Preparation, Characterization, and Rheological Behaviors of Polysiloxanes Presenting Densely Simple and Well‐Defined Short‐Branched Chains

Abstract

In this paper, a series of polysiloxanes, presenting different contents of densely simple and well‐defined short‐branched chains (G1–G5), are prepared by hydrosilylation of α,ω‐(dimethylvinylsiloxy)‐poly(dimethyl‐methylvinyl)siloxanes (P1–P5) with 1,1,1,3,5,5,5‐heptamethyltrisiloxane (MDHM) and characterized by 1H and 29Si nuclear magnetic resonance, Fourier transform‐infrared spectroscopy, Abbe refractometry, gel permeation chromatography, and differential scanning calorimetry. The rheological behaviors of the G1–G5 products are investigated to study the influences of the short‐branched chains. The rheological parameters including non‐Newtonian index (n) and the flow activation energy (ΔEη) are obtained and discussed. It is observed that the G1–G5 polymers belonged to pseudoplastic fluids and the ΔEη values of the G1–G5 products are significantly influenced by the short‐chain branching degree of the polymers.

Two‐Way Semicrystalline Shape Memory Elastomers: Development and Current Research Trends

“…[77] The idea is derived from the thermodynamic description of stress-induced crystallization and is predominant when the crystalline domains are oriented under the application of applied stress. [78][79][80] The crystalline domains are defined with lamellar structures which stack perpendicularly to the direction of the applied stress, which can thereby predict various interesting morphological features such as the number of crystal folds and size. [75] Huang et al performed in situ X-ray diffraction analysis of the crystals formed during crystallization-induced elongation in a polycaprolactone-based polymer.…”

Reprocessable Supramolecular Elastomers of Poly(Siloxane–Urethane) via Self‐Complementary Quadruple Hydrogen Bonding

“…[1][2][3][4] In particular, polydimethylsiloxane (PDMS) is praised for its excellent biocompatibility, high gas permeability, low glass transition temperature (T g ), low surface energy, good thermal and oxidative stability, and water repellency. [5][6][7][8] Over the past decade, supramolecular silicone materials [9,10] have attracted much attention due to their outstanding properties, such as high DOI: 10.1002/macp.202100116 stiffness, high stretchability, self-healing ability, and thermoplastic capacity. These unprecedented properties are attributed to the dynamic nature of supramolecular bonds, whose energies are low enough to allow bond exchanging under mild conditions.…”

Synthesis and coupling of ABx polysiloxane macromonomers to form highly branched polysiloxanes

“…Having multiple chain-ends and a branched architecture results in compact polymer structures, increased solubility and decreased viscosity. [1][2][3] Anionic polymerization is the optimal living chain-growth polymerization and provides control over molecular weight, dispersity (Ð), microstructure and chain-end functionality, while also enabling the synthesis of block and statistical copolymers in one-pot. [1,4,5] Such characteristics make anionic polymerization very suitable for the synthesis of branched polymer structures.…”

“…Different methods to synthesize branched polydimethylsiloxanes have been reported in the literature. [2,9,[13][14][15][16] In 2003, Chojnowski et al reported the synthesis of star and dendritic PDMS polymers where the researchers copolymerized hexamethylcyclotrisiloxane (D 3 ) and 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane (V 3 ) monomers by anionic ring-opening polymerization (AROP) to achieve macromolecules with pendant vinyl groups. [9] These living copolymerizations were then terminated by using a reactive core containing four Si-Cl bonds which ultimately resulted in the formation of star-branched polymers.…”