CROSS-REFERENCE TO RELATED APPLICATIONS
Priority of U.S. Provisional Patent Application Ser. No. 61/059,050, filed 5 Jun. 2008, hereby incorporated herein by reference, is hereby claimed.
U.S. patent application Ser. No. 11/865,589, filed 1 Oct. 2007, and International Application Number PCT/US2007/80116, filed 1 Oct. 2007, are hereby incorporated herein by reference.
U.S. Provisional Patent Application Ser. No. 60/827,559, filed 29 Sep. 2006, and U.S. Provisional Patent Application Ser. No. 60/884,821, filed 12 Jan. 2007, are hereby incorporated herein by reference.
This is not a continuation, continuation-in-part, or divisional of any patent application.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
REFERENCE TO A “MICROFICHE APPENDIX”
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a ‘second generation of ACOMP’ (Automatic Continuous Online Monitoring of Polymerization reactions). The present document also sets out principles and uses, for the first time, of ACOMP (U.S. Pat. No. 6,653,150) coupled to SMSLS (simultaneous multiple sample light scattering, a Reed patent (U.S. Pat. No. 6,618,144) held by Tulane), and expands the uses of SMSLS through specific design changes.
The present invention is particularly suited to monitoring special characteristics of polymers and colloids as they evolve during reactions, such as polymer synthesis or postpolymerization modification reactions. Special characteristics include the polymers' and/or colloids' ability to respond to environmental stimuli, such as temperature, light, and solution characteristics such as pH, ionic strength, presence of specific other substances, such as toxins, drugs, surfactants, and other molecules, including other polymers, colloids, and nanostructures, their ability to go through structural changes, such as conformational collapse, their ability to self-assemble into supramolecular structures, and their ability to encapsulate and bind other agents, and to release them. The use of the present invention in conjunction with multiple similar detectors in some contexts can allow determination of polymer and/or colloid phase behavior during reactions, and how the phase behavior changes during reactions.
Although the samples are prepared automatically and continuously, detection can be intermittent. Interrupted, chromatographic detection, such as size exclusion chromatography, can be used. A recent publication the inventor and his colleagues made in this area is: “Simultaneous continuous, non-chromatographic monitoring and discrete chromatographic monitoring of polymerization reactions”, Alina M. Alb, Michael F. Drenski, Wayne F. Reed, J. Appl. Polym. Sci., 13, 190-198, 2009. A stop-flow method is also described below.
2. General Background of the Invention
As polymers become more complex and sophisticated in architecture and composition, they gain the ability to perform more ‘intelligent’ functions than traditional polymers. The frontier of advanced polymeric materials in the 21st century will be dominated by these increasingly sophisticated polymers. The upcoming polymers can micellize, aggregate, and respond to stimuli, such as temperature, light, solvent polarity, different solvents and solvent mixtures, the presence of specific agents, metal ions, surfactants, multivalent ions, proteins, anti-bodies, receptors, etc. (see Langmuir (2007), 23, 1, 1-2; Polymer (2004), 45(2), 367-378; Macromolecular Chemistry II, University of Bayreuth, Bayreuth, Germany. Abstracts of Papers, 235th ACS National Meeting, New Orleans, La., United States, Apr. 6-10, 2008 (2008), POLY-599; Nano letters (2007), 7(1), 167-71; Journal of Materials Chemistry (2007), 17(38), 4015-4017; Langmuir, (1990), 6, 514-516; Macromolecules (2002), 35, 10182-10288; J. Phys. Chem. C (2007), 111, 8916-8924). The polymers and/or colloids may also undergo chemical reactions with other species.
Applications include sensing, encapsulation and release of agents (e.g. drugs, cosmetics, etc.), micropatterning, bioconjugated polymers for medical applications, self-healing, photosensitivity and/or electrically conductive properties for optical and electronics applications, photovoltaics etc. There is considerable interest in ‘fine tuning’ polymers to have well behaved stimuli responsiveness characteristics, interaction properties, specific phase behavior, etc.
Henceforth ‘stimuli responsiveness’ will be used to refer to one or more of the diverse types of behaviors that polymers and/or colloids can manifest, depending on their own structure, composition and other macromolecular and chemical characteristics, the conditions of their synthesis, and the details of the environment where they may be synthesized, transferred to, or otherwise used or applied. Such behaviors can include but are not limited to conformational changes, intra- and/or intermolecular micellization, intermolecular aggregation and/or supramolecular assemblage into organized structures, solubility, phase separation, ability to interact with other polymers or colloids or small molecules, such as metal ions, organic molecules, salts, surfactants, etc., abililty to no longer interact with certain substances, ability to encapsulate and/or release drugs and other biologically active agents, lower critical solution temperature (LCST), color changes, and ability to react chemically with other species.
For example, polymers in solution can acquire stimuli responsiveness in sharp or gradual ways; e.g. LCST (lower critical solution temperature), micellization, aggregation, helix-coil, and other intra- and intermolecular transitions. Such transitions are of fundamental and applied interest. Fundamentally, they arise from the thermodynamics of complex, interacting systems. Whether sharp or gradual, these transitions, and stimuli responsiveness in general, depend on many factors, such as pH, ionic strength, solvent type and polarity, solvent mixture types, solvent chaotropicity or cosmotropicity, temperature, irradiation by electromagnetic waves, including light, and addition of interacting agents (e.g. small molecules, dyes, etc.), as well as the molecular weight and copolymeric composition and microstructure of the polymers themselves. Other examples concern the many types of associations that can take place between polymers and other polymers, micelles, emulsions, vesicles, liposomes, proteins, polypeptides, etc. These often involve formation of supramolecular (non-covalent) structures promoted by electrostatic, hydrophobic, depletion, and other forces.
Another very important application for the present invention is in the field of polymers derived from natural products. Because of the increasing demand for renewable sources for polymeric materials, as well as biodegradability and environmental concerns, there is a growing number of natural products that are being used for medicine, food, cosmetics, water treatment, oil recovery, composite materials, etc. These include, but are not limited to polysaccharides such as xanthans, alginates, cellulose derivatives, chitin derivatives, galactomannans, pectins, etc. as well as proteins and fibers. In order to make use of these natural products it is necessary to extract the desired agents, and then often modify them chemically, enzymatically, or by radiation, until desired characteristics are obtained, such as solubility in a given solvent (e.g. water), ability to interact with other substances (e.g. surfactants), achieve desired levels of viscosification, self-assemble into nano and microstructures, etc. The present invention will allow all of these processes-extraction, modification, and special properties- to be monitored. This will allow for optimization of the processes used in extracting, modifying, and deploying natural product derived polymers and colloids. The ability to monitor and control these steps is particularly important for natural products because the raw material, of vegetable or animal origins are normally highly variable in the content and characteristics of the desired materials to be extracted, which is a perennial problem for natural product manufacturers.
‘Polymer and/or colloid synthesis’ includes any type of reaction in which a polymer and/or colloid is produced or modified. An example of the latter is when a polymer is first made and then specific functional groups are attached to it, such as charge groups (e.g. sulfate, quaternary amines, carboxylate, etc.), oligomers, grafted polymers, etc. Other examples include the modifications made to polymers and/or colloids extracted from natural biological sources (e.g. plants, wood, seeds, fruits, etc.), as described above.
Traditional methods for relating polymer characteristics to their stimuli responsiveness. These are time-consuming, cumbersome, and inefficient. They normally involve, even in modern high-throughput systems, the synthesis of a given end-product, or series of end-products, that are then subjected to various types of functionality characterization, and often also to standard polymer characterization methods. In many cases, the mere preparation of the endproduct can be disproportionately time-consuming, and require such steps as precipitation, purification, freeze-drying, re-dissolution, dialysis, etc., of the end-product. The usual ACOMP approach, (see W. F. Reed, U.S. Pat. No. 6,653,150, “Automatic mixing and dilution methods for online characterization of equilibrium and non-equilibrium properties of solutions containing polymers and/or colloids”; and A. M. Alb, M. F. Drenski, W. F. Reed, “Automatic continuous online monitoring of polymerization reactions (ACOMP)”, Polymer International, 57, 390-396, 2008) which has proven successful in a wide variety of contexts avoids these process steps by substituting ‘fluid-fluid’ sample handling. That is, the reactor fluid is continuously extracted, diluted with other fluids, and conditioned to produce a continuously measurable fluid sample of the reactor contents. No intermediate solid phase stages are normally used, and the often high levels of dilution (ranging up to dilution factors of many thousands) can even effectively change solvents by making the original solvent a tiny admixture to the dilution solvent. Such extraction/dilution/conditioning typically occurs on a time scale of tens of seconds to several minutes. The series of handling procedures in traditional methods can take hours, days, and even weeks.
The following references, and all references mentioned herein, are incorporated herein by reference:
Some additional bibliography showing LCST, micellization, bioconjugation, etc.:
Macromolecular Chemistry II, University of Bayreuth, Bayreuth, Germany.
Abstracts of Papers, 235th ACS National Meeting, New Orleans, La., United States, Apr. 6-10, 2008 (2008), POLY-599. Publisher: American Chemical Society, Washington, D.C.;
Abstracts of Papers, 233rd ACS National Meeting, Chicago, Ill., United States, Mar. 25-29, 2007 (2007);
Polymer (2003), 44(22), 6815-6823;
Polymer Preprints (American Chemical Society, Division of Polymer Chemistry) (2003), 44(1), 646-647;
Abstracts of Papers, 235th ACS National Meeting, New Orleans, La., United States, Apr. 6-10, 2008 (2008), POLY-596;
ACS Symposium Series (2008), 977(Polymers for Biomedical Applications), 78-94. Publisher: American Chemical Society;
Soft Matter (2007), 3(6), 725-731;
Macromolecules (Washington, DC, United States) (2007), 40(14), 4772-4779;
Abstracts of Papers, 231st ACS National Meeting, Atlanta, Ga., United States, Mar. 26-30, 2006 (2006), PMSE-224;
Macromolecules (1999), 32(21), 6917-6924;
Polymer Preprints (American Chemical Society, Division of Polymer Chemistry) (2002), 43(2), 969-970
PMSE Preprints (2002), 87 237-238. Publisher: American Chemical Society, CODEN: PPMRA9 ISSN: 1550-6703. Journal; Computer Optical Disk written in English.
SUMMARY OF THE INVENTION
Methods and instrumentation are disclosed for monitoring how polymer stimuli responsiveness evolves during the very process of polymer synthesis. Polymer stimuli responsiveness includes the ability of polymers, when certain characteristics are reached (e.g. molecular weight, composition, degree of postpolymerization modification etc.), to go through phase changes (e.g. micellization, formation of supramolecular structures), conformational changes, solubility changes, and other transformations (e.g. ability to interact with other polymers, or chemical or biochemical agents), often dependent on solution conditions (e.g. temperature, pH, ionic strength, specific electrolyte content, etc.).
A new generation of polymers is being designed with high stimuli responsiveness for diverse purposes such as biomedical assays, drug delivery, sensing, responsiveness to stimuli (e.g. heat, light, etc.), self-healing materials, and much more.
The current invention offers a way of monitoring the evolution of stimuli responsiveness in a continuous way, during polymer synthesis. ‘Polymer synthesis’ includes any type of reaction in which a polymer is produced or modified. An example of the latter is when a polymer is first made and then specific functional groups are attached to it, such as charge groups (e.g. sulfate, quaternary amines, carboxylate, etc.), oligomers, grafted polymers, etc. In its simplest form the present invention is already a high throughput screening platform. In its enhanced form, described below, the present invention becomes a ‘high throughput squared’ platform, and may challenge and even disrupt ongoing high throughput developments that use expensive, robotic, multi-reactor approaches for mere end product analysis.
The current invention builds on Tulane's patent estate developed by Wayne F. Reed (U.S. Pat. Nos. 6,052,184, 6,653,150, 6,618,144, others pending), and preferred embodiments of the present invention advantageously use the teachings of some of those same patents (U.S. Pat. Nos. 6,052,184, 6,653,150, 6,618,144, others pending).
The present invention builds on the present inventor's last decade of invention and development in monitoring polymerization reactions, denoted as the ACOMP platform (Automatic Continuous Online Monitoring of Polymerization reactions). That work extended ACOMP's reach to free radical and controlled radical homo- and copolymerization, other ‘living’ reactions, condensation polymerization, branching, grafting, copolymeric polyelectrolyte synthesis, and polymer modification processes, including postpolymerization modifications and modifications of natural products, in homogeneous, bulk, and emulsion phase, and in batch, semi-batch and continuous reactors, producing corresponding discoveries in fundamental reaction kinetics and mechanisms.
With its broad range of monitoring applicability now secured, the present invention is a ‘2nd generation ACOMP’ as it faces wholly new challenges; moving beyond monitoring to reaction control in order to produce polymers of desired characteristics, and extending the ACOMP platform to monitor, understand and control, the stimuli-responsiveness of polymers. These latter include polymers whose properties change with changing environmental factors, such as temperature, light, pH, solvent quality, presence of specific molecules, etc. The potential applications of these materials make them an exciting interface between chemical and biomolecular engineering, chemistry, materials science, and physics.
The discovery and development of new polymers require sophisticated analytical approaches that can solve basic and applied problems, and optimize processes. Currently, post-synthetic analyses on end-products with techniques such as size exclusion chromatography (SEC), nuclear magnetic resonance (NMR), etc. yield little information on the evolution of polymer characteristics and there is no opportunity for control. Utilizing a flexible detection platform that continuously or substantially continuously monitors reactions (e.g. light scattering, viscosity) ACOMP follows conversion kinetics, composition drift, and the evolution of average composition distribution, molar mass, and intrinsic viscosity distributions. The polymer is hence ‘born’ characterized, and there is also the opportunity for reaction control, a primary focus of the proposed work. The onset or change of stimuli responsiveness, such as conformational transformations, ability to interact with target molecules, copolymer micellization, etc. have complex relationships to polymer mass, architecture, and copolymer distribution, ‘blockiness’, sequence length distributions, etc. This work takes the novel approach of monitoring the onset of stimuli responsiveness during synthesis, focusing on lower critical solution temperature (LCST), with the subsequent ability for control, providing a powerful new tool for understanding underlying polymer physics and manipulating polymer structure/function relationships.
The present inventor aims to create a paradigm shift in polymer science, in which online monitoring and control become powerful adjuncts to polymer discovery, development and production, and for understanding stimuli responsive behavior in polymer solutions. Importantly, information-rich ACOMP results also provide a more complete database, and are available for polymer scientists in the broader community involved in modeling and reaction engineering. It is expected that the present invention will also quickly have real economic impact on polymer industries, yielding practical new materials and process monitoring and control that enhance savings of energy, petroleum, and other non-renewable resources, plant and labor time, and lead to better safety, and less greenhouse gas emissions and environmental pollution per kilogram of product.
The present invention includes a multi-purpose, multi-user 2nd generation ACOMP instrument (Automatic Continuous Online Monitoring of Polymerization reactions). The present invention has an even more massive data gathering and analysis capability than its predecessors.
The multi-purpose platform of the present invention allows different time-dependent processes in polymer and colloid solutions to be monitored, and also can be used to automatically map characteristics of multi-component solutions in equilibrium or quasi-equilibrium, such as automatic determination of phase diagrams, and combines sophisticated, interconnected optical detection methods, and a fully integrated multi-detector GPC.
A few Features and Types of Processes to be Monitored are Outlined Below.
Simultaneous monitoring of polymer properties, such as mass and composition, and the onset of stimuli responsiveness during synthesis (including any postpolymerization modifications), such as phase transitions, micellization, conformational changes, microgelation, ability to interact with other substances, such as drugs, etc. The SG-ACOMP will be the only instrument of its kind in the world, able to determine at what point in synthesis, (including postpolymerization reactions and modifications of polymers and colloids extracted from natural products), polymers and copolymers become stimuli responsive, whether sharply or gradually; e.g. the effect of solvent type on LCST (lower critical solution temperature) of an evolving polymer and the relationship with polymer composition and molecular weight distributions could be determined. The transition at the LCST will be automatically detected, and the threshold characteristics of the polymer stimuli responsiveness can be quantified.
High throughput capability for testing stimuli responsiveness of polymers during synthesis. This portion of the system makes use of multiple light scattering and other detectors, built according to the concept of one of Reed's earlier patents; SMSLS (Simultaneous Multiple Static Light Scattering). This allows for a plurality of independent SMSLS flow cells to simultaneously measure a highly diluted polymerization sample stream under different conditions; e.g. temperature, solvent ionic strength and dielectric constant, etc.
Other optical detectors will allow for numerous other measurements, including dynamic light scattering, depolarized light scattering, Mie scattering, circular dichroism, UV/visible spectroscopy, fluorescence, and birefringence. Depolarized light scattering will allow anisotropic particles (e.g. nanotubes, rigid nano fibers, bacteria, etc.) to be analyzed.
The entire system can be used with multi-detector GPC in series or in stand-alone mode. Other functions can be switched modularly into the data gathering base, and also separately used.
Applications to biomedical fields, including drug delivery. Core-shell micellization and phase transition of copolymers will be continuously monitored. Amphiphilic block copolymers that self-assemble into micelles in aqueous media can be extensively investigated and their properties of ‘nano-containers’ exploited.
Monitoring any change in particle shape and morphology. Light scattering detection with different polarizability will be customized to allow particle dimensions to be measured for particles with different shapes.
A complete multi-stage front-end that extracts, dilutes, and conditions sample from reactors and other vessels (i.e. also for equilibrium systems) to produce a continuous stream of highly dilute, conditioned sample for detection. This versatile front-end will allow extraction from low viscosity emulsion polymerization fluids up to pure bulk polymerization reactions where the viscosity can approach 106 cP. Conditioning steps will include filtration, debubbling, volatilizing monomers, inverting phase, etc.
There is also provision for interrupted sampling and auto-injection, whereas the system can be modularly switched into use as a comprehensive multi-detector chromatography system. Solenoid or other valves can be provided on those detectors that are flow or shear sensitive to provide a stop-flow capability that does not interfere in any way with the continuously flowing stream. In this mode, the continuous stream is periodically switched into the flow sensitive detector\'s sample cell by a diverter valve, stopped, and a measurement is made on the stationary solution. During the stopped time, the sample stream continues to bypass the flow sensitive detector\'s sample cell. Any time after the measurement the continuous flow can be rediverted through the flow sensitive detector\'s sample cell, then stopped, and another measurement cycle can be made. This strategy is used for example in the NanoDSL (a dynamic light scattering instrument by Brookhaven Instruments Corporation).
The detection end is highly modular, and consists of i) a polymer characterizing detector train—multiangle light scattering, refractive index, viscosity, UV absorption-, ii) a particle characterizing train, such as dynamic and Mie light scattering, and iii) a high throughput, multi-detector train, including a new family of SMSLS cells (simultaneous multiples sample light scattering, a Reed patent held by Tulane), adaptation of SMSLS to high throughput fluorescence detection, and a multi-head peristaltic pump approach to monitoring the effects of multiple solvents and interacting molecules on the polymer. Additionally, polarizing optics and a circular dichroism detector allow a range of new capabilities where particle anisotropy is involved. Where the stimuli responsiveness acquired is the ability to undergo chemical reactions with other specific reagents then it will be possible to use thermography, by mounting a thermally sensitive camera that can thermally image all the different channels in the multidetector train. In this way it can be detected whether an exothermic or endothermic chemical reaction is occurring. Where the stimuli responsiveness changes the color or visual aspect of the polymer and/or colloid, or the color of any complexes or associations that these may form with other agents, then an optical camera can be used to directly visualize and capture the different channels in the multidetector train.
A versatile platform of pumps and detectors is preferred to allow customized methods to be applied in the study of various processes. Components of the apparatus of the present invention and preparation of the apparatus for use can include the following:
Two Q-pumps (Fluid metering);
Five Shimadzu HPLC pumps;
Shimadzu quaternary mixer;
One Zenith gear pump;
Micro-flow controller w/feedback capability;
National Instruments comprehensive data interface;
Hardware and GUI integration software;
Two multi-head peristaltic pumps;
Machining of SMSLS cells;
Nano-DLS (BIC), dynamic light scattering;
BI-MwA (BIC) 7 angle multi-angle light scattering;
Shimadzu UV/visible diode array flow capable;
Technical support for construction of instrumentation;
GPC columns, autoinjector; and
Circular dichroism flow ready detector.
Thermal imaging camera
Optical imaging camera
The evolution of the properties of the polymers and/or colloids during synthesis can be monitored, for example, according to any of the methods of U.S. Pat. No. 6,653,150.
As used herein, a ‘reactive medium’ (sometimes referred to as reactor fluid), includes all reagents (such as monomers, initiators, catalysts, surfactants, natural and/or synthetic polymers, etc.), and any other supporting components or fluids (such as solvent or mixtures of solvents in which the reagents are dissolved or suspended, and components which control the characteristics of the reactive medium, such as temperature, pressure, viscosity, color, ionic strength, pH, concentration of the reagents, etc.). Note that not all of the components or fluids in the reactive medium are reagents; i.e. some just control characteristics of the reactive medium (e.g pH, ionic strength, viscosity) without themselves reacting.
The reactor is preferably ‘sampled’ continuously, or if not continuously substantially continuously. Detector measurements might better be termed ‘detector measurement rates’ rather than ‘sampling rates’, and they could also be called ‘detector readings’. Typically when a detector measurement is made, it means that at that time the signals from the multiplicity of detectors are captured and stored by the computer. E.g. every second one might measure the signals from all the detectors and store them. This act of measurement might include hundreds or even thousands of data points; e.g. 600 data points from a UV/visible detector, seven or more angles from light scattering, two or more signals from viscosity, multiple thermocouple (temperature) readings, etc.
Preferably, the material from the reactor is drawn continuously or substantially continuously, and readings are taken continuously or substantially continuously. Whether the withdrawals from the reactor are continuous or substantially continuous, the detector measurements are preferably taken at a frequency adequate to provide useful information about the process to allow the process to be advantageously modified to optimize desired results. Detector measurement intervals can be anywhere from every 0.01 s to hundreds of seconds to thousands of seconds, depending on how fast the reaction is. Typically one would set up the detector measurement interval so that there will be roughly ten thousand time points at which the ensemble of detector readings are made during the course of the experiment. E.g. for a three hour reaction one would likely record measurements from all the detector signals every second and get about 10,000 total detector measurement points. It is also frequently the case that different detector signals are measured at different rates.
For example, when interrupted chromatographic (GPC) detection is used, there will necessarily be a delay of at least several minutes between detector measurement due to the separation process, so that there will normally be only a few GPC measurement per hour (e.g. 6), and there will not be thousands of measurements.
The present invention can potentially provide continuous phase diagrams, which could be of immense value. As examples, one could determine, with the multi-head peristaltic approach and the temperature controlled SMSLS cells, an LCST phase diagram for a polymer during synthesis, which would demarcate the LCST transition as a function of both temperature and ionic strength. This is a major advance, because such phase diagrams take considerable time to determine individually using standard methods, and the possibility of having virtually a continuous set of phase diagrams at each point of a polymer\'s and/or colloid\'s synthetic evolution will be of critical importance in developing new polymers and/or colloids and formulations involving these. Other examples of determining phase diagrams at each moment of evolution can include how a given polymer and/or colloid at each instant of its synthesis interacts with different types and/or concentrations of surfactants, salts, and other agents.
Typical temperatures during polymer and/or colloid synthesis range from −20 C to 300 C, but are more usually in the range of 20 C to 180 C.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein:
FIG. 1 is a schematic flow chart of a preferred embodiment of the apparatus of the present invention;
FIG. 2 is an alternate preferred embodiment of the apparatus of the present invention;
FIG. 3 is schematic flow chart of an alternative embodiment of the apparatus of the present invention;