Peptide Domains as Reinforcement in Protein-Based Elastomers

Abstract

Proteins are a widely available biomass source for synthesizing strong and tough engineering polymers because of their propensity to hydrogen bond, chemically stable amide backbone, and demonstrated efficacy at forming relevant material structures in nature. Because the properties of polypeptides in many ways mimic urethane bonds and hard domains, herein proteins are explored as the reinforcing component in a polyurethane-inspired elastomer. Materials are synthesized using a two-step process: first, protein is methacrylated, and then copolymerized with (meth)acrylate comonomers to link protein domains with rubbery polymer chains. This is demonstrated with water-soluble proteins, whey protein and β-lactoglobulin, and a comonomer, hydroxypropyl acrylate (HPA). The resulting elastomers are amorphous and disordered but have microphase-separated morphologies. Materials with a wide range of stiffnesses have been prepared by varying the fraction of protein macro-cross-linkers in the materials. The protein aggregates function like fillers that strengthen the materials, which are shown to be tougher than both unreinforced homopolymers and unmodified proteins. Materials with low cross-link densities prepared using proteins modified at low methacrylation levels are also stiffer than protein−polymer blends. Above an optimal protein methacrylation level, increasing chemical cross-link densities led to lower extents of protein aggregation and decreased moduli.

Techno-Economic Assessment of Whey Protein-Based Plastic Production from a Co-Polymerization Process

“…To satisfy the protein:copolymer ratio of 30:70 (since this is the ideal concentration found earlier [23]), PEGMA (copolymer), ammonium persulfate (initiator) and TEMED (catalyst) were added at 2300 L, 92 L and 4.6 L, respectively. The polymerization reaction (described in [23,42]) lasted for 1 h and was then left at ambient condition for 2 h. The purpose of the washing procedure is to remove the unreacted monomer and other chemicals and to condition the plastic produced [43] since these impurities could lower the efficiency of the centrifugation and drying steps, thereby affecting the purity of the final product as well. The impurities were washed off as aqueous wastes, which were assumed to be charged by other waste treatment utility at $50/t (assumed to be about the same price as solid hazardous waste treatment cost in Abu Dhabi, UAE) [44].…”

“…The methacrylation level of the proteins to be used for polymerization is very crucial as it could affect the properties of produced plastics [42]. Therefore, changes in the contact time between the protein solution and the methacrylic anhydride (MA) were considered in the sensitivity analysis.…”

Designing Biomimetic Microphase‐Separated Motifs to Construct Mechanically Robust Plant Protein Resin with Improved Water‐Resistant Performance

“…To resolve this issue, researchers have employed a series of strategies such as chemical crosslinking, organic–inorganic hybrids, and interpenetrating polymer networks to increase the crosslinking degree of the protein matrix . In spite of the increased crosslinking degree improving the properties of SP resin, the adhesive layer becomes stiff and brittle thus leading to low impact resistance, which hinders the further processes and applications of wood products under certain requirements . According to the adhesion mechanism, the superior resin should be designed containing the following qualities: 1) a stable interior crosslinking skeleton, which facilitates effective stress transfer and stabilizes the bonded structure under the stimulus of external force and/or water molecules; 2) a proper toughness to accelerate the adhesive layer to form more permanent mechanical adhesion nails with effective energy dissipation effect to resist deformation .…”

Preparation and Characterization of Whey Protein-Based Polymers Produced from Residual Dairy Streams

“…The modified protein is then copolymerized with a monomer to form polymeric or plastic-like materials. Several factors are hypothesized to play an important role in formation of biomaterials and their final properties: protein formulation, polymerization stoichiometry, and the processing technique [15,23,24,25]. Protein formulation represents the quantitative and qualitative properties of bulk protein fraction obtained from the dairy products.…”

“…The method that is followed in this paper is based on the research done by Chan et al [24]. This study goes beyond that work, optimizing different polymerization proportions with the copolymer poly(ethylene glycol) methyl ether methacrylate (PEGMA) and comparing the two different types of whey proteins: whey protein concentrate (WPC) and whey protein isolate (WPI).…”