Hydrodynamic behavior of anionically prepared linear polyisoprenes and polystyrenes in carbon tetrachloride

Abstract

Intrinsic viscosity, [η], weight‐average molecular weight, Mw, relationships are reported for narrow molecular weight distribution linear polyisoprene and polystyrene samples in CCl4 at 25°C. Molecular weight values cover a range nearly two orders in magnitude, extending as low as 3 × 103. In the case of polystyrene there exists a molecular weight range (around Mw = 16,700) corresponding to a change in the Mark‐Houwink‐Sakurada (MHS) exponent from α = 0.71 to α = 0.54. Comparisons between the viscometric and hydrodynamic radii, from literature data, are made. For polyisoprene the MHS relationship is reported in CCl4, for the first time. For this case α = 0.713 for the whole range of molecular weights studied. Values for the second virial coefficient from low‐angle light‐scattering measurements support the conclusions drawn from viscometry that CCl4 is a good solvent for both polymers studied. The different behavior of the MHS exponent may be attributed to the difference in chain flexibility. © 1995 John Wiley & Sons, Inc.

Synthesis and characterization of isoprene polymers with polar groups via reversible addition‐fragmentation chain‐transfer polymerization

“…Determined by GPC, calibrated with standards of PS and converted to PIP using MHS constants according to the ref. .…”

“…The molecular weights relative to polystyrene (PS) standards were determined by GPC in a Waters 410 instrument coupled with a refractive index detector and ultraviolet detector using Ultrastyragel columns (1–40 K, 10–3 Å; 40 K–4 M, 10–5 Å, and 400 K–40 M, 10 −6 Å) and THF at 40 °C and a flow of 1 mL/min. A calibration curve of PIP was built to convert the molecular weights referred to PS standards ( M PS ) to molecular weights of PIP ( M PIP ) using Mark–Houwink–Sakurada (MHS) constants for both polymers in CCl 4 at 25 °C (eq ) . For PIP, the constants used are: K PIP = 2.44 × 10 −4 and α PIP = 0.712.…”

Isoprene (co)polymers with glycidyl methacrylate via bimolecular and unimolecular nitroxide mediated radical polymerization

“…A calibration curve of PIP was built to convert the molecular weights referred to PS standards (M PS ) to molecular weights of PIP (M PIP ) using Mark‐Houwink‐Sakurada (MHS) constants for both polymers in CCl 4 at 25 °C [eq. ] . For PIP, the constants used are: K PIP = 2.44 × 10 −4 and α PIP = 0.712.…”

Use of Solvent Effects to Improve Control Over Nitroxide‐Mediated Polymerization of Isoprene

“…A polyisoprene (PI) calibration curve was constructed by converting the PS standard peak molecular weights, M PS , to PI molecular weights, M PI , using Mark‐Houwink‐Sakurada (MHS) constants determined for both polymers in CCl 4 at 25 °C (Equation 1). 32 For PI, the MHS constants used were K PI = 2.44 × 10 −4 and α PI = 0.712. For PS, K PS = 7.1 × 10 −4 and α PS = 0.54 ($\overline{M}_{\rm w}$ < 16 700 g mol −1 ) or K PS = 1.44 × 10 −4 and α PS = 0.713 ($\overline{M}_{\rm w}$ ≥ 16 700 g mol −1 ).…”