The key difference between PLA and PLGA is that PLA is polylactic acid, which is synthesized via the condensation reaction of lactic acid, whereas PLGA is poly(lactic-co-glycolic acid), which is synthesized via the copolymerization of glycolic acid and lactic acid.
Both PLA and PLGA are polymer substances having a thermoplastic nature. However, they are different from each other because PLA is made from a single monomer while PGLA is made from two different monomers.
CONTENTS
1. Overview and Key Difference
2. What is PLA
3. What is PLGA
4. Side by Side Comparison – PLA vs PLGA in Tabular Form
5. Summary
What is PLA?
The term PLA stands for polylactic acid. It is a thermoplastic polymer we can classify as a polyester. The backbone formula of this polymer material is (C3H4O2)n. We can synthesize this polymer through a condensation reaction. The monomer used for this synthesis is lactic acid. During the condensation reaction of lactic acid, a water molecule is formed and released. Also, we can prepare this PLA polymer via ring-opening polymerization of lactide. Lactide is a cyclic dimer of the basic repeating unit, lactic acid.
Figure 01: Repeating Unit of PLA
PLA is a common polymer material because it is produced economically from renewable resources. It has the second most consumption among bioplastics. However, it is not used as a commodity polymer. The numerous applications of PLA have been hindered by some of its physical and processing drawbacks, but it is the most used plastic filament material in 3D printing applications.
When considering the production of PLA, we can get the monomer lactic acid from fermented plant starch; e.g. corn starch, cassava starch, sugarcane, sugar beet pulp, etc. The most common route for the production of PLA is ring-opening polymerization of lactide in the presence of metal catalysts in a solution or a suspension.
Lactic acid is a chiral compound. Therefore, if this polymer is produced from L,L-lactide, then the resulting polymer is PLLA (poly-L-lactide). We can observe that PLA is soluble in organic solvents such as benzene (hot solvent), tetrahydrofuran, dioxane, etc. When considering the mechanical properties of PLA, it can range from amorphous glassy polymer to semi-crystalline polymer. Sometimes, there are even highly crystalline polymers.
What is PLGA?
The term PLGA stands for poly(lactic-co-glycolic) acid. It is a copolymer that is made by ring-opening copolymerization of two different monomers: glycolic acid and lactic acid. We can synthesize these polymers as either random polymers or as block copolymers. Moreover, this production requires catalysts such as tin(II) 2-ethylhexanoate. During the process of this copolymerization, monomer units tend to link each other via ester bonds, yielding a linear, aliphatic polyester polymer material.
Furthermore, it is possible to obtain different forms of PLGA when we use different amounts of monomer compounds. These different forms are defined based on the molar ratio of the monomers used for the polymerization process. In addition to these, PLGA can vary from fully amorphous to fully crystalline structures based on the block structure and the molar ratio of the polymer.
Figure 02: Repeating Unit of PLGA
When considering the degradation of PLGA, it degrades via hydrolysis of its ester linkages in the presence of water. The time that is required for the degradation of PLGA depends on the monomer ratio that is used on its production.
What is the Difference Between PLA and PLGA?
PLA and PGLA are thermoplastic polymer materials. The key difference between PLA and PLGA is that PLA is polylactic acid which is synthesized via condensation reaction of lactic acid whereas PLGA is poly(lactic-co-glycolic acid) which is synthesized via copolymerization of glycolic acid and lactic acid.
Below infographic tabulates the differences between PLA and PLGA in more detail.
Summary – PLA vs PLGA
The term PLA stands for polylactic acid while the term PLGA stands for poly(lactic-co-glycolic) acid. The key difference between PLA and PLGA is that PLA is polylactic acid which is synthesized via condensation reaction of lactic acid whereas PGLA is poly(lactic-co-glycolic acid) which is synthesized via copolymerization of glycolic acid and lactic acid.
Reference:
1. “PLGA.” Wikipedia, Wikimedia Foundation, 25 Apr. 2020, Available here.
Image Courtesy:
1. “Polylactid sceletal” By Polimerek – Own work (Public Domain) via Commons Wikimedia
2. “PLGA” By Fvasconcellos (talk · contribs) – Vector version of w:Image:PLGA.jpg (Public Domain) via Commons Wikimedia
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