Ester Side Groups Research Articles

Synthesis and characterization of new biodegradable thermosensitive polyphosphazenes with lactic acid ester and methoxyethoxyethoxy side groups

Two novel biodegradable thermosensitive polyphosphazenes with lactic acid ester and methoxyethoxyethoxy side groups were synthesized via the macromolecular substitution reactions of poly(dichlorophosphazene) with the sodium salt of lactic acid ester and sodium methoxyethoxyethoxide. Their structures were confirmed by 31P NMR, 1H NMR, 13C NMR, IR, DSC, and elemental analysis. The lower critical solution temperature (LCST) behavior in water and in vitro degradation property of the polymers was investigated. The results indicated that two polymers showed LCST phase transition over a range of concentrations from 0.13 to 15 wt% and pH-sensitive degradation properties.

Synthesis of acyl chitin derivatives and miscibility characterization of their blends with poly( ε-caprolactone)

Chitin derivatives having a normal acyl group (side-chain carbon number, N = 2–6) at different degrees of substitution (DS) were synthesized by a homogenous reaction of crab-shell chitin with various acyl chlorides in N, N-dimethylacetamide–LiCl solution. NMR analysis quantitatively demonstrated the acylations not only for C3/C6 hydroxy protons but also for C2 amino proton(s). Solution cast blend films of the acyl chitin products with poly( ε-caprolactone) (PCL) were provided for the miscibility characterization by differential scanning calorimetry. The critical total-DS required for attaining a miscibility of the blending polymer pair decreased with an increase in N. The degree of miscibility was enhanced definitely with an increase in ester-DS, but it made less correlation with amide-DS. In analogy with cellulose ester/PCL blend systems, a structural affinity of the ester side-group of the chitinous component considered with a repeating unit of PCL may be a crucial factor for the miscibility attainment.

Hydrogen bonding in blends of polyesters with dipeptide‐containing polyphosphazenes

AbstractNew biomedically erodible polymer composites were investigated. Polyphosphazenes containing the dipeptide side groups alanyl–glycine ethyl ester, valinyl–glycine ethyl ester, and phenylalanyl–glycine ethyl ester were blended with poly(lactide‐co‐glycolide) (PLGA) with lactic to glycolic acid ratios of 50 : 50 [PLGA (50 : 50)] and 85 : 15 [PLGA (85 : 15)] with solution‐phase techniques. Each dipeptide ethyl ester side group contains two NH protons that are capable of hydrogen bonding with the carbonyl functions of PLGA. Polyphosphazenes that contain only the dipeptide ethyl ester groups are insoluble in organic solvents and are thus unsuitable for solution‐phase composite formation. To ensure solubility during and after synthesis, cosubstituted polymers with both dipeptide ethyl ester and glycine or alanine ethyl ester side groups were used. Solution casting or electrospinning was used to fabricate polymer blend matrices with different ratios of polyphosphazene to polyester, and their miscibilities were estimated with differential scanning calorimetry and scanning electron microscopy techniques. Polyphosphazenes with alanyl–glycine ethyl ester side groups plus the second cosubstituent were completely miscible with PLGA (50 : 50) and PLGA (85 : 15) when processed via solution‐casting techniques. This suggests that the hydrogen‐bonding protons in alanyl–glycine ethyl ester have access to the oxygen atoms of the carbonyl units in PLGA. However, when the same pair of polymers was electrospun from solution, the polymers proved to be immiscible. Solution‐cast miscible polymer blends were obtained from PLGA (50 : 50) plus the polyphosphazene that was cosubstituted with valinyl–glycine ethyl ester and glycine ethyl ester side groups. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Characterization and properties of a polythiophene with a malonic acid dimethyl ester side group

A new polythiophene derivative bearing a malonic acid dimethyl ester substituent attached to the 3-position of the repeat unit has been prepared by chemical oxidative-coupling polymerization. The chemical structure of poly(2-thiophen-3-yl-malonic acid dimethyl ester) has been analyzed by FTIR and 1H NMR spectroscopy and, additionally, the distribution of the head-to-tail and head-to-head diads arising from polymerization was found to be a 75–25%. The glass transition temperature identified for this polymer was 17.6 °C lower than that recently determined for a closely related polythiophene derivative, in which the ester substituent arose from acrylic acid rather than from malonic acid. On the other hand, the electrical conductivity of the new material, which was soluble in polar solvents but not in water, was higher than that typically found for poly(3-alkylthiophene) derivatives. Ab initio quantum mechanical calculations on simple model compounds were used to predict the regiochemistry of the polymer chain, which was in excellent agreement with the experimental observation, and the conformational preferences of both the inter-ring dihedral angle and the bulky side group. Interestingly, calculations predict that the inter-ring dihedral angles adopt a syn-gauche conformation rather than the anti-gauche arrangement typically found in substituted polythiophenes. Thus, in this case the former conformation reduces the strong repulsive interactions induced by the bulky substituent. The lowest π–π ∗ transition energy derived from calculations on an idealized molecular model is in agreement with the experimental estimation determined using UV–vis spectroscopy. This electronic property is significantly higher for poly(2-thiophen-3-yl-malonic acid dimethyl ester) than for other substituted polythiophene derivatives, which is consequence of the geometrical distortions induced by bulky side group.

Study of ion and vacuum ultraviolet-induced effects on styrene- and ester-based polymers exposed to argon plasma

Plasma-polymer interactions are important for the purpose of etching, deposition, and surface modification in a wide range of different fields. An Ar discharge from an inductively coupled plasma reactor was used to determine the factors in a simple plasma that control etch and surface roughness behavior for three styrene-based and three ester-based model polymers. The authors compared the etch behavior of polymers in Ar plasma discharges with low and high energy ions by changing the substrate bias, compared cooled and elevated substrate temperature conditions, and compared fully plasma-exposed conditions and vacuum ultraviolet (vuv)-only conditions by employing a magnesium fluoride window to prevent ion bombardment in the vuv-only case. It was found that ions, vuv radiation, and temperature all had significant impact on the etch behavior of polymers. The dependence of polymer structure on etch and surface roughness was also compared. Polymers with styrene and ester side groups were compared and polymers with α-hydrogen and with α-methyl were compared. It was found that for styrene-based polymers, there was a large difference in material removal between α-hydrogen [poly(4-methylstyrene)(P4MS)] and α-methyl [poly(α-methylstyrene) (PαMS)] structures. This difference was highly temperature dependent, and the ceiling temperature of the polymers was found to be the most important property to consider. Below the ceiling temperature, the amount of material removed in P4MS and PαMS was the same, but above it there was a dramatic material loss in PαMS not seen in P4MS. For the ester-based polymers, it was established that oxygen depletion occurred before any other mechanism and the most important factor to consider was oxygen content in the polymer. By using in situ ellipsometry, it was also found that at temperatures below the ceiling temperature modification by vuv radiation of PαMS created a slightly denser layer at the surface with higher index of refraction. This effect was not seen in P4MS. It was observed that in general, low energy ions contributed to material removal by physical sputtering at the polymer surface and the amount of material removal increased with oxygen content in the polymer. vuv radiation caused bulk depolymerization and oxygen depletion reactions that were highly polymer structure specific and temperature dependent. High energy ion bombardment was found to create an amorphous carbonlike damage layer with a thickness that was determined by the ion penetration depth. This damage layer could be characterized by ellipsometry. While for P4MS it was sufficient to model by ellipsometry the etch process using an ion-damaged layer on top of a bulk layer of unmodified polymer, the vuv effect needed to be added to the optical model in order to accurately characterize PαMS. Finally, surface roughening of polymers only occurred under ion bombardment. High energy ion bombardment produced the greatest roughness and corresponded to densification of the ion-damaged layer at the surface. Polymers that exhibited greater material loss to create the damaged layer showed the highest roughness.

Novel micelles from graft polyphosphazenes as potential anti-cancer drug delivery systems: Drug encapsulation and in vitro evaluation

In this study, a new class of amphiphilic methoxy-poly(ethylene glycol) grafted polyphosphazene with glycine ethyl ester side groups (PPP-g-PEG/GlyEt) was synthesized and characterized. An anti-cancer agent doxorubicin (DOX) was encapsulated into polymeric micelles derived from those copolymers, which exhibited considerably strong impact on micelle morphology: turned the rod-like and spherical drug free micelles into spheres and vesicles respectively. The in vitro release behavior of those drug-loaded micelles exhibits a sustained release manner and is affected by drug content. Cytotoxicity assay against adriamycin-resistant human breast cancer MCF-7 cell line showed that drug-loaded micelles based on PPP-g-PEG/GlyEt micelles can effectively suppress cell proliferation and the cytotoxicity was both time and concentration related, an enhanced cytotoxicity was observed either with increasing drug concentration or with prolonged incubation time. Moreover, flow cytometry results revealed a particle size dependency in cellular uptake of drug-loaded micelles. These findings suggest that the present copolymers can encapsulate water insoluble anti-cancer agents and contribute to improve drug sensitivity of adriamycin-resistant cell line.

Dielectric relaxation of monoesters based poly(styrene-co-maleic anhydride) copolymer

A series of alkyl-grafted copolymers based on styrene-maleic anhydride (SMA) copolymers were synthesized by esterification of SMA with several long chain normal aliphatic alcohols. The prepared copolymers were characterized by FT-IR and 1H NMR and DSC. The dielectric behavior of these copolymers was investigated in the frequency 20–105 Hz and temperature −40 to 180 °C ranges. Two relaxation processes were observed, α, and β-relaxation. The former is associated with the glass-rubber transition and is characterized by the Vogel–Fulcher–Tammann temperature dependence and the latter relaxation is related to the local motion of the ester side groups attached to the polymer backbone. The apparent activation energy for the β-relaxation was found to depend significantly on the alkyl chain length. The dielectric analysis of the β-relaxation process detected is discussed.

On the structural and electronic properties of poly(3-thiophen-3-yl-acrylic acid methyl ester)

Quantum chemical calculations on small idealized systems of poly(3-thiophen-3-yl-acrylic acid methyl ester), a new polythiophene derivative soluble in polar solvents, have been performed to propose a model for this polymer. The model, which was derived from calculations at the HF/6-31G(d) and B3PW91/6-31+G(d,p) levels is defined by both the head-to-tail polymer linkages and the conformation of the acrylic acid methyl ester side groups. The π–π∗ lowest transition energy predicted for the polymer is in excellent agreement with the experimental values, which were determined in this work using UV–visible experiments. Finally, we investigated the variation of the electronic properties produced by small chemical modifications in the side group of poly(3-thiophen-3-yl-acrylic acid methyl ester), such changes being designed to enhance the solubility of the polymer in water.

The effect of citrate esters as plasticizers on the thermal and mechanical properties of poly(methyl methacrylate)

AbstractPlasticizers play a key role in the formulation of polymers and in determining their physical properties and processability. This study examines the effects of citrate esters, triethylcitrate, and triacetine as plasticizers on the thermal and mechanical properties of poly(methyl methacrylate). The samples were characterized by differential scanning calorimetry, dynamical mechanical analysis, and mechanical testing under different plasticizer contents. Both citrate esters proved to be effective as plasticizers, DSC data for the triacetine additive fits with Fox equation. Microstructure and relaxation properties were studied by dynamic mechanical analysis where loss modulus shows clearly that absorbed plasticizer shifts the α‐transition to lower temperature and β‐relaxations associated to ester side groups are unchanged even up to 30 wt % plasticizer. Mechanical properties were evaluated with an Instron testing machine. Both additives produced (1) an initial plasticization, with a decrease in tensile strength and modulus; (2) an antiplasticization, reflected as an increase in tensile strength; and modulus and (3) a final plasticization, with a notable decrease in tensile strength and modulus and an increase in elongation where a 35 wt % of triethylcitrate added to the poly(methyl methacrylate) increased in 200% its elongation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Evidence for the molecular-scale origin of the suppression of physical ageing inconfined polymer: fluorescence and dielectric spectroscopy studies of polymer–silicananocomposites

Fluorescence spectroscopy was used to characterize the rate of physical ageing atroom temperature in nanocomposites of silica (10–15 nm diameter) nanoparticlesin poly(methyl methacrylate) (PMMA). The physical ageing rate was reducedby more than a factor of 20 in 0.4 vol% silica–PMMA nanocomposites relativeto neat PMMA. The molecular-scale origin of this nearly complete arresting ofphysical ageing was investigated with dielectric spectroscopy. The strength of theβ relaxationprocess was reduced by nearly 50% in the nanocomposite relative to neat PMMA. This reduced strengthof the β process results from dipoles (ester groups) having hindered motions or being virtuallyimmobile on the timescale being probed at a frequency of 100 Hz. This hindered mobilityresults from hydrogen bonding between PMMA ester side groups and hydroxyl unitson the surface of the silica nanoparticles. In contrast, no reduction in physicalageing rate was observed upon addition of silica to polystyrene, which cannotform hydrogen bonds with the silica surfaces. Thus, the molecular origin of thesuppressed physical ageing in silica–PMMA nanocomposites is the interfacialhydrogen bonding, which leads to a major reduction in the strength of theβ process,i.e., the β process is largely responsible for the observed physical ageing.

Synthesis and Characterization of Novel Poly[(organo)phosphazenes] with Cell-Adhesive Side Groups

There is a need to develop new scaffold materials with controlled surface properties for tissue engineering applications. For that purpose novel biodegradable poly[(organo)phosphazenes] were synthesized. A cell-binding molecule, galactose, was introduced via a spacer, either 6-aminohexanol (AH) or poly(ethylene glycol) (PEG; M(w) = 3400). Some polymers were substituted with an additional PEG chain of different molecular weights (M(w) = 750 or 5000). The polyphosphazene derivatives were characterized by 1H NMR. T(g) and T(m) were determined using differential scanning calorimetry. A detailed surface analysis of the polymers using X-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS), and dynamic contact angle (DCA) measurements was performed. Typical backbone and side chain fragments were detected by SIMS and confirmed the polymer composition. Compared to that of the reference polymer (having only amino acid ester side groups), an increased value of the specific ether carbon groups from PEG confirmed the enrichment of PEG at the surface of PEG-Gal polymers. However, the values were lower than expected. DCA studies showed that the galactose moieties were present at the surface after exposure to an aqueous environment. XPS results confirmed the similarity between experimental and theoretical values for the AH-Gal polymers. This indicated the presence of galactose moieties at the surface, which was confirmed by the DCA data because the contact angles were low compared to those of the other polymers.

Local Dynamics of Syndiotactic Poly(methyl methacrylate) Using Molecular Dynamics Simulation

The local dynamics of syndiotactic poly(methyl methacrylate) (PMMA) are investigated by explicit atom molecular dynamics (MD) simulations and quasielastic neutron scattering at temperatures well above the glass transition temperature. Using MD, we are able to isolate specific local motions well above Tg. These include rotations of the α-methyl and ester methyl, rotations of the entire ester side group and segmental motion of the chain backbone. This capacity is unique to simulation as proton motion at high temperatures necessarily involves multiple motions. The force field used is validated by direct comparison to structural and dynamic neutron scattering measurements, and by comparison via temperature extrapolation of activation energies and rotational times for methyl group rotations. We find that the rotation of the ester side group is consistent with the β-relaxation at low temperatures: the activation energy closely matches that assigned from dielectric spectroscopy (DS), and relaxation times are al...

Self- and Collective Dynamics of Syndiotactic Poly(methyl methacrylate). A Combined Study by Quasielastic Neutron Scattering and Atomistic Molecular Dynamics Simulations

We have investigated the molecular dynamics of syndiotactic poly(methyl methacrylate) well above the glass transition by combining quasielastic neutron scattering and fully atomistic computer simulations. The incoherent scattering measured by backscattering on a sample with deuterated ester methyl groups has revealed the single-particle motions of hydrogens in the main chain and in the α-methyl groups. Moreover, with neutron spin-echo experiments on the fully deuterated sample we have accessed the collective motions at the two first maxima of the structure factor. The simulated cell, which has been previously validated regarding the structural properties [Genix, A.-C.; et al. Macromolecules 2006, 39, 3947], shows a dynamical behavior that, allowing a shift in temperature, reproduces very accurately all the experimental results. The combined analysis of both sets of data has shown that: (i) The segmental relaxation involving backbone atoms deviates from Gaussian behavior. (ii) The dynamics is extremely heterogeneous: in addition to the subdiffusion associated with the α-process and the methyl group rotations, we have found indications of a rotational motion of the ester side group around the main chain. (iii) At a given momentum transfer and depending on the molecular groups considered, the time scales for collective motion are spread over about 1 order of magnitude, the correlations involving the main chain decaying much more slowly than those relating side groups. (iv) At the length scale characteristic for the overall periodicity of the system (that corresponding to the first structure factor peak), the experimentally observed collective dynamics relates to the backbone motions and is of interchain character; there, coherency effects are observed for all correlations, though side groups display weaker collectivity. (v) At the second structure factor peak, coherency remains only for correlations involving the main chains.

RAFT Polymerization with Phthalimidomethyl Trithiocarbonates or Xanthates. On the Origin of Bimodal Molecular Weight Distributions in Living Radical Polymerization

Phthalimidomethyl trithiocarbonate reversible addition−fragmentation chain transfer (RAFT) agents are effective in imparting living characteristics to radical polymerizations of butyl acrylate (BA) and N-isopropylacrylamide (NIPAM) and provide a route to end-functional polymers with predictable molecular weight and narrow molecular weight distributions (e.g., number-average molecular weight for PBA (M̄n) = 21 300 and polydispersity (M̄w/M̄n) = 1.1 at 96% conversion). End group determination suggests that bimodal molecular weight distributions and long chain branches in PBA arise by copolymerization of a PBA macromonomer formed by backbiting β-scission. The S-phthalimidomethyl xanthates provide good control over polymerizations of the less-activated monomers N-vinylpyrrolidone (NVP) and vinyl acetate (VAc). In the case of PBA with a trithiocarbonate end or PVAc with a xanthate end, the C−S bond to the thiocarbonylthio end group can be homolyzed by thermolysis at >180 °C leaving the phthalimidomethyl end group and the ester side groups intact providing macromonomers, with ω end group −CH2−C(CO2C4H9)(CH2) or −CH2−C(O2CCH3)(CH2) respectively, as the main products.

Local Structure of Syndiotactic Poly(methyl methacrylate). A Combined Study by Neutron Diffraction with Polarization Analysis and Atomistic Molecular Dynamics Simulations

The local structure of syndiotactic poly(methyl methacrylate) (PMMA) has been investigated by combining neutron scattering and fully atomistic molecular dynamics simulations. Selectively deuterating parts of the PMMA monomer, we have accessed five different partial structure factors in the glassy state by neutrons, and polarization analysis has allowed isolating the coherent contribution to the total scattering. In addition, the temperature dependence of the static structure factor has been determined on the fully deuterated sample. The different measured partial structure factors show qualitatively different features with respect to peak positions and heights and provide a very critical check to validate the simulated structure. To gain deep insight into the structure, we have grouped the simulation results in terms of three molecular substructures: the main chain, the α-methyl group, and the ester side group. The study of the resulting partial structure functions has revealed the origin of the diffraction peaks, including those in the X-rays pattern reported in the literature. In addition, a real-space evaluation of the characteristic radial distribution functions has allowed separating intra- and interchain contributions to the total correlation functions. We have found that (i) PMMA exhibits a strong local order with an average main-chain distance of ≈8.6 Å, (ii) this is the only average interchain distance and thus no precursor effect of a layered structure is found, (iii) the main chain shows a persisting all-trans structure, and (iv) a strong anticorrelation between the main chain and the ester side groups, together with an interdigitation of the side groups, suggests a marked separation between the backbone and the side-group spatial arrangements.

Degradation of Polyaminophosphazenes: Effects of Hydrolytic Environment and Polymer Processing

Polyphosphazenes with amino acid ester side groups show potential as hydrolytically degradable materials for biomedical applications. This study focuses on practical aspects of their use as biodegradable materials, such as effects of the hydrolytic environment and sample processing. Poly[di(ethyl glycinato)phosphazene], PEGP, and poly[di(ethyl alaninato)phosphazene], PEAP, were prepared by macromolecular substitution reaction, ensuring the absence of the residual chlorine atoms to avoid their influence on the hydrolysis. The kinetics of polymer degradation was studied by simultaneously measuring polymer mass loss, molecular weight decrease, and the release of phosphates and ammonia. The effect of pH, buffer composition, temperature, casting solvents, and film thickness were investigated.

Effect of Inorganic and Organic Salts on the Thermogelling Behavior of Poly(organophosphazenes)

AbstractSummary: The effect of various inorganic (NaCl, KCl, NaBr, LiCl and NaI) and organic (Et4NBr, n‐Pr4NBr and n‐Bu4NBr) salts on the thermogelling behavior of poly(organophosphazenes) with α‐amino‐ω‐methoxy‐poly(ethylene glycol) (AMPEG) and amino acid ester side groups was studied. The salting‐out or salting‐in effects of inorganic salts were in good agreement with the so‐called “Hofmeister series”. In the presence of inorganic salts other than NaI, the association temperature (Tass) and the temperature at the maximum viscosity (Tmax) shifted to lower temperatures. This indicates that the inorganic salts facilitated the thermosensitive gelation of the poly(organophosphazenes). The viscosity (Vmax) at Tmax was greatly augmented by the addition of inorganic salts, implying an increase in the number of hydrophobic association points. In contrast, NaI and organic salts dramatically suppressed the thermosensitive gelation of poly(organophosphazenes). The addition of these salts increased both Tass and Tmax, and decreased Vmax. In the inorganic salt systems, both the radius and the charge density of the anion seem to be the main decisive factors with regard to salting‐out and salting‐in effects. In the organic salt systems, the suppression of thermosensitive gelation may be attributed to the ionization of the hydrophobic side groups of the poly(organophosphazenes) upon binding of the large cations of the organic salts through hydrophobic interactions. magnified image

Poly( p-phenylene vinylene) derivatives with ester- and carboxy-functionalized substituents: a versatile platform towards polar functionalized conjugated polymers

A polar functionalized poly( p-phenylene vinylene) (PPV) derivative, ester containing poly(1,4-(2-(pentyloxy-5-carboxy methylester)-5-methoxyphenylene)vinylene), has been prepared via the sulfinyl precursor route. Subsequently, the carboxylic acid containing poly(1,4-(2-(5-carboxypentyloxy)-5-methoxyphenylene)vinylene) is readily obtained by the basic hydrolysis of the ester side groups. This carboxylic acid substituted polymer exhibits significantly improved optical properties as compared to previously reported similar polymers. To obtain polar functionalized PPV derivatives with more complex tailored substituents a versatile novel approach is presented based on the Mitsunobu reaction conditions via a post-polymerization functionalization of the carboxylic acid side groups. Using these reaction conditions substituents containing various ester groups, i.e. 4-nitrobenzyl, 2-nitrobenzyl, 5-(methyl)furfural and 3- N, N-dimethylamino-1-propane, have been covalently attached to the phenylene ring. Analytical data of the functionalized polymers are consistent with a quantitative functional group substitution. The results demonstrate that the employed functionalization method allows for the introduction of a large variety of polar substituents in a straightforward manner.

Acylated and hydroxylated polyamides derived from l-tartaric acid

A series of polyamides 6,4 were prepared from 1,6-hexanediamine and active esters of 2,3-di-O-acylated l-tartaric acid by polycondensation in solution. Both O-alkoyl and O-benzoyl esters were used as hydroxyl protecting groups. The resulting acylated polytartaramides were found to be semicrystalline polymers with T m between 100 and 200 °C and T g slightly above 100 °C. Controlled hydrolysis of the ester side group led to the preparation of poly(hexamethylene l-tartaramide)s with different content in free hydroxyl groups. These polyamides continue being crystalline but their properties largely differ from those displayed by their parent acylated polymers.

Surface-Catalyzed Growth of Polymethylene-Rich Copolymer Films on Gold

We report the preparation of a new class of copolymer films that consist of polymethylene (PM) with a low percentage ( approximately 1-4%) of randomly distributed ethyl ester side groups, consistent with poly(methylene-co-ethyl acetate). The films are prepared through a surface-catalyzed polymerization on gold surfaces upon exposure to a dilute solution of diazomethane (DM) and ethyl diazoacetate (EDA) in ether at 0 degrees C. While EDA alone does not polymerize at gold surfaces but DM does decompose on gold to grow PM films, the combined presence of EDA and DM results in dramatic enhancements in film growth and promotes an alternative mechanism for propagation as compared with that for the PM homopolymerization. The rate of copolymer film growth is constant over a approximately 24 h period, consistent with a controlled polymerization in which chain terminations are minimized. Carefully controlled experiments indicate that chain propagation does not occur at the outer film-solvent interface, but more likely, at the film-metal interface, suggesting a catalyzed insertion mechanism that extends the chain and pushes the outer chain termini further away from the metal-polymer interface. The results also suggest that adsorbed intermediates of EDA function as co-catalysts to promote the propagation reaction. Of particular importance for materials modification is that the ester side chains of these copolymer films can be hydrolyzed to carboxylate groups that exhibit pH-dependent wettability.