Poly (lactic-co-glycolic acid) (PLGA) copolymers have been broadly used in controlled drug release applications. Because these polymers are biodegradable, they provide an attractive option for drug delivery vehicles. There are a variety of material, processing, and physiological factors that impact the degradation rates of PLGA polymers and concurrent drug release kinetics. This work is intended to provide a comprehensive and collective review of the physicochemical and physiological factors that dictate the degradation behavior of PLGA polymers and drug release from contemporary PLGA-based drug-polymer products. In conjunction with the existing experimental results, analytical and numerical theories developed to predict drug release from PLGA-based polymers are summarized and correlated with the experimental observations. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1692-1716, 2017.

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Polylactide (PLA) is a bio-based, biodegradable polymer, which is derived from lactic acid and has numerous potential applications, some of which are limited by its moisture barrier and thermal properties. Prior studies have been inconsistent about how moisture sorption in PLA varies with crystallinity and molecular weight. This research is a systematic study of how moisture sorption in PLA depends on molecular weight and aliphatic content via end-group modification. PLA with varying aliphatic content was synthesized by ring-opening polymerization of L-lactide initiated with different longchain aliphatic alcohols. The terminating end groups were also modified from hydroxyl to acetoxy to eliminate hydrophilic end groups. Molecular weight was controlled by varying the ratio of L-lactide monomer to alcohol initiator, and triethylaluminum was used as the catalyst for precise control over molecular weight. The molecular weight and end-group compositions were verified by gel permeation chromatography and nuclear magnetic resonance. Moisture sorption of the modified PLA samples was measured with a quartz crystal microbalance. Quartz crystal microbalance experiments revealed that both molecular weight and aliphatic content contributed to the sorption properties of PLA.

Water sorption into polylactide (PLA) and polylactide‐montmorillonite (PLLA‐MONT) composites containing 5 wt % of montmorillonite (MONT) under different heat treatment conditions was studied using the quartz crystal microbalance/heat conduction calorimetry (QCM/HCC) technique. Results showed that water sorption in neat polymer films and composite films increased with heat treatment temperature up to 120 °C. Differential scanning calorimetry was used to measure the glass‐transition temperature and isothermal crystallization kinetics of all samples. The mobility of the amorphous domain in all samples increased with heat treatment temperature, indicated by the decrease in glass‐transition temperature. PLA composites crystallized at a much faster rate than neat PLA did because MONT acted as a nucleating agent. Under the same heat treatment condition, water sorption in PLLA‐MONT composites was always higher than that in neat PLA due to the presence of the hydrophilic hydroxyl groups on the surface of MONT particles. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011

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This paper investigates the relationship between morphology and water sorption in polylactide (PLA) films. Standard PLAs and palmityl initiated end-capped PLAs were synthesized with various terminating end groups such as hydroxyl, acetoxy, and palmitoyl end groups. Results from wide angle X-ray scattering and atomic force microscopy were correlated with different sorption phenomena, suggesting that crystallization and microphase separation between amorphous PLA and hydrophobic end-group-rich domains reduced water sorption in PLA. The morphological changes were affected by end-group composition, molecular weight and stereoisomerism.

Poly(vinyl alcohol) (PVA) having a number-average degree of polymerization of 7000 was obtained from the poly(vinyl acetate) (PVAc) having a number-average degree of polymerization 9000, a product of photo-induced emulsion polymerization of vinyl acetate (VAc), carried out at 0°C, using poly(oxyethylene) 10 nonyl phenyl ether ammonium sulfate as an anionic emulsifier. It was found that 100% conversion is always attained in the whole range of the investigation and the emulsifier plays an important role in the initiation process. The applicability of the photo-induced emulsion polymerization system to a relatively large-scale production was tested by using an apparatus equipped with an internal high-pressure Hg lamp with a capacity of several hundred grams per batch under nitrogen atmosphere. It was found that both the rate of polymerization and the degree of polymerization of resulting polymers are slightly lower than those obtained from corresponding small-scale polymerizations prepared on a high vacuum system because of the presence of oxygen.