Epoxidized Block and Statistical Copolymers Reinforced by Organophosphorus–Titanium–Silicon Hybrid Nanoparticles: Morphology and Thermal and Mechanical Properties

Abstract

Glycidyl methacrylate (GMA) and a mixture of alkyl methacrylates (average chain length of 13 carbons; termed C13MA; derived from vegetable oils) were copolymerized by nitroxide-mediated polymerization to form epoxidized statistical and block copolymers with similar compositions ( F GMA ∼0.8), which were further cross-linked by a bio-based diamine. Hybrid plate-like nanoparticles containing organophosphorus–titanium–silicon (PTS) with an average size of ∼130 nm and high decomposition temperature (485 °C) were synthesized via a hydrothermal reaction to serve as additives to simultaneously enhance the thermal and mechanical properties of the blend. Nanocomposites filled with PTS were prepared at different filler-loading levels (0.5, 2, 4 wt %). Transmission electron microscopy (TEM) of the cured block copolymer displayed reaction-induced macrophase-separated domains. TEM also showed an effective dispersion of PTS hybrids in the matrix without intense agglomeration. Thermogravimetric analysis at different heating rates revealed the activation energy of poly (GMA- stat -C13MA) at maximum decomposition increased from 143.5 to 327.2 kJ mol –1 with 4 wt % PTS. Decomposition temperature and char residue improved 12 °C and ∼7 wt %, respectively, and T g increased 12 °C by adding 4 wt % PTS. Targeting various PTS concentrations enabled tuning of the tensile modulus (up to 75%), tensile strength (up to 46%), and storage modulus in both glassy state (up to 59%) and rubbery plateau regions (up to 88%). Oscillatory frequency sweeps indicated that PTS makes the storage modulus frequency dependent, suggesting that the inclusion of the nanoparticles alters the relaxation of the surrounding matrix polymer.

Design of crosslinked networks with hydroxyurethane linkages via bio‐based alkyl methacrylates and diamines

“…Initially, two T g s suggest possible microphase separation or a blend of two homopolymers. The solubility parameters ( δ ) of C13MA/GMA ( δ C13MA = 15.43 MPa 0.5 and δ GMA = 19.25 MPa 0.5 ) are different enough to suggest possibility of micro‐phase separation 49 but the statistical nature of the microstructures seems to preclude micro‐phase separation while the GPC traces indicated monomodal peaks and contamination with a homopolymer was not observed. The T g s at higher temperatures can be due to backbone segmental motion and T g s at lower temperatures can be attributed to alkyl side chains 50–52 …”