Materials & Chemicals : Polymers


Stimuli-Responsive Smart Block Copolymers Improve Dispersion of Titanium Dioxide in Architectural Coatings

An associate professor of materials science and engineering at the University of Wisconsin-Eau Claire has synthesized a series of stimuli-responsive block copolymer dispersants optimized for use in architectural coating applications. These novel polymer dispersants are currently being developed as additives to existing coatings for improved dispersion of TiO2. Dispersant properties are tunable through modification of the polymer composition as a function of pH and temperature. Initial data shows that the addition of these polymers can decrease settling rate, control viscosity, and control interfacial activity, all of which are important for greater dispersant effectiveness and stability over time. These polymers have demonstrated the ability to interface with pigment particles, such as TiO2, resulting in improved dispersion of the pigment. Initial testing shows reduced TiO2 concentration while maintaining zero shear viscosity and shear thinning properties, which prevents drips in the coatings, and is comparable to commercially available formations. These properties are tunable and may be altered to tailor the product for a desired use or environment, or to readjust the properties of an aged existing product. New methods of synthesis to allow for the scaled-up production of these polymer additives are complete and new purification methods are in progress. Further development will also focus on maintaining additional properties like coverage and opacity, and testing of additional polymer compositions and particle surface coatings.

Novel Transparent Dilatant Materials Comprised of Single Chemical Component

Research from the University of Wisconsin-Stevens Point has resulted in the synthesis of a series of materials exhibiting a range of dilatant properties. The materials show good transparency and are chemically uniform (e.g. consisting of a single chemical component). The degree of dilatancy is easily controlled by adjusting the compositions of the materials. Due to the range of dilatant properties, good transparency, and single chemical component nature of the dilatant samples, these materials show significant promise for novel uses in protective equipment and other areas related to impact protection, especially where transparency is desirable.

Slippery Liquid-Infused Porous Surfaces (SLIPS) with Improved Antifouling Properties, Small Molecule Release

Building on their work, the researchers have now developed SLIPS capable of preventing adhesion and colonization by bacterial/fungal pathogens, and also killing and/or attenuating non-adherent pathogens in surrounding media. The new approach exploits the polymer and liquid oil phases of the slippery materials to sustain the release of small molecule compounds.

This controlled release approach improves the inherent antifouling properties of SLIPS, has the potential to be general in scope and expands the potential utility of slippery, non-fouling surfaces in diverse contexts.

Nylon-3 Polymers Active Against Clostridium Difficile

UW–Madison researchers and collaborators at Emory Medical School have developed nylon-3 polymers and copolymers active against C. difficile. The polymers have been shown to inhibit outgrowth/growth of the bacteria in spore and vegetative form.

Slippery Antifouling Surfaces with Health, Environmental and Consumer Applications

UW–Madison researchers have developed a new approach for fabricating and functionalizing SLIPS on objects of arbitrary shape, size and topology (e.g., inside a hollow tube, etc.). The new SLIPS have greater control over how fluids behave when they come in contact. For example, they can be designed with oil-free regions to immobilize fluid droplets and/or control how they slide across the surface.

The new SLIPS are antifouling to bacteria, fungi and mammalian cells, and may be used for the controlled release of antibiotics and to prevent thick liquids or dirt from building up on a surface. They are fabricated via the infusion of oils into reactive polymer multilayers.

Polymer Coating for Cell Culture Substrates

UW–Madison researchers have developed a new crosslinkable polymer coating for cell culture substrates. The nanometer-thin coating is made of glycidyl groups and azlactone groups distributed randomly along the copolymer backbone.

The coating is substrate independent and can be applied to a wide variety of organic and inorganic materials including plastic, silicon, glass and gold.

Gemini Surfactant LLC Membranes from Thiol-Ene Polymerizations

The researchers have now developed a new and highly efficient approach for synthesizing crosslinkable Gemini surfactants that can be turned into membranes featuring the desired gyroid morphology.

In the new method, an LLC structure is formed from a mixture containing the functionalized surfactants, a thiol-ene crosslinking agent and a polar solvent. Upon crosslinking, the lyotropic phase morphology is substantially retained.

Environmentally Green Glue

UW–Madison researchers have developed a process to transform soy flour into a strong, environmentally safe wood adhesive.

In the process, a suitable reagent is used to phosphorylate the flour’s lysine amino acid residues. The phosphorylated flour then is mixed with an oxidizing agent that drives the formation of cross-linking bonds. This improves the flour’s adhesive properties. Unwanted salts created in the process can be removed.

Flours of other legumes and/or oil seed crops (e.g., flax, canola) are suitable as well.

Dense Polymer Brush Growth with New Copolymer

UW–Madison researchers have developed a novel crosslinkable random copolymer and film. The film can be used as a grafting substrate to grow polymer brushes via SI-ATRP.

The copolymers are synthesized by standard techniques. They consist of a styrene or acrylate-based inimer for initiating ATRP and a monomer for crosslinking. Once the copolymers have been formed, they can be crosslinked into films by applying heat and/or light. This step can be carried out on different surfaces using spin-coating methods.

After the crosslinked films have been prepared, they can be used as grafting substrates for SI-ATRP growth of polymer and copolymer brushes. During SI-ATRP, a reaction generates a polymer brush composed of multiple polymer chains attached to the film.

Superior Plastic Parts

UW–Madison researchers have developed a new method to create foamed, injection-molded plastic blends with significantly increased toughness and ductility compared to conventional foamed parts.

The new process begins with a polymer blend with two properly selected polymer materials, such as polypropylene (PP) and high-density polyethylene (HDPE), or PP and low-density polyethylene (LDPE), which exhibit a dispersed secondary phase at sub-microscale in the primary matrix. The polymer blend is heated along with a supercritical fluid in an extruder to produce a melt, which is then extruded into gas-laden pellets. The gas-laden pellets can be fed into the injection barrel of a typical machine, plasticized and then injected into a mold cavity (or cavities) where the final part is made.

The process forms a lightweight component with microscale air cavities. Upon tensile loading, debonding of the secondary phase facilitates the interconnection of microcellular voids to form channels such that the stretched component becomes a bundle of fibrils. Compared to other toughening methods, this method achieves a more significant improvement in ductility and toughness. It also has the benefit of higher production efficiency, better dimensional stability, and greater design freedom thanks to the foamed injection molding process.

Block Copolymers for Sub-10 Nanometer Lithography

UW–Madison researchers have developed BCPs characterized by high Flory-Huggins interaction parameters (χ). They can self-assemble into domains having very small dimensions, and therefore are extremely useful in lithography.

The new BCPS may be polymerized from PHS monomers or from tert-butyl styrene and 2-vinylpyridine monomers. Overall degree of polymerization (N) can be experimentally controlled so that it’s high enough to form a desired phase (e.g., cylinders, spheres, lamellae, etc.) but low enough to produce very small dimensions.

Powering Devices with Piezoelectric ‘Sponge’

UW–Madison researchers have developed a thin piezoelectric film that converts ambient vibrations into electrical energy and can be directly integrated onto the surface of a device.

The film is made by dispersing metal oxide or other nanoparticles into a solution of a piezoelectrically active polymer like PVDF (polyvinylidene fluoride). The solution is allowed to dry into a sponge-like layer. The nanoparticles then are etched away or otherwise removed. This leaves a finely porous matrix that can be sandwiched between electrodes to create a nanogenerator.

Compostable Thermoset Polymers

Research from the University of Wisconsin-Stevens Point has resulted in the development of a series of crosslinkable, degradable thermoset polymers with reversible crosslinking from mercaptosuccinic acid and diols. This novel series of polymers have utility for a broad range of applications including health care, durable goods and packaging. Monomeric base materials are polymerized in a facile synthesis and crosslinked (cured) with methods compatible with current industry methods, allowing for the creation of resins with a wide variety of properties. The crosslinking reactions offer the unique feature of being readily reversible allowing for depolymerization to monomers, thereby providing for recyclability for use in sustainable commodity applications, aka “sustainable thermosets”. The polymers are degradable under commercial compost conditions comparable to current bio-derived compostable polymers such as PLA and polycaprolactone. Properties such as duration of degradation in a compost setting, material pliability, toughness and optical clarity are controllable via the degree of polymer crosslinking. In addition, copolymers with PLA, such as poly(lactic acid-copentylenemercaptocuccinate) have been developed in an effort to improve the physical characteristics of PLA.

New Surface-Modifying Film for BCP Formation

UW–Madison researchers have developed new surface-modifying layers made of crosslinked copolymer film. More specifically, the film is composed of styrene, (meth)acrylate and crosslinkable epoxy group-functionalized monomers.

Various styrene-containing BCPs can be deposited on top of the film and then subjected to conditions that cause them to self-assemble into vertically oriented domains.

Degradable Neutral Layer for BCP Lithography

UW–Madison researchers have developed easier-to-cleave neutral layers using a new type of polymer film. Linkages both within the film, as well as between the film and its substrate, may be cleaved apart using only a mild acid or light (‘photocleaving’).

The film is made of random copolymer chains having crosslinkable functional groups. The film can be coated on a BCP substrate and then selectively removed.

Masks for Growing Nanopatterned Polymer Brushes

UW–Madison researchers have developed a method for growing nanopatterned polymer brushes using SI-ATRP. The method relies on making and using a lithographic mask.

The mask has three layers: a surface, a neutral layer and a block copolymer (BCP) film. The neutral layer serves two purposes. First, it induces the overlying BCP film to form vertical domains. Secondly, it provides initiating sites from which to grow the polymer brush chains.

Before that can happen, parts of the BCP film are selectively removed by etching. This forms a desired pattern of exposed regions. During SI-ATRP, these regions are exposed to a growth solution. The result is a polymer brush made of multiple chains, each of which is attached to the neutral layer.

New Conductive Polymers for Lithium Ion Batteries

UW–Madison researchers have synthesized substituted metal bis(malonato)borate monomers, from which they have produced high molecular weight polymers via acyclic diene metathesis (ADMET) polymerization catalysis. When the metal is lithium, the polymers act as single ion conductors with high transference numbers favorable for battery usage. Previously, such conductors have been very difficult to synthesize.

Manufacturing Polymer Micropellets

A UW–Madison researcher has developed a micropelletizing method and apparatus for controlling the size and shape of polymer particles.

In the process, a thin melt of polymer material is extruded through a specialized nozzle. A jet of heated, pressurized air then is applied. This causes the thread to stretch and break up into individual droplets due to surface tension effects known as Rayleigh disturbances.

The droplets are allowed to cool and solidify into micropellets. Factors like temperature, speed and extrusion rate are used to control droplet formation.

Controlling the Size and Shape of Polymer Micropellets

UW–Madison researchers have developed a micropelletizing process for controlling the size and shape of polymer particles.

In the process, a thin melt of polymer material is extruded through a nozzle. The stream is fractured as it exits the nozzle using a blast of high-speed gas that generates drag force and breaks up the stream into droplets. The individual droplets cool and solidify into pellets. Factors like temperature, speed and extrusion rate are used to control droplet formation.

Highly Foamed Plastic Parts Are Stronger and Cheaper to Produce

UW–Madison researchers have developed a new method of fabricating highly foamed, injection-molded plastic parts. Firstly, a thermoplastic material like LDPE is heated along with supercritical nitrogen or carbon dioxide to produce a gas-polymer solution in an extruder, and then the melt is extruded and quenched into gas-laden pellets. These pellets are plasticized in an injection molding machine, and then injected into a mold to produce lightweight parts with fine foamed structure and/or improved part surface.

Compared with the conventional method, this method requires much lower equipment cost and process complexity, no modification to the injection molding machines is needed, and all the same benefits that the conventional method offers can be achieved.

Crosslinkable Gemini Dicarboxylate Surfactant LLCs and Their Membranes

UW–Madison researchers have built on their previous work to efficiently synthesize crosslinkable Gemini surfactants that adopt bicontinuous cubic phases, including the gyroid phase. By incorporation of a photoinitiator into the hydrophobic domains of the LLC, the assembly can be crosslinked with retention of the gyroid structure.

Degradable Polycations Derived from Amino Acid Vinyl Esters

UW–Madison researchers have developed monomers that can be used to synthesize cationically modified poly(vinyl alcohol) materials with a high degree of control over backbone charge density and hydrophilicity of the resulting material.

Specifically, the researchers have optimized the synthesis and polymerization of a series of N-Boc-protected amino acid vinyl ester (BAAVE) monomers derived from Boc-protected glycine, alanine, valine and proline. Direct free radical polymerization of the BAAVE monomers with vinyl acetate, followed by a deprotection step, can yield either hydrophilic or hydrophobic cationic materials.

Improved Nansocale Patterning by Directed Assembly of Triblock Copolymers

UW–Madison researchers have developed fabrication methods that involve directing the assembly of ABA triblock copolymers to form desired, complex features. In the process, a layer or thin film of the copolymer material is deposited on a nanopatterned surface and induced to separate, thus replicating the pattern in the layer. Chemical patterns with periods much different than the natural period of the ABA triblock copolymer may be used to direct the assembly process. The triblock includes a component from a polymer group that includes polystyrene (PS) and polyethylene oxide (PEO).

Click Chemistry-Based Multi-Enhanced Biomaterials Help Heal Wounds

The UW–Madison researchers have now adapted “click chemistry” in lieu of an external energy source to form the sIPNs. This allows a wider variety of sensitive bioactive molecules, including therapeutic cells, to be entrapped within the sIPNs, enhancing the clinical applicability of the technology.

More Efficient Production of Polymer Chemical from Biomass Glucose

UW–Madison researchers have developed a method to produce HMF from biomass-derived glucose in a two-phase reaction system using Lewis acid and Brønsted-Lowry acid catalysts.

Conducted in a two-phase reaction vessel, the method isomerizes the glucose feedstock material, chemically transforming it into fructose while simultaneously converting that fructose via dehydration into HMF. The aqueous component of the medium comprises the glucose and both types of homogenous acid catalysts. The solution may be saturated with sodium chloride. The organic extraction layer preferably contains one alkylphenol, and into this layer the HMF spontaneously separates.

The two sugar reactions—isomerization and dehydration into HMF—occur in tandem, result in high yields, increase separation efficiency and react in a system that can be conducted continuously or in batch fashion.

Improved Infrared-Responsive Hydrogel for Use in Microfluidics and Optics

UW–Madison researchers have developed an improved infrared-responsive hydrogel by incorporating graphene oxide flakes into a thermo-responsive hydrogel polymer. These composite hydrogels have an intrinsically higher surface area and absorbance band than conventional metal nanoparticles, resulting in a larger volumetric change in response to infrared light. The researchers also have provided a microfluidic device and a lens structure that incorporate these composite hydrogels as actuators. Both devices can be operated by heating the composite hydrogel in its swollen state to a temperature sufficient enough to shrink its volume. The hydrogel can be restored to its original volume by allowing it to cool and re-swell. In the microfluidic device volume reduction of the hydrogel allows fluid to flow through a channel and in the lens structure volume change relates to a change in focal length. 

Broad Application Bioresorbable Polymers

A researcher at the University of Wisconsin Stevens Point has developed a series of reversible cross linked biocompatible films with straightforward monomer synthesis from mercaptosuccinic acid and succinic acid. Base monomers are polymerized or crosslinked in a highly robust reaction without the need for protection and deprotection allowing for the creation of a wide variety of difunctional and polyfunctional monomers. To date polymers with a wide range of properties have been created, from those that are transparent and flexible to hard and tough polymers. The crosslinking is conducted at a low temperature and little to no lactic acid is needed depending on the application. These crosslinking reactions offer the unique feature of being readily reversible allowing for depolymerized to base monomers without degradation lending the polymers to highly effective recycling for sustainable commodity applications. The monomers can also have application in copolymers and dendrimers.

Microcellular Foamed Plastics with Reduced Cost and Improved Surface Quality

UW–Madison researchers have developed a method for fabricating injection molded components with higher quality and lower cost than conventional techniques. The method uses a liquid such as water combined with a nucleating agent such as commonly used additives or fillers to generate bubbles. The liquid is added into a hopper of an injection molding machine and combined with the nucleating agent. The liquid turns into a vapor during injection, which forms bubbles within the injection molded components. The nucleating agent acts to reduce bubble size and increase bubble density, resulting in finer surface quality in the molded parts. The method allows production of foamed plastic parts with a comparable weight reduction and similar mechanical properties as conventional microcellular foaming techniques with improved surface finish and reduced cost.

Smoother Plastic Products Using Microcellular Injection Molding

UW–Madison researchers and others have improved the microcellular injection molding process to create smoother plastic parts.

In the new process, a polymer is heated, melted and mixed with a low amount of supercritical fluid (such as nitrogen). The resulting mixture is a single-phase solution. The polymer and/or the supercritical fluid may be adjusted to control the weight of the component or its surface properties. Once adjusted, the mixture is injected into a mold. Proper control of the supercritical fluid content in the polymer causes bubbles in the polymer to nucleate in a controlled fashion, which leads to products with a much smoother surface.

Biodegradable Poly(Vinyl Ester) Block Copolymers and Related Poly(Vinyl Alcohol) Surfactants

UW–Madison researchers have developed PVA-based amphiphiles in which both the hydrophilic and hydrophobic blocks are biodegradable. Through careful selection of vinyl esters polymerized into a block copolymer structure, they have shown that ester functionalities along the backbone may be selectively hydrolyzed to unmask a PVA-block in a hydrophilic-hydrophobic diblock copolymer.

Given the well-known ability of PVA to self-associate and form gels, the polymer surfactants micellize and modify the rheological properties of the solutions in which they are dissolved. The tunable solution rheology of these surfactant dispersions, coupled with their environmental degradability, suits the polymers to a wide range of uses.

They can be synthesized using reversible-addition fragmentation chain transfer (RAFT) polymerization, organobismuth-mediated living radical polymerization or cobalt-mediated radical polymerization.

A Photopatternable Layer for Controlling Block Copolymer Microdomain Orientation

UW-Madison researchers have developed a surface modification chemistry that uses thin polymer films to control the orientation of BCP microdomains on different types of substrates.

A substrate is coated with a photo- or thermally-crosslinkable polymer film composed of three monomers.  In contrast to conventional BCP structures, the film is substrate independent and does not require high temperatures to induce crosslinking.  It can be ultrathin (two to six nm) to facilitate pattern transfer in bottom-up device fabrication.  And if a photo-crosslinkable film is used, alternate regions of the substrate may be photo-patterned by exposing only some regions of the polymer to light.

After crosslinking is induced in the polymer film, a patterned diblock copolymer film is disposed over it.  The BCPs then self-assemble into a pattern determined by the ratio of monomers in the underlying polymer film.  The pattern may include BCP microdomains oriented perpendicular or parallel to the substrate surface.  The domains may comprise cylinders, lamellae or other structures.

Layer-by-Layer Covalent Assembly of Reactive Ultrathin Films

UW–Madison researchers have developed robust methods for the layer-by-layer fabrication of covalently cross-linked ultrathin films.  This approach makes use of fast and efficient “click”-type interfacial reactions between poly(2-alkenyl azlactone)s and appropriately functionalized polyamines.  In contrast to conventional, aqueous methods for the layer-by-layer fabrication of thin films, fabrication of these ultrathin films occurs in organic solvents and is driven by rapid formation of covalent bonds during assembly. This approach also yields films with residual azlactone groups that can be used to tailor the surface properties of the films by treatment with a broad range of chemical and biological functionalities.

An Orthopedic Implant Coating for Enhanced Bone Growth

UW-Madison researchers have developed a biomaterial-based approach for directing bone regeneration to treat bony defects. This approach uses a biologically active calcium phosphate-based coating to target and control delivery of a bound growth factor molecule capable of inducing bone growth. This coating can be applied to all bioresorbable materials commonly used in orthopedic surgery, including nails, pins, anchors, screws, plates and scaffolds.

Under physiological conditions, the solubility of different calcium phosphate materials can vary by more than 5000 percent. To take advantage of this broad range of dissolution rates, the coating consists of several layers of calcium phosphate materials with distinct dissolution profiles. Bone growth factors are bound to the calcium phosphate and released based on the dissolution profile of each layer. To provide a delayed release, calcium phosphate layers that do not contain a growth factor or drug can be incorporated into the coating. This approach can be easily integrated with existing implants and surgical procedures in clinics.

Cost-Effective Synthesis of HMF from Fructose

UW-Madison researchers have developed a method for the selective dehydration of carbohydrates (preferably fructose) to produce furan derivatives (preferably HMF).  This new process provides a cost-effective way for making these valuable chemical intermediates, which could replace key petroleum-based building blocks used in production of plastics, fine chemicals, diesel fuel and fuel additives.

The method is more commercially viable than those previously developed because it yields a higher concentration of HMF and produces HMF in a separation-friendly solvent which does not require difficult extraction processes.  The dehydration process employs a two-phase reactor system in which a reactive aqueous phase containing fructose and a chemically modified acid catalyst is contacted with an organic extracting phase modified with a C1-C12 alcohol (preferably 2-butanol).

Directed Assembly of Triblock Copolymers

UW-Madison researchers have developed a method for the complex three-dimensional fabrication of nanoscale structures based on a two-dimensional chemical substrate. A triblock or greater order copolymer is deposited on a chemically patterned substrate that is symmetrical in two dimensions. The substrate has several different chemically active regions. As long as the number of distinct regions is one fewer than the order of the copolymer, the surface pattern can be directed to assemble into a three-dimensional structure by annealing the block copolymer above its glass transition temperature. This process provides conditions that energetically favor the desired three-dimensional morphology.

Fabrication of Complex 3-D Structures Based on Directed Assembly of Self-Assembling Materials

UW-Madison researchers have developed methods of fabricating a thermodynamically stable three-dimensional structure that varies perpendicularly to its substrate. They mismatched the symmetry of the substrate pattern to the block copolymer. When the copolymer is heated above its glass transition temperature, ordering of the material is induced. The interaction of the ordered copolymer with the mismatched substrate alters the energy balance so that three-dimensional structures are the most energetically favorable. As the copolymer materials self-assemble in the upward direction, they transition from following the exact pattern of the substrate to exhibiting a complex three-dimensional morphology.

Injection Molding Quality Control System

By making use of the unique signal of mold separation (MS), UW-Madison researchers have created an online and adaptive injection molding quality control system that outperforms conventional cavity or hydraulic pressure-based systems. MS is the momentary separation of a mold’s core and cavity plates that occurs at the end of filling step in the injection molding process. The maximum value of this separation is highly correlated with part weight, a key index of part consistency and quality.

To continuously monitor the small MS signal (in the micron range) the researchers mounted a non-intrusive, precision linear displacement transducer on the outside of the mold plates. The MS profile measured by the transducer is fed into adaptive control algorithms, which manipulate hydraulic pressure and the switchover point to maintain part consistency from cycle to cycle. Within a single cycle, the system also adjusts hydraulic pressure during the packing step to control the MS profile.

Materials and Methods for Creating Nanoscale Patterned Features with Atomically Smooth Surfaces

The methods developed by UW-Madison researchers can now produce “Manhattan-style” patterned features less than 50 nm in size, with tall vertical sidewalls, high aspect ratios and atomically smooth surfaces. These patterned features are called “polymer brushes.” To make them, polymers such as styrenes, acrylates, and silanes are grown and covalently bonded to a substrate at an initiation, or grafting, site. The principal innovation is that surface tension between the polymer and air, or between the polymer and a solvent, is exploited to produce atomically smooth surfaces on features as small as 25 nm. The researchers also showed that by varying the polymers’ grafting density and molecular weight, they could control polymer brush height and aspect ratio.

Methods and Compositions for Forming Aperiodic Patterned Copolymer Films

UW-Madison researchers have developed methods of using block copolymers to replicate patterns with irregular features. Block copolymer materials are deposited onto patterned substrates, and then components in the copolymer material are ordered to replicate the pattern. The ordering may be facilitated through the use of blends of the copolymer material and/or by configuring substrate patterns so that regions of the substrate pattern interact in a highly preferential manner with at least one of the components in the copolymer material.

Organoelement Resists for EUV Lithography

UW-Madison researchers have developed organoelement resist materials that are robust to processing with both UV and EUV. Unlike current resist materials, these materials contain an oxygen and fluorine content of 14 percent or less, and are primarily composed of low-absorbing elements, such as hydrogen, carbon, silicon and boron. The incorporation of silicon- and boron-containing polymers into a resist material can reduce ion reactive etch rates and improve transmission characteristics, both of which are needed during EUV lithography. The invention also includes methods for synthesizing silicon- and boron-containing materials for use in resist compositions.

Protein-Polysaccharide Hybrid Hydrogels

A UW–Madison researcher has developed a biodegradable, hybrid protein-polysaccharide hydrogel capable of absorbing large volumes of water or other liquids, and retaining the liquid in its structure without dissolving. The hydrogel consists of two matrices: an acylated, cross-linked protein matrix and an anionic polysaccharide matrix. The matrices interpenetrate, resulting in a homogeneous hydrogel with superior saline absorption and retention characteristics as compared to hydrogels fabricated solely from protein matrices.

To form the hybrid hydrogel, the polysaccharide matrix can simply be trapped within the protein matrix, or the two matrices can be covalently cross-linked by bridging moieties. The biodegradable nature of this hybrid hydrogel overcomes problems with current, synthetic hydrogels, which are extremely slow to degrade and may be composed of toxic components.

Solid Polysiloxane Electrolyte for Use in Lithium Batteries

UW-Madison researchers have now developed a solid, polysiloxane-containing polymer composition for lithium batteries. In addition to polysiloxanes, the polymer mixture contains a cross-linking molecule, a catalyst and an inhibitor. The mixture exists initially as a liquid that can be poured into batteries. When heated to 50 to 75°C, the polymer gradually solidifies into a soft, flexible gel.

Multi-Functional Matrix to Promote Wound Healing and for Other Biomedical Applications

Using Biofunctionalized Biomaterials to Recapitulate Tissue Structure Lost Due to Trauma or Underlying Disease to Improve Healing
UW–Madison researchers have developed semi-interpenetrating networks (sIPNs), a platform material that mimics the extracellular matrix and allows delivery of factors like therapeutic cells that promote healing to the wound bed. The sIPNs use a multi-functional hydrogel as a scaffold for damaged tissues. The polymer material consists of a biochemically-modified and cross-linked gelatin matrix, onto which are grafted various heterodifunctional polyethylene glycols (hPEGs). The hPEGs increase the biocompatibility and durability of the hydrogel and also provide attachment sites for therapeutic molecules. The biodegradable matrix allows for temporally and spatially controlled delivery of bioactive signals to modulate and complement the dynamics of the wound healing process, making these materials functional and clinically viable as wound dressings.

Guided Self-Assembly of Block Copolymer Films on Interferometrically Nanopatterned Substrates

UW-Madison researchers have developed a new strategy for controlling the ordering of micro-phase separated domains in thin films of self-assembling block copolymers. Using advanced interferometric lithographic techniques, the researchers have created chemically patterned surfaces that act as templates for the self-assembly of block co-polymer films. Extreme ultraviolet interferometric lithography is ideal for this purpose because it produces the periodic surface pattern in the underlying substrate that is needed to guide self-assembly of the periodic domain structure in the overlying block copolymer film.