Macroporous polyacrylates from terpene–acrylate thermoreversible photopolymerizable vehicle

Abstract

Novel thermoreversible polymerizable vehicle was prepared from terpenes, such as camphene, camphor and menthol and acrylate monomers. The vehicle exhibits liquidity above room temperature and rigidity at room temperature, where the terpenes are crystalline dendrites and the acrylate monomer fills up the interdendritic space. The rigid vehicle polymerizes on UV illumination and the terpenes sublimed subsequently from the polymerized samples leaving highly porous polymeric samples with dendritic-shaped interconnected porosity up to *92 vol%. Increasing the terpenes content, the thermoreversible component, results in coarser dendritic structures. Lower recrystallization temperatures produce finer dendritic network, whereas recrystallization close to terpenes melting point results in larger continuous macropores. The proposed advantages include fast manufacturing because of fast recrystallization, achieving large pore size up to 13 lm and tailoring of the porosity through the portion of the sublimable vehicle and recrystallization temperature. The applicability of this novel technique in the biomedical field is demonstrated on a composition containing triethylene glycol dimethacrylate (TEGDMA), a monomer widely used for biomedical applications.

Porous Ceramics by Photopolymerization with Terpene–Acrylate Vehicles

“…The range of compositions of monomers with terpenes which are liquid at 100°C and sufficiently rigid at 25°C has been reported elsewhere. 13 These terpenes are polar substances, and work well with water-dispersible monomers such as polyethylene glycol (400) diacrylate (SR344; Sartomer Co., Exton, PA). Polyethylene glycol (400) diacrylate is a bifunctional acrylate monomer that produces soft flexible films upon polymerization.…”

“…Polyethylene glycol (400) diacrylate is a bifunctional acrylate monomer that produces soft flexible films upon polymerization. As presented in detail elsewhere, 13 a vehicle consisting of 40 wt % diacrylate, 40 wt% camphene, and 20 wt% camphor was a clear single phase liquid solution above 50°C. Below 40°C, the camphene/camphor portion is completely frozen, with the diacrylate monomer (and suspended powder) as an interdendritic liquid.…”

“…(B) Porous Ceramics After Sintering: Menthol-diacrylates were explored as an alternative vehicle. The morphology of menthol crystallized from solution is spherulitic, 13 as opposed to the branched dendrites of camphor/camphene. A series of compositions with a diacrylate/menthol (40/60 wt%) vehicle was used with the finer silica at powder loadings of 15, 25, and 35 vol%.…”

“…The vehicle consists of a mixture of acrylate monomers (which can be polymerized) and terpenes which are liquid when warm, but are crystalline at room temperature. Certain compositions of terpene-acrylate mixtures 13 are fluid singlephase solutions at 100°C, and two-phase soft solid systems at room temperature. The room temperature solid consists of crystalline dendrites of the terpenes, with the acrylate monomer as an interdendritic liquid.…”

“…Removing the terpene dendrites by melting or sublimation produces ice-templated porous plastic films. 13 Here we use the terpene-acrylate mixture as the suspension medium for ceramic powders, and use the freeze casting/photopolymerization method for ice-templated porous ceramic layers. This process is demonstrated for a silicon dioxide and alumina ceramic.…”