Synthesis, characterization, and enzymatic degradation of starch-grafted poly(methyl methacrylate) copolymer films

Biodegradation behavior and digestive properties of starch-based film for food packaging - a review

Non-degradable plastic places a serious burden on the environment, so consumers and researchers are working to develop biodegradable, safe, and sustainable food packaging materials. The starch-based film has become emerging material for food packaging. Not only does it shows excellent physicochemical properties, but also provides the desired degradation characteristics after use or the digestive properties after consumption, thus needing to comprehensively evaluate the quality of starch-based food packaging materials. This review summarizes the degradation behavior of the starch-based film in different degradation environments, and compares the suitability of degradation environments. Besides, the physicochemical properties of the composite or blend film during the degradation process were further discussed. The factors affecting the digestibility of starch-based edible film were reviewed and analyzed. Finally, the application and the future trend of the biodegradable starch-based film in the food packaging field were proposed. Future studies should combine and evaluate the physical properties and biodegradability of the composite/blend film, to develop food packaging materials with good characteristics and biodegradability.

Development of Starch-Based Materials Using Current Modification Techniques and Their Applications: A Review

Starch is one of the most common biodegradable polymers found in nature, and it is widely utilized in the food and beverage, bioplastic industry, paper industry, textile, and biofuel industries. Starch has received significant attention due to its environmental benignity, easy fabrication, relative abundance, non-toxicity, and biodegradability. However, native starch cannot be directly used due to its poor thermo-mechanical properties and higher water absorptivity. Therefore, native starch needs to be modified before its use. Major starch modification techniques include genetic, enzymatic, physical, and chemical. Among those, chemical modification techniques are widely employed in industries. This review presents comprehensive coverage of chemical starch modification techniques and genetic, enzymatic, and physical methods developed over the past few years. In addition, the current applications of chemically modified starch in the fields of packaging, adhesives, pharmaceuticals, agriculture, superabsorbent and wastewater treatment have also been discussed.

All carbohydrate-based nanocomposites composed of sorbitol polyglycidyl ether, aminated trehalose and cellulose nanofiber

Renewable resources-derived nanocomposites are receiving extensive attention because of increasing environmental concern and restricted availability of petrochemical resources. The thiol-ene reaction of cysteamine hydrochloride and allyl-etherified trehaloses (AxTs) with allyl functionalities of x = 6 and 8 produced aminated trehaloses (NxTs). Sorbitol polyglycidyl ether (SPE) was cured with NxTs in the presence or absence of cellulose nanofibers (CNFs) to give all carbohydrate-based nanocomposites (SPE-NxT/CNFs) or cured resins (SPE-NxTs). The α-dispersion temperature (T_α) of SPE-N6T was higher than that of SPE-N8T. The T_α for SPE-N6T/CNFs was lowered with increasing CNF content over the range of 0-5 phr, and shifted from lowering to rising at 10 phr. The T_α for SPE-N8T/CNFs was not lowered with increasing CNF content, and SPE-N8T/CNF 10 phr exhibited the highest T_α among SPE-N8T/CNFs 0-10 phr. The tensile strength and modulus of SPE-N6T/CNF 10 phr were the highest among all the samples, which were much higher than those of SPE-N6T.

Amphoteric natural starch-coated polymer nanoparticles with excellent protein corona-free and targeting properties

The protein corona on nano drug carriers is an important well-known biological issue that often induces biological incompatibility and screens the targeting molecules on the surfaces of carriers, thus causing a loss of targeting specificity. Although polyethylene glycol (PEG) and zwitterionic polymers have been widely used as anti-fouling materials, there still remain critical challenges for their use as protein-corona agents for drug delivery and targeting. Here, we have designed novel amphoteric natural starch-stabilized core-shell colloidal nanoparticles with more efficient protein corona-free properties, under long term circulation, at different protein concentrations and in different protein charge environments, compared to typical anti-fouling materials such as PEG and zwitterionic polymers. More importantly, the starch-coated polymer nanoparticles can be further functionalized by antibodies to achieve additional excellent targeting and cell internalization capabilities for their use in photodynamic therapy. Our findings demonstrate a novel protein-free or anti-fouling natural material that is very promising for use as highly efficient nano drug carriers and marine coatings.

On the Use of Starch in Emulsion Polymerizations

The substitution of petroleum-based synthetic polymers in latex formulations with sustainable and/or bio-based sources has increasingly been a focus of both academic and industrial research. Emulsion polymerization already provides a more sustainable way to produce polymers for coatings and adhesives, because it is a water-based process. It can be made even more attractive as a green alternative with the addition of starch, a renewable material that has proven to be extremely useful as a filler, stabilizer, property modifier and macromer. This work provides a critical review of attempts to modify and incorporate various types of starch in emulsion polymerizations. This review focusses on the method of initiation, grafting mechanisms, starch feeding strategies and the characterization methods. It provides a needed guide for those looking to modify starch in an emulsion polymerization to achieve a target grafting performance or to incorporate starch in latex formulations for the replacement of synthetic polymers.

Characterization and properties of biodegradable thermoplastic grafted starch films by different contents of methacrylic acid

Due to poor mechanical and thermal properties of native starch (NS) film; in the present work; NS was modified by graft copolymerization. Thermoplastic starch (TPS) grafted by methacrylic acid (MAA) with different percentage of grafting, i.e., 0%, 18.3%, 36.3%, 52.1% and 89.7% were prepared and tested. The result demonstrated that the intensity of IR peak of acrylic group increased with the increasing percentage of grafting. The higher graft copolymerization with MAA also significantly reduced degree of crystallinity. The strain at maximum load of TPS film grafted by MAA increased with the increasing percentage of grafting. However, water uptake of TPS film grafted by MAA reduced with high percentage of grafting (52.1% and 89.7%). In addition, different TPS films grafted by MAA were also examined for morphology, water vapor permeability, thermal property and biodegradable property by soil buried test.

Properties and Biodegradability of Thermoplastic Starch Obtained from Granular Starches Grafted with Polycaprolactone

Granular starches grafted with polycaprolactone (St-g-PCL) were obtained using N-methylimidazole (NMI) as a catalyst. The effect of the starch/monomer ratio and catalyst content was studied to obtain different levels of grafted PCL. The highest grafting percentage (76%) and addition (43%) were achieved for reactions with a starch/monomer ratio of 50/50 and 25% catalyst. The grafting of PCL on the starch granule was verified by the emergence of the carbonyl group in the FTIR spectra and the increased diameter of the grafted starch granule. Thermoplastic starch from ungrafted starch (TPS) and grafted starch (TPGS) was obtained by mixing ungrafted or grafted starch granules with water, glycerol, or sorbitol in a mixer. TPS and TPGS behave as plastic materials, and their mechanical properties depend on the type of plasticizer used. Materials with glycerol as the plasticizer exhibited less rigidity. The presence of starch-g-PCL results in a dramatic increase in the elongation of the thermoplastic material. The starch present in the TPS or TPGS was completely biodegraded while the grafted PCL was partially biodegraded after the enzymatic degradation of the materials.

Surface Molecularly Imprinted Polymer of Chitosan Grafted Poly(methyl methacrylate) for 5-Fluorouracil and Controlled Release

The molecular surface imprinted graft copolymer of chitosan with methyl methacrylate (MIP-CS-g-PMMA) were prepared by free radical polymerization with 5-fluorouracil (5-FU) as the template molecule using initiator of ammonium persulfate as adsorption system. MIPs were characterized by FTIR, X-ray diffraction, thermo-gravimetric analysis, (1)H NMR and SEM. The mechanism of graft copolymerization and factors affected graft reaction were studied in details, and the optimum reaction conditions (to the highest %G and %E as the standard) were obtained at [MMA] 1.2 mol/L, [Chitosan] 16.67 mol/L, [initiator] 0.0062 mol/L, temperature 60 °C and reaction time 7 h. MIPs exhibited high recognition selectivity and excellent combining affinity to template molecular. The in vitro release of the 5-FU was highly pH-dependent and time delayed. The release behavior showed that the drugs did not release in simulated gastric fluid (pH = 1.0), and the drug release was small in the simulated small intestinal fluid (pH = 6.8), and drug abrupt release will be produced in the simulated colon fluid (pH = 7.4), indicating excellent colon-specific drug delivery behavior.

Double-Hydrophilic Block Copolymer as an Environmentally Friendly Inhibitor for Calcium Sulfate Dehydrate (Gypsum) Scale in Cooling Water Systems

In this study, a novel environmentally friendly copolymer acrylic acid-itaconic acid-allylpolyethoxy maleic carboxylate was synthesized and used for inhibiting the calcium sulfate dehydrate (gypsum) scale. The properties of the synthesized copolymer were characterized by Fourier-transform infrared, nuclear magnetic resonance spectroscopy and thermal gravity analysis. Also, the structure and morphology changes of scale crystals were studied by scanning electronic microscopy, transmission electron microscopy and X-ray powder diffraction analysis. The copolymer inhibition ability was evaluated by means of static scale inhibition experiments. Results show that the copolymer was effective in inhibiting the scales by changing the size and morphology of the crystals. The maximum inhibition efficiency was 99.8% at a concentration of 2 mg · L– 1, far more efficient than most commercial inhibitors.

Biodegradation of polystyrene-graft-starch copolymers in three different types of soil

Materials based on polystyrene and starch copolymers are used in food packaging, water pollution treatment, and textile industry, and their biodegradability is a desired characteristic. In order to examine the degradation patterns of modified, biodegradable derivates of polystyrene, which may keep its excellent technical features but be more environmentally friendly at the same time, polystyrene-graft-starch biomaterials obtained by emulsion polymerization in the presence of new type of initiator/activator pair (potassium persulfate/different amines) were subjected to 6-month biodegradation by burial method in three different types of commercially available soils: soil rich in humus and soil for cactus and orchid growing. Biodegradation was monitored by mass decrease, and the highest degradation rate was achieved in soil for cactus growing (81.30%). Statistical analysis proved that microorganisms in different soil samples have different ability of biodegradation, and there is a significant negative correlation between the share of polystyrene in copolymer and degree of biodegradation. Grafting of polystyrene on starch on one hand prevents complete degradation of starch that is present (with maximal percentage of degraded starch ranging from 55 to 93%), while on the other hand there is an upper limit of share of polystyrene in the copolymer (ranging from 37 to 77%) that is preventing biodegradation of degradable part of copolymers.