Compressible Porous Hybrid Monoliths: Preparation via A Low- molecular Mass Gelators-based Gel Emulsion Approach and Exceptional Performances

Figure Captions and Table Legends: Figure S1 1H NMR spectra of BuDphe Figure S2 FTIR spectra of BuDphe Figure S3 MS spectra of BuDphe Figure S4 Gelation behaviors of BuDphe in various solvents Figure S5 Phase behavior of BuDphe/t-BMA (2%, wt%) after 10 minutes standing Figure S6 Phase behaviour of BuDphe /water /t-BMA (total volume is 1 mL) with different water contents: (a) 0%, (b) 20%, (c) 50%, (d) 80%, (e) 100% (v/v) Figure S7 TGA curves of M-1 (black line), M-4 (red line), M-5 (blue line) under oxygen flow Figure S8 (a) Maximum absorption capacities of M-5 to some organic-solvent mixtures*; (b) Selectivity of the materials to the solvents* under test, results from GC-MS studies


Introduction
With fast industrialization, clean up organic pollutants, in particular oil leakages, has attracted increasing attention during the last few decades.This is because the pollutants may cause irrecoverable damage to eco-systems via contamination of water and soil.However, treatment of the pollutants in an efficient and practical way is a burning challenge to scientists working in the field.Till now, the most efficient way to clean up the pollutants from water is separation via selective absorption.2][3][4][5][6][7] In fact, absorbents from natural materials such as expanded perlite, zeolites and graphite, as well as activated carbon, sawdust have long been used as absorbents, but the performance of them is not as good as expected because of low oil loading density and low oil-water selectivity.
1, 8 It is of the reasons that people has tend their attention to synthetic porous materials, including silicas, 9 carbon nanotubes, 10 organic-inorganic hybrids, 11 functionalized polymers and resins, 12,13 etc.For example, Wu and co-workers 10 reported a sponge-like material, which is composed of self-assembled, interconnected carbon nanotubes (CNT).The sponge in densified state swell instantaneously upon contact with organic liquids.Zhou and coworkers 14 prepared porous polystyrene, and the materials as prepared exhibit idea oil-water separation and gas permeability properties.Guo and colleagues 15 prepared special xerogels from a dendrimer of poly-propylenimine and a block co-polymer that is sulfonated polystyrene-block-poly-(ethylene-ran-butylene)-block-polystyrene.
The porous materials could be used as oil absorbents for the clean-up of oil spills, and show high oil absorption capacity, ideal absorption speed, and in addition, the materials are reusable.The materials or the methods used for the preparation of them, however, suffered from some drawbacks such as complicated preparation processes, high costs for reagents and apparatus, and energy-consuming for drying, which may prevent their real-life uses.8][19][20] In a typical preparation, a biphasic system is generated and then the continuous phase is polymerized.The colloidal entities serve to create porosity in the final polymeric materials and are removed after polymerization.The colloidal systems could be emulsions, 21 micro-emulsions, 22,23 solid particles, 18,24,25   breath figure droplets, 26,27 and gel emulsions, [28][29][30] and the pore sizes can range from a few nanometres to hundreds of micros.Among the colloidal templates, gel emulsions are more unique due to the fact that their internal structures could be easily adjusted by varying their composition.Gel emulsions were discovered earlier but only till 1966 a clear definition was given by Lissant and co-workers. 31In the definition, gel-emulsions are recognized as two-phase systems, of which one is the continuous phase and the other the dispersed phase.In particular, the volume fraction of the second one is greater than 0.74, which is a critical value in geometry for a container to be fully filled by non-deformed balls.In other words, the continuous phase must be networked thin films with porous structures, which are the bases for them to be used as templates.
32-34 Accordingly, gel emulsion is also named as high internal phase emulsion (HIPE) and the porous polymeric monoliths obtained from them are v u • ^‰}oÇ,/W _X It is not difficult to understand that the structure and property of the porous materials created in the template way are determined by the structure and the chemical nature of the gel-emulsions, of which they are produced from.By this token, development of gel-emulsions with distinctive structure and property is the priority in the creation of porous polymeric monoliths with predetermined structure and property.7][38][39] Even though surfactants are easily found, available and most commonly used stabilizers, yet they are not very efficient since a large u}µvšU ñ>ñì9 ~ÁlÀ• }( šZ }vš]vµ}µ• ‰Z • , is required.As for gel emulsions stabilized by micro-/nano-particles, the so called Pickering emulsions, they may suffer from phase inversion when the volume fraction of the dispersed phase emulsions was reported by us recently, of which lowmolecular mass gelators (LMMGs) were used as stabilizers.[28][29][30]40,41 The most distinct difference between the two kinds of gel emulsions is that both the continuous phase and the dispersed phase are liquids, but for the ones reported by us, the continuous phase is gelled due to presence of the LMMGs. It isthe difference that makes the volume fraction of the dispersed phase need not to be greater than 0.74 because it is physically trapped within the continuous phase.Moreover, preparation of gel-emulsions by using LMMGs as stabilizers is so simple that only agitation at room temperature is required, and procedures like heating, cooling, and addition of co-solvent are not at all necessary, and furthermore, 2.5% (w/v) or even less than that of the stabilizer is enough to produce a gel-emulsion with good stability.No doubt, these advantages must be beneficial for the practical production of gelemulsions, and for their template application.

42-46
Herein, we report on the preparation of some new LMMGsbased gel-emulsions, and their utilization in the template preparation of porous poly-t-BMA and relevant hybrid monoliths, which exhibit good mechanical property, ideal oil absorptivity, and excellent reusability.In addition, the preparation is easy, the energy consumption is low, and their internal structure is highly adjustable.This paper reports the details.

Experimental Materials
Tertiary butyl methacrylate (t-BMA, 99%, Sigma-Aldrich), acrylonitrile (AN, 99%, Sigma-Aldrich), styrene (St, 99%, Sigma-Aldrich), methyl methacrylate (MMA, 99%, Sigma-Aldrich) and p-divinylbenzene (DVB, Aldrich) were purified before use by passing through a neutral aluminum oxide column to eliminate the pre-added inhibitor in the reactants.After purification, the monomer and the cross-linker were stored in a freezer if they were not used directly.2,2;-Azobis(isobutyronitrile) (AIBN, 97%) was purchased from Sigma-Aldrich, and was purified by recrystallization using ethanol before use.Sylgard 184 silicone elastomer base and curing agent were purchased from Dow Corning (Midland, USA), and Boc-phenylalanine was purchased from Chengdu enlai biological technology Co., LTD.Water used throughout was doubly distilled.Other reagents were of, at least, analytical grade, and used without further purification.

Syntheses of the cholesteryl derivative (BuDphe)
The methods used for the preparation of BuDphe, which is a succinic acid derivative of cholesteryl D-phenylalanine, are schematically shown in Scheme 1. Specifically, cholesteryl Lphenylalanine with a primary amine group in its end was synthesized according to a previous report. 47The compound (5.34 g, 0.01 mol) was dissolved in 100 mL THF and stirred at room temperature to make sure its full dissolution.To the system, 100 mL THF solution of succinic anhydride (1.00 g, 0.01 mol) was added drop-wise.After the addition, the mixture was Please do not adjust margins Please do not adjust margins heated and refluxed for 24 h.The reaction was monitored by TLC.Then, the mixture was filtered, and the filtrate was evaporated to dryness.The solid as obtained was recrystallized from methanol for two times, and then dried in vacuum to give a desired product (BuDphe) in 70% yield as white powders.

Gelation test
A weighted amount (0.025 g) of BuDphe and a measured volume (1 mL) of a chosen liquid were placed into a sealed test tube (diameter: 1.2 cm, height: 6 cm ) and the mixture was oscillated at room temperature for 5 min, then the test tube was inversed to observe if a gel had been formed or not.Gels obtained after oscillation at room temperature were denoted -like gel may coexist within a system.This kind of system was referred to as • ^/_ (insoluble).Similar test was also conducted for mixture solvents of water and water immiscible organic liquids.At this

Gel-emulsion preparation
The gel emulsions used in the present studies could be prepared in the way as described below.For a typical system, its internal phase or dispersed phase is water, which accounts 80% of the total volume of the gel emulsion to be prepared, and the remaining is the continuous phase, which contains nearly 72% of monomer liquids (t-BMA, St or MMA), 25% of DVB, 2% of the gelator, BuDphe, and 1% of AIBN.To make a gel emulsion, a given amount of water was added, in a dropwise manner, into the organic phase under stirring, and then the system (a homogeneous emulsion) becomes a gel after a while at room temperature.For the introduction of silanes, two different ways were adopted.One is dissolved into the continuous phase, the oil phase, directly, and the other is physically dispersed into the dispersed phase, water, since they are water insoluble.

Template preparation of porous polymeric monoliths
The gel emulsion as prepared was heated to 40 ºC and maintained at the temperature for 4 h in an oil bath to start pre-polymerization, and then the temperature of the bath was raised to 85 ºC and reacted at the temperature for another 12 h to complete the polymerization.After polymerization, the monolith was removed from the reaction vessel, and then washed with ethanol (50 mL) four times.Finally, the polymeric monolith was naturally dried at ambient temperature until its weight became constant.

Characterization of the gel-emulsion SEM observation of xerogel
SEM images of the xerogel were taken on a Quanta 200 scanning electron microscope (Philips-FEI).The accelerating voltage was 20 kV and the emission current was 10.0 mA.The xerogel for the measurement was prepared by freezing the gel formed in the concerned liquid at a measured concentration in liquid nitrogen, and evaporated by a vacuum pump for 24 h.Before the examination, the sample was attached to a copper holder by conductive adhesive tape, and then it was coated with a thin layer of gold.

Characterization of the monoliths SEM observation
The diameters of the pores and pore throats of the porous polymeric or hybrid monoliths as prepared were semiquantitatively calculated by using the images taken on a Quanta 200 Scanning Electron Microscopy spectrometer (Philips-FEI, 15 kV and 10 mA).Prior to observation, approximately 1 cm 3 of each sample was mounted on a sample holder and sputtered with gold for 80 s to ensure sufficient conductivity.The pore size was also measured through the SEM images using software of Image J. The pore sizes of the porous materials as created were measured in a literature method, that is for each measurement, more than 100 pores were taken into account.

TGA measurements
Thermo-gravimetric analysis (TGA) was conducted on a thermal analyser (Q1000 DSC+LNCS+FACS Q600SDT).All the measurements were run at a heating rate of 10 /min from 15 to 800 in oxygen atmosphere.

Mechanical measurements
Mechanical testing under compression with a CTM 2500 universal testing machine frame, following the testing procedures specified in ASTM D1621-04a (Standard Test Method for Compressive Properties of Rigid Cellular Plastics).The length and diameter of the specimen used for the test are 2.0 cm and 1.0 cm, respectively.

Hydrophilic and lipophilic tests
The contact angle of the monolith was measured in a routine way on a Dataphysics OCA20 contact-angle system at ambient temperature.