Manipulating Interfaces through Surface Confinement of Poly(glycidyl methacrylate)-block-poly(vinyldimethylazlactone), a Dually Reactive Block Copolymer

Abstract

InstrumentationThermal Analysis. Standard thermal gravimetry experiments were performed on a TA Instruments Q5000IR TGA. Samples were heated in platinum pans from ambient temperature to 600.0°C at 20.0°C/min. A TA Instruments Q1000 Differential Scanning Calorimeter (DSC) was used to evaluate thermal transitions of the (co)polymers. Samples (~ 3-8 mg) were prepared in standard aluminum pans/lids and were first heated from ambient temperature to 160.0°C at a ramp rate of 20.0°C/min. Samples were subsequently cooled to -50.0°C at 25.0°C/min and finally heated to 160.0°C at 20.0°C/min. Glass transition temperatures are reported from the second heating as the mid-point of the heat flow derivative curve. The DSC was calibrated using indium standard (In; melting point, T m, In = 156.6 °C; provided by TA Instruments) according to the manufacturer's recommendation, which includes baseline and temperature calibrations.Additionally, standard thermal gravimetry experiments were performed on a TA Instruments Q5000IR TGA. Samples were heated in platinum pans from ambient temperature to 600.0°C at 20.0°C/min. Raman Microspectroscopy. Raman spectroscopy of thin polymer films were performed using a Renishaw 100 confocal micro-Raman system equipped with a CCD detector. A 632.8 nm HeNe laser was focused to 2 µm spot size with a 50x objective. Raman spectra were acquired using a 60 s integration time. Atomic ForceMicroscopy. A Digital Instruments Dimension 3100 atomic force microscope (AFM) was used in tapping mode to obtain height images of 1000 µm lines of a PGMA 73 -b-PVDMA 174 copolymer spin-coated from solution in CHCl 3 at a concentration of 0.75% wt and annealed under vacuum at 110 °C. The micropattern was made by photolithographic techniques. 1The amplitude set-point and proportional and integral gains were adjusted for each sample assuring optimal image quality. All measurements were done at a scanning rate of 0.5 Hz using silicon nitride cantilevers. An area of 8 µm × 8 µm at the edge of the pattern was initially surveyed in order to obtain a direct comparison of layer thickness values obtained by AFM and by ellipsometry. Then, a 2 µm × 2 µm area on the polymer layer was sampled, which allowed the film's topography and roughness to be examined.

Effect of amine content and chemistry on long‐term, three‐dimensional hepatocyte spheroid culture atop aminated elastin‐like polypeptide coatings

“…In the so‐called “Direct Reaction Scheme,” ELP (MW = 17,000 Da) was directly conjugated to different polycations, including PEI (Sigma, St Louis, MO, MW = 1200 Da), polylysine (Sigma, MW = 1000–5000 Da), or polyarginine (Sigma, MW = 5000–10,000 Da) to create an Aminated‐ELP conjugate. In the “Reactive Polymer Linker Scheme,” ELP was conjugated to the reactive polymer, poly(2‐vinyl‐4,4‐dimethylazlactone) (PVDMA), which was synthesized by reversible addition‐fragmentation chain transfer polymerization and characterized as described previously (MW = 5420 Da, approximately 30 azlactone moieties, dispersity = 1.13) . Analysis by comparison to protein ladder assay shows that nucleophilic addition of ELP to PVDMA tethers 1 or 2 ELPs to the PVDMA, which allows small‐molecule (protected) electrolytes—including N‐Boc ethylenediamine, N‐Boc‐1,4‐butanediamine, or l ‐arginine (all Sigma)—to be reactively coupled through nucleophilic addition, which after deprotection yields the ELP–PVDMA conjugates.…”

“…Analysis by comparison to protein ladder assay shows that nucleophilic addition of ELP to PVDMA tethers 1 or 2 ELPs to the PVDMA, which allows small‐molecule (protected) electrolytes—including N‐Boc ethylenediamine, N‐Boc‐1,4‐butanediamine, or l ‐arginine (all Sigma)—to be reactively coupled through nucleophilic addition, which after deprotection yields the ELP–PVDMA conjugates. It is worth noting that the nucleophilic addition of primary amines to the azlactone rings of PVDMA proceeds without by‐product formation . OPA fluorescence assay (Thermo Scientific, Pittsburgh, PA) was used to measure primary amine content of Aminated‐ELPs.…”

“…In the "Reactive Polymer Linker Scheme," ELP was conjugated to the reactive polymer, poly(2-vinyl-4,4dimethylazlactone) (PVDMA), which was synthesized by reversible addition-fragmentation chain transfer polymerization and characterized as described previously (MW 5 5420 Da, approximately 30 azlactone moieties, dispersity 5 1.13). [19][20][21][22] Analysis by comparison to protein ladder assay shows that nucleophilic addition of ELP to PVDMA tethers 1 or 2 ELPs to the PVDMA, 19 which allows small-molecule (protected) electrolytes-including N-Boc ethylenediamine, N-Boc-1,4-butanediamine, or L-arginine (all Sigma)-to be reactively coupled through nucleophilic addition, which after deprotection yields the ELP-PVDMA conjugates. It is worth noting that the nucleophilic addition of primary amines to the azlactone rings of PVDMA proceeds without by-product formation.…”

“…It is worth noting that the nucleophilic addition of primary amines to the azlactone rings of PVDMA proceeds without by-product formation. [19][20][21][22] OPA fluorescence assay (Thermo Scientific, Pittsburgh, PA) was used to measure primary amine content of Aminated-ELPs. To facilitate comparison of different conjugates, an "amine content grade" labeling system was assigned based on the ratio of fluorescence intensity measured for an OPA-treated Aminated-ELP sample (5 mg/mL) to the fluorescence intensity measured for the OPA-treated ELP (5 mg/mL).…”

Covalently Crosslinked and Physically Stable Polymer Coatings with Chemically Labile and Dynamic Surface Features Fabricated by Treatment of Azlactone-Containing Multilayers with Alcohol-, Thiol-, and Hydrazine-Based Nucleophiles

“…Several recent reports highlight the utility of azlactone groups and the use of azlactone-functionalized polymers as reactive platforms for the design of new functional materials, surfaces, and interfaces of interest in many other contexts. 15,23,[29][30][31][32][33][34][35][36][37][38][39][40][41][42] In this current study, we sought to develop new approaches to tailor the surface and bulk properties of azlactone-containing materials using other classes of non-amine-based nucleophiles (Scheme 1). Azlactone groups are understood to react with primary alcohols and thiols under certain conditions (e.g., in the presence of a catalyst and at higher temperatures), 23,43-45 but the use of these nucleophiles to design new materials is far less developed than approaches that exploit the reactivity of azlactones with more nucleophilic primary amines.…”