On the entanglement density of differently N-substituted alternating styrene-maleimide copolymers

Abstract

Differently N-substituted maleimides were copolymerized with styrene to yield alternating styrene-maleimide copolymers (SMI-R) with different chain diameters. The polymers were obtained by free radical polymerization and characterized by NMR and size exclusion chromatography / differential viscometry. Glass transition temperatures were measured by differential scanning calorimetry. An increase in chain diameter and chain stiffness is accompanied by a decrease in the entanglement density, reflected in lower values of the plateau modulus, which were corrected for the low molecular weight portion using the Wasserman/Graessley model. Increasing the chain diameter by a factor of two results in a decrease of the entanglement density to one third. SMI-Me showed a much lower entanglement density than polystyrene (PS) although they have the same chain diameter. SMIMe however is more rigid than PS because of the maleimide five-membered ring structure in the main chain. SMI-Me and SMI-PhOPh show the same glass transition temperature. However, because of the larger chain diameter of SMIPhOPh, it has a much lower entanglement density. Thus, both the chain flexibility and the chain diameter, two parameters that are strongly related, affect the entanglement density.

High Tg microspheres by dispersion copolymerization of N‐phenylmaleimide with styrenic or alkyl vinyl ether monomers

“…A poly(S‐ co ‐PMI) sample made by dispersion polymerization in MEK/EtOH (35:65) gave T g = 223 °C, within the range of values (215–235 °C) reported in the literature for poly(S‐ co ‐PMI) of approximately 50:50 composition 6–8, 10. Several poly (tBS‐ co ‐PMI) samples were made by both solution and dispersion polymerization and showed an average T g = 226 ± 3 °C, similar to the value observed for poly(S‐ co ‐PMI).…”

“…The compositions and T g values of copolymers of PMI with S, nBS, tBS, nBVE, tBVE, or DDVE prepared by solution polymerization are shown in Table 1. The copolymers of PMI with S, nBS, or tBS showed comonomer ratios close to a 1:1 ratio, consistent with the known tendency of S/PMI to form alternating polymers 6–8, 10, 31–33. A poly(nBS‐ co ‐tBS‐ co ‐PMI) terpolymer was similarly found to have a composition with a 1:1 ratio of styrenics to PMI.…”

“…It is known that the incorporation of maleimides into styrenic or acrylic polymers results in elevated T g and in improved resistance to thermal degradation. For instance, the 50:50 copolymer of styrene and N ‐phenylmaleimide (PMI) has a T g of ∼230 °C6–8 and an onset of thermal degradation at ∼340 °C,6, 7 compared with 100 °C9 and 273 °C,7 respectively, for polystyrene. Koning and coworkers8 studied a series of styrene‐maleimide copolymers made with different N ‐substituted maleimides.…”

“…For instance, the 50:50 copolymer of styrene and N ‐phenylmaleimide (PMI) has a T g of ∼230 °C6–8 and an onset of thermal degradation at ∼340 °C,6, 7 compared with 100 °C9 and 273 °C,7 respectively, for polystyrene. Koning and coworkers8 studied a series of styrene‐maleimide copolymers made with different N ‐substituted maleimides. The T g values of the 50:50 copolymers were much higher than that of polystyrene, but were not simply related to the relative sizes of the N ‐substituents: H (252 °C); Me (205 °C); t Bu (178 °C); Ph (221 °C); 4‐ t BuPh (237 °C); and 4‐PhOPh (194 °C).…”

Rheological characteristics and morphologies of styrene–butadiene–maleic anhydride block copolymers

“…M e has also been reported to affect the micromechanisms of deformation (crazing and shear yielding) and the failure of polymers in the solid state. [26][27][28][29][30] There are many methods to determine G 0 N in different cases. [31][32][33][34][35][36] Usually, G 0 N for amorphous polymer can be estimated from G 0 at x, where the loss tangent (tan d) approaches a minimum 31 : Figure 6 shows the master curves of G 0 and G 00 for two copolymers at the reference temperature of 473 K. The TTS based on the Williams-Landel-Ferry (WLF) equation was successfully applicable.…”