NANOSCALE COATING OF WOOD SURFACES

Author
Source: VIRGINIA POLYTECHNIC INSTITUTE submitted to 

Sponsoring Institution

National Institute of Food and Agriculture

Project Status

TERMINATED

Funding Source

MCINTIRE-STENNIS

Reporting Frequency

Annual

Accession No.

0216634

Grant No.

(N/A)

Project No.

VA-136611

Proposal No.

(N/A)

Multistate No.

(N/A)

Program Code

(N/A)

Project Start Date

Oct 1, 2008

Project End Date

Sep 30, 2013

Grant Year

(N/A)

Project Director
RENNECKAR, S.

Recipient Organization
VIRGINIA POLYTECHNIC INSTITUTE
(N/A)
BLACKSBURG,VA 24061

Performing Department
Sustainable Biomaterials 

Non Technical Summary
Wood-based composites are key products of the Forest Products Industry which supports many manufacturing jobs in the state of Virginia. These materials allow for increased utilization of forest resources (from the amount usable fiber from a log to the dimension and types of logs used) and increased product uniformity over dimensional lumber. However, a major drawback of wood composites is the use of petroleum based adhesives. In the current climate of record oil prices, material costs for manufacturing are increasing. Alternatives are to use less adhesive or find non-petroleum based sources for their replacement. Because the adhesive is the largest material cost, manufactures already have optimized the amount of adhesive in the bondline to meet minimum performance requirements. This optimization is based on their current adhesive systems. The focus of this proposal is the development of alternative adhesives for wood composites that create bondlines 100x to 1000x thinner than current adhesives by using nanoscale coatings composed of polyelectrolytes. These polyelectrolytes are based on current biobased materials reducing the need for petroleum based materials. Wood surface modification, through irreversible polyelectrolyte adsorption, will provide a path towards new materials with previously unattainable controlled functionality to address the performance of, health issues, and the adaptability of wood composite materials of tomorrow.

Animal Health Component

(N/A)

Research Effort Categories

Basic

(N/A)

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
511	0650	2000	100%

Knowledge Area
511 - New and Improved Non-Food Products and Processes;

Subject Of Investigation
0650 - Wood and wood products;

Field Of Science
2000 - Chemistry; 

Keywords

wood

wood composites

nanoscience

nanotechnology

adhesives

coating

polyelectrolyte

Goals / Objectives
This project will create novel strategies of engineering wood surfaces by the adsorption of cationic polyelectrolytes under ambient conditions. Wood surfaces are enormously complex, chemically and morphologically; under hydration they exhibit a molecularly fuzzy solid/liquid interface. This research will characterize fundamental parameters that control the irreversible adsorption of polyelectrolytes to wood surfaces. 1. Measure polyelectrolyte adsorption onto xylem surfaces with wet chemical analysis and surface spectroscopy as a function of polyelectrolyte type and solution conditions 2. Systematically measure isolated lignin assembly (change in mass/thickness, concentration per unit area) on charged surfaces as a function of concentration and solution conditions. 3. Determine the adhesion between wood substrates adhered by oppositely charged polyelectrolytes.

Project Methods
Obj 1. Adsorption of strong and weak polyelectrolytes that have amine functionality to wood surfaces will be quantified through nitrogen analysis using a CNS elementary analyzer and a depletion method of measuring a change in polyelectrolyte solution concentration. Solution conditions, such as pH, ionic strength, and temperature will be varied to influence the amount of polyelectrolyte adsorbed onto wood surfaces. X-ray photoelectron spectroscopy will be used to measure the amount of surface nitrogen as well as carbon ratios, and it will be compared to the total nitrogen from wet analysis. Surface energy analysis using sessile drop contact angle tests will be used to follow the changes of the characteristics of the wood surface as a function of nitrogen content and polycation type. Obj 2. The real time assembly of isolated lignin onto ionic surfaces will be measured with quartz crystal microbalance with dissipation monitoring (QCM-D) and surface plasmon resonance (SPR). Atomic force microscopy (AFM) will be used to characterize the adsorbed lignin. A wide range of lignin solutions will be prepared for the adsorption studies as a function of pH, salt content, and concentration. By comparing the data from the two systems (SPR and QCM-D), the quantity and conformation of the adsorbed macromolecules will be deduced. These methods offer complimentary information, where the surface concentration is determined through the de Feijter relationship and the thickness of the lignin is determined by the Sauerbrey relationship and density ratio related to the adsorbed film layer. Obj 3. Based on conditions found in Objective 1, wood substrates will be modified with layer-by-layer films with opposite terminal charges and bonded together. Adhesion testing of LbL bonded wood will be conducted in mode-I fracture cleavage, using the dual cantilever beam (DCB) specimen geometry [13]. The adhesion will be measured as a function of number of LbL layers, polyelectrolyte chemistry, and thermal treatment.

Progress 10/01/08 to 09/30/13 Outputs Target Audience: The primary target of this project was scientists in the field to spur innovation in the arena of sustainable materials grown from the forests and fields of the United States. These scientists ranged from other researchers working in the area of wood composite materials, to scientists that are in traditional engineering and chemistry departments. The secondary target was the wood based composites industry. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Over the entire project, 7 graduate students participated in this research providing them fundamental knowledge about forest products and skills/abilities to characterize and measure these materials. These graduate students helped to mentor 10 undergraduate students in the laboratory that helped to collect and analyze data. How have the results been disseminated to communities of interest? Dr. Renneckar has published much of this research in high impact journals: 9 papers were published about nanoscale coatings and adsorption/assembly of these materials to wood surfaces. He also participated in the Wood-Based Composites Center technical meetings, an NSF I/UCRC. At these meetings his graduate students provide poster presentations to the research and development managers from the major wood composites and wood adhesives companies. Additionally, Renneckar has developed a webpage that has a Twitter feed and Engagement page to provide background and information about the work performed in his research group. This engagement section can be found at http://sawmil.sbio.vt.edu . He has also provided instruction to elementary school children that visited the College of Natural Resources and Environment. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported Impacts What was accomplished under these goals? Over the reporting period all three of the project goals were addressed and completed. Polyelectrolyte (and nanoparticle) adsorption was quantified on wood and wood fiber surfaces. Lignin assembly onto positively charged surfaces was measured and this data was used to build free standing films of lignin and nanocellulose with a charged linking layer. Finally the mechanical performance of these composites with charged polymers and nanoparticle as an adhesive layer was measured. IMPACT: Surface modification of wood with charged polymers and nanoparticles enhances the durability and performance of these composite materials. Data showed that surface modification of wood with charged polymers could retard the growth rate of mold and decay fungi. This result is important as the charged polymers are non-toxic and have a small environmental footprint compared to other wood treating agents. Additionally, it was found that lignin could make a highly uniform film material. Lignin is widely viewed as one of the most under-utilized and under-valued materials from the forest products industries. Fundamental science from this work on lignin assembly, was used to identify a mechanism on how wood fibers could undergo modification with charged polymers and clay nanoparticles to form hybrid-clay-wood fiber nanocomposites. The adsorption of clay enhanced the thermal stability of wood fiber creating a wood fiber that would char instead of undergo complete burning. Other polyelectolytes that could "cross-link" were used to make wood fiber composites with water proof bondlines. These polyelectrolytes have chemistries that are very similar to nylon. Finally, nanocellulose with charged surfaces were evaluated in a variety composite applications. These charged nanoparticles could be easily functionalized with hydrophobic groups. This modification allowed the formation of paper-based materials that were water-proof and stronger than typical paper. By changing these fundamental properties of paper, it opens a new pathway towards utilization of paper-based materials in applications of packaging and other value-added applications. Publications Type: Journal Articles Status: Published Year Published: 2013 Citation: Zhang, W., R.K. Johnson, Z. Lin, C. Chandoha-Lee, A. Zink-Sharp, and S. Renneckar (2013). In situ generated cellulose nanoparticles to enhance the hydrophobicity of paper, Cellulose, in press, DOI: 10.1007/s10570-013-0062-9. Type: Journal Articles Status: Awaiting Publication Year Published: 2014 Citation: Pillai, K., F. Navarro, W. Zhang, and S. Renneckar (2013). Towards biomimicking wood: Fabricated free-standing films of nanocellulose, lignin, and a synthetic polycation, Journal of Online Visual Experiments Type: Journal Articles Status: Published Year Published: 2013 Citation: Lin, Z., W. Zhang, and S. Renneckar (2013). Impact of clay nanoparticles on glutaraldehyde crosslinked fiber composites. Journal of Materials Science, 48(17), 5983-5989. Type: Journal Articles Status: Published Year Published: 2013 Citation: S. Renneckar (2013). "State of the Art Paper: Biomimetics: Adapting Performance and Function of Natural Materials for Biobased Composites," Wood and Fiber Science, 45(1), 3-14.

Progress 10/01/11 to 09/30/12 Outputs OUTPUTS: A number of experiments were conducted related to polyelectrolytes that could be used to modify the surface chemistry of wood surfaces along with controlled modification of cellulose fiber surfaces. Experiments such as wood derived polyelectrolyte characterization were conducted. In one set of experiments nanocellulose materials with negative charges were isolated and characterized with x-ray diffraction, vibrational spectroscopy, and titration (wet chemical analysis). A new collaboration was fostered based on this material, nanocellulose, with faculty in Civil and Envrionmental Engineering, Geology, and Materials Science and Engineering at Virginia Tech, under the program "VT Sustainable Nanotechnology." A new method to isolate lignin (a weak polyelectrolyte) was also investigated and resulted in a university disclosure with a collaborator in Biological Systems and Engineering. Additionally, a hybrid coating material of nanocellulose and exfoliated graphite was investigated (scanning electron microscopy for imaging, tensile testing for mechanical properties, x-ray diffraction for structure analysis, and atomic force microscopy for nanoscale imaging). Also, experiments in creating magnetic cellulose coatings were conducted by undergraduate researchers. Various results were presented at the American Chemical Society Spring Meeting in San Diego, on campus, such as the Biobased Materials Graduate Symposium, REU Bioprocessing poster session, and in the classroom as a guest lecturer in a senior level Green Chemistry course in the department of chemistry. PARTICIPANTS: Scott Renneckar was the lead PI on the project. Wei Zhang and Qingqing Li were graduate students that were involved in the research. Mandi Lu, Andrew Plaut, Peter Nixon, Cody Chandoha-Lee, and Dana Kazerooni were undergraduate researchers involved in the project. 7 students, two female, made samples, tested specimens, and analyzed data. The students were trained in polymers and nanomaterials derived from natural materials. TARGET AUDIENCES: Target audiences were students and colleagues at Virginia Tech. The research led to interdisciplinary research team looking at the sustainability of nanoparticles for high performance coatings, films, and materials. PROJECT MODIFICATIONS: Not relevant to this project. Impacts The collective efforts of this research have lead to a dissertation on the subject of nanoscale cellulose (a charged biobased nanoparticle), a proposal funded by the National Science Foundation on the environmental impact of nanocellulose production, a collection of interdisciplinary faculty that meet biweekly under VT Sustainable Nanotechnology to discuss how to quantify the environmental footprint of nanocellulose and how to reduce the environmental footprint of other nanoparticles. These discussions are germane to nanoscale coatings on wood as new technologies with limited environmental impact must be developed for wood coatings with enhanced performance. Interdisciplinary training of graduate students and undergraduate students in this area is highlighted in the mission of VT Sustainable Nanotechnology with support from the university through its "Interdisciplinary Graduate Education Program." Additionally research topics have provided unique opportunities for undergraduate engineering majors to participate in projects that involve these coating materials, providing an unique perspective to their engineering education. New hybrid materials were fabricated that changed the electrical and magnetic properties of the biobased coating materials. Publications Qingqing Li, (2012) NANOCELLULOSE: PREPARATION, CHARACTERIZATION, SUPRAMOLECULAR MODELING, AND ITS LIFE CYCLE ASSESSMENT. Dissertation. Katia Rodriguez, Paul Gatenholm, and Scott Renneckar. (2012). Electrospinning Cellulosic Nanofibers for Biomedical Applications: Structure and in vitro Biocompatibility. Cellulose Volume 19, Issue 5, pp 1583-1598 Rodriguez, K., S. Renneckar, and P. Gatenholm. (2011). Biomimetic Calcium Phosphate Crystal Mineralization on Electrospun Cellulose-Based Scaffolds. ACS Applied Materials and Interfaces 3(3):681-689.

Progress 10/01/10 to 09/30/11 Outputs OUTPUTS: A number of activities were undertaken in the period 10/2010 to 10/2011 related to alternative adhesives for wood-composites and wood polymer surface modification. PI Renneckar, mentored a number of students related to their MS (1 student) and PhD (4 students) projects. In addition, Renneckar mentored 4 undergraduate students and 1 post-doc. This mentoring activity involved working with the students on their projects for project design and data collection, data analysis, and data communication in a variety of forms (poster presentations, oral presentations, manuscripts). The projects Renneckar mentored students focused on modification of wood fibers with polyelectrolytes for adhesion and durability, developing charged polyelectrolyte nanoparticles from wood sources, understanding reactive adhesive systems for wood composite bonding, and polyelectrolyte modified fiber surfaces functionalized with bioactive minerals. EVENTS: Renneckar and his graduate students were active in presenting their findings at local, national, and international meetings. Local and regional communication of findings included 6 presentations to faculty at Virginia Tech (Institute for Critical Technology and Applied Science (ICTAS) Doctoral Scholars Program and ICTAS Biobased Materials Center Spring Symposium), industrial guests at Virginia Tech (Eastman Graduate Symposium, NSF I/UCRC Wood-based Composite Center Industry Advisory Board Spring Meeting), and at regional industry (Eastman Chemical Company, Eastman Focus Program). Additional presentations were given at the American Chemical Society Spring Meeting and the Society of Wood Science and Technology Annual Meeting. At these meetings the audience was composed of academic, industrial, and governmental scientists. PRODUCTS: Three graduate students were completed in this past year (2 PhD and 1 MS). These students obtained employment in building products, food packaging, and biomedical materials industries based upon their training. PARTICIPANTS: Scott Renneckar, lead PI, Associate Professor Department of Wood Science and Forest Products, Affiliate Professor Department of Materials Science and Engineering. Karthik Pillai, PhD graduate student, Macromolecular Science and Engineering W. Travis Church, MS graduate student, Macromolecular Science and Engineering Katia Rodriguez, PhD graduate student, Materials Science and Engineering Qingqing Li, PhD graduate student, Wood Science and Forest Products Zhiyuan Lin, Post doctoral researcher, Wood Science and Forest Products Jeffrey Dolan, undergraduate student, Wood Science and Forest Products Peter Nixon, undergraduate student, Wood Science and Forest Products Cole Burch, undergraduate student, Wood Science and Forest Products Kyle Mirabile, undergraduate student, Wood Science and Forest Products TARGET AUDIENCES: Target audience is a combination of students and faculty colleagues, industry, and governmental scientists. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period. Impacts The above research has been published in leading scientific journals. Support for research activities has allowed Dr. Renneckar to develop a clear path for the modification of wood and cellulose fiber surfaces with polyelectrolytes and nanoparticles. With the technologies that his research group developed using non-covalent adsorption methods, they created a novel inorganic-wood fiber composite material with enhanced thermal properties. This is significant because wood fiber surfaces are very complicated and the work shows that they can be customized in a uniform manner. Overall, the work provides a novel path to modify fibers in composites that contain functional nanoparticles and polymer chemistries, providing a route to create innovative products based on developing nanotechnologies. Additionally, the wood products industry has been in significant decline because of the poor housing market. We have applied the same adsorption techniques to cellulose fibers to create materials for other growth industries like biomedical products so forest products companies may diversify their markets in the future. We have shown that by polyelectrolyte adsorption to cellulose we can make bioactive cellulose tissue engineering scaffolds that are mineralized with Ca-P ions. Mineralization within a SBF solution indicated that cellulose scaffolds could be made into a bioactive substrates for bone tissue engineering applications. These resultes have been communicated to small businesses for product innovation, such as BC Genesis a local cellulose biomedical company, and Trasian Development, an international business development firm. Publications Rodriguez, K., S. Renneckar, and P. Gatenholm (2011). "Biomimetic Calcium Phosphate Crystal Mineralization on Electrospun Cellulose-based Scaffolds," ACS Appl. Mater. Interfaces, 3(3):681-689. Li, Q. and S. Renneckar (2011). "Supramolecular structure characterization of molecularly thin cellulose 1 nanoparticles," Biomacromolecules, 12(3):650-659. Lin, Z. and S. Renneckar (2011). "Nanocomposite-based lignocellulosic fibers 3. Polyelectrolyte adsorption onto heterogeneous fiber surfaces," Cellulose, 18:563-574. Lin, Z. and S. Renneckar (2011). "Nanocomposite-based lignocellulosic fibers 2. Layer-by-layer modification of wood fibers as reinforcement in thermoplastic composites," Composites, Part A. 42(1), 84-91. Rodriquez, K. (2011) Electrospun Nanocellulose: A New Biomaterial. Dissertation, Virginia Tech, Blacksburg, VA. Pillai, K. (2011) Bio-inspired cellulose nanocomposites. Dissertation, Virginia Tech, Blacksburg, VA. Church, W.T. (2010) Light activated bonding of wood. Thesis, Virginia Tech, Blacksburg, VA.

Progress 10/01/09 to 09/30/10 Outputs OUTPUTS: Activities within this progress period were focused on taking the fundamental knowledge developed in the last annual report on the mechanism of nanoscale film coatings and applying this to woody materials to enhance properties such as durability. We successfully applied these coatings to solid wood materials, wood fiber, and created translucent stand alone films with the wood polymers. The latter was performed by creating an automated spray deposition equipment for nanoscale layer deposition. These activities led to proof of concept materials that were communicated to technical audiences, locally, nationally, and internationally: (1) Renneckar, S. Renewable nanotechnologies based on nanoscale celluloses. Presented at the Department of Material Science and Engineering Seminar Series, September 17, 2010. This seminar provided opportunity to share research findings with faculty in the engineering and chemistry departments. (approximately 50 attendees); (2) Renneckar, S. Fundamentals of wood surfaces: from structure and chemistry to developing nanotechnologies. Keynote address for the 4th Wood Coatings and Substrates Conference, Greensboro, NC, September 10, 2010. This address provided opportunity to share research on nanoscale coatings with approximately 80 industrial representatives, students, and scientists involved in wood coatings; (3) Renneckar, S. Bottom-up composites of cellulose and lignin nanocomposite films. Presented at Chalmers University of Technology and broadcasted live to KTH Royal Institute of Technology, for the inaugural Wallenberg Wood Science Center Seminar Series, August 26, 2010. This addressed shared technical knowledge with two leading international institutions involved in the multimillion dollar Wallenberg Wood Science Center. 20 attendees for video broadcast.; (4) Lin, Z., and S. Renneckar. Towards commodity biofiber-clay nanocomposites. Poster at the WBC Center Advisory Board Meeting, Virginia Tech, Blacksburg, Virginia, May 25, 2010. Information was shared directly with a half dozen research managers; (5) Pillai, K.V. and S. Renneckar. Mimicking wood lamellar structure, free standing LbL films of wood polymers. Presented at the 239th American Chemical Society National Meeting, San Francisco, CA, March 2010. Communicated results to audience of national and international researchers; and (6) Pillai, K. V. and S. Renneckar. Biomimetic wood nanocomposites. Presented at the Adhesion Society Annual Meeting, Daytona Beach, Florida, February 21-24, 2010. Communicated results to audience of national researchers. Additionally, a website was created to facilitate engagement activities and is currently being updated: www.sawmil.woodscience.vt.edu PARTICIPANTS: Dr. Zhiyuan Lin, 540-231-0093, linzy@vt.edu, 248 Cheatham Hall, Virginia Tech. Karthik V. Pillai, 540-231-0093, karthvp@vt.edu, 248 Cheatham Hall, Virginia Tech. Scott Renneckar, 540-231-7100, srenneck@vt.edu, 230 Cheatham Hall, Virginia Tech. TARGET AUDIENCES: The three main target audiences were internationally recognized academic researchers in biobased polymers, industrial researchers and managers that work with wood based materials or coatings for wood composites, and graduate students working in the field of wood, polymer, and material sciences. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period. Impacts Since communicating the results of the project I have had a faculty contact me in another department and he proposed an inter-departmental research plan on how these materials may be used for high value applications, serving as "metamaterials". These coatings have a potential to develop negative refractive indexes that provide opportunity for cloaking. Additionally, I have had further contact with researchers at the Wallenberg Wood Science Center planning additional research opportunities on utilization of these woody polymer films. The research has provided great potential to create substrates for carbonization, and potentially, biobased carbon nanotubes. Furthermore, after the Wood Coatings conference meeting I have had industrial contacts indicate they are interested in using their commercial particles with the chemistries in the nanoscale coatings to improve the durability of wood and wood composite materials. Finally, the publication indicated below on layer-by-layer bondlines provides a route to substantially reduce the reliance on petroleum based chemistries. Highly functional plant derived materials may be used for adhesion, replacing formaldehyde resins. Publications Zhou, Y., S. Renneckar, Q. Li, K.V. Pillai, Z. Lin and W.T. Church (2010). Layer-by-layer nanoscale bondlines for macroscale adhesion, BioResources 5(3):1530-1541. Eichhorn, S. J., A. Dufresne, M. Aranguren, N. E. Marcovich, J. R. Capadona, S. J. Rowan, C. Weder, W. Thielemans, M. Roman, S. Renneckar, W. Gindl, S. Veigel, H. Yano, K. Abe, M. Nogi, A. N. Nakagaito, A. Mangalam, J. Simonsen, A. S. Benight, A. Bismarck, L. A. Berglund and T. Peijs (2010). Review: Current international research into cellulose nanofibres and nanocomposites, Journal of Materials Science 45(1):1-33. Li, Z., S. Renneckar and J. Barone (2010). Nanocomposites prepared by in-situ enzymatic polymerization of phenol with TEMPO-oxidized nanocellulose, Cellulose 17(1):57-68. Lin, Z. 2009, Nanocomposite-based Lignocellulosic Fibers. PHD Dissertation, Virginia Tech, Blacksburg VA.

Progress 10/01/08 to 09/30/09 Outputs OUTPUTS: Experiments were conducted to understand the modification of wood surfaces by the adsorption of polyelectrolytes to enhance adhesion, promote durability, and lead to functionalization, providing value added properties to wood and wood fibers. These experiments consisted of determining deposition conditions that enhance adsorption of polymers onto wood surfaces based on the surface chemistry of wood. These results were analyzed to obtain the information related to the creation of nanoscale films on wood surfaces. These research activities were conducted by a graduate student mentored by Dr. Renneckar that successfully finished her MS program. Data was presented to wood industry representatives (research managers) at the Wood-based Composite Advisory meeting as summarized in final project report for the organization. Additional research was conducted on the use of isolated technical lignins as polyelectrolytes by studying the adsorption of lignin to model surfaces using QCM-D and AFM. The work was presented at the Macromolecular and Interfaces Institute Technical Review attended by a wide audiences of chemical companies. PARTICIPANTS: Karthik Pillai, graduate student, Virginia Tech Yu (Angela) Zhou, graduate student, Virginia Tech Zhiyuan Lin, graduate student, Virginia Tech W. Travis Church, graduate student, Virginia Tech Qingqing Li, graduate student, Virginia Tech TARGET AUDIENCES: As indicated in activities section data was directly communicated to research managers in the forest products industry via the Wood Based Composite Center Advisory Board. Additionally, data was communicated to fellow scientists (domestic and international) at the American Chemical Society spring meeting in 2009. PROJECT MODIFICATIONS: none Impacts New knowledge was created based on the above activities. For the first time it was shown that nanoscale films could be created on wood surfaces. What this means is that wood surfaces were completely covered with uniform films only a millionth of a millimeter in thickness. The nanoscale coating significantly changes the surface chemistry, but does not impact the microscale and macroscale texture. With the proper polyelectrolytes chosen, the nanoscale coatings were used for adhering wood substrates together and slowing the rate of fungal decay. It was also discovered that isolated lignin interacts with ammonium compounds via a new mechanism. This finding has potential to develop novel techniques in recovery of lignin and the use of lignin in coatings and modyfiying wood surfaces containing lignin. The new knowledge was published in leading peer-reviewed journals. Publications Pillai, K. V. & Renneckar, S. (2009) Cation-pi Interactions as a Mechanism in Technical Lignin Adsorption to Cationic Surfaces. Biomacromolecules 10, 798-804. Renneckar, S. & Zhou, Y. (2009) Nanoscale Coatings on Wood: Polyelectrolyte Adsorption and Layer-by-Layer Assembled Film Formation. ACS Appl. Mater. Interfaces 1, 559-566. Zhou, Y. (2008) Nanoscale surface modification of wood veneers for adhesion,. MS Thesis, Virginia Tech, Blacksburg, VA. Renneckar, S. and Lin, Z. (2009) Nanocomposite-based lignocellulosic fibers: A simple route for lignocellulosic fiber reinforced inorganic composites. Presented at the 237th ACS National Meeting, Salt Lake City, Utah, March 22-26.

For further details log on website :
https://portal.nifa.usda.gov/web/crisprojectpages/0216634-nanoscale-coating-of-wood-surfaces.html