Polymer Chemistry: Synthesis & Properties

Learning Goal: Master the foundational concepts of polymer chemistry, ranging from the fundamental classification of macromolecules and monomers to the step-by-step synthetic mechanisms (addition, condensation, ionic). Gain practical competency in interpreting macromolecular characterization data (such as molecular weight averages, polydispersity, GPC, and FTIR) and evaluating how molecular structure dictates thermal and mechanical properties (Tg, Tm, and stress-strain relationships) for advanced structural and sustainable materials.

• Prerequisites: High School Chemistry, basic understanding of Organic Chemistry functional groups.
• Estimated Total Study Time: 12 Hours

Module 1: Introduction to Macromolecules & Monomers

This module establishes the conceptual foundation of polymer science. You will learn the difference between single-unit monomers and high-molecular-weight macromolecules, explore the classification of polymers (natural vs. synthetic, structural geometry, homopolymers vs. copolymers), and trace the historical evolution of the field from accidental industrial discoveries to Hermann Staudinger's breakthrough macromolecular hypothesis.

Recommended Videos

Polymers - Basic Introduction

@TheOrganicChemistryTutor04:17258,477

Polymers - Basic Introduction

Polymers are large macromolecules composed of many smaller units called monomers. The prefix 'mono' means one, while 'poly' means many. During polymerization, monomers join to form larger macromolecules containing hundreds or thousands of repeating units. The identity of the repeating units determines the physical properties of the polymer, while end groups become less significant in long chains. Common natural polymers include DNA (nucleotide monomers), proteins (amino acid monomers), and polys

@TheOrganicChemistryTutor · 04:17

• Why this video: This video acts as a highly accessible gateway. It uses simple animations and clear organic structures to break down the "building block" analogy, explaining how repeating monomers undergo polymerization to yield enormous macromolecules. It is the perfect conceptual starting point.
• Knowledge Checkpoint:
  • Understand the root Greek terms poly and meros and define a repeating unit.
  • Differentiate between a single monomer unit and the final polymer chain.
  • Identify key structural changes that occur when monomer units link together via chemical bonds.

Mod-01 Lec-01 Introduction to Polymers

@iit57:3268,192

Mod-01 Lec-01 Introduction to Polymers

Polymers are large macromolecules composed of many repeating structural units, derived from Greek words 'poly' (many) and 'mers' (parts). They are classified into homopolymers (made from a single monomer type) and copolymers (made from two or more different monomers). Key polymer terminology includes monomers (building blocks with at least two functional groups), repeating units (the structural segment that repeats), and oligomers (shorter chain precursors). The degree of polymerization refers t

@iit · 57:32

• Why this video: This rigorous university-level lecture provides deep technical taxonomy. It covers the categorization of polymers into homopolymers and copolymers, linear vs. branched vs. cross-linked structural geometries, and provides a formal chemical engineering perspective on material classification.
• Knowledge Checkpoint:
  • Explain the structural difference between a homopolymer and a copolymer (random, alternating, block, graft).
  • Describe how linear, branched, and cross-linked molecular architectures influence overall physical space and density.
  • Define high molecular mass limits (typically $10^3$ to $10^7$ units) that characterize true polymeric materials.

Lec 29 | MIT 3.091SC Introduction to Solid State Chemistry, Fall 2010

@mitocw04:5130,473

Lec 29 | MIT 3.091SC Introduction to Solid State Chemistry, Fall 2010

Polymers were first discovered in 1839 by Eduard Simon, who made polystyrene without understanding the chemistry. In 1922, Hermann Staudinger explained polymers are macromolecules, earning the Nobel Prize in 1953 after 30 years of acceptance delay. Wallace Carothers invented neoprene (synthetic rubber) and nylon (1937) at DuPont, crucial for WWII when natural rubber was unavailable. Synthetic polymers democratized materials: nylon stockings replaced expensive silk, polymers replaced ivory for bi

@mitocw · 04:51

• Why this video: This lecture segment provides essential historical context, telling the story of Eduard Simon's accidental 1839 synthesis of polystyrene and detailing the pivotal contributions of Hermann Staudinger. This historical perspective explains why early chemists struggled to accept the existence of giant macromolecules.
• Knowledge Checkpoint:
  • Explain why early 19th-century chemists believed polymers were merely aggregate colloidal clusters rather than single covalent molecules.
  • State the significance of Hermann Staudinger’s 1922 paper and how it changed the scientific consensus.
  • Identify the historical milestone of the first commercial synthetic polymer (Bakelite, 1907).

Module 2: Polymerization Synthesis Mechanisms

This module addresses the chemical reaction pathways used to construct polymers. You will contrast the step-growth (condensation) and chain-growth (addition) polymerization mechanisms. Additionally, you will master the kinetics of free radical polymerization (initiation, propagation, and termination) and examine ionic polymerization pathways (both anionic and cationic).

Recommended Videos

Ep4 Step-growth polymerization, Carothers equation, molecular weight

@djlipomi03:1021,842

Ep4 Step-growth polymerization, Carothers equation, molecular weight

Polymerization reactions are classified into two main mechanisms: step-growth and chain-growth. In step-growth polymerization, any reactive end can react with any other reactive end, allowing random combination of chains of any length. In contrast, chain-growth polymerization involves only the growing chain end being reactive, adding monomers one at a time. Uncontrolled chain-growth results in a popcorn-like mechanism where chains grow randomly and terminate unpredictably, while controlled/livin

@djlipomi · 03:10

• Why this video: Professor Darren Lipomi explains the fundamental step-by-step kinetic differences between step-growth and chain-growth. He clarifies how any two reactive end groups in a reaction mixture can react with each other in step-growth, leading to a slow, progressive increase in molecular weight across the entire system.
• Knowledge Checkpoint:
  • Explain why monomer concentration drops rapidly at the very start of step-growth polymerization while average molecular weight increases slowly.
  • Write the basic premise of the Carothers Equation linking fractional conversion ($p$) to the average degree of polymerization ($X_n$).
  • Contrast step-growth reaction progression with chain-growth, where high-molecular-weight chains form almost instantaneously.

Introduction to Polymers - Lecture 6.2 - Free radical polymerization

@vmugaz06:3628,914

Introduction to Polymers - Lecture 6.2 - Free radical polymerization

Free radical polymerization is a chain-growth polymerization process consisting of three key steps: initiation (creation of free radical active sites through homolytic cleavage of initiators like benzoyl peroxide or AIBN, or via redox reactions), propagation (sequential addition of monomers to growing chains with the same rate constant k_p), and termination (formation of inactive/dead polymers through either disproportionation termination or combination termination). The decomposition of the ini

@vmugaz · 06:36

• Why this video: This video focuses on free radical chain-growth polymerization. It visually breaks down the three essential mechanistic stages—initiation (homolytic cleavage of organic peroxides like benzoyl peroxide), propagation (radical addition to alkene monomers), and termination (combination or disproportionation).
• Knowledge Checkpoint:
  • Draw the homolytic cleavage of a common initiator (such as benzoyl peroxide) to yield active primary radicals.
  • Write out the chemical equation showing radical attack on an asymmetric alkene monomer (like vinyl chloride or styrene), showing regioselectivity.
  • Differentiate between the two termination pathways: coupling/combination (which doubles molecular weight) and disproportionation (which yields one saturated and one unsaturated polymer end).

cationic polymerization

@sonny-824708:3355,935

cationic polymerization

Cationic polymerization is a chain-growth polymerization process initiated by a Lewis acid-co-initiator system, where the Lewis acid accepts electrons from a base to generate a proton initiator; this proton then activates monomers by accepting both electrons from their double bonds, creating a positively charged chain end that propagates by repeatedly adding new monomers; termination occurs through either chain transfer (where the proton transfers to another monomer, creating a new chain) or com

@sonny-8247 · 08:33

• Why this video: This tutorial covers ionic polymerization by exploring cationic pathways. It details how Lewis acids (such as $BF_3$ or $AlCl_3$) act as co-initiators with a proton source to generate carbocation active centers, specifying which monomer substituents stabilize this intermediate.
• Knowledge Checkpoint:
  • Identify which monomer classes undergo cationic polymerization (monomers with electron-donating substituents like alkyl, alkoxy, or vinyl groups).
  • Describe the initiation step involving a Lewis acid co-initiator complex generating a carbocation.
  • Explain the common chain-transfer and termination routes in cationic systems, highlighting why they require low temperatures to prevent premature termination.

anionic polymerization

@sonny-824704:3945,743

anionic polymerization

Anionic polymerization is a controlled polymerization technique where a negatively charged nucleophile (such as organolithium compounds) initiates the reaction by attacking a monomer, followed by propagation steps where additional monomers add to the growing chain; since this is a living polymerization, termination requires adding an external molecule like methanol to donate a proton and neutralize the active chain end, allowing precise control over molecular weight.

@sonny-8247 · 04:39

• Why this video: This video covers anionic chain-growth, demonstrating how strong nucleophiles (such as organolithium compounds like n-butyllithium) initiate anionic centers. It addresses the concept of "living polymers," where the absence of inherent termination steps allows for precise macromolecular design.
• Knowledge Checkpoint:
  • Identify monomer structures suitable for anionic polymerization (monomers with electron-withdrawing groups like cyano, nitro, or ester groups).
  • Explain why anionic systems are highly sensitive to protic impurities (like water or alcohols) which act as immediate terminating agents.
  • Define the term "living polymerization" and explain how block copolymers are synthesized by sequentially adding different monomers to a living anionic system.

Module 3: Polymer Characterization Techniques

Note: While the original feedback flagged characterization as a critical video gap, our revised pool contains excellent resources. We address these gaps using highly focused lectures.

In this module, you will learn how chemists characterize synthetic polymers. Unlike small organic molecules, polymers possess a statistical distribution of chain lengths. You will master the concepts of Number Average Molecular Weight ($M_n$), Weight Average Molecular Weight ($M_w$), and the Polydispersity Index (PDI). You will also learn the analytical mechanics of Gel Permeation Chromatography (GPC/SEC) and functional group identification via Fourier Transform Infrared (FTIR) spectroscopy.

Recommended Videos

Polymer Chemistry - Crash Course

@gatechemistry11:1537,113

Polymer Chemistry - Crash Course

This video covers essential polymer chemistry concepts including four types of molecular weight averages: number average molecular weight (MN = Σmi×ni/Σni), weight average molecular weight (MW = Σmi×ni²/Σmi×ni), Z-average molecular weight (MZ = Σmi×ni³/Σmi×ni²), and viscosity average molecular weight; the polydispersity index (PDI = MW/MN) which equals 1 for monodisperse polymers with uniform chain sizes; and tacticity classifications (isotactic, syndiotactic, and atactic) describing the spatial

@gatechemistry · 11:15

• Why this video: This crash course provides the exact mathematical formulas for the different molecular weight averages. It walks through how $M_n$, $M_w$, viscosity-average molecular weight ($M_v$), and z-average molecular weight ($M_z$) are mathematically defined, calculated, and compared.
• Knowledge Checkpoint:
  • Write out the mathematical summation formulas for: $M_n = \frac{\sum N_i M_i}{\sum N_i}$ $M_w = \frac{\sum N_i M_i^2}{\sum N_i M_i}$
  • Define the Polydispersity Index (PDI) as $M_w / M_n$ and explain what a PDI value of $1.0$ indicates versus values greater than $1.0$.
  • Explain why $M_w$ is always mathematically greater than or equal to $M_n$ for a polydisperse sample.

Number Average Molecular Weight of Polymers

@MK-Chem04:1724,494

Number Average Molecular Weight of Polymers

The number average molecular weight (Mn) characterizes polymer samples by representing the average chain size, calculated as the sum of (number of chains × molecular weight) divided by the total number of chains; for example, with chains of 10, 15, 20, and 25 kg/mol having 20, 25, 20, and 5 chains respectively, Mn equals (20×10 + 25×15 + 20×20 + 5×25)/(20+25+20+5) = 17.5 kg/mol.

@MK-Chem · 04:17

• Why this video: This video focuses on $M_n$, demonstrating how colligative property measurements (such as osmotic pressure, freezing point depression, and boiling point elevation) are physically used to calculate the absolute number of polymer chains present in a known mass sample.
• Knowledge Checkpoint:
  • Explain why colligative properties depend strictly on the number of particles in solution, making them ideal for determining $M_n$.
  • Solve a basic calculation of $M_n$ given the number of chains ($N_i$) in each molecular weight fraction ($M_i$).
  • Describe the physical significance of $M_n$ (e.g., its correlation with polymer transition temperatures and flow behavior).

Introduction to GPC in 30 minutes

@MalvernPanalytical29:4968,343

Introduction to GPC in 30 minutes

Gel Permeation Chromatography (GPC), also known as Size Exclusion Chromatography (SEC), is an analytical technique that separates macromolecules based on their hydrodynamic size rather than molecular weight, using a column packed with porous gel particles where larger molecules elute first and smaller molecules penetrate deeper into the pores; the technique employs various detectors including refractive index, UV/Vis, light scattering, and viscometer detectors to characterize molecular propertie

@MalvernPanalytical · 29:49

• Why this video: This comprehensive webinar explains the analytical principles of Gel Permeation Chromatography (GPC), also called Size Exclusion Chromatography (SEC). It clearly explains that the separation is driven by the hydrodynamic size (or volume) of the polymer chains in solution, rather than their chemical affinity or absolute mass.
• Knowledge Checkpoint:
  • Describe the internal structure of GPC column packing (porous gel beads) and explain why large polymer chains elute first while small chains elute last.
  • Draw a representative GPC chromatogram showing concentration vs. retention volume (or time) and identify where $M_n$ and $M_w$ fall relative to the peak.
  • Explain the role of mobile phase solvent choice (e.g., THF or DMF) and calibration standards in GPC analysis.

FTIR Analysis (FTIR Spectroscopy)

@labtesting05:46459,537

FTIR Analysis (FTIR Spectroscopy)

FTIR (Fourier Transform Infrared) spectroscopy is a molecular analytical technique that identifies organic, polymeric, and some inorganic materials by measuring how samples absorb infrared light, revealing unique chemical bond patterns; the analysis involves preparing samples through methods like potassium bromide pellet pressing, thin film insertion, liquid cell placement on sodium chloride plates, or attenuated total reflectance (ATR), then comparing the resulting absorbance/transmittance spec

@labtesting · 05:46

• Why this video: This video shows how FTIR spectroscopy is used to analyze polymer molecular structures. It explains how exposing samples to infrared light causes specific functional groups to absorb characteristic frequencies, creating a unique spectroscopic fingerprint.
• Knowledge Checkpoint:
  • Define the units of the horizontal axis in an FTIR spectrum (wavenumber, measured in $cm^{-1}$) and the vertical axis (Transmittance or Absorbance).
  • Identify key infrared absorption regions for common polymer functional groups (e.g., $C-H$ stretch, $C=O$ carbonyl stretch, $O-H$ hydroxyl stretch).
  • Explain how FTIR can verify that an addition polymerization reaction went to completion (e.g., monitoring the disappearance of the monomer's vinyl $C=C$ stretch around $1640\ cm^{-1}$).

Module 4: Thermal and Mechanical Properties

In this module, you will explore how a polymer's molecular architecture and chemical composition dictate its macro-scale physical behavior. You will study the differences between amorphous and semi-crystalline polymers, define the critical transition temperatures ($T_g$ and $T_m$), analyze polymer stress-strain behavior during mechanical deformation, and learn how Differential Scanning Calorimetry (DSC) is used to track these transitions.

Recommended Videos

What Is The Difference Between Melting Temperature And Glass Transition Temperature?

@Chemistry-For-Everyone03:15140

What Is The Difference Between Melting Temperature And Glass Transition Temperature?

Melting temperature (Tm) is the point where crystalline polymers transition from solid to liquid, involving a phase change where polymer chains break free from their organized structure, while glass transition temperature (Tg) marks the transition of amorphous polymers from a hard brittle state to a softer, more flexible state without a phase change, reflecting increased chain mobility; crystalline polymers have a sharp Tm, whereas amorphous polymers only exhibit Tg and gradually soften as tempe

@Chemistry-For-Everyone · 03:15

• Why this video: This concise comparison distinguishes between $T_g$ (glass transition temperature) and $T_m$ (melting temperature). It explains that $T_g$ is a second-order thermodynamic transition representing the onset of cooperative chain mobility in amorphous regions, whereas $T_m$ is a first-order phase change representing the transition of crystalline domains from solid to liquid.
• Knowledge Checkpoint:
  • Describe the physical state of a polymer below its $T_g$ (hard, glass-like, brittle) versus its state above $T_g$ but below $T_m$ (rubbery, ductile, flexible).
  • Explain why purely amorphous polymers exhibit only a $T_g$, while semi-crystalline polymers exhibit both a $T_g$ and a $T_m$.
  • Explain how chemical structural factors (such as chain stiffness, bulky side groups, and intermolecular forces) affect the value of $T_g$.

Back to Basics: Differential Scanning Calorimetry

@TMGPlastics12:18189,865

Back to Basics: Differential Scanning Calorimetry

Differential scanning calorimetry (DSC) is a thermal analytical technique that measures physical and chemical changes in polymers by subjecting a small sample to controlled temperature variations and measuring its heat flow response; the technique produces characteristic graphs showing transitions such as glass transition temperature, melting points, and recrystallization events, which can be used for material identification, evaluating material condition, detecting degradation or contamination,

@TMGPlastics · 12:18

• Why this video: This practical guide explains the operation of Differential Scanning Calorimetry (DSC). It demonstrates how a polymer sample and an inert reference pan are heated at a constant rate, tracking heat capacity changes and heat flow to identify thermal transitions.
• Knowledge Checkpoint:
  • Identify a $T_g$ transition on a DSC thermogram (visible as a step-change in the baseline heat capacity).
  • Identify crystallization peaks (exothermic peak) and melting peaks (endothermic peak) on a DSC curve, and explain the direction of heat flow for each.
  • Calculate the percent crystallinity of a semi-crystalline polymer by comparing its experimental enthalpy of melting ($\Delta H_m$) to the theoretical enthalpy of a $100\%$ crystalline reference sample ($\Delta H_m^\circ$).

Mechanical Properties of Polymer and the Stress-Strain Curve - Tensile Testing

@PolymerWorld16:2960,175

Mechanical Properties of Polymer and the Stress-Strain Curve - Tensile Testing

This video explains how to measure and understand the mechanical properties of polymeric materials using tensile testing and stress-strain curves. Key properties include: (1) Strength is the maximum stress at break, representing the material's ability to resist failure; (2) Toughness is the total energy absorbed before failure, measured as the area under the stress-strain curve, which differs from strength because a weak but highly elongatable material can be tougher; (3) Stiffness relates to th

@PolymerWorld · 16:29

• Why this video: This video explains how to measure and interpret the mechanical behavior of polymers using tensile testing. It walks through the step-by-step changes a polymer specimen undergoes when subjected to tension, connecting the molecular rearrangement of chains to regions of the stress-strain curve.
• Knowledge Checkpoint:
  • Identify the following points on a polymer stress-strain curve: Elastic Region, Yield Point, Necking/Plastic Deformation Region, and Ultimate Tensile Strength.
  • Contrast the stress-strain curves of: (a) a glassy, brittle polymer, (b) a ductile thermoplastic, and (c) an elastomer (rubber).
  • Define Young's Modulus (Elastic Modulus) as the slope of the initial linear elastic region and explain its physical meaning on the molecular level.

Module 5: Advanced Polymers & Sustainability

This module explores cutting-edge applications and environmental solutions in modern polymer science. You will study how conjugation and doping turn insulating plastics into conductive polymers, examine the 3D network structure and water absorption capacity of smart hydrogels, and analyze the chemical synthesis and degradation pathways of biodegradable plastics.

Recommended Videos

MECHANISM OF CONDUCTION IN CONDUCTING POLYMERS

@viewchem33815:4125,630

MECHANISM OF CONDUCTION IN CONDUCTING POLYMERS

Conducting polymers differ from conventional insulating polymers (like polyethylene, PVC, and Teflon) because they possess sp2 hybridized carbon backbones with unhybridized p-orbitals that enable electron delocalization; this delocalization creates conjugated pi-electron systems that allow electrical conduction. The conductivity is significantly enhanced through doping—either p-doping (using Lewis acids like iodine or FeCl3 to remove electrons and create positive charge carriers called polarons

@viewchem338 · 15:41

• Why this video: This video provides an animation explaining how certain polymers conduct electricity. It details how $sp^2$ hybridized carbon backbones generate a continuous system of overlapping, unhybridized $p$-orbitals, creating a delocalized $\pi$-bond system that allows electron movement when doped.
• Knowledge Checkpoint:
  • Identify the structural requirement for polymer conductivity (alternating single and double carbon-carbon bonds, or a conjugated backbone).
  • Explain the difference between p-doping (oxidation/removing electrons) and n-doping (reduction/adding electrons) in conductive polymers like polyacetylene or polyaniline.
  • Explain how polaron and bipolaron charge carriers form and migrate along the conjugated polymer backbone.

Not quite a solid, not quite a liquid: Meet hydrogels

@mit04:59150,785

Not quite a solid, not quite a liquid: Meet hydrogels

Hydrogels are soft, flexible, water-rich materials composed of polymer networks that can absorb up to 99% water by weight, existing in a state between solid and liquid; they have diverse applications including biomedical uses like tissue engineering and scar tissue prevention, agricultural sensors for real-time crop monitoring, and atmospheric water harvesting systems that capture moisture from air using salt-tailored hydrogels, offering promising solutions for healthcare, food security, and cle

@mit · 04:59

• Why this video: This video introduces hydrogels, describing them as soft, flexible materials composed of highly hydrophilic polymer networks. It explains how chemical or physical cross-links prevent these structures from dissolving, allowing them to absorb and retain enormous volumes of water.
• Knowledge Checkpoint:
  • Define physical cross-linking (hydrogen bonding, ionic interactions) vs. chemical cross-linking (covalent bonds) within hydrogel networks.
  • Explain why hydrogels are highly hydrophilic and describe the thermodynamic balance between the osmotic swelling force and the elastic retractive force of the network.
  • List two biomedical applications of hydrogels, explaining how their soft, water-rich structure mimics natural extracellular matrices.

The Chemistry of Bioplastics

@scienceislifeofficial08:546,559

The Chemistry of Bioplastics

Bioplastics are plastics made from renewable resources like plants that work similarly to oil-based plastics but are biodegradable; they are created through polymerization where monomers (such as lactic acid derived from corn starch) bond together to form long polymer chains, and their properties can be modified by adjusting the degree of polymerization or adding additives like glycerin to increase elasticity.

@scienceislifeofficial · 08:54

• Why this video: This educational video covers the chemistry of bioplastics and biodegradable polymers. It contrasts oil-based, non-degradable polymers with plant-derived, biodegradable alternatives like polylactic acid (PLA), detailing how ester linkages in PLA are broken down through hydrolytic and enzymatic cleavage.
• Knowledge Checkpoint:
  • Differentiate between bio-sourced (made from renewable resources) and biodegradable (capable of decomposing under environmental conditions) polymers.
  • Describe the chemical synthesis of PLA (ring-opening polymerization of lactide).
  • Explain the chemical mechanism of PLA degradation (ester hydrolysis, breaking the polymer chain down into lactic acid monomers).

Course Map

Key People Index

• Hermann Staudinger (1881–1965)
  • Context: Mentioned in Module 1 (MIT Lecture). Staudinger is considered the father of macromolecular chemistry. He proposed that polymers are giant molecules held together by standard covalent bonds, a concept for which he received the 1953 Nobel Prize in Chemistry.
• Leo Baekeland (1863–1944)
  • Context: Highlighted in Module 1 as the commercializer of Bakelite (1907), the world’s first fully synthetic plastic, which catalyzed the growth of the modern plastics industry.
• Eduard Simon (1789–1856)
  • Context: Mentioned in Module 1 (MIT Lecture). An apothecary who accidentally synthesized polystyrene in 1839 by distilling storax resin, though he did not understand the macromolecular nature of the product.
• Wallace Carothers (1896–1937)
  • Context: Highlighted in Module 2 (UCSD NANO 134 Darren Lipomi). Carothers developed the kinetic equations governing step-growth polymerization and led the DuPont team that invented Nylon-6,6 and Neoprene.

Final Self-Assessment

Complete this comprehensive self-assessment to verify your mastery of the curriculum:

• Monomer vs. Polymer: Can you define a repeating unit and write out the structural formula of a polymer chain given its monomer structure?
• Step-Growth vs. Chain-Growth: Can you list three key differences in polymerization kinetics, monomer consumption, and average molecular weight development between these two mechanisms?
• Free Radical Polymerization: Can you draw the complete curved-arrow mechanism for the initiation, propagation, and termination of polystyrene from styrene monomers and a peroxide initiator?
• Ionic Polymerization: Can you explain why cationic polymerization requires electron-donating substituents, while anionic polymerization requires electron-withdrawing substituents?
• Molecular Weight Calculations: Can you write the formulas for $M_n$ and $M_w$ and calculate the Polydispersity Index (PDI) of a polymer sample given its molecular weight distribution?
• GPC Separation Mechanism: Can you explain why larger polymer chains elute faster than smaller chains in a Gel Permeation Chromatography column?
• FTIR Spectroscopy: Can you identify the wavenumber region for a carbonyl group stretch ($1700\text{--}1750\ cm^{-1}$) and explain how FTIR is used to monitor polymerization progress?
• $T_g$ vs. $T_m$: Can you explain the structural and mechanical changes that occur when an amorphous polymer is heated through its glass transition temperature?
• DSC Interpretation: Can you look at a DSC thermogram and identify the step-change ($T_g$), the exothermic crystallization peak ($T_c$), and the endothermic melting peak ($T_m$)?
• Stress-Strain Behavior: Can you sketch and label the stress-strain curves for a brittle polymer, a ductile plastic, and an elastomer, and explain how chain orientation relates to yield behavior?
• Conductive Polymers: Can you describe how conjugation along a carbon backbone, combined with doping, allows polymers to conduct electricity?
• Biodegradable Chemistry: Can you explain the chemical mechanism of polylactic acid (PLA) degradation and how its ester bonds make it susceptible to hydrolysis?