Renewable Terpene Derivative as a Biosourced Elastomeric Building Block in the Design of Functional Acrylic Copolymers.

In order to move away from traditional petrochemical-based polymer materials, it is imperative that new monomer systems be sought out based on renewable resources. In this work, the synthesis of a functional terpene-containing acrylate monomer (tetrahydrogeraniol acrylate, THGA) is reported. This monomer was polymerized in toluene and bulk via free-radical polymerizations, achieving high conversion and molecular weights up to 278 kg·mol-1. The synthesized poly(THGA) shows a relatively low Tg (-46 °C), making it useful as a replacement for low Tg acrylic monomers, such as the widely used n-butyl acrylate. RAFT polymerization in toluene ([M]0 = 3.6 mol·L-1) allowed for the well-controlled polymerization of THGA with degrees of polymerization (DP n) from 25 to 500, achieving narrow molecular weight distributions ( D̵ ≈ 1.2) even up to high conversions. At lower monomer concentrations ([M]0 = 1.8 mol·L-1), some evidence of intramolecular chain transfer to polymer was seen by the detection of branching (arising from propagation of midchain radicals) and terminal double bonds (arising from ß-scission of midchain radicals). Poly(THGA) was subsequently utilized for the synthesis of poly(THGA)- b-poly(styrene)- b-poly(THGA) and poly(styrene)- b-poly(THGA)- b-poly(styrene) triblock copolymers, demonstrating its potential as a component of thermoplastic elastomers. The phase separation and mechanical properties of the resulting triblock copolymer were studied by atomic force microscopy and rheology.

Do encapsulated heat storage materials really retain their original thermal properties?

The encapsulation of Rubitherm®27 (RT27), which is one of the most common commercially supplied heat storage materials, by polystyrene (PS), polydivinyl benzene (PDVB) and polymethyl methacrylate (PMMA) was carried out using conventional radical microsuspension polymerization. The products were purified to remove free RT27 and free polymer particles without RT27. In the cases of PS and PDVB microcapsules, the latent heats of melting and crystallization for RT27 ( and , J/g-RT27) were clearly decreased by the encapsulation. On the other hand, those of the PMMA microcapsules were the same as pure RT27. A supercooling phenomenon was observed not only for PS and PDVB but also for the PMMA microcapsules. These results indicate that the thermal properties of the heat storage materials encapsulated depend on the type of polymer shells, i.e., encapsulation by polymer shell changes the thermal properties of RT27. This is quite different from the idea of other groups in the world, in which they discussed the thermal properties based on the ΔHm and ΔHc values expressed in J/g-capsule, assuming that the thermal properties of the heat storage materials are not changed by the encapsulation. Hereafter, this report should raise an alarm concerning the "wrong" common knowledge behind developing the encapsulation technology of heat storage materials.