Latex Films Research Articles

Carboxymethyl chitosan capped copper oxide nanomaterials as antibacterial and antibiofilm coating for vulcanized natural rubber film

The constant menace of infections caused by many microorganisms is one of the significant concerns to humankind. Also, implant-associated biofilms are prevalent in the healthcare sector, which opens up the need for various protective armories against diseases, including antibacterial coatings. In the current context, developing an appropriate antibacterial coating for the materials utilized in the health sector has significance. Synthesis of copper oxide (CuO) nanoparticles (NPs) by the chemical precipitation method and capping of CuO with carboxymethyl chitosan (CMC) provides outstanding antibacterial action. Natural rubber is widely used for various biomedical purposes, regardless its dormancy against most pathogens. An economical and practical method has been developed to transform the Natural Rubber Latex (NRL) film surface to be sufficiently antibacterial by CuO/CMC lamination. This paper discusses the antibiofilm activity of the rubber films against Escherichia coli (MTCC No. 729) and Staphylococcus aureus (MTCC No. 902), and the non-cytotoxicity of the NRL films after CuO/CMC lamination. Hence this surface modification over the NRL film provides excellent prospects for antibacterial polymer materials.

Coupled effect of water absorption and ion transport in hydrated latex anti-corrosion coatings

Water-based anti-corrosion coatings, which are environmentally-friendly replacements for organic solvent-based coatings, do not perform well enough for use in the most challenging corrosion environments. The high water absorption capacity of water-based latex films may reduce barrier performance by contributing to corrosive reactant/product transport. We seek to understand the coupled effects of water absorption and ion transport in hydrated latex films, and to propose mechanisms explaining these effects. Water absorption and ion transport in films immersed in deionized (DI) water were monitored by mass gain and electrical conductivity measurements, respectively. Despite very similar polymer compositions between films, large differences in water absorption and ion transport rates were observed and explained by percolating networks at latex particle boundaries which facilitate transport. A semi-continuum model with three-component diffusion and convection-like elastic relaxation supported the assumptions of the physical mechanisms governing water absorption and ion transport. The evidence of the coupled processes of water absorption and ion transport in hydrated latex films revealed in this study are useful for designing water-based coatings that provide high levels of corrosion resistance.

Nanoscale polymer encapsulated pigment hybrid latexes with high pigment content for binder-free pigment printing of cotton/polyester blend fabrics

Pigment printing of cotton/polyester (C/P) blend fabrics is an environment-friendly technology for achieving cleaner fabric coloration. However, the application of conventional pigment-printing technology is restricted owing to the stiff feeling and low crocking fastness of the printed goods. In this study, a novel polymer-encapsulated pigment hybrid latex with nanoparticle morphology and high pigment content was synthesized for binder-free pigment printing of C/P fabrics via sulfur-free reversible addition-fragmentation transfer (SF-RAFT) emulsion polymerization using allyloxy polyoxyethylene (10) nonyl ammonium sulfate (DNS-86) as the reactive surfactant. The pigment content of the hybrid latex was as high as 83.8%, with an average particle size of 251 nm. The surface of single C/P fibers was uniformly wrapped by the hybrid latex film, where the highly encapsulated pigment accelerated pigment fixation on the fibers, improving the color depth, color fastness, air-permeability, and hand-feel of the binder-free printed C/P fabrics in comparison with those of the control system with low pigment content (traditional free radical polymerization). More importantly, the highly encapsulated pigment hybrid latex particles promoted the formation of a new discontinuous film coating on the surface of single fibers, which opens up a promising avenue for replacing conventional fabric printing techniques.

Designing Multicomponent Polymer Colloids for Self-Stratifying Films.

Aqueous polymer colloids known as latexes are widely used in coating applications. Multicomponent latexes comprised of two incompatible polymeric species organized into a core-shell particle morphology are a promising system for self-stratifying coatings that spontaneously partition into multiple layers, thereby yielding complex structured coatings requiring only a single application step. Developing new materials for self-stratifying coatings requires a clear understanding of the thermodynamic and kinetic properties governing phase separation and polymeric species transport. In this work, we study phase separation and self-stratification in polymer films based on multicomponent acrylic (shell) and acrylic-silicone (core) latex particles. Our results show that the molecular weight of the shell polymer and heat aging conditions of the film critically determine the underlying transport phenomena, which ultimately controls phase separation in the film. Unentangled shell polymers result in efficient phase separation within hours with heat aging at reasonable temperatures, whereas entangled shell polymers effectively inhibit phase separation even under extensive heat aging conditions over a period of months due to kinetic limitations. Transmission electron microscopy is used to track morphological changes as a function of thermal aging. Interestingly, our results show that the rheological properties of the latex films are highly sensitive to morphology, and linear shear rheology is used to understand morphological changes. Overall, these results highlight the importance of bulk rheology as a simple and effective tool for understanding changes in morphology in multicomponent latex films.

A relationship between cross-link concentration and physical properties in natural rubber latex films at different calcium carbonate loadings

A relationship between cross-link concentration and physical properties in natural rubber latex films at different calcium carbonate loadings

Environmentally-friendly short-chain perfluoropolyether polyacrylates emulsion films for high water barrier coating applications

Water-based protective coatings have gained wide popularity because of their low toxicity and volatile organic compounds (VOCs) emissions. However, improving water barrier performance is a significant challenge. An environmentally friendly short-chain perfluoropolyether carboxylic acid (PFPE-MMA) material has been synthesized in this study, and a series of PFPE-based polyacrylates were prepared using RAFT miniemulsion copolymerization. The impact of PFPE chains and crystalline stearyl methacrylate (SMA) on the wettability of copolymer latex films and their use in protective coatings were studied. Based on the surface and bulk morphology of latex films, the addition of SMA to PFPE-based polyacrylates promoted PFPE chains to migrate toward the air/film interface, leading to exceptional wettability and water resistance through the matrix, resulting in remarkable water barrier properties. After 192 h, the water absorption ratio of 25% PFPE-7% SMA latex film was 3.98%, while that of 25% PFPE latex film was 6.03%. Not only are PFPE-based polyacrylates excellent protective materials with potential applications, but they are also an effective preparation strategy for improving the high barrier property in waterborne protective coatings.

Understanding the role of TEMPO-oxidized cellulose nanofiber on natural rubber latex nanocomposites

Cellulose nanofibers (CNF) were isolated from raw cotton fibers via 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO) oxidation process. The isolated CNF were morphologically characterized using Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). Entangled fibrous morphology with diameter in nano regime (15–20 nm) has been observed for the isolated nanofibers. X-ray diffraction (XRD) analysis confirms the high crystallinity of the isolated CNF. Further, the isolated CNF was used to reinforce natural rubber (NR) latex films. The crystallographic, morphological, and spectroscopic analysis of the NR/CNF nanocomposites was carried out. A strong interaction between the CNF and NR matrix has been identified and which reflects in the thermal stability and swelling behavior of NR/CNF nanocomposite films in toluene. The uniform dispersion and tangling effect of CNF along with strong NR-CNF interaction restrict the uptake of solvent through NR matrix.

Design and synthesis of waterborne light-responsive cellulose nanocrystal/fluorinated polyacrylate films toward oil/water repellent and self-healing properties

The development of environmentally friendly waterborne polymeric materials is becoming critical today. In this study, a kind of self-healing cellulose nanocrystal/fluorinated polyacrylate based on the reversible photo-induced dimerization of coumarin groups was prepared via RAFT-mediated Pickering emulsion polymerization using cellulose nanocrystal (CNC) particles modified with light-responsive amphiphilic copolymers as Pickering stabilizers. Emulsion polymerization and latex film properties were significantly varied in dependence on the amount of 7-(2-methacryloyloxyethoxy)-4-methylcoumarin (CMA) monomer. Hydrophobic, oleophobic and mechanical properties of the latex film were dynamic in response to UV light. The maximum water contact angle and CH2I2 contact angle increased by 6.1° and 2.3°on the irradiation of UV light at 365 nm, respectively. The tensile strength of latex film increased initially with increasing amount of CMA increased, from 0 up to 4 wt%, and then decreased. The maximum tensile value increased from 3.0 MPa to 6.4 MPa after the dimerization reaction activated by 365 nm UV light. Results from atomic force microscope (AFM) and energy dispersive X-ray spectrometer (EDX) revealed that latex film possessed a roughness structure and the fluorine had a remarkable enrichment on the film-air interface. Moreover, latex films showed an excellent surface scratch self-healing ability owing to the reversible dimerization reaction of the coumarin groups, and the reversible dimerization reaction of coumarin groups within cellulose nanocrystal/fluorinated polyacrylate polymer was extensively investigated via FT-IR spectrometer and differential scanning calorimetry (DSC). The fruitful outcomes indicated that light-responsive cellulose nanocrystal/fluorinated polyacrylate exhibited a greatly potential application as a smart material.

Self-Powered Flexible Sensor Based on Triboelectric Nanogenerators for Noncontact Motion Sensing

Flexible sensors with surface suitability for complex-shaped objects generally sense object motion through a contact mode, which limits their application range and shortens their service life. The development of flexible sensors with noncontact working modes can overcome these shortcomings. Herein, superhydrophobic and self-powered flexible sensors based on a triboelectric nanogenerator (TENG) were fabricated by a step-by-step swelling-permeation method to prepare natural latex films with carbon black and silica nanoparticles embedded on their inner and outer surfaces, respectively. In addition to sensing object motion through contact, the TENG-based sensor can also sense charged object motion in noncontact mode based on the principle of electrostatic induction. The TENG-based sensor can sense horizontal and vertical movements of objects above it and can even detect the movement of objects with speeds as low as 0.04 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}/\text{s}$ </tex-math></inline-formula> . Interestingly, the sensor’s ability to monitor object motion in noncontact mode remains unchanged even at 70% strain. The TENG-based sensor can also be used to distinguish the type and amount of charge carried by an object and can harvest energy from moving objects in noncontact mode. Combining a single-electrode TENG with a freestanding TENG allows monitoring of the motion direction of an object loading an unknown type of charge in a noncontact mode. Based on the characteristics of our TENG-based flexible sensors to sense moving objects in both contact and noncontact modes, they have potential applications for human-machine interfaces, smart wearable devices, and flexible robots.

Natural Rubber (NR) Latex Films with Antimicrobial Properties for Stethoscope Diaphragm Covers.

Systematic disinfection of the stethoscope diaphragm is required to ensure that it does not act as a vector for cross-transmission of health-related diseases. Thus, an antimicrobial latex film could be used as a cover to inhibit pathogenic bacteria from growing on its surface. The aim of this work is to determine the antimicrobial activity and mechanical properties of antimicrobial natural rubber (NR) latex films with different types of antimicrobial agents (mangosteen peel powder (MPP), zinc oxide nanoparticles (ZnO NP), and povidone-iodine (PVP-I)). The antimicrobial loading was varied from 0.5, to 1.0, and 2.0 phr to monitor the effective inhibition of Gram-negative bacteria and fungi growth. For MPP and PVP-I antimicrobial agents, a loading of 2.0 phr showed good antimicrobial efficacy with the largest zone of inhibition. Simultaneously, ZnO NP demonstrated excellent antimicrobial activity at low concentrations. The addition of antimicrobial agents shows a comparable effect on the mechanical properties of NR latex films. In comparison to control NR latex film (29.41 MPa, 48.49 N/mm), antimicrobial-filled films have significantly greater tensile and tear strengths (MPP (33.84 MPa, 65.21 N/mm), ZnO NP (31.79 MPa, 52.77 N/mm), and PVP-I (33.25 MPa, 50.75 N/mm). In conclusion, the addition of antimicrobial agents, particularly ZnO NP, can be a better choice for NR latex films because they will serve as both an activator and an antimicrobial. In a clinical context, with regard to frequently used medical equipment such as a stethoscope, such an approach offers significant promise to aid infection control.

Fluorinated acrylic monomer modified core-shell polyacrylate latex particles: Preparation, properties and characterizations

The core-shell acrylic emulsion was synthesized by a semicontinuous seeded emulsion polymerization with acrylate monomers as the main materials and octafluoropentyl methacrylate (OFPMA) as modified monomers. The influences of OFPMA on the hydrophobicity, thermal stability and mechanical properties of acrylic latex film were investigated. Fourier transform infrared spectroscopy (FTIR) analysis and X-ray photoelectron spectroscopy (XPS) indicated that the OFPMA was successfully incorporated into the acrylic resin chain. Transmission electron microscope (TEM) image showed a core-shell structure of the emulsion particles. The addition of OFPMA reduced the water absorption ratio (3.2 wt%) of the latex film and improved its water resistance. Contact angle of coating film surface increased from 80.7° to 90.7°. Moreover, TGA curves showed that the addition of OFPMA increased the initial decomposition temperature of the polymer from 355 to 370 °C. Additionally, with the addition of OFPMA, the tensile strength of modified polymers was also improved to 7.77 MPa compared to pure acrylic resin. The application of the core-shell structure can reduce the amount of fluorine-containing acrylic monomers and environmental pollution, and improve economic benefits. This study provides a new kind of environmentally friendly waterborne acrylic resin and a simple method for optimizing the performance of waterborne resins. • The core-shell acrylic emulsion modified by octafluoropentyl methacrylate was synthesized via a semicontinuous seeded emulsion polymerization. • The core-shell acrylic emulsion exhibited excellent water resistance and thermal stability. • The core-shell structure reduces the amount of fluorine-containing acrylic monomers.

Investigation of the water barrier properties of graft copolymer latex films of acrylate and poly(dimethylsiloxane) macromonomers synthesized by RAFT miniemulsion polymerization

It is challenging to improve the water barrier performance for waterborne protective coating. We synthesized a series of acrylic-polydimethylsiloxane (PDMS) graft copolymer latexes p(MMA-co-BA)-g-PDMS) with high PDMS content of up to 50%, which were considered as bottle-brush polymers using reversible addition-fragmentation chain transfer mediated “macromonomer” miniemulsion copolymerization. We investigated the effect of PDMS side chains on the water barrier performance of graft copolymer latex film derived from these particles and their utilization in anti-corrosion coatings. The water contact angle reaches 117° for films cast from aqueous dispersions of graft copolymers with 50% PDMS, which indicates that their surface is significantly enriched with PDMS. The increase in PDMS content has a highly positive effect on the water barrier performance. Differential scanning calorimeter (DSC) on copolymer films after soaking in water indicates that the high PDMS content (50% PDMS) graft copolymer has only freezing bound water in films. Electrochemical impedance spectra tests showed that the graft copolymer exhibited a significant improvement in corrosion resistance over the control polyacrylate sample without PDMS. Furthermore, transmission electron microscopy observations reveal that the PDMS phase changes from a spherical domain texture to a bicontinuous gyroid texture in the bulk of latex films with the increasing PDMS content, which makes them suitable as waterborne anti-corrosion silicone coatings.

Stretchable vertical graphene arrays for electronic skin with multifunctional sensing capabilities

Electronic skin (e-skin) has significant application prospects in soft robotics, prosthetics, medical monitoring, and wearable equipment. However, it remains a great challenge for e-skin to comprehensively mimic the multifunctional sensing capabilities and characteristics of human skin. Herein, vertical graphene arrays (VGA) were directly fabricated on the surface of a natural latex film using a facile method. The e-skin based on VGA combines the intrinsic properties of graphene and flexible substrates, as well as the morphological advantages of VGA, giving it multifunctional sensing capabilities similar to those of human skin. The e-skin not only exhibited multifunctional tactile perception of the pressure, airflow, and surface morphology of objects, but could also percept the difference in temperature between the detected object and the e-skin in a noncontact manner. Moreover, the sensing characteristics, including an ultrafast responsiveness (6.7 ms) and resilience (13.4 ms), a broad pressure sensing range (2.5 Pa – 1.1 MPa), a high sensitivity, and a robust cyclability, further demonstrate the similarity to that of human skin. The outstanding stretchability of the substrate endows the e-skin with an ultrabroad strain detection range (0.5%∼250%). Furthermore, the e-skin can still maintain the VGA structure, as well as the sensing capability under large tensile deformations. The facile preparation methods and excellent performance mean this e-skin is expected to be applied as a multifunctional integrated e-skin in smart flexible electronics.

Study on preparing of diallyl maleate modified acrylic resin

PurposeThere are three double bonds in the chemical structure of diallyl maleate. The purpose of this study is that the acrylate is modified with diallyl maleic anhydride to make the propionate resin present a spatial network structure, thereby improving the performance of the acrylate resin.Design/methodology/approachMethyl methacrylate (MMA) and butyl acrylate(BA) were used as were used as main monomers. Diallyl maleate (DAM) was used as crosslinking monomer and dodecafluoroheptyl methacrylate (DFMA) was used as fluoromonomer. Potassium persulfate (KPS) was used as thermal decomposition initiator, sodium lauryl sulfate (AS) and sodium dodecyl sulfonate (SDS) were used as anionic emulsifiers, and EFS-470 (Alkyl alcohol polyether type nonionic emulsifier) was a non-ionic emulsifier.FindingsThrough optimizing the reaction conditions, the uniform and stable latex is obtained. The polymer of structure was characterized by Fourier transform infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA) and contact angle (CA) were tested on latex films. The particle size and distribution range of emulsion were tested with nano particle size analyzer.Originality/valueThe experimental results showed that the thermal decomposition temperature of the acrylic coating film increased by 20.56°C after modification. In addition, the effect of cross-linking density on the water contact angle of the fluorocarbon groups in DFMA when they migrate to the surface of the latex film during drying has been explored. The experimental results show that a higher degree of cross-linking will hinder the migration of fluorocarbon groups to the surface of the resin film.

Guayule Natural Rubber Latex and Bi2O3 Films for X-ray Attenuating Medical Gloves

Existing natural latex radiation-attenuating gloves (RAGs) contain a high loading of radiation attenuation filler that reduces their mechanical properties to below Food and Drug Administration (FDA) medical glove requirements. RAGs are commonly formulated using Hevea natural rubber latex and lead-based fillers. The former can cause life-threatening allergic responses and the latter are known for their toxicity. In this work, a new lead-free RAG formulation based on circumallergenic guayule natural rubber latex (GNRL) and non-toxic radiation attenuation filler bismuth trioxide (Bi2O3) was developed. GNRL films with Bi2O3 loadings ranging from 0 to 300 PHR at different thicknesses were prepared. Radiation attenuation efficiencies (AE) at 60, 80, 100, and 120 kVp were determined and attenuation isocontour curves predicted film thickness and Bi2O3 loading required to meet or exceed the radiation attenuation requirements of ASTM D7866 and commercial RAGs. Optimal curing conditions for GNRL/Bi2O3 films with 150 PHR Bi2O3 were investigated by varying curing temperatures and time from 87 °C to 96 °C and 65 min to 90 min, respectively. In general, as the loading of the filler increased, the density of the films increased while the thickness decreased. GNRL/Bi2O3 films with 150 PHR Bi2O3 and 0.27 mm provided 5% more AE than RAG market average attenuation at the same thickness. The films with 150 PHR Bi2O3 cured under near-optimal conditions (90 °C/85 min, and 87 °C/65 min) met both the radiation attenuation standard (ASTM D7866) and the natural latex surgeon and examination glove standards (ASTM D3577 and D3578, respectively). Thus, gloves made using our formulations and protocols demonstrated potential to meet and surpass medical natural latex glove standards, offer a single product for both infection control and radiation protection instead of double-gloving, provide a greater degree of comfort to the user, and simultaneously reduce contact reactions and eliminate potential latex allergic reaction.

Mechanical properties and thermogravimetric analysis of peroxide prevulcanized natural rubber latex induced by Co-60 γ radiation

The radiation and peroxide vulcanizations of natural rubber latex are sharing the same problem which is low mechanical properties on their latex. This makes it unsuitable to be use in the production of premium latex products such as surgical glove. Moreover, there are some cases where the use of sensitizers in radiation vulcanization and activators in peroxide vulcanization tends to produced latex film with unpleasant smell and darken color respectively during the drying process. For this study, radiation of latex formulations based on 0.1 pphr of tert-butyl hydroperoxide and 0.06 pphr of potassium laurate at various radiation doses showed increment of tensile strength with increasing of radiation doses; radiation at 25 kGy produced rubber film with tensile strength of 20.7 MPa which is almost 7 times higher than control.

Antibacterial natural rubber latex films with surface-anchored quaternary poly(4-vinylpyridine) polyelectrolyte

Device-associated biofilms and infections generated thereby are of important concern in healthcare sector wherein efficacious antimicrobial surfaces are of extreme relevance. Natural Rubber is widely used for diverse biomedical applications; however, is inherently inactive against most of the pathogens. A facile and effective approach is presented herein to transform Natural Rubber latex (NRL) film surfaces into sufficiently antibacterial via surface conjugation of a cationic polyelectrolyte, quaternized Poly(4-vinylpyridine), QP4-VP through amide linkage using Chloroacetic acid. 1H NMR, FT-IR, TGA and zeta potential measurements affirmed quaternization and functionalities of QP4-VP while antibacterial efficacy is certified by significant zones of inhibition against standard strains, Escherichia coli and Staphylococcus aureus using Ciprofloxacin as positive control. Chloroacetic acid reacts with –OH group of surface-oxidized NRL establishing ester linkage which facilitates anchoring of QP4-VP onto NRL film surface through amide linkage; authenticated by ATR spectra and contact angle measurements. Accelerated leaching (50 °C for 4 days) demonstrated minimal weight loss for the conjugated films and assuring stability of the conjugate. Contact killing assay results indicated significant bacterial killing rate (99.99%) against the tested clinical strains; P. aeruginosa PAO1 and Acinetobacter baumannii C80 validate the antibacterial efficacy of the films.

Effect of Fatty Acid Polyunsaturation on Synthesis and Properties of Emulsion Polymers Based on Plant Oil-Based Acrylic Monomers.

This study demonstrated that polymerization behavior of plant oil-based acrylic monomers (POBMs) synthesized in one-step transesterification reaction from naturally rich in oleic acid olive, canola, and high-oleic soybean oils is associated with a varying mass fraction of polyunsaturated fatty acid fragments (linoleic (C18:2) and linolenic (C18:3) acid esters) in plant oil. Using miniemulsion polymerization, a range of stable copolymer latexes was synthesized from 60 wt.% of each POBM and styrene to determine the impact of POBM chemical composition (polyunsaturation) on thermal and mechanical properties of the resulted polymeric materials. The unique composition of each plant oil serves as an experimental tool to determine the effect of polyunsaturated fatty acid fragments on POBM polymerization behavior and thermomechanical properties of crosslinked films made from POBM-based latexes. The obtained results show that increasing polyunsaturation in the copolymers results in an enhanced crosslink density of the latex polymer network which essentially impacts the mechanical properties of the films (both Young’s modulus and toughness). Maximum toughness was observed for crosslinked latex films made from 50 wt.% of each POBM in the monomer feed.

Novel self-cross-linking fluorinated polyacrylate latex films with short chain perfluoroalkyl group: Surface free energy and surface reorganization

Fluorinated polymers with chains longer than six carbon perfluoroalkyl groups have been banned due to their detrimental effects on environment and human health, and other alternatives are of increasing concerns. In this study, an environmentally friendly self-cross-linking fluorinated polyacrylate hybrid latex with short perfluoroalkyl group has been synthesized from the monomers of (2-(perfluorobutyl) ethyl acrylate (PFHEA, four carbon atoms), stearyl acrylate (SA)), methyl methacylate (MMA), butyl acylate (BA), octamethylclotetrasiloxane (D4) and cross-linking agent (vinyltriethoxysilane, VTES) by a simple one-step miniemulsion copolymerization. The wetting properties, surface energy and surface reorganization, microstructure, and mechanical properties of the synthesized hybrid latex films were systematically investigated. Results showed that the stable low surface energy of these synthesized self-cross-linking fluorinated polyacrylate hybrid latex films with short chain perfluoroalkyl group were attributed to the synergetic effect of crystal side chains of stearyl pendant groups and cross-linking structure effectively restricted the reconstruction of short fluorine chains. Furthermore, the optimum VTES content was 5 wt%, the obtained latex film exhibited excellent mechanical properties. We envision that this new class of self-crosslinking fluorinated polymer latexes has great potential as nonwetting coatings.

Influence of intraparticle cross-linking on polymer diffusion in latex films prepared from secondary dispersions

In this work, we synthesized surfactant-free latex dispersions of nanoparticles (NPs) based upon emulsification of a preformed proprietary BASF polymer (MnGPC = 5000 g/mol, Ð = 3, denoted as Pol), in which the —COOH groups were partially neutralized by ammonia. To obtain useful coatings with polymers of such low molecular weight (MW), we approached this problem through the reaction of carboxylated polymer dispersions with neopentyl glycol diglycidyl ether (NGDE, 20 to 60 mol% based on carboxyl groups) to increase the MW and to introduce gel content. We employed AFM to monitor the influence of cross-link density on the surface roughness and found the presence of cross-links increases the resistance of particles to deformation. Fluorescence resonance energy transfer (FRET) measurements were carried out to determine the extent of polymer mixing upon film formation. Our most important finding is that the gel content substantially limited the extent of molecular mixing at long annealing times or in corresponding solvent-cast films. In parallel, we carried out a series of similar reactions on the secondary dispersion particles with a monoepoxide, consisting of a mixture of dodecyl and tetradecyl glycidyl ether. This reaction maintained the size and size distribution of the latex particles. These polymers had no gel content, but the reaction with the epoxide lowered the Tg of the polymer. FRET studies showed a pronounced influence of Tg on the rates of polymer diffusion in these films.