Layer-by-Layer Membrane Fabrication for Permeability-Selectivity Trade-off

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Solution Overview

Problem

Synthetic polymeric membranes face a trade-off between permeability and selectivity due to structural variations, limiting their performance in applications like water desalination and gas separations, while biological membranes offer high permeability and selectivity but are costly and difficult to scale up.

Innovation Solution

A layer-by-layer approach is used to create membrane compositions with a porous support and layers of positively and negatively charged polymers and nanosheets, incorporating artificial channels like peptide-appended pillar[5]arene channels to achieve high permeability and selectivity, overcoming the trade-off by designing membranes with precise pore structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If synthetic polymeric membranes use structural variations to affect separation, then selectivity is improved, but permeability deteriorates

Engineering Contradiction:

ImproveselectivityVSAvoidpermeability

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent employs porous support structures with controlled pore sizes and distributions to enable selective transport. The porous architecture allows multiple transport pathways including pore flow, surface diffusion, and solution-diffusion mechanisms, thereby achieving both high selectivity through precise pore sizing and high permeability through optimized porosity and interconnected pore networks

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent utilizes composite membrane structures combining different materials with complementary properties. This includes incorporating inorganic fillers, organic-inorganic hybrids, and multi-layer compositions to simultaneously achieve molecular-level selectivity and enhanced permeability that cannot be obtained with single-material systems

Inventive Principle:

Principle #40Composite materials

2Productivity

If biological membrane proteins are used to achieve high permeability and selectivity, then performance is improved, but fabrication difficulty and cost increase

Engineering Contradiction:

ImprovepermeabilityVSAvoidfabrication difficulty

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent creates synthetic copies of biological channel proteins with defined pore geometries and functional groups that replicate the size-exclusion and selective transport mechanisms of natural channels. These synthetic analogs can be manufactured through conventional polymer processing techniques, eliminating the fabrication difficulties and high costs associated with incorporating actual biological proteins while maintaining their superior separation performance

Inventive Principle:

Principle #26Copying

3Productivity

If porous membranes are used for ultrafiltration and microfiltration, then permeability is improved, but selectivity deteriorates due to broad pore size distribution

Engineering Contradiction:

ImprovepermeabilityVSAvoidselectivity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent implements local quality control by creating membranes with spatially varying pore size distributions tailored to specific separation requirements. Different regions or layers of the membrane have optimized pore sizes and densities for selective rejection of target molecules, achieving sharp molecular weight cutoffs and high selectivity while maintaining overall high permeability through the porous structure

Inventive Principle:

Principle #3Local quality

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 membranes with significantly enhanced permeability and selectivity, achieving performance orders of magnitude better than commercial membranes, with dense channel packing and scalable fabrication without defects, suitable for precise molecular separations.

Implementation Method 1

A layer-by-layer approach is used to create membrane compositions with a porous support and layers of positively and negatively charged polymers and nanosheets

Methodology Applied

Scientific EffectElectrostatic interaction: Electrostatics

Implementation Method 2

size exclusion is the major mechanism for water-over-solute selectivity of biological water channel proteins, aquaporins

Methodology Applied

Scientific EffectSize exclusion: Molecular Sieve

Implementation Method 3

In the cases of angstrom-scale separations such as water desalination and gas separations, where nonporous polymeric membranes operate via the solution-diffusion mechanism, the variable size of the free volume elements through which diffusion occurs hampers membrane performance

Methodology Applied

Scientific EffectSolution-diffusion: Diffusion

Data Source

PatentUS11745146B2Method for biological or biomimetic channel-based membrane fabrications using layer-by-layer structure

Publication Date: 2023.09.05 THE PENN STATE RES FOUND INC

AI summary

The present disclosure describes membrane compositions and methods for preparing membrane compositions. In particular, the methods employ a layer-by-layer approach to membrane preparation. The membrane compositions provide significantly enhanced membrane performance over existing commercial membranes, particularly in terms of permeability and selectivity.