Sequence-Uniform Aliphatic Copolyester Via Controlled Monomer Feed
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Solution Overview
Problem
Conventional batch ring-opening copolymerization processes fail to control monomer sequence distribution in PLGA, leading to non-uniform polymer chains and poor performance in pharmaceutical applications, particularly in drug release.
Innovation Solution
A scalable semi-batch copolymerization protocol with controlled comonomer feed rates, known as feed rate-controlled polymerization, is used to produce statistically sequence-controlled PLGA polymers, ensuring uniform monomer distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional batch ring-opening copolymerization is used, then the polymerization process is simple, but the monomer sequence distribution is non-uniform leading to poor drug release performance
Solution Approach 1:
The patent applies dynamic control of monomer feed rates during polymerization. The feed rates of lactide and glycolide are continuously adjusted based on their respective reactivity ratios and desired sequence distribution, transforming a static batch process into a dynamic semi-batch process that achieves uniform monomer sequencing despite varying reactivities.
Solution Approach 2:
The patent changes the polymerization parameters by controlling monomer feed rates as key variables. By adjusting the feed rates of different monomers (lactide and glycolide) to match their consumption rates, the process achieves uniform sequence distribution. This parameter control approach allows precise manipulation of polymer structure while maintaining process feasibility.
2Manufacturing precision
If only the more reactive monomer is continuously added, then the reactive monomer consumption is compensated, but the monomer sequence distribution remains non-uniform
Solution Approach 1:
The patent applies local quality control by treating each monomer type differently in the feed system. Instead of uniform addition, each monomer (lactide and glycolide) is fed at its own optimized rate based on its reactivity and desired local sequence composition, achieving uniform overall distribution while maintaining high polymerization efficiency.
Solution Approach 2:
The patent implements feedback control where the monomer feed rates are determined based on their consumption rates during polymerization. The system continuously adjusts the feed of lactide and glycolide to match their respective consumption, ensuring uniform sequence distribution is maintained throughout the polymerization process without sacrificing productivity.
3Manufacturing precision
If simultaneous feeding of multiple monomers is used, then the monomer sequence uniformity is improved, but the process control complexity increases
Solution Approach 1:
The patent segments the monomer feed system into separate controlled streams for lactide and glycolide. Each monomer has its own feed rate control mechanism, allowing independent optimization of feed rates based on reactivity ratios. This segmentation simplifies the control strategy by treating each monomer separately rather than managing complex simultaneous interactions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method results in PLGA polymers with improved drug release characteristics and favorable drug loading, demonstrating significant variation in key physicochemical properties based on monomer sequence control.
Implementation Method 1
continuously contacting at least, a first monomer and a second monomer with an initiator and a catalyst to initiate ring-opening copolymerization of the first monomer and the second monomer
Implementation Method 2
continuously contacting at least, a first monomer and a second monomer with an initiator and a catalyst to initiate ring-opening copolymerization
Data Source
AI summary
Various aspects disclosed relate to a method of preparing a substantially sequence-uniform aliphatic copolyester. The method includes continuously contacting at least, a first monomer and a second monomer with an initiator and a catalyst to initiate ring-opening copolymerization of the first monomer and the second monomer. In the method the first monomer and the second monomer are contacted with the initiator and catalyst at a feed rate that is slower than a polymerization rate of the first monomer and the second monomer.