Dilute solution properties of poly(p-t-butylstyrene)

George, A.; Wilson, William W.; Lindner, J. S.; Mays, Jimmy W.

doi:10.1016/0032-3861(94)90518-5

Cited by 9 publications

(4 citation statements)

References 32 publications

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“…It is noteworthy that the amount of PTBS incorporated in the nanosized diesel droplets in the unstirred experiments is slightly lower (Table ) than that observed in turbulence-induced emulsification. This would be expected if the size of the emulsion approaches the radius of gyration of the polymer (10–16 nm), as an entropic penalty has to be paid in trapping and confining a polymer in a confined space. However, the agitation of the interface is stronger as would be the case with a high concentration (500 ppm) of surfactant in spontaneous emulsification or with turbulence; this limitation seems to be alleviated to some extent as we observe similar amount of PTBS incorporated in oil in both the cases.…”

Section: Resultsmentioning

confidence: 99%

Thermodynamic and Kinetic Pathways to Agitated and Spontaneous Emulsification

Kullappan

Chaudhury

2020

Langmuir

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Emulsification of an oil (dodecane and diesel fuel) in salinized water was studied under turbulent and agitation-free conditions in the presence of a mixture of an ionic and a nonionic surfactant. The properties of the air−water and the oil−water interfaces were investigated using the methods of du-Nouy ring, drop resonance vibrometry, and Langmuir film balance that allowed pinpointing the relevance of certain interfacial properties in emulsification. Estimation of the droplet size and its distribution from the nanometer-tomicrometer range was carried out with optical microscopy, acoustic attenuation spectroscopy, and continuous hydrodynamic flow fractionation. These measurements provided the platform for the comparison of the emulsion droplet size with those predicted from the fluctuation of the dynamic stress in the turbulent water via a capillary hydrodynamic model. While such a comparison was reasonably meaningful for micron size emulsion droplets, production of nanometer size droplets was beyond such a rudimentary expectation. We thus carried out systematic investigations into other factors that contribute to emulsification under both agitated and agitation-free conditions. An important finding of these studies is that the infusion of air bubbles that profoundly enhance the hydrodynamic fluctuation produces mainly submicroscopic emulsion droplets, while a fluctuation inhibiting water-soluble polymer has the opposite effect. Furthermore, while a hydrophilic polymer dissolved in water enhances the ripening of the droplets with time, hydrophobic polymer in oil thwarts aging, plausibly by osmotic backpressure and interfacial stiffening, which, upon compression, acts against surface tension, thereby decreasing the chemical potential of the trapped oil molecules inside the droplet. These effects are similarly observed in spontaneous emulsifications, that is, when a layer of oil containing the additives is deposited upon the surface of the aqueous phase in the absence of any external work input.

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Section: Resultsmentioning

confidence: 99%

Thermodynamic and Kinetic Pathways to Agitated and Spontaneous Emulsification

Kullappan

Chaudhury

2020

Langmuir

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“…The SEC is equipped with a Wyatt Technology DAWN DSP multiangle laser light scattering (MALLS) detector in addition to a Wyatt Optilab EX RI detector. Size exclusion was performed with three successive Phenomenex Phenogel-5 columns, and M w values are determined from the d n /d c value of PtBS (0.129 mL/g) homopolymer reported in the literature . The volume fractions ( f ) of each block were calculated from the molar block fractions determined by 1 H NMR in CDCl 3 on a Varian Inova 500 MHz spectrometer using a 1 s relaxation time.…”

Section: Methodsmentioning

confidence: 99%

“…Size exclusion was performed with three successive Phenomenex Phenogel-5 columns, and M w values are determined from the dn/dc value of PtBS (0.129 mL/g) homopolymer reported in the literature. 27 The volume fractions ( f) of each block were calculated from the molar block fractions determined by 1 H NMR in CDCl 3 on a Varian Inova 500 MHz spectrometer using a 1 s relaxation time. Chemical shifts referenced from tetramethylsilane at 0.00 ppm.…”

Section: ■ Experimental Detailsmentioning

confidence: 99%

Synthesis, Thermodynamics, and Dynamics of Poly(4-tert-butylstyrene-b-methyl methacrylate)

2012

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A series of symmetric poly(4-tert-butylstyreneblock-methyl methacrylate) (PtBS-b-PMMA) diblock copolymers with varying molar masses and narrow molar mass distributions were prepared using sequential anionic polymerization. Order-to-disorder transition (ODT) temperatures were determined as a function of the overall degree of polymerization, N, using a combination of low-frequency dynamic mechanical spectroscopy (DMS) and variable temperature small-angle X-ray scattering (SAXS), leading to a mean-field expression for the segment−segment interaction parameter, χ = (41.2 ± 0.9)/T − (0.044 ± 0.002). This material is characterized by a larger value of χ, and much greater temperature sensitivity, than polystyrene-b-PMMA, providing access to tunable lamellar periods (pitch) down to 14 nm at technologically relevant temperatures. Nucleation and growth of lamellae, following cooling from the disordered state, was characterized by SAXS well above the glass transition temperature (T g ≈ 130 °C) and extrapolated to lower processing temperatures based on polymer chain relaxation times extracted from time− temperature superposed DMS data. These results qualify PtBS-b-PMMA as an attractive candidate for development as a new lithographic material.

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“…For the PS segment, M n values were determined by SEC analysis of an aliquot removed from the reaction and terminated in methanol prior to MEA addition. The same procedure was used to retrieve a sample of the PtBS segment and M n was determined by MALLS‐SEC analysis using the d n /d c value of 0.141 mL g −1 for PtBS in THF at 25 °C . 1 H NMR spectroscopy was used to determine the molar ratio of each block based on peak integrations of PS or PtBS aryl hydrogens and PMEA methyl ester hydrogens (Figure S4, Supporting Information).…”

Section: Results and Analysismentioning

confidence: 99%

Revisiting the Anionic Polymerization of Methyl Ethacrylate

Kennemur

Bates

2017

Macro Chemistry & Physics

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Synthesis of poly(methyl ethacrylate), (PMEA), in tetrahydrofuran at −78 °C using anionic polymerization techniques results in high molar mass (>30 kg mol−1), low dispersity (1.3), and high conversion (>81%). The molar masses of a series of samples are consistent with values anticipated by the monomer‐to‐initiator ratio and conversion. These results represent a significant improvement to earlier reported attempts to prepare PMEA using anionic methods. Successful diblock polymerization of polystyrene‐block‐PMEA, (PS‐PMEA), and poly(4‐tert‐butylstyrene)‐block‐PMEA, (PtBS‐PMEA), is achieved through sequential anionic polymerization techniques with dispersities as low as 1.06 and segment molar fractions close to those targeted. Broad principal scattering peaks observed by small‐angle X‐ray scattering (SAXS) for symmetric PS‐PMEA at relatively high molar mass (39 kg mol−1) suggests an effective interaction parameter (χeff) that is smaller than for PS‐block‐poly(methyl methacrylate). On the other hand, PtBS‐PMEA block polymers form a well‐ordered morphology based on SAXS measurements and is attributable to the more hydrophobic PtBS segment. These results confirm the viability of PMEA as a new constituent in the expanding suite of polymers suitable for preparing nanostructured block polymers.

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Dilute solution properties of poly(p-t-butylstyrene)

Cited by 9 publications

References 32 publications

Thermodynamic and Kinetic Pathways to Agitated and Spontaneous Emulsification

Thermodynamic and Kinetic Pathways to Agitated and Spontaneous Emulsification

Synthesis, Thermodynamics, and Dynamics of Poly(4-tert-butylstyrene-b-methyl methacrylate)

Revisiting the Anionic Polymerization of Methyl Ethacrylate

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