Effect Of Crosslink Density Research Articles

Fabrication and Spectroscopic Broadening Properties for 1.5 μm Amplification of Er3+-Doped BaF2 Nanoparticles

Hybrid microgel particles were prepared by one step incubation of poly(N-isopropylacrylamide)-co-poly(acrylic acid) (PNIPAM-co-PAA) and gold nanoparticles (AuNPs). PNIPAM-co-PAA microgel particles were synthesized by surfactant-free emulsion polymerization with different crosslinking densities (4.5 wt.-%, 10 wt.-%, 15 wt.-%, MBA to NIPAM) and AuNPs obtained by trisodium citrate reduction method independently. The effect of crosslinking density of synthesized microgel particles on the loadings of AuNPs was investigated. The results showed that 18 +/- 2 nm AuNPs could be well entrapped in the loosely crosslinked (4.5 wt.-%, MBA to NIPAM) PNIPAM-co-PAA microgel particles with high loadings. The final hybrid microgel particles were well characterized by transmission electron microscopy (TEM), UV-vis spectra, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and FT-IR. In particular, the PNIPAM-co-PAA/AuNPs hybrid microgel particles were thermoresponsive and completely reversible with several heating/cooling cycles. Therefore, the PNIPAM-co-PAA/AuNPs hybrid microgel particles allow for combined surface plasmon and thermal switching applications.

Gelation of konjac glucomannan crosslinked by organic borate

A series of thermoreversible konjac glucomannan gels crosslinked by organic borate were prepared. The gel network was formed through the crosslinking reaction between borate ions dissociated from organic borate and the cis-diol hydroxyl groups on the mannose units of polysaccharide chains. The rheological properties of the complex gels were studied by dynamic viscoelastic measurement. The gelation kinetics of the gels were studied and the critical gelation points of the gels were exactly determined by the Winter–Chambon criterion. The effects of temperature and composite ratio on the shear storage modulus ( G ′), the loss modulus ( G ″), and the sol-gel transition points were investigated. The critical gel-sol temperatures of the complex gels were successfully elucidated by Winter–Chambon criterion. The effect of crosslinking density on the critical gelation temperature and the elasticity of the gels were discussed.

Effects of synthesis-solvent on swelling and elastic properties of poly( N-isopropylacrylamide) hydrogels

Thermosensitive N-isopropylacrylamide (NIPA) hydrogels were synthesized by a free radical copolymerization with N, N′-methylenebisacrylamide (MBAA) in four solvents: water, ethanol, acetone and N, N-dimethylformamide. The swelling and elastic properties of the hydrogels were affected by the synthesis-solvents; the hydrogels (e.g. NIPA/MBAA = 1000/50 mol/m 3-pre-gel solution) synthesized in water have smaller swelling volume and larger shear modulus at 10 °C than those synthesized in amphiphilic solvents. The network structure of hydrogels was estimated in terms of the conversion and two sorts of effective crosslinking density based on the Flory theory and the concentration of crosslinker. The hydrogels synthesized in water can have the microscopic inhomogeneous network arising from the entanglement of polymer chains, while the hydrogels synthesized in amphiphilic solvents can have the homogeneous network arising from the polymer concentration lower than the pre-gel solution and can be similar in network structure to the lightly crosslinked hydrogel synthesized in water.

Immobilization of Candida rugosa lipase on poly(allyl glycidyl ether-co-ethylene glycol dimethacrylate) macroporous polymer particles

Macroporous polymer particles containing surface epoxy groups were synthesized for immobilization of Candida rugosa lipase (CRL). The effect of incorporation of two different sets of monomers [allyl glycidyl ether (AGE) and glycidyl methacrylate (GMA)] and the effect of crosslinking density on immobilization of lipase were studied. AGE-co-EGDM polymers gave higher binding and expression of lipase than GMA-co-EGDM polymers. Optimization of immobilization parameters was done with respect to immobilization time and enzyme loading. Amongst AGE-co-EGDM polymer series, AGE-150 polymer found to give maximum lipase activity yield and therefore evaluated for temperature, pH and storage stability. Under optimum conditions, AGE-150 polymer gave 78.40% of activity yield. Immobilized lipase on AGE-150 showed a broader pH, higher temperature and excellent storage stability.

Network and thermodynamic properties of hydrogels of poly[1-(3-sulfopropyl)-2-vinyl-pyridinium-betaine

Samples of poly[1-(3-sulfopropyl)-2-vinyl-pyridinium-betaine] (PSPV) have been synthesized to high conversion by free radical polymerization in aqueous solution of the zwitterionic monomer SPV with several concentrations of the crosslinker N, N′-methylene-bis-acrylamide (MBA). Hydrogels obtained by swelling them in water and aqueous KSCN solution were examined by gravimetric and dimensional analysis, and by compression–strain measurements. The derived effective crosslinking density ν e was only ca. 11% of the theoretical value, indicating low efficiency of chemical crosslinking by MBA. At 298 K increasing content of MBA produces increases in the values of ν e, elastic moduli and polymer–water interaction parameter χ. At a fixed MBA content, increasing temperature led to decreases in the values of ν e, elastic moduli and χ, but an increase in water content of hydrogel. For swelling in aq. KSCN solution the mechanical properties are insensitive to content of salt. Experimental and theoretical analysis afforded values of the water/polymer, salt/water and salt/polymer interaction parameters. Where appropriate the findings are compared with those reported for a different zwitterionic hydrogel and a neutral non-zwitterionic hydrogel.

Development of pH sensitive polyacrylamide grafted pectin hydrogel for controlled drug delivery system

In the present study an attempt was made to graft polyacrylamide on pectin. The grafted polymer was characterized by FTIR spectroscopy, differential scanning calorimetry and X-ray diffraction. Rheological property of pectin solution was compared with the product solution. The grafted polymer was cross-linked with varying amount of glutaraldehyde. The swelling properties of the cross-linked product were also studied. The salicylic acid, an antipyretic drug, was incorporated in the cross-linked gel as a model drug and the drug release studies were done in a modified Franz's diffusion cell. The effect of cross-linking density on the release property of salicylic acid was studied through the cross-linked product. The product showed better film forming property and gelling property than pectin. The comparative rheological properties of pectin and grafted copolymer indicated change in the property of the product. FTIR studies indicated incorporation of amide group. Differential scanning calorimetry and XRD suggested formation of a new polymer. Swelling study indicated pH dependent swelling of the cross-linked hydrogel. Salicylic acid release indicated pH dependent release from the hydrogel.

Mechanical properties and degradation behaviors of hyaluronic acid hydrogels cross-linked at various cross-linking densities

The effect of cross-linking density of hyaluronic acid (HA) hydrogels on mechanical properties and degradation behaviors has been investigated. HA hydrogels were prepared by the covalent cross-linking of HA with poly(ethylene glycol)-diamine with two different molecular weights at various cross-linking densities. The elastic modulus increased gradually as the theoretical cross-linking density of HA hydrogels increased from 0% to 20%. However, as the theoretical cross-linking density increased above 20%, the elastic modulus decreased. At a theoretical cross-linking density of 20%, the elastic modulus increased as the molecular weight of the cross-linking molecule decreased. In vitro degradation rates of HA hydrogels decreased as the molecular weight of the cross-linking molecule decreased at a theoretical cross-linking density of 20%. The degradation rate of the cross-linked HA hydrogels decreased with increases in the theoretical cross-linking density from 0% to 20%. However, there was no significant difference in the degradation rate as the theoretical cross-linking density increased above 30%. With controllable mechanical properties and degradation rates, the developed HA hydrogels would be further investigated for various medical applications.

Molecular Dynamics of Poly(ethylene glycol) and Poly(propylene glycol) Copolymer Networks by Broadband Dielectric Spectroscopy

The dynamic relaxation properties of amorphous rubbery networks prepared by the UV photopolymerization of poly(ethylene glycol) diacrylate [PEGDA] and poly(propylene glycol) diacrylate [PPGDA] cross-linkers have been investigated using broadband dielectric spectroscopy. Effective cross-link density in the networks was controlled by copolymerization of the diacrylate cross-linkers with monofunctional acrylates of similar chemical composition. For all of the networks examined, three motional transitions were detected with increasing temperature, including an intermediate “fast” relaxation located between the typical sub-glass and glass−rubber processes and corresponding to a subset of constrained segmental motions that were more local and less cooperative in nature as compared to those associated with the glass transition. The properties of the intermediate relaxation were sensitive to the degree of constraint imposed by the cross-link junctions: the dielectric intensity of the fast process decreased with ...

Swelling behavior, mechanical properties and network parameters of pH- and temperature-sensitive hydrogels of poly((2-dimethyl amino) ethyl methacrylate- co-butyl methacrylate)

In this study, swelling behavior and mechanical properties of polyelectrolyte cationic hydrogels of poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA), and poly((2-dimethylamino) ethyl methacrylate- co-butyl methacrylate) (P(DMAEMA- co-BMA)), were investigated. Hydrogels were prepared by free-radical solution copolymerization of DMAEMA and BMA using ethylene glycol dimethacrylate (EGDMA) as the crosslinking agent. Compression-strain measurements were used to analyze the mechanical properties of the hydrogels. It was found that increasing the amount of BMA comonomer in the gel structure increases the compression modulus of the material. The results of mechanical measurements were used to characterize the network structure of the hydrogels, namely the effective crosslinking density ( ν e ∗ ) . It was found that ν e ∗ exceeds the theoretical crosslinking density ( ν t) calculated from the initial amount of EGDMA used for hydrogel synthesis. These hydrogels demonstrated dual sensitivity to both pH and temperature. It was shown that the pH-sensitive or temperature-sensitive phase transition behavior of the gels can be changed by changing the temperature or pH of the swelling medium at constant hydrogel composition. Increasing the temperature decreased the transition pH of the pH-sensitive phase transition. On the other hand, increasing the pH of the surrounding medium decreased the transition temperature of the temperature-sensitive phase transition. Incorporation of BMA in the gel structure has a significant effect on the transition point of the gel. Increasing the BMA content reduced the transition pH and temperature of the pH- and temperature-sensitive phase transition, respectively. The similar effect of increasing temperature or BMA content can be explained by the role of hydrophobicity in the phase transition behavior of hydrogels. Finally, the results of equilibrium swelling and compression-strain measurements were used to calculate the polymer–solvent interaction parameters of these hydrogels using the Flory–Rehner equation of equilibrium swelling.

Semi-interpenetrating networks based on POLY(N-isopropyl acrilamide) and POLY(N-vinylpyrrolidone)

Three series of semi-interpenetrating polymer networks based on cross-linked poly(N-isopropylacrylamide), PNIPA, and 1, 2 and 3 wt% of linear poly(N-vinylpyrrolidone), PVP, were synthesized in order to improve the mechanical properties of PNIPA gels. The effect of the incorporation of the linear PVP polymer into the temperature responsive networks on the phase transition temperature, swelling behavior and mechanical properties was studied. Polymer networks with four different crosslinking densities were prepared with various molar ratios (25/1 to 100/1) of the monomer (N-isopropylacrylamide) to the cross linker (N,N'-methylene-bisacrylamide). The hydrogels were characterized by determination of the equilibrium degree of swelling at 25 ?C, the dynamic shear modulus and the effective crosslinking density, as well as the ultimate hydrogel properties, such as the tensile strength and elongation at break. Furthermore, the deswelling kinetics of the hydrogels was also studied by measuring their water retention capacity. The inclusion of the linear hydrophilic PVP in the PNIPA networks increased the equilibrium degree of swelling, the highest values of which were obtained for samples with 2 and 3 wt% of PVP and the NIPA/MBA molar ratio of 75/1 and 100/1. The highest reinforcement effect, evaluated from the ratio of G'red(semi-IPN) to G'red(PNIPA), was obtained by incorporation of 2 wt% PVP. The tensile strength of the semi-IPNs reinforced with linear PVP was higher than that of the PNIPA networks. The elongation at break of these semi-IPNs varied between 22 and 55%, which are 22^11% larger than those for single PNIPA networks. The tensile measurements confirmed that the presence of 2 wt% of the linear polymer significantly reinforced the PNIPA network.

Molecular Dynamics Simulations of Polymer Networks Undergoing Sequential Cross-Linking and Scission Reactions

The effects of sequential cross-linking and scission of polymer networks formed in two states of strain are investigated using molecular dynamics simulations. Two-stage networks are studied in which a network formed in the unstrained state (stage 1) undergoes additional cross-linking in a uniaxially strained state (stage 2). The equilibrium stress is measured before and after removing some or all of the original (stage 1) cross-links. The results are interpreted in terms of a generalized independent network hypothesis. In networks where the first-stage cross-links are subsequently removed, a fraction (quantified by the stress transfer function Φ) of the second-stage cross-links contribute to the effective first-stage cross-link density. The stress transfer functions extracted from the MD simulations of the reacting networks are found to be in very good agreement with the predictions of Flory and Fricker. It was found that the fractional stress reduction upon removal of the first-stage cross-links could be accurately calculated from the slip tube model of Rubinstein and Panyukov modified to use the theoretical transfer functions of Fricker.

Studies on swelling behaviors, mechanical properties, network parameters and thermodynamic interaction of water sorption of 2-hydroxyethyl methacrylate/novolac epoxy vinyl ester resin copolymeric hydrogels

A series of the highly cross-linked hydrogels has been developed by the syntheses of bulk copolymers based on 2-hydroxyethyl methacrylate (HEMA) and novolac epoxy vinyl ester resin (NEVER). The resulting hydrogels were investigated on their equilibrium water content (EWC), swelling behaviors and tensile properties. Dynamic swelling behaviors of copolymeric hydrogels indicate that the swelling process of these polymers follows Fickian behavior. The EWC decreased and volume fraction of polymer in hydrogel ( ϕ 2) increased with NEVER content increasing due to its hydrophobicity. The increase of ionic strength of swelling medium or temperature results in a decrease in EWC and an increase in values of ϕ 2. Young’s modulus and tensile strength of hydrogels, as well as effective cross-link density ( v e), increased as NEVER content increased or ionic strength of swelling medium increased, attributing to increasing interaction between hydrophobic groups and polymer–polymer interaction with an increase in NEVER content or in ionic strength. The polymer–solvent interaction parameter χ reflecting thermodynamic interaction was also studied. As NEVER content, ionic strength of swelling medium or temperature increased, the values of χ increased. The values of χ and its two components χ H and χ S varied with increasing T. The negative values and trend of the enthalpy and entropy of dilution derived from values of χ H and χ S, could be explained on the basis of structuring of water through improved hydrogen bonding and hydrophobic interaction.

Correlation of swelling and crosslinking density with the composition of the reacting mixture employed in radical crosslinking copolymerization

AbstractThis article reports the scaling laws relating the synthesis conditions with the crosslinking density (νe) and swelling degree (S) of poly(N‐vinylimidazole) hydrogels (PVI) prepared by radical crosslinking copolymerization in aqueous solution, with N,N′‐methylene bisacrylamide (BA) as crosslinker. Multiple linear regression of νe versus BA concentration ([BA]) and total comonomers concentration (CT) in double log scale render the scaling law νe ∼ C × [BA]1.04 as comparable to that predicted by the model of polymer network with pendant vinyl groups (νe ∼ CT × [BA]), and showing inverse dependence on CT to that expected, following from stoichiometry, for an ideal network (νe ∼ 2[BA]/CT). S scales with νe through a solvent‐dependent exponent ranging from −0.46 to −0.54, only slightly over the value predicted by the Flory–Rehner theory (−0.6) or the blob's model by de Gennes (−0.5 to −0.8). Finally, the scaling law of S with the composition of the reacting mixture is also solvent‐dependent and it seems to result not only from the dependence of νe on CT and [BA] but also from that of v2r, the polymer volume fraction in the reference state, and χ, the polymer–solvent interaction parameter. Models used seem to overestimate the contribution of entanglements to the effective crosslinking density of PVI. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 263–269, 2007

Swelling behavior and drug release of NIPAAm/PEGMEA copolymeric hydrogels with different crosslinkers

Poly(ethylene glycol) methylether acrylate (PEGMEA) and tetraethylene glycol diacrylate (TEGDA) were first synthesized. The thermosensitive hydrogels were then prepared from N-isopropylacrylamide (NIPAAm), PEGMEA, and three crosslinkers with different structures such as N, N′-methylene-bis-acrylamide (NMBA), TEGDA, and poly(ethylene glycol) dimethacrylate (EGDMA). The influence of polymerization factors such as the kind and amount of crosslinker and initial total monomer concentration on the swelling behavior, gel strength, effective crosslinking densities, and number-average molecular weight between crosslink points ( \(\overline {{M}}_{\rm c}\)) for the present copolymeric hydrogels was investigated. The results indicate that the swelling ratios for the present copolymeric gels decrease with increase in temperature. In addition, the results also showed that the higher swelling ratios for the present gels prepared from TEGDA were obtained due to the larger space between the gel networks. The crosslinking density depends on the swelling ratio and the kind and extent of crosslinker. In addition, the drug release behavior for the present copolymeric gels was investigated.

Effect of porosigen on the swelling behavior and drug release of porous N‐isopropylacrylamide/poly(ethylene glycol) monomethylether acrylate copolymeric hydrogels

AbstractA series of porous thermoreversible hydrogels were prepared from N‐isopropylacrylamide (90 mol %) and poly(ethylene glycol) methylether acrylate (10 mol %), which was derived from poly(ethylene glycol) monomethylether, N,N′‐methylenebisacrylamide, and porosigen, or poly (ethylene glycol) (PEG) with different molecular weights (MWs). The influence of pore volume in the gel on the physical properties, swelling kinetics, and solute permeation from these porous gels was investigated. The results show that the surface areas, pore volumes, and equilibrium swelling ratios for the porous gels increased with increasing MW of PEG, but the shear moduli and effective crosslinking densities decreased with increasing MW of PEG. The results from the dynamic swelling kinetics show that the transport mechanism was non‐Fickian. The diffusion coefficients of water penetrating into the gels increased with increasing pore volume of the gels. In addition, we also studied solute permeation through the porous gel controlled by temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5490–5499, 2006

Effect of cross-linking density on coating properties of a polyurea coating system

Polyamides were prepared from a dimer fatty acid, triethylene tetramine and diethylene triamine, and cross-linked using e-caprolactam-blocked isophorone diisocyanate. These thermoset coatings were then evaluated for various mechanical, chemical and electrical properties. The effect of the cross-linking density on the coating properties was studied. It was observed that with the increase of the cross-linking density, the general toughness of the coatings increased along with chemical resistances, except for acid resistance and the breakdown voltage. However, it was observed that the flexibility and resistance to rapid deformation of the coatings (ie the rigidity of the coatings) decreased with an increase in the cross-linking density of the coating.

Characterization of chondroitin sulfate and its interpenetrating polymer network hydrogels for sustained-drug release

The goal of this work was to utilize the chondroitin sulfate (CS) based hydrogels for a drug delivery matrix. CS is a good structure/disease-modifying anti-osteroarthritis drug (S/DMOAD). However, the readily water-soluble nature limits its application as a solid-state drug-delivery vehicle. In this study, two methods were used to prepare CS hydrogels: directly crosslinking CS with poly(ethylene glycol) diglycidyl ether (EX-810) abbreviated as CS-EX or forming an interpenetrating polymer network named CS-EX-IPN. The CS-EX-IPN hydrogel was carried out by sequentially crosslinking reaction between CS and EX-810 in one phase and acrylic acid and di(ethylene glycol) diacrylate (DEGDA) as a counter phase. The swelling percent, cross-section morphology, and effective crosslinking density of hydrogels were characterized. The values of compression modulus and effective crosslinking density of CS-EX-IPN were ∼3.6-fold higher than CS-EX. We also characterized the release of a model drug, diclofenac sodium (DS) and a model protein, bovine serum albumin (BSA), from CS-EX and CS-EX-IPN. The similar release profiles of DS were observed in the both hydrogels but slower release rate of BSA occurred in CS-EX-IPN. The release profiles of the two model drugs fit in a diffusion-controlled mechanism. The D eff values are in the order of 10 −5 for DS and 10 −7 for BSA.

Surfactant and Polyelectrolyte Gel Particles that Swell Reversibly

Mixing of oppositely charged surfactants and polyelectrolytes in aqueous solutions can lead to associative phase separation, where the concentrated phase is a viscous liquid, gel, or precipitate. In recent years, this phenomenon has been exploited to form gel-like particles, ranging from approximately 100 to 4000 microm in diameter, whose stability depends on equilibrium phase behavior. As the sample composition is varied, these particles either remain stable (in a two-phase mixture) or dissolve over time. Here, we present the formation of reversibly swelling gel particles from mixtures of N,N,N-trimethylammonium-derivatized hydroxyethyl cellulose (JR-400) and sodium dodecyl sulfate (SDS), whose swelling is controlled by the ambient solution conditions. The effects of cross-linking density and surfactant concentration are investigated by gravimetry and confocal microscopy. The resulting particles have a core/shell morphology and undergo reversible swelling/collapse transitions which, depending on the cross-link density, can be either gradual or abrupt with changing SDS concentration.

Effect of the amount and type of the crosslinker on the swelling behavior of temperature-sensitive poly(N-tert-butylacrylamide-co-acrylamide) hydrogels

Temperature-sensitive poly(N-tert-butylacrylamide-co-acrylamide) [P(NTBA-co-AAm)] hydrogels were synthesized by free-radical copolymerization in a water–methanol mixture using three types of crosslinkers: 1,2-ethyleneglycol dimethacrylate, N,N-methylenebisacrylamide, and 1,3-butandiol dimethacrylate. These thermosensitive hydrogels were swollen to equilibrium in water at 20°C and examined by gravimetric measurements. The influence of type and content of crosslinkers on the swelling ratio, the polymer–solvent interaction parameter (χ), the average molecular mass between crosslinks \({\left( {\overline{M} _{c} } \right)},\) and the effective crosslinking density (νE) of the hydrogels were reported and discussed. The swelling process in water was found to be non-Fickian diffusion. The enthalpy (ΔH) and entropy (ΔS) changes appearing in the χ parameter for the hydrogels were determined by using the Flory–Rehner theory based on the phantom network model of swelling equilibrium. Negative values for ΔH and ΔS indicated that the hydrogels had a negative temperature-sensitive property in water; that is, swelling at a lower temperature and shrinking at a higher temperature. The temperature-reversibility and on–off switching properties of the P(NTBA-co-AAm) hydrogels may be considered as good candidates for designing novel drug-delivery systems.

Contact Angle Analysis, Surface Dynamics, and Biofouling Characteristics of Cross-Linkable, Random Perfluoropolyether-Based Graft Terpolymers

The conventional approach to prevention of marine biofouling has been the use of antifouling paints and coatings which function through the release of toxins in the immediate vicinity of the ship. Such technology, while admittedly effective, has proven to be responsible for an alarming increase in the levels of organotin and other toxic materials in and around dry docks, harbors, and shipping lanes which experience significant commercial and tourist traffic. Therefore, our objective is the rational design of minimally adhesive, mechanically stable, nontoxic fouling release coatings as responsible and practical alternatives to antifouling technologies. Herein we report on the synthesis and characterization of a series of cross-linkable perfluoropolyether (PFPE) graft terpolymers containing various alkyl (meth)acrylate monomers with glycidal methacrylate as the cure-site monomer. These materials were targeted for use as coatings to prevent marine biofouling. A series of terpolymers were prepared through application of the macromonomer approach, allowing for control of cross-link density, Tg, and modulus. Structure/property relationships were established through compositional variation with regard to the three classes of monomers. The first monomer class was an alkyl (meth)acrylate used to create the continuous phase of the microphase-separated graft terpolymers. Variation between methyl methacrylate (MMA) and n-butyl acrylate (BA) provided materials with a low (−10 °C) and a high (95 °C) Tg for the continuous phase. This was a means of isolating the effect of modulus and Tg on surface properties, while the basic chemical nature of the monomer remained unchanged. The second monomer class contained a curable functional group. Through incorporation of glycidyl methacrylate (GMA) in the monomer feed and manipulation of curing conditions, the relative effect of cross-link density on surface dynamics has been evaluated. The third monomer class was the PFPE macromonomer itself. The incorporation of this macromonomer was used to enhance the release properties of the resulting materials which relied on surface enrichment of the low surface energy PFPE component. Dynamic surface properties of these materials have been evaluated through dynamic surface tensiometry (DST). Herein, it has been demonstrated that contact angle hystersis can be significantly mitigated (i.e., θr is maximized) by as much as 50° through variation in bulk polymer composition, the chemical nature of monomers, cross-link density, modulus, and environmental conditions at the time of cure. The antifouling and fouling-release potential of the experimental coatings were also evaluated by laboratory assays employing the green fouling macroalga Ulva. The results from these initial studies suggest promising antifouling properties, especially with regard to spore settlement which was strongly inhibited on the experimental surfaces. Additionally, those that did settle were only weakly attached with one sample set exhibiting fairly moderate release of the young Ulva plants.