Polyurethane (PU)-based pads are commonly used in the chemical-mechanical planarization (CMP) process in semiconductor manufacturing. With a range of properties available through rational design of monomers, additives, and processing conditions, they are an indispensable workhorse in semiconductor fabrication. However, current CMP is largely driven by abrasive-containing slurries with highly corrosive chemical additives to planarize the surface through chemical etching followed by mechanical abrasion. This can result in severe defects such as scratches, particle contamination, as well as dishing and erosion on the wafer surface. Furthermore, abrasive slurries are not reusable and hence are a contributor to environmental waste. Our work addresses this concern with chemically functionalized polyurethane CMP pads in combination with abrasive-free polishing solutions; thus, the planarization predominantly occurs through chemical processes. Since even abrasive-free CMP is a complex process, where multiple parameters affect the planarization efficiency during polishing, an understanding of pad chemistry and their structure-property relation require special attention. Here, we examine the thermal and mechanical properties of a series of model functional PUs as a function of different type and concentration of functional compounds. This presentation will discuss the findings and prospects of these chemically functional polymers for CMP pads in abrasive-free polishing systems. Figure 1

Abstract Polymer-based bone cements have long been central to orthopedic and dental repair, providing structural fixation and reliable clinical outcomes. Among them, poly(methyl methacrylate) (PMMA) remains the dominant material because of its favorable handling characteristics and mechanical stability. However, its chemical inertness, high curing temperature, and nonresorbable nature have driven efforts to develop more biologically responsive alternatives. Current research explores initiator-activator systems, modified monomer matrices, and composite formulations that incorporate bioactive and degradable components. These strategies aim to balance injectability, curing control, and mechanical integrity with improved biological performance. This review examines the evolving chemistry, physicochemical properties, and clinical roles of polymeric bone cements, emphasizing advances in degradable and multifunctional systems. By bringing together insights from polymer design, materials characterization, and clinical translation, this review outlines how next-generation polymer-based cements are being engineered to shift from passive fixation toward active facilitation of bone regeneration.

Clarkson University’s Center for Advanced Materials Processing (CAMP) has been influential in educating and mentoring students in the field of chemical-mechanical planarization (CMP) for over three decades. Throughout this time, CAMP has been a strategic partner of many chip manufacturers and their suppliers, becoming a world leader in innovative research in CMP while also helping to meet their workforce needs. Undergraduate and graduate students benefit from the industry-focused engagement of the research projects they work on in multiple ways: they get to know CMP and semiconductor manufacturing from those who work directly in the industry; they work on problems that are industry-inspired and highly practical; and they begin to create a professional network. Many students take up industrial co-op and internship opportunities during their studies, and these often have a significant impact on their career development. In fact, it is often the case that such industrial experiences impact their careers more than their academic experience. This presentation will examine how students benefit from this industry-focused approach taken by Clarkson faculty and researchers.

This study explores the structure-property relationships of polyhydroxyurethanes (PHUs), sometimes called non-isocyanate polyurethanes (NIPUs), produced from the polymerization of 1,5-pentanediamine, a bio-sourced diamine, with biosourcable cyclic carbonates of diverse structures, such as aromatic and aliphatic backbones with ether and ester linkages. Comprehensive structural, thermal and mechanical characterizations were performed to evaluate polymer thermal stability and mechanical properties. Importantly, all polymers adsorbed moisture under common conditions (50% relative humidity, 22 degrees C) and this significantly impacts the thermal and mechanical properties. Results of dried samples revealed that aromatic homopolymers exhibited higher thermal stability and glass transition temperatures (T-g) compared to their aliphatic counterparts as measured by differential scanning calorimetry (DSC). The T-g values correlated with polymer backbone structures, decreasing in the order: aromatic ester-ether > aromatic diether approximate to aromatic diester > aliphatic diether (short chain) > aliphatic diester > aliphatic diether (long chain). Dynamic mechanical analysis (DMA) confirmed that aromatic polymers demonstrated glassy behavior at room temperature, while aliphatic homopolymers exhibited were either rubbery or viscous liquids. Furthermore, variations in cyclic carbonate structure significantly influenced polymer mechanical performance, with shorter aliphatic chains showing sharp tan delta transitions, whereas longer chains displayed broader tan delta peaks. This study provides valuable insights into the structure-property relationships of bio-based PHUs, highlighting their potential as sustainable thermoplastic alternatives.

Cyclopolymerization of methacrylic anhydride (MAA) by conventional radical polymerization using cobaloxime boron fluoride (CoBF) as a chain transfer agent allows high conversion synthesis of fully soluble cyclopoly(methacrylic anhydride) (PMAA). Specifically, soluble PMAA was attainable even at moderate MAA concentrations with no cross-linking in the presence of CoBF. This was achieved by studying various MAA concentrations and temperatures with and without CoBF and examining these parameters' impact on the PMAA microstructure, including the acyclic, cyclic, and cross-linked forms. Infrared and H-1 nuclear magnetic resonance (NMR) spectroscopy confirmed the formation of cyclic anhydride groups and the presence of unsaturated end groups created in the presence of CoBF. The molecular weight of the synthesized PMAA decreased with an increase in CoBF concentration. C-13 NMR spectra of PMAA confirmed the cyclization through the presence of a single peak in the carbonyl region. Importantly, the nondiluted MAA polymerization in the presence of CoBF led to the production of cyclic six-membered soluble polymers. On the other hand, cross-linked PMAA resulted from the polymerization of MAA at 3.4 M monomer concentration in the absence of CoBF.

Radical-mediated thiol-ene polymerizations (RMTEPs) conducted under typical emulsion polymerization conditions were studied with the aim of determining how various experimental parameters impact particle nucleation and growth. These colloids are unusual since they are made by step-growth polymerizations, which can be thermally initiated in an aqueous emulsion system. Four pairs of thiol-ene monomers were used to probe how composition impacts the nucleation loci. Kinetic studies were carried out to understand how monomer conversion, molecular weight, and particle size change throughout the reaction. Additionally, the number of particles formed as a function of surfactant and initiator concentrations were studied and this data, along with information from dye partition experiments, were used to determine polymer colloid nucleation mechanisms and how monomer/polymer structure impacts nucleation processes. Within the four pairs of monomers studied, three proceeded via homogeneous nucleation (via chain collapse in the aqueous phase), while one pair, which gave the highest degree of crosslinking, underwent heterogeneous nucleation (nucleation occurs in the micellar phase). Possible factors that impact which nucleation mechanism dominates a given set of monomers, such as crosslink density, water solubility, and thiol/ene reactivity, is discussed, although no clear set of delineating guidelines can be offered with this current set of data.

Methacrylic anhydride (MAA)-based copolymers were synthesized to probe how the molecular environment around the anhydride moieties impacts the ability of dynamic covalent exchange between anhydrides impacts the ability to recyclable the crosslinked (co)polymers. The comonomers methyl methacrylate (MMA) and n -butyl acrylate (BA) were copolymerized with MAA to yield crosslinked copolymers with varying compositions and their thermal and physical properties were studied as a function of the number of recycling events and copolymer composition. Dynamic covalent exchange was studied via recycling through repetitive grinding and compression molding at elevated temperatures and pressures (130 degrees C and 152 MPa for 2 h). It is concluded that adjacent anhydride moieties can undergo exchange to produce cyclic anhydrides, as observed through IR spectroscopy after heat treatments. Peak deconvolution was utilized to determine the degree of cyclization. Significant increases in monomer conversion occurred and anhydride cyclization was apparent during the first recycling process. Additional recycling processes continued to change the degree of cyclization, but the extent was dependent on the comonomer type. The degree of cyclization was found to be lower in the co-polymers compared to the homopolymer, probably because the interruption of MAA units by the comonomer units along the backbone reduces the ability to cyclize. Thermal properties (glass transition temperature, Tg) of the polymers were also impacted, however the static material properties (modulus and hardness) did not exhibit any dependence on cyclization due to the immobile nature of the highly crosslinked network at room temperature.

Methacrylic anhydride (MAA)-based copolymers are synthesized to probe how comonomer composition and type affect the erosion profiles. Anhydrides readily undergo hydrolysis, which when combined with high crosslink density and hydrophobicity tend to exhibit an ideal surface erosion mechanism for drug delivery, tissue adhesives, and biocement applications. The cylindrical (10 mm diameter x 5 mm height) polyanhydrides are degraded under pseudo-physiological conditions and surface erosion is qualitatively observed via photographs. The non-anhydride comonomer can be utilized to tune erosion profiles while retaining degradability and product solubility. The comonomer can accelerate or slow the degradation process to a greater extent at low MAA concentrations. Drug release is conducted using purpurin to model hydrophobic drugs. Purpurin concentration is quantified using UV-visible spectral analysis. Purpurin extends the degradation profile due to a combination of local pH changes, hydrophobicity, and molecular diffusion. Linear purpurin release is observed as a function of polymer erosion (0.9897 R-2) thus confirming a surface erosion-mediated drug release mechanism.

Gradient copolymers of n-butyl acrylate (nBA) and isobornyl acrylate (IBA) were prepared using reversible additionfragmentation chain transfer (RAFT) emulsion polymerization. Gradient copolymerizations were conducted using stepwise monomer addition such that the system was monomer-starved. Using the stepwise monomer addition process with a fixed comonomer ratio during the polymerization allows for pre-specified gradient compositions to be obtained. The structural properties of copolymers were confirmed via kinetic investigations and two-dimensional chromatography. H-1 nuclear magnetic resonance (NMR) characterization revealed the gradient behavior of the prepared copolymers. The degree of change in monomer composition along the copolymer chain strongly affects the thermal properties of the final polymer product. Thus, gradient copolymers were examined to determine how the strength of the gradient impacts the glass-transition temperature (T-g). Comparisons were also made between the gradient copolymers and their corresponding statistical copolymers and homopolymers. Differential scanning calorimetry analysis of gradient copolymers demonstrated that such copolymers had much broader glass-transition regions compared to homopolymers and statistical copolymers. Furthermore, both the midpoint of the transition (i.e., T-g) and the breadth of the transition were found to be predeterminable through a judicious choice of the comonomer feed composition and the steepness of the comonomer feed in the subsequent monomer additions.

Anhydride dynamic covalent exchange crosslinked poly(methacrylic anhydride) allows recycling at elevated temperatures and pressures and also produces cyclic anhydrides.

CD4+ T cells enable the critical B cell humoral immune protection afforded by most effective vaccines. We and others have recently identified an alternative source of help for B cells in mice, invariant NK T (iNKT) cells. iNKT cells are innate glycolipid-specific T cells restricted to the nonpolymorphic Ag-presenting molecule CD1d. As such, iNKT cells respond to glycolipids equally well in all people, making them an appealing adjuvant for universal vaccines. We tested the potential for the iNKT glycolipid agonist, α-galactosylceramide (αGC), to serve as an adjuvant for a known human protective epitope by creating a nanoparticle that delivers αGC plus antigenic polysaccharides from Streptococcus pneumoniae αGC-embedded nanoparticles activate murine iNKT cells and B cells in vitro and in vivo, facilitate significant dose sparing, and avoid iNKT anergy. Nanoparticles containing αGC plus S. pneumoniae polysaccharides elicits robust IgM and IgG in vivo and protect mice against lethal systemic S. pneumoniae However, codelivery of αGC via nanoparticles actually eliminated Ab protection elicited by a T-independent S. pneumoniae vaccine. This is consistent with previous studies demonstrating iNKT cell help for B cells following acute activation, but negative regulation of B cells during chronic inflammation. αGC-containing nanoparticles represent a viable platform for broadly efficacious vaccines against deadly human pathogens, but their potential for eliminating B cells under certain conditions suggests further clarity on iNKT cell interactions with B cells is warranted.

A near-infrared (NIR) mechanophore was developed and incorporated into a poly(methyl acrylate) chain to showcase the first force-induced NIR chromism in polymeric materials. This mechanophore, based on benzo[1,3]oxazine (OX) fused with a heptamethine cyanine moiety, exhibited NIR mechanochromism in solution, thin-film, and bulk states. The mechanochemical activity was validated using UV-vis-NIR absorption/fluorescence spectroscopies, gel permeation chromatography (GPC), NMR, and DFT simulations. Our work demonstrates that NIR mechanochromic polymers have considerable potential in mechanical force sensing, damage detection, bioimaging, and biomechanics.

This review article covers recent developments in thiol-X polymerizations as applied to the production of polymer colloidal particles. These polymerizations include thiol-ene, thiol-yne, thio-Michael, and thio-isocyanate polymerizations. Such thiol-X chemistries are facile reactions that offer high yields, rapid synthesis using mild conditions, orthogonality with other methods of organic synthesis, compatibility with a variety of monomer species, and can be radical or base mediated. Recent years have seen the employment of these reactions for the synthesis of polymer colloids in heterogeneous polymerizations such as suspension, dispersion, emulsion, and miniemulsion polymerizations, using microfluidic and batch production methods. A particular feature of thiol-X chemistries is their step-growth mechanism for molecular weight development, which contrasts with chain-growth polymerizations that are more commonly used in heterogeneous polymerizations. This aspect of thiol-X polymerizations allows for straightforward polymer functionalization simply through controlling the functional group stoichiometry. Another benefit is that radical-mediated thiol-X chemistries can be conducted with photo, thermal, or redox initiation, which epitomizes the practicality/adaptability of these reactions. Examples of highly functionalized thiol-X colloidal polymers are provided along with how such functionalization can be leveraged in order to provide desired properties. Therefore, polymer colloids made by thiol-X chemistries are expected to be a platform upon which many new technologies can be built.

Dynamic covalent exchange (DCE) of anhydride moieties is examined in both model compounds and network polymers.

The correlation between erosion and drug (lidocaine and 6-mercaptopurine, 6-MP) release from amorphous poly(thioether anhydrides), which are synthesized using radical-mediated thiol-ene polymerization, is reported. Cytotoxicity studies of the polymer toward human fibroblast human dermal fibroblasts adult, melanoma A-375, and breast cancer MCF-7 cells are conducted, and drug efficacy of a cancer and autoimmune disease drug (6-MP) when released from the poly(thioether anhydrides) is examined against two cancerous cell types (A-375 and MCF-7). Erosion and drug release studies reveal that lidocaine release is governed by network erosion whereas 6-MP is released by a combination of erosion and diffusion. The cytotoxicity studies show that all three cell types demonstrate high viability, thus cytocompatibility, to poly(thioether anhydrides). Toxicity to the material is dose dependent and comparable to other polyanhydride systems. The 6-MP cancer drug is shown to remain bioactive after encapsulation in the poly(thioether anhydride) matrix and the polymer does not appear to modify the efficacy of the drug.

Polyanhydrides exhibit great potential in biomedical applications, including drug-delivery systems, and are of great interest due to their unique properties such as degradability and surface erosion. Here we report the cellular delivery of a model fluorescent cytotoxin molecule, Hoechst 33342 (H33342), from crosslinked poly(thioether anhydrides) (PAHs) that are made using radical-mediated thiol–ene polymerization. The crosslinked network degraded hydrolytically, resulting in the release of the encapsulated H33342. Subsequently, we evaluated the bioactivity of the released H33342, a reported inhibitor of DNA topoisomerase, in A-375 cell culture. In vitro toxicity evaluations using conventional 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and propidium iodide (PI) exclusion assays indicated that the polymer and its degradation products were nontoxic toward the tested cells. Furthermore, cell morphology remained unchanged after incubation with the polymer, as determined by phase contrast light microscopy. However, upon release of drug from the polymer, we saw suppressed cell growth in MTT assays that correlated with a significant loss of cell viability as assessed by PI exclusion assay. Additionally, while the hydrophobic H33342 (75 μM) caused visible precipitation when added to culture medium alone, no such precipitation was observed in the presence of PAH loaded with 75 mM H33342. Overall, the results of our work demonstrate that encapsulated drug was successfully released, leading to changes in cell morphology and increased cell death. The results we present therefore provide further evidence that this type of polyanhydride network has the ability to encapsulate a bioactive molecule (H33342) and release it without compromising its bioactivity.

Pickering stabilization is a facile method to create composite colloidal particles. Inorganic colloidal SiO2 nanoparticles are often used as the stabilizer for particles instead of the more common amphiphilic surfactants. Here the use of this approach in radical-mediated thiol-ene suspension polymerizations using monomers 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TTT) and pentaerythritol tetrakis (3-mercaptopropionate) (PETMP) is described. The resulting micron-sized crosslinked poly(thioether) colloidal particles are coated with 80 nm silica nanoparticles. The addition of a small amount of various costabilizers is examined (hexadecane, cetyl alcohol and toluene), and while all yielded particles, cetyl alcohol provide more consistent results. Scanning electron microscopy and thermal analysis of the composite particles demonstrate morphologies that are consistent with a raspberry-like structure. No significant changes to the glass transition temperature are observed, which is consistent with the silica nanoparticles being located at the surface of the polymer particles.

Raman microspectroscopy was employed in this work to study the degradation of a polyanhydride network polymer synthesized from 4-pentenoic anhydride and pentaerythritol tetrakis(3-mercaptopropionate) monomers in order to illustrate the utility of this method and improve the understanding of the polyanhydride degradation and erosion. Disk-shaped polymer samples were immersed in buffer solutions for different periods of time, and hydrolytic degradation was monitored spatially and temporally via kinetic Raman studies at various depths of penetration into the samples. Erosion, meanwhile, was monitored via mass loss measurements. Dispersive Raman microspectroscopy is shown to be a particularly valuable tool for the study of the hydrolytic degradation of these materials. It confirms that these thiol-ene polyanhydrides are indeed surface eroding, while also revealing that degradation starts to occur at the core of samples on a short time scale (less than 5 h). At any given degradation time, there is a concentration gradient of the unreacted anhydride, with the unreacted anhydride concentration increasing from the outer edge to the center of the polymer samples. Further, the anhydride functionality is found to decrease approximately linearly with degradation time at all depths in the samples, though the degradation rate does appear to increase slightly as degradation occurs.

The synthesis and aqueous solution properties of copolymers comprised of N- vinylpyrrolidone (NVP) and vinyl laurate (VL) with three different architectures is reported. By using reversible addition-fragmentation chain-transfer (RAFT) polymerization, statistical, forced gradient, and block copolymers were synthesized with varying compositions and molecular weights. Surface tension, critical micelle concentrations (CMCs) and micelle size were determined, and related to copolymer composition, molecular weight and architecture. It was observed that more block-like polymer architectures produced from the block copolymerizations and forced gradient copolymerizations were likely to self-assemble in solution, indicating that the degree and placement of the hydrophilic (NVP) and hydrophobic (VL) monomer units are important in predicting solution behavior of such copolymers.