Preparation of Porous Organogels Using Water Soluble Polymer Templates

Abstract

This study presents a new method for the preparation of organogels embedded with interconnected macropores tunable in size from 180 to 700 μm. The gels are molded in porous polyvinyl alcohol (PVOH) polymer templates obtained from melt‐processed cocontinuous blends of PVOH and poly(ε‐caprolactone) (PCL). The blends are subsequently annealed under quiescent conditions to let their morphology coarsen, and are rendered porous by selectively extracting the PCL. After the injection in the PVOH molds and in situ gelling of a dilute solution of an organic liquid and a low molecular weight gelling agent, 12‐hydroxyoctadecanoic acid, the molds are extracted with water. This yields porous organogels with microstructural features corresponding relatively well to those of the original molds, as revealed by X‐ray microtomography. This method allows control over the gels' average pore size, pore interconnectivity, and volume fraction, and is compatible with a variety of organic liquids and low molecular weight gelators.

Review on Cell Structure Regulation and Performances Improvement of Porous Poly(Lactic Acid)

“…However, there remains a powerful connection between the choices of template materials and cell morphologies. [77,78] Salt particles act as rigid templates that can change its own size and shape to obtain the expected cell structure. Meantime, heterogeneous system can occur, where salt particles are dispersed in the polymer matrix as a dispersed phase, forming sea-island structure that can eventually have a significant impact on the cell morphology obtained after removal of salt particles.…”

Tailored Macroporous Hydrogels with Nanoparticles Display Enhanced and Tunable Catalytic Activity

“…13,14,18,19 Porous PNIPAam gels were prepared by using porous polymer templates, based on a method illustrated in Scheme 1 and described in previous publications. 16,20,21 The method consists in (1) preparing a cocontinuous polymer blend by melt-processing, 22−27 This technique possesses the following features and advantages: (1) the polymer molds and gels show nearly identical macroscopic dimensions (Figure 2b, c); (2) the average pore diameter can be tuned from ∼1 to 1000 μm; (3) the pores are fully interconnected; (4) several choices of polymer blends, gels and NPs chemistries can be selected; 20,21,23 (5) scale up is possible by polymer meltextrusion; 20 (6) the resulting macroporous gels possess enhanced stimuli-sensitive properties due to coupling between mass and energy transfers. 16 The polymer blend morphology significantly coarsens with increasing annealing time t anneal (Figure 1a−c), the process being driven by the polymer pair interfacial tension, [22][23][24]26 and slowed down by viscosity.…”

“…Porous PNIPAam gels were prepared by using porous polymer templates, based on a method illustrated in Scheme and described in previous publications. ,, The method consists in (1) preparing a cocontinuous polymer blend by melt-processing, − herein comprised of ethylene propylene diene monomer and poly­(ε-caprolactone) (EPDM/PCL 50/50 vol %, T processing = 180 °C, t mixing = 7 min, see Experimental Details in the Supporting Information); (2) annealing the polymer blend under quiescent conditions to allow microstructure coarsening ( T anneal = 180 °C, t anneal = 60 or 240 min); − (3) extracting selectively the EPDM phase with cyclohexane to obtain porous PCL molds (Figure a – c, SEM observations), herein trimmed into 1 cm 3 cubes; (4) injecting the solution containing the monomers, cross-linker, and other necessary reagents, within the molds, followed by in situ gelling; (5) extracting selectively the PCL molds with toluene to obtain macroporous PNIPAam hydrogels (Figure d–f, X-ray microcomputed tomography (microCT)). NPs are subsequently synthesized within the hydrogel phase following well established protocols (demonstrated herein for Au and silver (Ag) NPs). , Figure a–d displays the initial polymer blend and PCL mold, and the resulting porous gel, before and after AuNPs synthesis.…”

“…This technique possesses the following features and advantages: (1) the polymer molds and gels show nearly identical macroscopic dimensions (Figure b, c); (2) the average pore diameter can be tuned from ∼1 to 1000 μm; (3) the pores are fully interconnected; (4) several choices of polymer blends, gels and NPs chemistries can be selected; ,, (5) scale up is possible by polymer melt-extrusion; (6) the resulting macroporous gels possess enhanced stimuli-sensitive properties due to coupling between mass and energy transfers …”