Synthesis of pH- and Temperature-Responsive Hydrogels

Hydrogels were synthesized by copolymerizing chitosan, MAA, NIPAM, and MBA using ammonium persulfate as an initiator.

Material samples were analyzed using a spectrometer to identify and quantify components.

FTIR analysis provided information about the relative changes in different components in the hydrogel by analyzing the peak areas of various molecules.

Solid-state 13C NMR was used to support FTIR analysis and provide further details about different components of the hydrogel.

1% glacial acetic acid was used to dissolve chitosan in deionized water; part of the hydrogel preparation.

Hydrogels were freeze-dried and processed using membrane filtration.

A molecular-porous membrane used for separating components in the hydrogel preparation during analysis using filtration.

The ratio of peak areas from FTIR analysis indicates the relative amounts of components (MAA, PNIPAM, chitosan) compared to other component peaks.

A measure of the electrical charge on the surface of a particle in a solution. It determines how particles interact and influences the stability of the hydrogel.

A technique used to determine the zeta potential of particles, using a Zetasizer instrument that measures the movement of charged particles in an electric field.

Changes in temperature can affect the stability of hydrogels by altering the zeta potential of particles within the hydrogel. Higher temperatures can lead to increased particle movement and potential destabilization.

Different pH values can alter the charge of the particles in a hydrogel, affecting their zeta potential and ultimately impacting the stability of the hydrogel.

SPAN 80 acts as a stabilizer in the emulsion by forming a monolayer film at the oil-water interface. It helps control the formation of homogeneous hydrogels with well-defined shapes.

Hydrogels can swell and shrink in response to changes in their environment. This behavior is influenced by factors like pH, temperature, and the composition of the hydrogel.

A technique used to analyze the chemical composition and structure of materials by examining the interaction of infrared radiation with the sample.

FTIR analysis can help determine the relative amounts of different components (MAA, PNIPAM, chitosan) in hydrogels based on the intensity of specific peaks in the spectra.

Hydrogels are materials that absorb water and swell, creating a gel-like substance.

These hydrogels are made by combining chitosan, MAA, NIPAM, and MBA, forming a network structure that can absorb water.

This refers to the movement of the carbon-oxygen double bond (C=O) in a molecule, observed as a specific peak in FTIR spectra.

This refers to the bending motion of the carbon-hydrogen bond (C-H) in a molecule, also detected in FTIR spectra.

Methacrylic acid (MAA) is a component of the hydrogel network, contributing to its structure and properties.

N-isopropylacrylamide (NIPAM) is another component of the hydrogels, affecting their response to temperature.

Cross-linking refers to the formation of connections between polymer chains in the hydrogel, giving it its structure and strength.

Hydrogels expand when exposed to certain environment changes like pH or temperature, due to the absorption of water within the network.

More cross-linking in a hydrogel leads to a more rigid structure and less swelling since the network is more constrained.

The duration of the hydrogel synthesis affects the size, swelling, and zeta potential, as the amount and distribution of components vary over time.

Repulsion forces between charged particles within the hydrogel, which can prevent shrinkage or collapse by keeping the network expanded.

The temperature at which the hydrogel shrinks due to the loss of water and a change in the structure.

The effective size of a particle in solution, taking into account its shape and hydration. It measures the size of the particle as it moves through a fluid.

The amount of poly(N-isopropylacrylamide), a temperature-sensitive polymer, present in the hydrogel. It significantly affects how the hydrogel responds to changes in temperature.

The process of methacrylic acid (PMAA) gaining a negative charge when exposed to a solution. It can influence the hydrogel's swelling behavior.

The disruption of weak bonds between molecules, often caused by temperature changes. It can affect the hydrogel's structure and properties.

The final size of the hydrogel after it loses water and collapses. It reflects how much the hydrogel shrinks from its maximum swelling point.

Changes in temperature can directly influence the swelling of a hydrogel. Increased temperature can cause expansion or contraction depending on the hydrogel's composition.

Higher zeta potentials can lead to increased swelling of hydrogels, as the charged particles repel each other, creating space for water to enter.

Hydrogels are materials that absorb water and swell, forming a gel-like substance. They are made by cross-linking polymer chains, creating a network that holds water.

Chitosan is a natural polymer derived from chitin, a component of shellfish shells. It has unique properties that make it useful in biomaterials and drug delivery.

Methacrylic acid (MAA) is a monomer used in the synthesis of hydrogels. It adds acidic properties and contributes to the network structure.

N-isopropylacrylamide (NIPAM) is a monomer that makes hydrogels sensitive to temperature. It influences the swelling and shrinking of the hydrogel.

Cross-linking in hydrogels involves the formation of connections between polymer chains, creating a strong and stable network structure. This gives the hydrogel its shape and strength.

Zeta potential is the electrical charge on the surface of a particle in a hydrogel. It influences how particles interact and affects the stability of the hydrogel. A high zeta potential means more repulsion between particles, leading to better stability.

Temperature changes can affect the swelling and shrinking of hydrogels, especially those containing NIPAM. At higher temperatures, the hydrogel can shrink, while at lower temperatures, it can swell more.

Changes in pH can affect the swelling, shrinking, and stability of hydrogels. Some hydrogels are pH-sensitive, meaning they swell more at certain pH values.