39 Questions
What type of interactions can cause crosslinks in hydrogels?
Covalent bonding, hydrogen bonds, van der Waals interactions, ionic interactions
What type of polymer yields a hydrogel when lightly crosslinked?
Lightly crosslinked hydrophilic polymer
What forces can form non-covalent physical hydrogels?
Molecular entanglements, van der Waals, hydrogen bonding, hydrophobic forces
What is the classification based on ionic charges for hydrogels?
Neutral, Anionic, Cationic or Ampholytic
What type of hydrogel classification involves more than three types of mers?
Multipolymer hydrogels
What is the term for the connections between chains in a hydrogel?
Crosslink
What is the ideal network structure involving tetrafunctional covalent crosslinks called?
Ideal network with tetrafunctional covalent crosslinks
What can be controlled by polymer composition and crosslink density in hydrogels?
Swelling Ratio
What is the term for a polymer comprising two or more networks which are at least partially interlaced on a molecular scale but not covalently bonded to each other?
Interpenetrating Polymer Network (IPN)
What is the purpose of blood-compatible coatings using hydrogels?
Preventing protein deposition and platelet adhesion
What type of hydrogel is used for tissue engineering scaffolds such as artificial tendon and cartilage?
Hydrogels with controlled swelling ratio
What is the term for a polymer network that absorbs water and expands after polymerization?
Swelling hydrogel
What is the term for the ratio of the weight of swollen sample to that of the dry sample expressed as percentage?
Weight ratio
What is the term for a mixture of two or more preformed polymer networks that is NOT an Interpenetrating Polymer Network (IPN)?
A mixture of two or more preformed polymer networks
What type of interactions can cause crosslinks in hydrogels?
Chemical reaction
Match the following with their description:
Hydrogels = Water swellable crosslinked polymers Thermoset = Highly crosslinked polymer Elastomer = Lightly crosslinked polymer JELL-O = Hydrogel made from a naturally derived polymer
Match the following with their examples:
Covalently Crosslinked Hydrogels = pHEMA + EGDMA (Ethylene Glycol Dimethacrylate) Non-covalent Physical Hydrogels = Formed by molecular entanglements and/or secondary forces such as van der Waals, H-bonding or hydrophobic forces Polymers = Comprising two or more networks which are at least partially interlaced on a molecular scale but not covalently bonded to each other Crosslinks = Connections between chains in a hydrogel
Match the following with their primary cause of crosslinks:
Covalently Crosslinked Hydrogels = Crosslinks caused by reaction (covalent bonding) between 'mers' Non-covalent Physical Hydrogels = Formed by molecular entanglements and/or secondary forces such as van der Waals, H-bonding or hydrophobic forces Ionic interactions = Cause of crosslinks in hydrogels van der Waals interactions = Cause of crosslinks in hydrogels
Match the following hydrogel classification with their descriptions:
Homopolymer hydrogels = Hydrogels formed from one type of hydrophilic mer Copolymer hydrogels = Hydrogels formed from two types of mers, at least one hydrophilic Multipolymer hydrogels = Hydrogels formed from more than three types of mers Interpenetrating polymeric hydrogels = Hydrogels formed by swelling a network of polymer1 in mer2 or making intermeshing network of polymer1 and polymer2
Match the following hydrogel classification with their structural or morphological properties:
Amorphous hydrogels = Hydrogels with a random network structure Semicrystalline hydrogels = Hydrogels with dense regions of 'order' Non-covalently bonded hydrogels = Hydrogels formed through assembly systems Crosslink structure = The ideal network structure with tetrafunctional covalent crosslinks (rare)
Match the following hydrogel classification with their ionic charges:
Neutral hydrogels = Hydrogels with no net charge Anionic hydrogels = Hydrogels with a negative charge Cationic hydrogels = Hydrogels with a positive charge Ampholytic hydrogels = Hydrogels with both positive and negative charges
Match the following components with their role in the design of hydrogels:
Hydrophilic component = Monomers, oligomers, or polymers bearing polar groups like hydroxyl (-OH), carboxyl (-COOH), amide (-CONH), sulfhydryl (-SH), sulfate (-SO3H) etc. Crosslinking component = Bifunctional or multifunctional mer used for crosslinking the hydrogel Radiation reactions = Inducing crosslinks in hydrogels through electron beams, gamma-rays, X-rays, or UV Chemical crosslinking = Creating crosslinks in hydrogels using small molecular weight crosslinking agents or copolymerization-crosslinking reactions
Match the following forces with their role in the swelling of hydrogels:
Swelling force = The thermodynamically driven force that causes the polymer network to absorb water and expand Retractive force = The force of the crosslinked structure that counterbalances the swelling force Equilibrium = When the swelling force and retractive force become equal Degree of swelling = Influences solute diffusion coefficient, polymer surface properties, optical properties, and mechanical properties
Match the following hydrogels with their examples:
Highly swollen hydrogels = Cellulose derivatives, poly(vinyl alcohol), poly(N-vinyl 2-pyrrolidone), PNVP, poly(ethylene glycol) Moderately or poorly swollen hydrogels = Poly(hydroxyethyl methacrylate) (PHEMA) and derivatives Controlled release drug delivery devices = Application of highly swollen hydrogels Blood-compatible coatings = Application of highly swollen hydrogels to prevent protein deposition and platelet adhesion
What type of hydrogel classification involves more than three types of mers?
Multipolymer hydrogels
What is the term for a polymer comprising two or more networks which are at least partially interlaced on a molecular scale but not covalently bonded to each other?
Interpenetrating Polymer Network (IPN)
What is the ideal network structure involving tetrafunctional covalent crosslinks called?
Ideal network with tetrafunctional covalent crosslinks
What is the term for the connections between chains in a hydrogel?
Crosslink or junction
What is the classification based on ionic charges for hydrogels?
Neutral, Anionic, Cationic, or Ampholytic
What forces can form non-covalent physical hydrogels?
Assembly systems
What is the term for a polymer network that absorbs water and expands after polymerization?
Hydrophilic gel
What type of polymer yields a hydrogel when lightly crosslinked?
Hydrophilic polymer
What is the purpose of blood-compatible coatings using hydrogels?
Prevents protein deposition and platelet adhesion
What can be controlled by polymer composition and crosslink density in hydrogels?
Swelling ratio
What is the term for the ratio of the weight of swollen sample to that of the dry sample expressed as percentage?
Swelling ratio
What is the term for a mixture of two or more preformed polymer networks that is NOT an Interpenetrating Polymer Network (IPN)?
Not an IPN
Explain the difference between covalently crosslinked hydrogels and non-covalent physical hydrogels, and provide an example of each type.
Covalently crosslinked hydrogels are formed by covalent bonding between polymer chains, while non-covalent physical hydrogels are formed by molecular entanglements and/or secondary forces such as van der Waals, hydrogen bonding, or hydrophobic forces. An example of covalently crosslinked hydrogel is pHEMA + EGDMA (Ethylene Glycol Dimethacrylate), used for soft contact lenses. An example of non-covalent physical hydrogel is JELL-O, made from a naturally derived polymer collagen.
What are the different types of interactions that can cause crosslinks in hydrogels, and how do they contribute to the formation of hydrogels?
The different types of interactions that can cause crosslinks in hydrogels are covalent bonding between polymer chains, hydrogen bonds, van der Waals interactions, and ionic interactions. Covalent bonding leads to the formation of covalently crosslinked hydrogels, while hydrogen bonds, van der Waals interactions, and ionic interactions contribute to the formation of non-covalent physical hydrogels.
What is the relationship between crosslink density and the properties of hydrogels, and how does it impact their applications in medicine?
Crosslink density in hydrogels is related to their swelling behavior, mechanical strength, and biocompatibility. Higher crosslink density generally leads to reduced swelling, increased mechanical strength, and improved biocompatibility. This relationship impacts the design of hydrogels for specific medical applications, such as drug delivery, tissue engineering, and wound healing, where controlled swelling, mechanical properties, and biocompatibility are crucial factors.
Test your knowledge on hydrogels in medicine with this quiz based on the lecture by Anirban Sen Gupta, Ph.D. Explore the properties and crosslinking mechanisms of hydrogels, and assess your understanding of their applications in the medical field.
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