Renewable nanocomposite polymer foams synthesized from Pickering emulsion templates

Abstract

Fully renewable highly porous thermosetting and UV-cured cellulose nanocomposites have been synthesised from medium and high internal phase water-in-acrylated soybean oil emulsions stabilised solely by hydrophobised bacterial cellulose nano-fibrils. Research efforts are being focused on the development of environmentally friendly renewable highly porous nanocomposite foams in the desire to seek alternatives to petroleum-based materials. Emulsion templating has emerged as an effective route to prepare porous polymer foams with a well-defined morphology since the latter is defined by the structure of the emulsion template at the gel-point of the polymerisation [1]. Commonly, water-in-oil (w/o) emulsions are stabilised against droplet coalescence by large amounts (5-50 vol.%) of suitable but structurally parasitic non-ionic surfactants [2,3], which must be removed during post-processing. Pickering emulsions are emulsions that are solely stabilised by small particles [4, 5]. These emulsions are extremely stable due to the irreversible adsorption of particles at the interface between the dispersed and continuous phase [6]. Bacterial cellulose is attractive as a source of renewable nano-fibrils because unlike plant-based cellulose it has the advantage of being free from lignin, hemicellulose and pectin [7]. Whilst cotton is relatively free from these components it does have a wax layer between the cellulose micro-fibrils, which must be removed by extraction. Bacterial cellulose has widths already in the nanometre size range and possesses a high Young's modulus, reported at 114 GPa [8]. It is highly hydrophilic and therefore, lacks compatibility with many polymers. However, the nano-fibrils can be modified in order to tune their surface chemistry and wettability. Plant oils, such as soybean oil, castor oil and linseed oil are important natural resources, consisting predominantly of triglycerides, which are themselves composed of three fatty acids by a glycerol centre through ester linkages. The fatty acids range

Nanocellulose properties and applications in colloids and interfaces

“…50% of acrylated soybean oil as continuous phase were stabilized solely by bacterial cellulose nanofibrils hydrophobized by silylation or esterification. Upon polymerization and water removal, polymer foams were obtained (Blaker et al, 2009). Likewise, CNC-stabilized W/O emulsions having poly(lactic acid) (PLA) solution as continuous phase was found to be an effective dispersion and alignment method to control assembly of CNC into continuous composite ultrafine fibers produced by electrospinning (Li et al, 2013a).…”

Aligned unidirectional PLA/bacterial cellulose nanocomposite fibre reinforced PDLLA composites

“…Pyridine (analaR NORAMPUR, ≥ 99.7% purity), methanol (GPR, ≥ 99% purity), ethanol (GPR, ≥ 99% purity) were purchased from VWR. p-Toluenesulfonyl chloride (Aldrich, ≥ 99% purity) was purchased from [29], followed by multiple centrifugation, rinsing and homogenization cycles to return the aqueous dispersion of BC to neutral pH, according to our previous work [28,30]. BC was then modified via an organic acid esterification procedure, described in detail [28].…”

Functional nanomaterials through esterification of cellulose: a review of chemistry and application

“…Surface-modified nanocelluloses by alkylacyl chains are supposed to be well miscible with other synthetic polymers and exist as reinforcing nanofillers in diverse materials, including films and foams (Blaker et al 2009;Fujisawa et al 2011;Habibi et al 2010;Johnson et al 2011;Siqueira et al 2009). Generally, a post esterification of hydroxyl groups on nanocelluloses surface has been used for the immobilization of alkylacyl groups on nanocelluloses surface.…”