Vitrimers can combine the advantageous properties of cross-linked materials with thermoplastic processability. For prominent case polyethylene, established post-polymerization introduction cross-linkable moieties results in extremely heterogeneous compositions chains. Here, we report generation functionalized polyethylenes directly by catalytic insertion polymerization, incorporated aryl boronic esters or alternatively acetal-protected groups suited for cross-linking difunctional esters. In...

High-performance polystyrene (PS)–polyisoprene (PI) low-disperse thermoplastic elastomers with a well-defined pom-pom topology are synthesized via anionic polymerization techniques, where two stars each about 13 PS-b-PI arms connected by linear PS chain, PI forming the inner core of star. Samples 70, 50, 30, and 10 vol % total content were prepared. First, PI-b-PS-b-PI triblock copolymer (short block, Mw,PI = 5 kg mol–1, Mw,PS 100 mol–1) was polymerization; second, blocks functionalized...

The understanding of long chain branched homopolymer melts in shear flow is significant interest to polymer science and critical ensure stable processing. We report on the startup at a constant rate well-defined pom-pom shaped melts. Pom-poms consist two stars covalently connected by single backbone. For low-arm numbers short arms, stress overshoot followed steady state observed, similar linear star one highly with entangled branches, double during could be observed before reaching...

The POM–POM architecture is the simplest yet defined branched architecture, showing both strain hardening in elongation and softening shear. molecular structure consists of q side chains at each end a backbone segment. To study rheological mechanical properties, we synthesized low-disperse POM–POM-shaped polystyrenes (PS) with well-defined properties via anionic polymerization grafting-onto method. All samples had weight-average weight Mw,b ≅ 100 kg mol–1 approximately similar numbers per...

The shear and elongational rheology of linear pom-pom shaped polystyrene (PS) blends was investigated experimentally modeled using constitutive models such as the Doi–Edwards molecular stress function (MSF) model. molecule is simplest topology to combine thinning with strain hardening in flow. A PS a self-entangled backbone (Mw,bb = 280 kg mol−1) 22 entangled sidearms (Mw,a at each star blended two weight average weights Mw 43 90 mol−1 low polydispersities (Ð < 1.05). semilogarithmic...

Abstract A Pom-Pom polymer with q a side chains of molecular weight M w,a at both ends backbone chain w,b is the simplest branched topology. Ten nearly monodisperse polystyrene systems synthesized via an optimized anionic polymerization and grafting-onto method 100 to 400 kg/mol, 9 50 between 22 are considered. We analyze elongational rheology Pom-Poms by use hierarchical multi-mode stress function (HMMSF) model, which has been shown predict viscosity linear long-chain (LCB) melts based...

Abstract The elongational rheology of blends a polystyrene (PS) Pom-Pom with two linear polystyrenes was recently reported by Hirschberg et al. (J. Rheol. 2023, 67:403–415). PS280k-2x22-22k self-entangled backbone ( M w,bb = 280 kg/mol) and 22 entangled sidearms w,a at each the branch points blended weight fractions from 75 to 2 wt% having w 43 kg/mol (PS43k) 90 (PS90k), respectively. While pure shows strong strain hardening in flow (SHF > 100), 10) is still observed Pom-Pom/linear...

Abstract Defined, branched polymer architectures with low dispersity and architectural purity are of great interest to science but challenging synthesize. Besides star comb, especially the pom‐pom topology is as it simplest exactly two branching points. Most synthetic approaches a reported lack full control variability over one three topological parameters, backbone or arm molecular weight number. A new, elegant, fast, scalable route without need for post‐polymerization modification (PPM)...

Rheological properties highly impact the foaming behavior of polymers, as a high melt strength and low shear viscosity support cell expansion by reducing coalescence rupture. Since rheological originate from molecular topology, topology is consequently governing parameter for foaming. We synthesized well-defined polystyrene (PS) POM-POM-shaped model systems to study topology-originated parameters on physical within purely amorphous polymers without any crystallization effects. Therefore, we...

We present a model-driven predictive scheme for the uniaxial extensional viscosity and strain hardening of branched polymer melts, specifically pom-pom architecture, using small amplitude oscillatory shear mastercurve architecture. A shaped is simplest architecture with at least two branching points, needed to induce hardening. It consists stars, each

The synthesis, characterisation and reactivity of new phosphine-functionalised tris(pyrazolyl)methane ligands (TpmPR2, 2a-c, with R = Ph, nBu, iPr) are presented. reaction 2a-c [Rh(CO)2Cl]2 furnished N,P-heterochelate carbonyl complexes (3a-c), which were used to quantify the donor abilities via IR spectroscopy. coordination flexibility was demonstrated by treating representative members this ligand class [CpRu(acn)3][PF6] (acn acetonitrile), [(tht)AuCl] (tht tetrahydrothiophene)...

Abstract We consider the elongational rheology of model polystyrene topologies with 2, 3 and 4 stars, which are connected by one (2-star or “Pom-Pom”), two (3-star) three (4-star) linear backbone chains. The number arms each star varies from q a = to 24, molecular weight M w,a 25 kg/mol 300 kg/mol, chains w,b 100 382 kg/mol. If length arm is shorter than backbone, i.e. < , despite vastly different considered, stress growth coefficient can be modeled Hierarchical Multi-mode Molecular...