance the mechanical properties of the blends. 3 wt % ionomer based on the blend can increase the tensile strength and ultimate elongation of the blend nearly twice. The compatibility of the blends enhanced by adding the ionomer was shown by scanning electron microscopy. The blend of equal parts of SBS and CSPE compatibilized by the ionomer behaves as an oil resistant thermoplastic elastomer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 792–798, 2006     

Ionomer-silica hybrids via sol-gel reaction

Ionomer-silica hybrid materials were made from polyethylene-co-acrylic acid neutralized by a zinc salt (PI) and tetraethoxy silane (TEOS) via the sol-gel reaction. The effects of various experimental parameters such as solvents, H₂O/Si ratio and the amount of TEOS in the ionomer solution on the hybrid structure and properties were examined. The spectroscopic results show that solvents do not affect the structure of the hybrids, but influence the thermal properties. The hybrids made using highly polar solvent exhibit better thermal stability and dynamic mechanical properties at high TEOS contents. The amount of water used for hydrolysis and subsequent condensation play a significant role in the network formation. The varying amount of TEOS in solutions gives rise to different silica content of the hybrid. Above 50 wt%, the sample becomes opaque due to silica aggregation. The high ratio of H₂O/Si leads to phase separation during the reaction. Transparent hybrid materials can only be obtained when the ratio of H₂O/Si is below 5.