About this family
Ring-opening polymerisation gets its driving force from somewhere the other families do not: the strain in a cyclic monomer. Open a three-membered epoxide or a four-membered lactone and the relief of bond-angle strain pays for the polymerisation, which is why these reactions run under mild conditions and why ring size predicts reactivity so well. Five- and six-membered rings are nearly strain-free and are correspondingly reluctant – six-membered lactones barely polymerise at all, while the strained three- and four-membered rings go readily.
The linkages produced are not new. A lactone opens to an ester, so poly(caprolactone) and polylactide are polyesters by a different route; an oxazoline opens to an amide. What ring-opening changes is the control you get on the way there, and that is the reason this family carries most of the library's prepolymers.
What sets the properties
Many of these polymerisations can be run as living systems, with every chain initiated at once and no inherent termination. That gives a narrow distribution and, more usefully, a chain end that is still active when the monomer runs out – so molecular weight is set by the monomer-to-initiator ratio, blocks can be added in sequence, and the ends can be capped with whatever functional group the next step needs. Nearly every telechelic and multi-arm prepolymer in this library comes from here for that reason: the poly(ethylene glycol) diols, thiols, azides, maleimides and 4- and 8-arm stars used to build hydrogels are all ring-opened ethylene oxide with a defined end group installed deliberately.
Backbone flexibility across the family is unusually high, because an ether oxygen in the chain has a low rotational barrier and no substituent at all. Poly(ethylene oxide) has a Tg of −60 °C and melts at 65 °C; poly(tetrahydrofuran), with three more methylenes between oxygens, falls to −84 °C. Symmetry decides whether the chain crystallises: poly(ethylene oxide) is regular and crystalline, while poly(propylene oxide) – identical but for a methyl on every repeat, which also creates a stereocentre – is an amorphous liquid at the same Tg. That pairing is why PEO is the water-soluble crystalline block and PPO the hydrophobic amorphous one in the Pluronic surfactants.
Poly(ethylene oxide) is also the family's naming trap. Above roughly 20,000 g/mol it is conventionally called poly(ethylene oxide) and below it poly(ethylene glycol), for the same polymer – the older name simply reflects that short chains were made as glycols. Both names appear in this library against the entries the trade uses them for.
All 93 in the library
Sorted by parent name, ignoring the leading "poly" and any locants – so poly(2-hydroxyethyl methacrylate) files under H. 82 of the 93 carry a note, and every one is searchable by drawn structure on the structure search page. 20 have a CAS registry number for the polymer; most specialty polymers have never been assigned one, and the number you find in a catalogue is usually the monomer's, which is why the field is blank rather than borrowed here.
A
Poly(amino acid ester phosphazene)
The degradable branch of the family: hanging amino acid esters on the phosphazene backbone makes the whole chain hydrolyse, and it does so to phosphate, ammonia and the amino acid - products that buffer one another, so unlike a polyester it does not acidify the tissue around it as it goes. Degradation rate is set by which ester was chosen. Not drawn: the substituent varies by design.
4-arm PEG-acrylate, 20 kDa
Photocrosslinked rather than step-grown: a radical initiator or UV light chains the acrylates together, so the junctions are short polyacrylate runs rather than single bonds and the network is less ideal than a Michael-addition gel of the same arms. It ships with about 200 ppm of MeHQ to stop it curing in the bottle, which has to be accounted for when the same inhibitor quenches the initiator you meant to use.
4-arm PEG-amine, 2 kDa
Short arms - 500 g/mol, roughly eleven oxyethylenes each - so this is a crosslinker rather than a network-forming star: it pairs with a 4-arm NHS ester or an activated acid to give a tight, high-modulus gel. The free amine is the base, not the salt, so it takes up CO2 and water on standing; that is what the substitution specification degrades against.
8-arm PEG-carboxyl, 20 kDa (tripentaerythritol core)
Sold as the acetic acid derivative, so the acid sits on a CH2 hung off the terminal ether oxygen rather than directly on the chain end. Activated in situ with a carbodiimide it couples to amines, which makes it the partner for a PEG-amine star, and the 95% substitution specification earns its keep here: every unconverted arm is a junction that never forms.
4-arm PEG-maleimide, 20 kDa
The electrophilic half of the standard synthetic-ECM hydrogel: maleimide plus a dithiol crosslinker or a cysteine-bearing peptide gels in seconds near neutral pH, which is fast enough to encapsulate cells and fast enough to be difficult to mix. Doubling the star from 10 to 20 kDa doubles the arm to 5,000 g/mol and opens the mesh accordingly. Maleimide hydrolyses to the unreactive maleamic acid above about pH 7.5, so the buffer is part of the recipe.
4-arm PEG-OH, 10 kDa
The parent of every other 4-arm PEG: pentaerythritol ethoxylated on all four hydroxyls, then usually derivatised at the arm ends into something reactive. The number in the name is the whole molecule, so a 10 kDa star has 2,500 g/mol arms - and it is the arm length, not the total, that sets the distance between crosslinks and therefore the mesh size of any gel made from it.
8-arm PEG-OH, 20 kDa (hexaglycerol core)
The generic 8-arm PEG: eight 2,500 g/mol arms on six condensed glycerols, whose eight hydroxyls - two on each end unit and one on each of the four in between - are where the arms grow. Doubling the arm count at a fixed total halves the arm, so this has the same arm as a 4-arm 10 kDa star but twice the junction density, which is what stiffens a gel made from it and lowers its swelling.
8-arm PEG-OH, 20 kDa (tripentaerythritol core)
Same arm count, same arm mass, different core - which is the whole reason the core is recorded. Three pentaerythritols joined by two ether bridges give three arms, two, then three again. JenKem states this grade has higher purity by MALDI than the hexaglycerol one and publishes a tighter polydispersity, 1.08 against 1.12, and the reason is visible in the two drawings: tripentaerythritol is one discrete molecule, while hexaglycerol is a condensate that is itself a distribution, so those stars start from a less uniform centre.
4-arm PEG-thiol, 10 kDa
The nucleophilic half of a thiol-Michael or thiol-ene gel, and the usual partner for a 4-arm maleimide or a dithiol-reactive peptide. The substitution figure is not cosmetic: at >90% the average arm count that can actually react is nearer 3.6 than 4, and gelation depends on that effective functionality rather than the nominal one. Thiols also oxidise to disulfide on standing, which consumes ends before the reaction it was weighed for.
8-arm PEG-thiol, 20 kDa (hexaglycerol core)
Eight thiols per molecule, so even at the specified >90% substitution the average molecule still carries about seven reactive arms - far above the gel point, and it will network with almost any difunctional partner. That is the point when it is wanted and the problem when it is not: the pot life is short and gelation during mixing is the usual way it fails.
Poly(aryloxyphosphazene)
The aromatic derivative of the reactive chloro polymer, and the one that made polyphosphazenes commercially interesting: aryloxy groups give a material that does not burn, producing very little smoke, while the inorganic backbone stays flexible far below zero. Those two properties together are why it was developed as fire-safe foam and wire insulation for submarines and aircraft.
B
Polybenzoxazine
A phenolic that cures by ring opening rather than condensation, so it releases no water and needs no pressure to avoid voids - the failing that has always limited conventional phenolics. It also shows near-zero cure shrinkage, and in some formulations a slight expansion, because the hydrogen-bonded network that forms is looser than the crystalline monomer it came from. Undrawn as a network.
Poly(bis(trifluoroethoxy)phosphazene)
The best-known derivative of poly(dichlorophosphazene), made by displacing both chlorines with a fluorinated alkoxide. The inorganic backbone is extraordinarily flexible - the glass transition is around -66 C - while the fluorinated side groups give a low-energy, blood-compatible surface, so it is used as a stent coating and as a fuel-resistant elastomer. It shows what the parent polymer is for: the backbone stays, the properties come entirely from what was substituted.
Polyborazylene
Built from borazine, the boron-nitrogen analogue of benzene, and pyrolysed to boron nitride - the preceramic route to a material that cannot be melted or shaped directly. Boron nitride's combination of electrical insulation with high thermal conductivity is otherwise almost impossible to obtain, and this is how it is deposited as fibre coatings and matrices. Not drawn: the polymerisation gives a crosslinked network of fused rings.
Poly(butylene oxide)
C
Capa 2201A polycaprolactone diol
A premium-grade linear polycaprolactone diol terminated in primary hydroxyls, a white waxy solid melting at 40-50 °C. Polyester polyols of this kind give cast and thermoplastic urethane elastomers better mechanical properties than the polyethers, at the cost of the ester's vulnerability to hydrolysis - the A grade exists specifically to improve prepolymer stability and hydrolysis resistance over the standard one.
Poly(caprolactone)
Cyclic olefin polymer
The homopolymer route to the same class: a substituted norbornene is ring-opened by metathesis and the resulting backbone double bonds are hydrogenated away, leaving a saturated amorphous polymer with rings hanging off it. Compared with the ethylene copolymer it is more uniform and has lower birefringence, which matters for optical discs and lenses. Not drawn: the norbornene derivative varies by grade.
D
Poly(dichlorophosphazene)
The gateway to the polyphosphazenes, and useless on its own - the P-Cl bonds hydrolyse in damp air. Its value is that both chlorines on every phosphorus can be displaced by alkoxides or amines, so a single backbone gives access to hundreds of derivatives whose properties are set entirely by what was substituted onto it, from fluoroelastomers to water-soluble drug carriers to biodegradable amino acid esters. Few polymers separate backbone from properties so cleanly.
Polydicyclopentadiene
ROMP opens the strained norbornene double bond of dicyclopentadiene and leaves the cyclopentene ring untouched - both are drawn here, the opened one as the backbone alkene and the survivor as the pendant ring. That surviving double bond is the whole point: it crosslinks during or after moulding, which turns what would be a linear ROMP polymer into a tough thermoset, and is why the monomer is injected as a liquid and cures in the mould.
Poly(dioxanone)
The ether oxygen in the backbone gives the flexibility used in monofilament absorbable sutures.
Poly(1,3-dioxolane)
A polyacetal that alternates an acetal oxygen pair with an ethylene unit, so it sits between polyoxymethylene and poly(ethylene oxide) and shares the weakness of both acetals: the chain unzips back to monomer under acid or heat. That reversibility has become the point rather than the flaw - it polymerises in place inside a lithium cell to form a solid electrolyte, and can be depolymerised and repolymerised, which is a rare example of a genuinely chemically recyclable backbone.
E
Epichlorohydrin rubber
A polyether elastomer whose chloromethyl groups provide both cure sites and polarity. The ether backbone stays flexible to about -40 C while the chlorine gives fuel resistance and, unusually for a rubber, very low permeability to hydrocarbon vapour - which is why it is used in fuel hose where emissions regulations bite. Copolymerising ethylene oxide in trades some of that barrier for better cold flexibility. Not drawn: the ratio is the grade.
Poly(epichlorohydrin)
Poly(2-ethyl-2-oxazoline)
A pseudo-polypeptide; studied as a stealth alternative to PEG.
Poly(ethylene carbonate)
Half its mass is carbon dioxide, taken straight from a cylinder and copolymerised with ethylene oxide. It is the cleanest-burning of the sacrificial binders: heated above 200 C the backbone unzips entirely to CO2 and ethylene carbonate, leaving no carbon residue, which is why it is used to hold ceramic powders in shape until firing removes it.
Poly(ethylene glycol) dimethyl ether
The repeat unit is oxyethylene, identical to poly(ethylene oxide), because that is exactly what this is - the difference is entirely at the two chain ends, where methyl ethers replace the hydroxyls. That single change removes every hydrogen-bond donor and all the reactivity, which is why the material is used as an inert, high-boiling solvent and as an electrolyte carrier rather than as a building block. No repeat unit can show an end group.
Poly(ethylene oxide)
Poly(ethylene sulfide)
Poly(ethylene oxide) with sulfur in place of oxygen, and almost its opposite: highly crystalline, melting near 200 C, and insoluble in water despite the analogy. Sulfur's larger size and weaker hydrogen-bond acceptance change the chain's whole character, which makes the pair a clean demonstration that a backbone heteroatom is not a minor substitution.
Polyethylenimine
The benchmark for getting DNA into cells, and the benchmark for polymer toxicity too. Every second backbone atom is a nitrogen, so it has the highest charge density of any common polycation and buffers strongly across the endosomal pH range - the proton-sponge effect usually invoked for its efficiency at escaping endosomes. Made by ring-opening aziridine it is heavily branched with primary, secondary and tertiary amines; made by hydrolysing a polyoxazoline it is strictly linear. The drawn repeat is the linear form.
G
Glycerine-initiated polyether triol 3000
Propylene oxide grown on glycerine, so three arms rather than two. This is the hydroxyl counterpart of a trifunctional amine: a diol and a diisocyanate give a linear chain and nothing else, and something in the recipe has to exceed a functionality of two before a network can form at all. Used for flexible slab and moulded foam. The data sheet quotes only the hydroxyl value, so no molar mass is stated here - at 56 mg KOH/g and three arms it works out near 3000, which is where the grade number comes from.
Poly(glycidol)
A polyether with a hydroxyl on every repeat - PEG with handles. Polymerised without protection it branches, because the pendant alcohols initiate new chains, giving the hyperbranched polyglycerol used as a PEG alternative in bioconjugation; protecting the hydroxyl first gives a strictly linear chain. It is as water-soluble and as protein-resistant as PEG, and unlike PEG can be loaded with many attachment points.
Poly(glycolide)
H
Poly(hexafluoroisopropylidene oxide)
Two trifluoromethyls on the same backbone carbon, the same hexafluoroisopropylidene group that separates the rings in fluorinated polyimides. It disrupts chain packing severely, so the polymer has high free volume and correspondingly high gas permeability - the structural motif behind most of the fluorinated gas separation membranes.
Poly(hexafluoropropylene oxide)
A completely fluorinated polyether, liquid over an enormous temperature range and chemically inert enough to sit in contact with liquid oxygen or fuming acid. It is the lubricant used where a hydrocarbon oil would ignite or dissolve - oxygen service, vacuum pumps, spacecraft mechanisms - and its vapour pressure is so low that it stays put in vacuum.
Poly(3-hydroxybutyrate)
The archetypal bacterial polyhydroxyalkanoate; also made by ROP of beta-butyrolactone.
Poly(3-hydroxyvalerate)
The ethyl-branched PHA; copolymerized with PHB (as PHBV) to toughen it.
J
JEFFAMINE D-2000 polyetheramine
The long member of the D series, about 33 oxypropylene units between the two amine ends. The equivalent weight is high enough that it is used less as a whole curative than as a flexibiliser blended with a shorter one: it puts a long, mobile polyether segment between crosslinks and turns a glassy network rubbery.
JEFFAMINE D-230 polyetheramine
A poly(propylene oxide) chain of one to two oxypropylene units capped at both ends with a primary amine. The amines sit on secondary carbons, so the pendant methyl sterically hinders the nitrogen and the reactivity is moderate rather than fast - which is the point in epoxy work, where it buys pot life. At an AHEW of 60, 32 parts cure 100 parts of an epoxy resin of EEW 185.
JEFFAMINE D-400 polyetheramine
The same amine-terminated poly(propylene oxide) as D-230 with a longer chain - about five to six oxypropylene units. Doubling the backbone roughly doubles the equivalent weight, so twice the mass is needed per epoxy group, and the extra ether backbone between crosslinks is what lowers the modulus and raises the elongation of the cured network.
JEFFAMINE T-403 polyetheramine
Trifunctional rather than difunctional: propylene oxide grown on a trimethylolpropane initiator, x+y+z about 5.3, then all three ends aminated. The third arm is what makes it a crosslinker rather than a chain extender - a difunctional amine and a difunctional epoxy give a linear chain, and something has to exceed two for a network to form at all.
L
Poly(lactide)
Poly(limonene carbonate)
Built entirely from orange-peel limonene and carbon dioxide, with no petrochemical carbon in the backbone at all. It is glassy and optically clear with a glass transition near 130 C, above polycarbonate's service temperature, and the isopropenyl group left dangling on each ring is a handle for thiol-ene modification after the chain is made.
M
Poly(3-methyl-3-oxetanemethanol)
A polyether carrying a free primary alcohol on every repeat unit, from cationic opening of a four-membered oxetane. The pendant hydroxyls make it a hyper-functional polyol - crosslink density is set by the backbone length rather than by end groups - which is why it turns up in high-solids urethane coatings where a conventional diol would give too loose a network.
N
Polynorbornene
The polymer ROMP was built for. Norbornene carries about 27 kcal/mol of ring strain, and relieving it drives metathesis to completion, which is why norbornene macromonomers are the standard route to bottlebrush polymers. Ring-opening is an isomerisation, so the repeat unit has the same formula as the monomer. Commercially it is sold as an oil-extended damping rubber.
O
Polyoctenamer
Made by ring-opening cyclooctene, giving a long run of methylenes between backbone double bonds. Its distinguishing behaviour is that it is partly crystalline and low in molar mass, so it melts to a thin liquid at about 55 C and then recrystallises - which makes it a processing aid that liquefies a rubber compound during mixing and stiffens it again afterwards, and a compatibiliser for recycled rubber crumb.
Poly(oxetane)
The polyether one methylene longer than poly(ethylene oxide). The four-membered ring is strained enough to open cationically but far less reactive than an epoxide, so the polymerisation is controllable; the resulting chain is more hydrophobic than PEO and crystallises well. Its substituted relatives are the interesting ones, oxetane being an easy handle for building energetic and functional polyethers.
Polyoxymethylene
Made two ways: cationic ring-opening copolymerization of trioxane (the tougher acetal copolymer) or anionic chain polymerization of formaldehyde (the Delrin homopolymer). Standard tables (Brandrup/Odian) list Tg near -83 °C and Tm near 181 °C.
P
PEG diacrylate, 2 kDa
The photocrosslinker behind most PEG hydrogels: two acrylates per chain, radical-cured in seconds, with the molar mass between them setting the mesh size and therefore the modulus and what can diffuse through it. The ester links are hydrolysable, so these gels degrade over weeks in buffer where the ether-linked ones do not.
PEG diacrylate, 3.5 kDa
The photocrosslinker behind most PEG hydrogels: two acrylates per chain, radical-cured in seconds, with the molar mass between them setting the mesh size and therefore the modulus and what can diffuse through it. The ester links are hydrolysable, so these gels degrade over weeks in buffer where the ether-linked ones do not.
PEG diacrylate, 35 kDa
The photocrosslinker behind most PEG hydrogels: two acrylates per chain, radical-cured in seconds, with the molar mass between them setting the mesh size and therefore the modulus and what can diffuse through it. The ester links are hydrolysable, so these gels degrade over weeks in buffer where the ether-linked ones do not.
PEG diacrylate, 5 kDa
The photocrosslinker behind most PEG hydrogels: two acrylates per chain, radical-cured in seconds, with the molar mass between them setting the mesh size and therefore the modulus and what can diffuse through it. The ester links are hydrolysable, so these gels degrade over weeks in buffer where the ether-linked ones do not.
PEG diacrylate, 7.5 kDa
The photocrosslinker behind most PEG hydrogels: two acrylates per chain, radical-cured in seconds, with the molar mass between them setting the mesh size and therefore the modulus and what can diffuse through it. The ester links are hydrolysable, so these gels degrade over weeks in buffer where the ether-linked ones do not.
PEG dialkyne, 5 kDa
Half of a click pair, drawn here as the propargyl ether. The copper-catalysed cycloaddition it is made for is essentially quantitative and orthogonal to everything in a protein, but the copper it needs is what keeps this chemistry out of live cells - which is why the strained-alkyne reagents exist.
PEG diamine, 2 kDa
A difunctional PEG spacer that couples through amide, urethane, urea or secondary-amine links - the stable-linkage workhorse of PEGylation, as distinct from the hydrolysable ester-linked reagents. It ships as the hydrochloride because the free amine slowly attacks the ether backbone and picks up carbon dioxide from the air; the salt has to be neutralised in situ before it will react.
PEG diamine, 3.5 kDa
A difunctional PEG spacer that couples through amide, urethane, urea or secondary-amine links - the stable-linkage workhorse of PEGylation, as distinct from the hydrolysable ester-linked reagents. It ships as the hydrochloride because the free amine slowly attacks the ether backbone and picks up carbon dioxide from the air; the salt has to be neutralised in situ before it will react.
PEG diamine, 5 kDa
A difunctional PEG spacer that couples through amide, urethane, urea or secondary-amine links - the stable-linkage workhorse of PEGylation, as distinct from the hydrolysable ester-linked reagents. It ships as the hydrochloride because the free amine slowly attacks the ether backbone and picks up carbon dioxide from the air; the salt has to be neutralised in situ before it will react.
PEG diamine, 7.5 kDa
A difunctional PEG spacer that couples through amide, urethane, urea or secondary-amine links - the stable-linkage workhorse of PEGylation, as distinct from the hydrolysable ester-linked reagents. It ships as the hydrochloride because the free amine slowly attacks the ether backbone and picks up carbon dioxide from the air; the salt has to be neutralised in situ before it will react.
PEG diazide, 10 kDa
The other half of the click pair, and the one that survives more: the azide is inert to almost everything in a biological buffer until it meets an alkyne. It is also the reason these are shipped and stored cold - organic azides decompose on heating, and a low-molar-mass one would be a genuine hazard.
PEG diazide, 3.4 kDa
The other half of the click pair, and the one that survives more: the azide is inert to almost everything in a biological buffer until it meets an alkyne. It is also the reason these are shipped and stored cold - organic azides decompose on heating, and a low-molar-mass one would be a genuine hazard.
PEG diglycidyl ether, 3.4 kDa
Crosslinks amines and hydroxyls without a catalyst or a radical source, which is why it is used to gel proteins, polysaccharides and amine-functional surfaces where a photoinitiator would not be tolerated. The oxirane opens to a secondary alcohol, so the link it forms is a stable ether rather than an ester.
PEG dimaleimide, 2 kDa
A thiol-selective crosslinker: between pH 6.5 and 7.5 the maleimide adds to a cysteine thiol far faster than to any amine present, which is what makes site-specific protein conjugation possible. Above pH 8 the ring hydrolyses to an unreactive maleamic acid, so the same buffer that speeds the reaction destroys the reagent. The substitution figure matters - at 90% the average functionality is 1.8, not 2.
PEG dimaleimide, 3.5 kDa
A thiol-selective crosslinker: between pH 6.5 and 7.5 the maleimide adds to a cysteine thiol far faster than to any amine present, which is what makes site-specific protein conjugation possible. Above pH 8 the ring hydrolyses to an unreactive maleamic acid, so the same buffer that speeds the reaction destroys the reagent. The substitution figure matters - at 90% the average functionality is 1.8, not 2.
PEG dimaleimide, 5 kDa
A thiol-selective crosslinker: between pH 6.5 and 7.5 the maleimide adds to a cysteine thiol far faster than to any amine present, which is what makes site-specific protein conjugation possible. Above pH 8 the ring hydrolyses to an unreactive maleamic acid, so the same buffer that speeds the reaction destroys the reagent. The substitution figure matters - at 90% the average functionality is 1.8, not 2.
PEG dimaleimide, 7.5 kDa
A thiol-selective crosslinker: between pH 6.5 and 7.5 the maleimide adds to a cysteine thiol far faster than to any amine present, which is what makes site-specific protein conjugation possible. Above pH 8 the ring hydrolyses to an unreactive maleamic acid, so the same buffer that speeds the reaction destroys the reagent. The substitution figure matters - at 90% the average functionality is 1.8, not 2.
PEG dimethacrylate, 1 kDa
The methacrylate analogue of PEG diacrylate. The alpha-methyl slows propagation, so cure needs more initiator or a longer exposure, but the resulting network is less prone to the oxygen inhibition that leaves acrylate gels tacky at the surface, and the ester is more hydrolytically stable.
PEG dimethacrylate, 2 kDa
The methacrylate analogue of PEG diacrylate. The alpha-methyl slows propagation, so cure needs more initiator or a longer exposure, but the resulting network is less prone to the oxygen inhibition that leaves acrylate gels tacky at the surface, and the ester is more hydrolytically stable.
PEG dimethacrylate, 20 kDa
The methacrylate analogue of PEG diacrylate. The alpha-methyl slows propagation, so cure needs more initiator or a longer exposure, but the resulting network is less prone to the oxygen inhibition that leaves acrylate gels tacky at the surface, and the ester is more hydrolytically stable.
PEG dimethacrylate, 3.4 kDa
The methacrylate analogue of PEG diacrylate. The alpha-methyl slows propagation, so cure needs more initiator or a longer exposure, but the resulting network is less prone to the oxygen inhibition that leaves acrylate gels tacky at the surface, and the ester is more hydrolytically stable.
PEG dimethacrylate, 600 Da
The methacrylate analogue of PEG diacrylate. The alpha-methyl slows propagation, so cure needs more initiator or a longer exposure, but the resulting network is less prone to the oxygen inhibition that leaves acrylate gels tacky at the surface, and the ester is more hydrolytically stable.
PEG dimethacrylate, 8 kDa
The methacrylate analogue of PEG diacrylate. The alpha-methyl slows propagation, so cure needs more initiator or a longer exposure, but the resulting network is less prone to the oxygen inhibition that leaves acrylate gels tacky at the surface, and the ester is more hydrolytically stable.
PEG dinorbornene, 10 kDa
A thiol-ene gel former that avoids the two failings of the acrylates: the strained alkene reacts by a step-growth radical addition rather than chain growth, so the network is far more uniform, and the amide link does not hydrolyse. It also needs a thiol partner to react at all, which means it will not homopolymerise in the vial.
PEG dinorbornene, 3.4 kDa
A thiol-ene gel former that avoids the two failings of the acrylates: the strained alkene reacts by a step-growth radical addition rather than chain growth, so the network is far more uniform, and the amide link does not hydrolyse. It also needs a thiol partner to react at all, which means it will not homopolymerise in the vial.
PEG dithiol, 3.5 kDa
The linear partner for a multi-arm maleimide or norbornene in thiol-Michael and thiol-ene gels, and the standard way to tether PEG to gold. Both ends oxidise to disulfide on standing, which quietly consumes the functionality that was weighed out - degassed solvent and an inert headspace are not optional here.
PEG dithiol, 5 kDa
The linear partner for a multi-arm maleimide or norbornene in thiol-Michael and thiol-ene gels, and the standard way to tether PEG to gold. Both ends oxidise to disulfide on standing, which quietly consumes the functionality that was weighed out - degassed solvent and an inert headspace are not optional here.
Polypentenamer bottlebrush
The same architecture on a thinner backbone, and a clean test of how much the backbone matters. Polynorbornene carries a fused imide ring at every repeat, which takes up room next to the backbone and pushes the side chains outward; a polypentenamer backbone, made by ring-opening cyclopentene, has nothing there. The grafts can then occupy space close to the backbone, so the molecule packs denser and its intrinsic viscosity scales more weakly with molar mass - for polystyrene grafts the scaling exponent was 0.11 against 0.19 for the polynorbornene analogue, nearly a factor of two. If a bottlebrush is being used because it is a stiff extended cylinder, the choice of backbone is part of the design rather than a detail. Leo, Jang and co-workers (Kennemur group, Florida State), ACS Polymers Au 2024, 4, 235. Drawn with the graft attached straight to a backbone carbon, which is the point of the comparison - there is no ring next to this backbone to hold the side chain off.
Poly(phenyl glycidyl ether)
An epoxide with an aryl ether side group, used chiefly as the mono-functional model for the epoxy network chemistry that DGEBA undergoes - having one epoxide rather than two it reacts with amine and stops, so the reaction can be followed to completion without gelling. It is how epoxy cure kinetics are measured.
Polyphosphoester
A backbone built on the same phosphate ester linkage that DNA uses, which makes it degradable by ordinary hydrolysis and by phosphatases, into phosphate and an alcohol. Its distinguishing feature is the fifth valence on phosphorus: a side group can be varied independently of the backbone, so charge, hydrophobicity or a drug can be changed without touching the degradation chemistry.
Poly(phthalaldehyde)
A polyacetal with a ceiling temperature below room temperature, held together only by capping both ends: remove one cap and the whole chain unzips to monomer in seconds. That makes it the model self-immolative polymer - a material designed to disappear on command - used in transient electronics and in amplified sensors where one binding event destroys an entire chain. Left undrawn because the acetal connectivity through the ring is reported inconsistently and I will not guess at it.
Poly(propiolactone)
Poly(propylene carbonate)
A polymer that is roughly half carbon dioxide by mass, made by copolymerising CO2 with an epoxide over a zinc or cobalt catalyst - one of the few routes that uses CO2 as a feedstock rather than emitting it. It is amorphous with a glass transition near room temperature, so it is soft and creeps, and it depolymerises cleanly back to the cyclic carbonate when heated, which makes it useful as a sacrificial binder that burns out without residue.
Poly(propylene glycol) 2000 diol
The workhorse polyether diol: cast elastomers, sealants, adhesives, reaction injection moulding, plasticisers and de-emulsifiers. The methyl on every repeat is what keeps it a liquid where PTMEG of the same molar mass is waxy, but it also puts the hydroxyls on secondary carbons, so it is measurably slower with isocyanate than a primary-terminated polyol - the reason formulations mix the two or cap this one with ethylene oxide.
Poly(propylene imine)
The linear polyamine one methylene longer than polyethylenimine, made by opening the strained four-membered azetidine ring. The extra carbon spaces the nitrogens far enough apart that neighbouring amines no longer suppress each other's basicity, so it protonates more completely at a given pH than the ethylene version does.
Poly(propylene oxide)
Poly(propylene sulfide)
The sulfur analogue of poly(propylene oxide), and hydrophobic where that is not. Its interest is chemical rather than mechanical: the thioether oxidises to a sulfoxide and then a sulfone, which turns the block hydrophilic, so a block copolymer containing it disassembles in the presence of reactive oxygen species. That makes it the standard oxidation-responsive block for delivery to inflamed tissue.
PTMEG 2000 polyether diol
A linear polyether diol from ring-opened tetrahydrofuran, and the soft segment behind most high-performance polyurethanes - spandex fibre, TPU, cast elastomers. Its hydroxyls are primary, so it reacts faster with isocyanate than a poly(propylene glycol) of the same molar mass, whose ends are secondary. The tetramethylene backbone is regular enough to crystallise, which is where the strength comes from and also why the neat polyol is a waxy solid near room temperature.
S
Poly(styrene oxide)
T
Poly(tetrahydrofuran)
Common soft segment in thermoplastic polyurethanes and elastomers.
Poly(tetrahydropyran)
The polyether one carbon longer than poly(tetrahydrofuran), and a useful negative result: the six-membered ring is essentially strain-free, so it will not polymerise under ordinary conditions - ring strain, not ring size, is what drives a ring-opening polymerisation. The polymer therefore has to be reached by other routes, and it exists mainly to make that point.
Poly(thionylphosphazene)
A phosphazene backbone with sulfur(VI) centres inserted, which makes the chain more polar and more thermally robust than the parent and gives a second kind of substitution site. Like the polyphosphazenes it is made as a reactive chloro polymer and then derivatised, so the backbone is fixed and the properties come from what is hung on it. Not drawn: the substituent defines the material and varies.
Poly(trifluoromethyl ethylene oxide)
A polyether with a trifluoromethyl on every repeat, so it keeps the low glass transition of poly(propylene oxide) while gaining fuel and solvent resistance the hydrocarbon version has none of. It stays flexible below -50 C, which is the combination a low-temperature fuel-system seal needs and which fluorosilicones only partly deliver.