Tissue engineering (TE) and regenerative medicine integrate information and technology from various fields to restore/replace tissues and damaged organs for medical treatments. To achieve this, scaffolds act as delivery vectors or as cellular systems for drugs and cells; thereby, cellular material is able to colonize host cells sufficiently to meet up the requirements of regeneration and repair. This process is multi-stage and requires the development of various components to create the desired neo-tissue or organ. In several current TE strategies, biomaterials are essential components. While several polymers are established for their use as biomaterials, careful consideration of the cellular environment and interactions needed is required in selecting a polymer for a given application. Depending on this, scaffold materials can be of natural or synthetic origin, degradable or nondegradable. In this review, an overview of various natural and synthetic polymers and their possible composite scaffolds with their physicochemical properties including biocompatibility, biodegradability, morphology, mechanical strength, pore size, and porosity are discussed. The scaffolds fabrication techniques and a few commercially available biopolymers are also tabulated.

A Comparative Review of Natural and Synthetic Biopolymer Composite Scaffolds.

Challenges and new opportunities on barrier performance of biodegradable polymers for sustainable packaging

Although Staudinger realized makromolekules had enormous potential, he likely did not anticipate the consequences of their universal adoption. With 6.3 billion metric tons of plastic waste now cont...

100th Anniversary of Macromolecular Science Viewpoint: Redefining Sustainable Polymers

For many years, conventional plastics are manufactured and used for packaging applications in different sectors. As the food industries are increasing, the demand for packaging material is also increasing. Plastics have transformed the food industry to higher levels; however, conventional petroleum-based plastics are non-degradable which has created severe ecological problems to the environment like a threat to aquatic life and degrading air quality. Biodegradable polymers or biopolymers emerged as an alternative approach for many industrial applications to control the risk caused by non-biodegradable plastic. According to the type of starting material, they have been categorized as polymers extracted from biomass, synthesized from monomers, and produced from microorganisms. The quality of biopolymers depends on the physical, mechanical, thermal, and barrier properties. The present review highlights the characteristics of various biopolymers and their blends, comparison of properties between non-biodegradable and biopolymers, the market potential for food packaging applications. The review also emphasizes different commercial forms like films, trays, bags, coatings, and foamed products for application as modified atmosphere packaging, active packaging, and edible packaging. Different issues affecting market growth like harmful products formed during production and consumer perception have also been discussed. Information on biopolymers is widely scattered over many sources, this article aims to provide an overview of biodegradable polymer packages for food applications.

An overview of biodegradable packaging in food industry.

The global market for 3D printing materials has grown exponentially in the last decade. Today, photopolymers claim almost half of the material sales worldwide. The lack of sustainable resins, applicable in vat photopolymerization that can compete with commercial materials, however, limits the widespread adoption of this technology. The development of "green" alternatives is of great importance in order to reduce the environmental impact of additive manufacturing. This paper reviews the recent evolutions in the field of sustainable photopolymers for 3D printing. It highlights the synthesis and application of biobased resin components, such as photocurable monomers and oligomers, as well as reinforcing agents derived from natural resources. In addition, the design of biologically degradable and recyclable thermoset products in vat photopolymerization is discussed. Together, those strategies will promote the accurate and waste-free production of a new generation of 3D materials for a sustainable plastics economy in the near future.

Sustainable Photopolymers in 3D Printing: A Review on Biobased, Biodegradable, and Recyclable Alternatives.

Poly(glycolic acid) (PGA): a versatile building block expanding high performance and sustainable bioplastic applications

Among commercial biodegradable polyesters, poly(glycolic acid) (PGA) has been rarely investigated for packaging applications, despite its unique advantages such as 100% compostability, high degree of crystallinity, high thermal stability and high gas barrier properties. The application of PGA has been limited by its mechanical brittleness, moisture sensitivity, and high melting temperature (~240 oC), restricting its processing and applications for film packaging. In this study, PGA was modified by blending with poly (butylene adipate-co-terephthalate) (PBAT) via melt-extrusion. A commercial terpolymer of ethylene, acrylic ester and glycidyl methacrylate (EMA-GMA) was selected for compatibilization. The phase morphology, rheology, thermal, mechanical and gas barrier properties of the blends were investigated. With addition of 20 wt. % EMA-GMA, the elongation of PGA/PBAT (50/50 wt. %) blends was improved from 10.7 to 145%, the oxygen permeability was reduced from 125 to 103 (cm3mm) / (m224h atm), and the water vapour barrier performance was improved by ~47%. The enhancement in ductility, oxygen and water vapor barrier properties of the flexible blends were ascribed to the interfacial bonding between PBAT and PGA enabled by EMA-GMA. The compatibilized PGA/PBAT blends with high thermal stability up to 300 oC are preferable for high temperature or hot food packaging.

Reactive extrusion of biodegradable PGA/PBAT blends to enhance flexibility and gas barrier properties

The rise in demand for biodegradable plastic packaging with high barrier properties has spurred interest in poly(lactic acid-co-glycolic acid) (PLGA) copolymers with a relatively high glycolide content. In this work, we examined how reaction conditions affect the synthesis of PLGA25 (L:G 25:75) through the ring-opening polymerisation of d-l-lactide (L) and glycolide (G), using tin 2-ethylhexanoate (Sn(Oct)2) as the catalyst and 1-dodecanol as the initiator. The effects of varying the initiator concentration, catalyst concentration, reaction time, and temperature on the molecular weight, monomer conversion, and thermal properties of PLGA25 were investigated. Increasing the reaction temperature from 130 to 205 °C significantly reduced the time required for high monomer conversions but caused greater polymer discolouration. Whilst increasing the [M]:[C] from 6500:1 to 50,000:1 reduced polymer discolouration, it also resulted in longer reaction times and higher reaction temperatures being required to achieve high conversions. High Mn and Mw values of 136,000 and 399,000 g mol−1 were achieved when polymerisations were performed in the solid state at 150 °C using low initiator concentrations. These copolymers were analysed using high temperature SEC at 80 °C, employing DMSO instead of HFIP as the eluent.

Zhaoyang Sun

Papers

Poly(glycolic acid) (PGA): a versatile building block expanding high performance and sustainable bioplastic applications

Reactive extrusion of biodegradable PGA/PBAT blends to enhance flexibility and gas barrier properties

Synthesis of Poly(Lactic Acid-co-Glycolic Acid) Copolymers with High Glycolide Ratio by Ring-Opening Polymerisation.