Tetramethyl bisphenol-A Research Articles

Anti-thyroid hormonal activity of tetrabromobisphenol A, a flame retardant, and related compounds: Affinity to the mammalian thyroid hormone receptor, and effect on tadpole metamorphosis

The thyroid hormone-disrupting activity of tetrabromobisphenol A (TBBPA), a flame retardant, and related compounds was examined. TBBPA, tetrachlorobisphenol A (TCBPA), tetramethylbisphenol A (TMBPA) and 3,3′-dimethylbisphenol A (DMBPA) markedly inhibited the binding of triiodothyronine (T 3; 1 × 10 −10 M) to thyroid hormone receptor in the concentration range of 1 × 10 −7–1 × 10 −4 M, while bisphenol A and 2,2-diphenylpropane were inactive. TBBPA, TCBPA, TMBPA and DMBPA did not exhibit thyroid hormonal activity in a thyroid hormone-responsive reporter assay using a Chinese hamster ovary cell line (CHO-K1) transfected with thyroid hormone receptor α1 or β1, but TBBPA and TCBPA showed significant anti-thyroid hormone effects on the activity of T 3 (1 × 10 −8 M) in the concentration range of 3 × 10 −6 – 5 × 10 −5 M. The thyroid hormone-disrupting activity of TBBPA was also examined in terms of the effect on amphibian metamorphosis stimulated by thyroid hormone. TBBPA in the concentration range of 1 × 10 −8 to 1 × 10 −6 M showed suppressive action on T 3 (5 × 10 −8 M)-enhancement of Rana rugosa tadpole tail shortening. These facts suggest that TBBPA, TCBPA, TMBPA and DMBPA can act as thyroid hormone-disrupting agents.

Blends Based on Polystyrene and Statistical Aromatic Copolycarbonates

AbstractThe compatibility of polystyrene (PS) with aromatic copolycarbonates containing bisphenol A (BPA) and tetramethyl bisphenol A (TMBPA) was investigated. The simple prevision scheme developed by Sonja Krause was employed to evaluate the effect of the copolymer molecular structure on the miscibility with polystyrene. These prevision data were used to select copolycarbonates of potential interest. Statistical copolycarbonates (CPC) containing different BPA/TMBPA molar ratios were synthesised by polycondensation reaction between a mixture of the two monomers and phosgene. PS/polycarbonates blends, prepared by casting from chloroform solution, were studied with differential scanning calorimetry and optical microscopy to evaluate the components compatibility, which increases with the TMBPA copolymer content.

Effect of Linkage Groups on Motional Cooperativity in the Secondary Relaxations of Some Glassy Polymers

The secondary relaxation of bisphenol A polycarbonate (BPA-PC) is due to a cooperative motion that includes several repeat units. We believe that the linkage between neighboring BPA segments plays an important role in requiring this long-range cooperativity. It is expected that a more flexible linkage would require less motional cooperativity. To demonstrate this idea, polyformals based on the comonomer BPA, tetramethylbisphenol A (TMBPA), and methylene chloride with controlled sequence structure were synthesized, and DMA studies were conducted. The results show that the secondary relaxation behavior of copolyformals is not dependent on the block length of BPA segments, which suggests that the molecular motion does not require in-chain cooperation. The lower in-chain motional cooperativity of BPA-PF is attributed to the lower rigidity of the formal linkage.

Influence of the chemical structure of polycarbonates on the contribution of crosslinking and chain scissions to the photothermal ageing

The relative importance of crosslinking and chain scissions reactions involved in the photothermal ageing of polycarbonates is shown to depend on the chemical structure of the polymer. The orientation of these reactions is linked to the modifications of the chemical structure resulting from photolysis, photooxidation and thermooxidation. In this paper, the effects of crosslinking and chain scission of tetramethyl bisphenol-A polycarbonate (TMPC) are determined by size exclusion chromatography (SEC) and gel fraction measurements. These evolutions are correlated to the modifications of the chemical structure observed by FTIR spectroscopy. The presence of the four ortho-methyl substituants on the aromatic rings accounts for the difference in the photothermal ageing of TMPC compared to bisphenol-A polycarbonate (PC). Tetramethyl substitution inhibits photo-Fries rearrangements in TMPC, but in contrast these methyl groups involve crosslinks under irradiation and are the source of a higher oxidizability of TMPC compared to PC. A proposal for the various routes accounting for the crosslinking and the formation of the oxidation products in TMPC is reported in this paper.

Phase separation of polymer blend TMPC/PS: dependence on blending method

Phase separation of polymer mixtures of tetramethyl bisphenol-A polycarbonate (TMPC) and polystyrene (PS) was studied by real-time small angle neutron scattering. Depending on the blending method (solution casting or melt mixing), samples are shown to exhibit different kinetics of spinodal decomposition and subsequent coarsening.

Miscibility of polymer blends of poly(styrene‐co‐4‐hydroxystyrene) with bisphenol‐A polycarbonate

The miscibility of blends of bisphenol-A polycarbonate (BAPC) and tetramethyl bisphenol-A polycarbonate (TMPC) with copolymers of poly(styrene-co-4-hydroxystyrene) (PSHS) was studied in this work. It has been demonstrated that BAPC is miscible with PSHS over a region of approximately 45–75 mol % hydroxyl groups in the copolymer. TMPC has a wider miscible window than BAPC when blended with PSHS. The blend miscibility was considered to be driven by the intermolecular attractive interactions between the hydroxyl groups of the PSHS and the π electrons of the aromatic rings of both polycarbonates (PCs). As the FTIR measurements showed, after blending of BAPC with PSHS, there is no visible shift of the carbonyl band of BAPC at 1774 cm−1, whereas the stretching frequency of the free hydroxyl groups of the copoly- mers at 3523 cm−1 disappeared. The large positive values of the segment interaction energy density parameter Bst-HS calculated from the group contribution approach indicated that the intramolecular repulsive interaction may also have played a role in the promotion of the blend miscibility. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 639–646, 1999

Miscibility of polymer blends of poly(styrene-co-4-hydroxystyrene) with bisphenol-A polycarbonate

The miscibility of blends of bisphenol-A polycarbonate (BAPC) and tetramethyl bisphenol-A polycarbonate (TMPC) with copolymers of poly(styrene-co-4-hydroxystyrene) (PSHS) was studied in this work. It has been demonstrated that BAPC is miscible with PSHS over a region of approximately 45–75 mol % hydroxyl groups in the copolymer. TMPC has a wider miscible window than BAPC when blended with PSHS. The blend miscibility was considered to be driven by the intermolecular attractive interactions between the hydroxyl groups of the PSHS and the π electrons of the aromatic rings of both polycarbonates (PCs). As the FTIR measurements showed, after blending of BAPC with PSHS, there is no visible shift of the carbonyl band of BAPC at 1774 cm−1, whereas the stretching frequency of the free hydroxyl groups of the copoly- mers at 3523 cm−1 disappeared. The large positive values of the segment interaction energy density parameter Bst-HS calculated from the group contribution approach indicated that the intramolecular repulsive interaction may also have played a role in the promotion of the blend miscibility. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 639–646, 1999

Structure and property relationships in model diglycidyl ether of bisphenol-a and diglycidyl ether of tetramethyl bisphenol-a epoxy systems. I. Mechanical property characterizations

Model epoxy networks, with variations in crosslink density and in epoxy monomer rigidity, were prepared to study how the network structure affects modulus, Tg, and toughness/toughenability of epoxy resins. Diglycidyl ether of bisphenol-A and diglycidyl ether of tetramethyl-bisphenol-A, along with the corresponding chain extenders, were chosen to study how monomer backbone rigidity and crosslink density affect physical and mechanical properties of epoxies. The present study indicates that, as expected, the backbone rigidity of the epoxy network, not the crosslink density alone, will strongly influence modulus and Tg of epoxy resins. Upon rubber toughening, it is found that the rigidity of the epoxy backbone and/or the nature of the crosslinking agent utilized are most critical to the toughenability of the epoxy. That is, the well-known correlation between toughenability and the average molecular weight between crosslinks (Mc) does not necessarily hold true when the nature of epoxy backbone molecular mobility is altered. The potential significance of the present findings for a better design of toughened thermosets for structural applications is discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2137–2149, 1999

Binary interaction parameters from blends of SMA copolymers with TMPC-PC copolycarbonates

Miscibility maps for blends of copolycarbonates based on various proportions of tetramethyl bisphenol-A and bisphenol-A (TMPC—PC) with copolymers of styrene—maleic anhydride (SMA) have been established and interaction energies have been calculated from the data using a binary interaction model combined with the Flory—Huggins theory. This analysis provides an independent assessment of all six interaction energies between the various repeat unit pairs. These include the first reported estimates for the binary interaction energies of MA with TMPC and with PC. The other four interaction energy values found here are in excellent agreement with earlier reports. LCST-type phase separation temperatures were determined and compared with values predicted by the Sanchez—Lacombe equation-of-state theory.

The phase behavior of tetramethyl bisphenol-A polyarylate/aliphatic polyester blends

The phase behavior of blends of tetramethyl bisphenol-A polyarylate (TMPAr) with various linear aliphatic polyesters characterized by the ratio of aliphatic carbons to ester groups in the repeating unit, CH2/COO = 3 ∼ 9, was examined by differential scanning calorimetry and dynamic mechanical analysis. TMPAr/aliphatic polyester blends prepared by solvent casting were found to be miscible when the CH2/COO ratio of aliphatic polyesters was larger than 4 and up to 9. The thermodynamic interaction parameter, B for the miscible blends was determined by the analysis of the depression of the melting point of polyester using the Hoffman-Weeks method. From the analysis of the heat of mixing data using a binary interaction model, it was concluded that strong unfavorable intramolecular interaction exists between the CH2 and COO units in aliphatic polyesters and that four substituted methyl groups produces more favorable effects on the miscibility TMPAr with aliphatic polyesters. © 1998 John Wiley & Sons, Inc. J Polym Sci 36: 201–212, 1998

The phase behavior of tetramethyl bisphenol‐A polyarylate/aliphatic polyester blends

The phase behavior of blends of tetramethyl bisphenol-A polyarylate (TMPAr) with various linear aliphatic polyesters characterized by the ratio of aliphatic carbons to ester groups in the repeating unit, CH2/COO = 3 ∼ 9, was examined by differential scanning calorimetry and dynamic mechanical analysis. TMPAr/aliphatic polyester blends prepared by solvent casting were found to be miscible when the CH2/COO ratio of aliphatic polyesters was larger than 4 and up to 9. The thermodynamic interaction parameter, B for the miscible blends was determined by the analysis of the depression of the melting point of polyester using the Hoffman-Weeks method. From the analysis of the heat of mixing data using a binary interaction model, it was concluded that strong unfavorable intramolecular interaction exists between the CH2 and COO units in aliphatic polyesters and that four substituted methyl groups produces more favorable effects on the miscibility TMPAr with aliphatic polyesters. © 1998 John Wiley & Sons, Inc. J Polym Sci 36: 201–212, 1998

Gas sorption and transport in UV-irradiated polyarylate copolymers based on tetramethyl bisphenol-A and dihydroxybenzophenone

Gas sorption and transport properties at 35°C are reported for a series of ultraviolet irradiated polyarylates prepared from tetramethyl bisphenol-A (TMBPA), 4,4′-dihydroxybenzophenone (DHB), and 5-tertiary-butyl isophthalic acid dichloride (tBIA). UV irradiation induces crosslinking and photo-Fries rearrangements in these polymers. The gas permeability of the polyarylates decreases with UV irradiation due to reductions in the diffusion coefficient; however, the ideal selectivity for all gas pairs increases with UV irradiation. The effect of UV irradiation on the gas transport properties of the polyarylates is compared with that reported in the literature for similar polyimide materials. The polyimides show much greater improvement in selectivity than do the current polyarylate materials. The photo-Fries rearrangements limit the amount of crosslinking achievable in these polyarylate materials in spite of the fact that additional benzophenone units are formed.

Polymer-polymer interactions via analog calorimetry. 2. Blends of polystyrene with bisphenol-A polycarbonate and tetramethyl bisphenol-A polycarbonate

Analog calorimetry is used as a tool to study the interaction of polystyrene, PS, with bisphenol-A polycarbonate, PC, and with tetramethyl bisphenol-A polycarbonate, TMPC. Electrostatic charge calculations were used as a guide to divide polymer repeat units and analogs into groups. A mean-field binary interaction model was used to evaluate group interaction energies. The enthalpic interaction energy obtained from this study for the PS-PC pair is 0.41 ± 0.13 cal/cm3 while that for the PS-TMPC pair is 0.19 ± 0.34 cal/cm3. The result for PS-PC blends is in good agreement with values obtained from studies using the critical molecular weight approach and the phase behavior of copolymer blends. The value for PS-TMPC does not correctly predict the phase behavior of this blend; however, its standard deviation (on both an absolute and relative basis) is large and the range of possible interaction energies includes the negative values obtained from neutron scattering. The results of this study indicate that the presence of methyl groups on the aromatic ring of TMPC repeat unit is the main factor favoring the miscibility of PS-TMPC blends. © 1997 John Wiley & Sons, Inc.

Miscibility of polyarylate copolymers with poly(styrene- co-acrylonitrile)

The miscibility of random copolymers of bisphenol-A polyarylate and tetramethyl bisphenol-A polyarylate (PAr- co-TMPAr) with poly(styrene- co-acrylonitrile) (SAN) was studied based on the glass transition behaviour measured by differential scanning calorimetry. Analysis of the miscibility map by using the mean field theory showed that the intramolecular repulsion between styrene and acrylonitrile units in SAN gives a large contribution to the miscibility of PAr- co-TMPAr and SAN.

Polymer‐polymer interactions via analog calorimetry. 2. Blends of polystyrene with bisphenol‐A polycarbonate and tetramethyl bisphenol‐A polycarbonate

Analog calorimetry is used as a tool to study the interaction of polystyrene, PS, with bisphenol-A polycarbonate, PC, and with tetramethyl bisphenol-A polycarbonate, TMPC. Electrostatic charge calculations were used as a guide to divide polymer repeat units and analogs into groups. A mean-field binary interaction model was used to evaluate group interaction energies. The enthalpic interaction energy obtained from this study for the PS-PC pair is 0.41 ± 0.13 cal/cm3 while that for the PS-TMPC pair is 0.19 ± 0.34 cal/cm3. The result for PS-PC blends is in good agreement with values obtained from studies using the critical molecular weight approach and the phase behavior of copolymer blends. The value for PS-TMPC does not correctly predict the phase behavior of this blend; however, its standard deviation (on both an absolute and relative basis) is large and the range of possible interaction energies includes the negative values obtained from neutron scattering. The results of this study indicate that the presence of methyl groups on the aromatic ring of TMPC repeat unit is the main factor favoring the miscibility of PS-TMPC blends. © 1997 John Wiley & Sons, Inc.

Dielectric method for detection of phase separation and its kinetics in TMPC/PS blends

A new method for the detection of phase separation and its kinetics through real-time measurements is presented using the dielectric technique. The kinetics of phase separation were determined for a blend of tetramethyl bisphenol-A polycarbonate TMPC and polystyrene PS at different temperatures. The temperature dependence of the rate constant of phase separation was determined. The activation energy of phase separation process is found to be equal to 46 kcal/mole. In addition, it was possible to determine the variation in the composition of the TMPC-rich phase with time. The results obtained were compared with the literature data and were found to be in good agreement.

Miscibility of poly(styrene-co-acrylonitrile) with random copolymers of tetramethyl bisphenol-A polyarylate and tetrabromo bisphenol-A polyarylate

Tetramethyl bisphenol-A polyarylate (TMPAR) was miscible with poly(styrene-coacryloni trile) 's(SANs) containing 4, 7, 10, and 13wt% of acrylonitrile(AN) repeating unit. As the content of tetrabromo bisphenol-A polyarylate(TBPAR) repeating unit in the random copolymer of TMPAR and TBPAR was increased, the miscibility window in the blends with SANs was narrowed. The intramolecular repulsion between styrene and AN repeating units in SAN was suggested to be the main driving force for the miscibility of SANs with the random copolymers of TMPAR and TBPAR.

A Positron-Annihilation-Lifetime study of Polymer Blends

ABSTRACTPositron-annihilation-lifetime (PAL) spectroscopy has been utilized to investigate the free-volume properties of two types of polymer blends, a miscible blend of bisphenol-A polycarbonate (PC) and tetramethyl bisphenol-A polycarbonate (TMPC), and an immiscible blend of PC and polystyrene (PS). In the miscible blend, the free-volume hole size and its fraction follow a linear relationship with respect to the weight fraction while in the immiscible blend, the relationship is not linearly additive. The free-volume hole distributions in the immiscible blend are found to be significantly broader than those in the pure polymers. The difference is thought to be a result of the free volume formed and associated with the conformation and interchain packing between the dissimilar chains in incompatible polymers.

Electron microscopic observation of spinodal decomposition in blends of tetramethyl polycarbonate and polystyrene

The time development of spinodal decomposition in a blend of tetramethyl bisphenol-A polycarbonate with polystyrene can be followed using permanganic etching and scanning electron microscopy. This method of observation provides a real-space technique for observing the morphology of spinodal decomposition at high resolution.

Permeation of oxygen, argon and nitrogen through polymer membranes

In order to screen polymer materials suitable for the separation of O 2/Ar mixtures, gas permeability coefficients of O 2, Ar and N 2 through a total of 19 polymers were measured at 25°C and atmospheric pressure. Diffusion coefficients and solubility coefficients were calculated from time-lag data. The gas permeabilities and diffusivities in all polymers tested are in the order of O 2>Ar>N 2, while the gas solubilities are in the order of Ar>O 2>N 2. Higher permselectivities are observed in glassy polymers than in rubbery polymers. Permeability ratios, which denote the ideal separation factors, for O 2/Ar in glassy polymers are strongly affected by the contribution of the diffusivity ratios. The absolute diffusivities and the diffusivity ratios are correlated rather well using the free volume theory of polymers which employs the group contribution method based on the chemical structure of polymers. Slight deviations from the expected values are discussed by introducing a factor of polymer chain fluctuation speed. Poly (2,6-dimethyl-1,4-phenylene oxide) and tetramethyl bisphenol-A polycarbonate exhibit a relatively high permeability of O 2 and a high permeability ratio of O 2/Ar. Temperature and pressure dependencies of gas permeabilities are examined with these two polymers.