Entanglement Transition in Hyperbranched Polyether‐Polyols

Abstract

Are hyperbranched polymers capable of forming entanglements? This is the central issue of this contribution. Hyperbranched polyglycerol (hbPG) samples with different molecular weights (600-106 000 g · mol(-1) ), narrow polydispersities (1.2-1.8) and high degrees of branching (≈0.6) were prepared by anionic ring-opening polymerization. The viscoelastic properties of these polymers with respect to molecular architecture and molar mass were investigated. At low molecular weights "classical" scaling behavior between zero shear viscosity and molecular weight can be observed, whereas between 3 000 and 10 000 g · mol(-1) a plateau-like area is found. The results indicate entanglement dynamics when exceeding a critical molar mass ($\overline {M} _{{\rm c}}^{*} $ ≈ 20 000 g · mol(-1) ) due to entangled hyperbranched polyglycerols.

Shear-stress relaxation and ensemble transformation of shear-stress autocorrelation functions

“…While the present work focuses on permanent elastic networks let us mention that this study can be extended naturally on self-assembled transient networks as hyperbranched polymer chains with sticky end-groups [32] or microemulsions bridged by telechelic polymers [33]. Such networks may be modeled using purely repulsive LJ beads representing the oil droplets of the microemulsion which are connected reversibly by ideal springs similarly as in MC simulations of equilibrium polymers [48].…”

“…The static equilibrium shear modulus G eq [1][2][3][4][5][6][7] is an important order parameter [8][9][10] characterizing the transition from the liquid/sol (G eq = 0) to the solid/gel state (G eq > 0) where the particle permutation symmetry of the liquid state is lost for the time window probed [6,7]. Examples of current interest for the determination of G eq include crystalline solids [11], glass-forming liquids and amorphous solids [5,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27], colloidal gels [28], permanent polymeric networks [2,[29][30][31], hyperbranched polymer chains with sticky end-groups [32] or networks of telechelic polymers [33]. As emphasized by the thin horizontal line in Fig.…”

Fluctuation-dissipation relation between shear stress relaxation modulus and shear stress autocorrelation function revisited

“…Examples of current interest for the determination of G eq include crystalline solids [10], glass forming liquids and amorphous solids [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], colloidal gels [27], polymeric networks [1,[28][29][30], hyperbranched polymer chains with sticky end-groups [31] or bridged equilibrium networks of telechelic polymers [32]. * Electronic address: hongxu@univ-lorraine.fr temperature T (β = 1/k B T denoting the inverse temperature) [33].…”

Branched aliphatic polyesters by ring-opening (co)polymerization

“…An comprehensive review by Long et al appeared [31], However, some general features should be mentioned. The presence of branches in highly branched polymers prevents chain entanglements [28,31,168,169,170].…”