Vapor Sorption Characterisation of Materials

Transcription

1 Vapor Sorption Characterisation of Materials Dr. Daryl Williams Surface Measurement Systems

2 Overview 1. Vapor Sorption Techniques Molecules as Probes (DVS, igc) Sorption Mechanisms 2. DVS Applications Isotherms and Isotherm Shape Phase Transitions Sorption Kinetics 3. IGC/SEA Applications Surface Energy Adhesion/Cohesion Bulk Properties 2

3 Based in London The Company Invented the Dynamic Vapor Sorption Instrument in 1993 Currently 50 staff- London, USA, France, Germany- 7 PhD scientists Installed base >1000 instruments Technological market leader in sorption instrumentation

4 Characterisation of Solids 1. Radiation as a Probe Raman, NMR, FTIR Spectroscopy Light, x-rays, lasers, etc. Analytical and structural information- what where how much 2. Heat as a Probe Calorimetry and Thermal Methods Thermodynamic information- rates DH DS DG 3. Molecule as a Probe Sorption and wetting techniques Thermodynamic, chemical, and structural information Process rates, DH DS DG, diffusion constants, surface energy 4

5 1. Structural Information XRD, XRPD 2. Chemical Information XPS (ESCA), NMR, FTIR 3. Visual Information Light Microscopy (polarized) AFM, SEM Particle size measurements (laser diffraction) Particle shape Radiation as a Probe 5

6 Heat as a Probe 1. Thermodynamic Information DSC (modulated; hyper) TGA DMA TAM 2. Chemical Reactions Reaction Calorimetry 6

7 Molecule as a Probe 1. Chemical Interactions IGC, DVS, Wetting, TAM, Chemisorption analyzers 2. Physical Structure (surface area, pore size, density, etc.) DVS, IGC, Volumetric sorption (i.e. BET analyzers), Chemisorption, Pycnometer 3. Thermodynamic Information IGC, DVS, TAM 7

8 Adsorption Physisorption Chemisorption Absorption Bulk absorption Absorption into lattice structure Reactions Hydration and solvation Condensation Pore filling Types of Molecule-Solid Interactions 8

9 Adsorption Adsorption-Physisorption Molecules In Molecules Out Molecules Weakly Adsorbed 9

10 Physisorption Weak interactions Molecules only on surface Probe molecules not chemically bound to surface Reversible sorption Associated properties measured Physical Structure: surface area, pore size, surface roughness Chemical Interactions: surface sorption capacity, surface energy, hydrophilicity, Lewis acidity-basicity, surface heterogeneity Thermodynamic: heat of sorption, free energy 10

11 Adsorption Adsorption-Chemisorption Molecules In Molecules Covalently Bonded to Surface 11

12 Chemisorption Strong interactions Molecules only on the surface Probe molecules are covalently bound to surface Can be reversible or irreversible sorption Associated properties measured Titrate acid-base sites Active surface area Catalyst Dispersion 12

13 Absorption-Bulk Bulk Absorption Molecules In Molecules Out-Diffusion Limited Molecules Interact with Bulk Molecules Absorbed 13

14 Absorption-Bulk Penetrate surface Desorption is often diffusion limited Reversible or irreversible sorption Associated properties measured Physical Structure: vapor-induced phase changes (glass transition, crystallization, deliquescence), glass transition temperatures, crosslink density Chemical: total sorption capacity, solubility parameters Kinetic: diffusion coefficients, solid-solid phase transformation, drying kinetics 14

15 Dynamic Vapour Sorption Dynamic Gravimetric Vapor Sorption (DVS) Invented by SMS in 1993 Long Term Baseline Balance Stability is Key Controlled humidity and temperature Dynamic Flowing Gas System means Fast Thermal and Mass Equilibrium Conceptual similarities to TGA- but RH the key variable Static Sorption Dynamic Sorption 15

16 DVS Introduction 16

17 DVS Introduction Dynamic gravimetric Vapor Sorption (DVS) Fully automatic sorption instrument Fast equilibrium: significantly improved kinetics over static sorption systems SMS pioneer in vapor sorption technology SMS UltraBalance Up to 0.1 µg sensitivity; unrivaled long-term baseline stability Allows use of small samples 1-10 mg Real-world conditions Wide range of temperatures: measurement and preheat conditions Wide range of vapors: water and organic vapors 17

18 DVS Advantage Microbalance Sample mass: up to 1g Mass change: up to ±150mg Resolution: 0.1µg High-mass option also available Additional optional modular features Modular color video microscope for qualitative sample data (use with a limited temperature range) Dual fiber-optic probe adaptors for coupling with Raman/NIR spectrometers (use with a limited temperature range) Modular expandable manifold for use with large-sized samples Experimental temperatures System incubator: 5 C to 60 C Upper local sample temp: up to 125 C Pre-experimental temperatures Optional modular coil pre-heaters (large and small for temperatures up to 150 C) Optional modular high-temperature pre-heater (for temperatures up to 350 C) 18

19 DVS Advantage Family Preconditioning with preheater 150 C or 350 C Vapor sorption till 85 C optional till 125 C/20%RH using 150 C preheater Humidity or solvent vapor steps, ramps and Isohum/Isochore measurements Diffusion / activation energy of diffusion Permeation (with Payne Cell) T g versus RH or temperature Heat of sorption/micro/mesopore size distribution Stability tests

20 Isotherm Types (BDDT) Type I: Langmuir isotherm; chemisorption Type II: Monolayer formation, BET equation Type III: Strong sorbate-sorbate interactions; water often has this behavior Type IV: Monolayer formation, BET equation, capillary condensation at high pressures Type V: Strong sorbate-sorbate interacitons; capillary condensation at high pressures Type VI: only at liquid Kr temperatures 20

21 DVS-Typical Data- Kinetics Date: 07 Dec 2001 Time: 4:14 pm File: ricestarch071201_reduced.xls Sample: rice starch 25 DVS Change In Mass (dry) Plot dm - dry Target RH Temp: 24.8 C Meth: duncan.sao M(0): Change In Mass (%) - Dry Target RH (%) DVS - The Sorption Solution Time/mins Surface Measurement Systems Ltd UK Moisture sorption behavior of rice starch at 25 C- 2 cycle experiment 21

22 DVS-Typical Data-Equilibrium Date: 07 Dec 2001 Time: 4:14 pm File: ricestarch071201_reduced.xls Sample: rice starch 25 DVS Isotherm Plot Cycle 1 Sorp Cycle 1 Desorp Temp: 24.8 C Meth: duncan.sao M(0): Change In Mass (%) - Dry DVS - The Sorption Solution Target RH (%) Surface Measurement Systems Ltd UK

23 Norit GAC-Mesopore Sorption Hysteresis gap suggests mesoporosity (2 to 50 nm) Date: 11 Mar 2010 Time: File: 1 - Norit GAC - Thu 11 Mar xls Sample: Norit GAC DVS Isotherm Plot Temp: 25.0 C Meth: GAC 0-95 B.sao MRef: Cycle 1 Sorp Cycle 1 Desorp Change In Mass (%) - Ref Target % P/Po DVS - The Sorption Solution Surface Measurement Systems Ltd UK

24 Channel Hydrate Water sorption on Channel Hydrate 0.2% RH steps: 0 to 10% RH Date: 15 Dec 2011 Time: File: Channel Hydrate - Thu 15 Dec xls Sample: Channel Hydrate 4 DVS Isotherm Plot Cycle 1 Sorp Cycle 1 Desorp Temp: 25.0 C Meth: Channel Hydrate small steps 2.sao MRef: Change In Mass (%) - Ref Target RH (%) DVS - The Sorption Solution Surface Measurement Systems Ltd UK

25 Quartz-Surface Adsorption Isotherm shape (Type II) and low uptake indicate surface dominated sorption Date: 05 Mar 2003 Time: 3:47 pm File: quartz-gt-106.xls Sample: Quartz > 106 microns 1 DVS Isotherm Plot Cycle 1 Sorp Temp: 24.9 C Meth: BEToctane.SAO M(0): Change In Mass (%) - Dry Target RH (%) DVS - The Sorption Solution Surface Measurement Systems Ltd UK

26 Fuel Cell Proton Exchange Membranes DVS Isotherm Plot Temp: 25.0 C 18 BPSH-30 Sorp BPSH-30 Desorp Nafion 1135 Sorp Nafion 1135 Desorp 16 Change In Mass (%) - Dry DVS - The Sorption Solution Target RH (%) Surface Measurement Systems Ltd UK Nafion-1135 sample sorbs less water than BPSH-30 sample across humidity range 26

27 Water Sorption on Hair DVS Change In Mass (ref) Plot Change In Mass (%) - Ref Target % P/Po DVS - The Sorption Solution Time/mins Surface Measurement Systems Ltd UK Moisture sorption behavior of three hair samples at 25 C 27

28 Water Sorption on Keratinized Tissues SC: Stratum Corneum Nail: Human Nail Hair: Human Hair GK Johnsen, ØG Martinsen, and S Grimmes, J of Physics: Conference Series, 224 (2010)

29 Sorption Isotherms of three different cellulose -cellulose sorption isotherms linter Water kinetics: mass uptake vs time MCC Yanjun Xie, Callum A. S. Hill, Zaihan Jalaludin, Dongyang Sun. The water vapour sorption behaviour of three celluloses: analysis using parallel exponential kinetics and interpretation using the Kelvin-Voigt viscoelastic model. Cellulose. June 2011, Volume 18, Issue 3, pp

30 Vapor-Induced Phase Transitions Water vapor is a strong plasticiser Glass transitions Transition kinetics from glassy to crystalline phases 30

31 Material Morphology and Vapour Sorption Amorphous- Glassy Solid T <T g Mainly surface adsorption Fast kinetics and low uptake levels Amorphous- Rubbery Solid T >T g Deep bulk sorption Slow kinetics and large uptake levels Crystalline No T g Surface adsorption Fast kinetics and very low uptake

32 Vapor-Induced Transitions Date: 05 Dec 2002 Time: 11:58 am File: lactoseramp900.XLS Sample: amorphous lactose 14 DVS Change In Mass (dry) Plot % Change in Mass Target RH Recrystallization Temp: 25.1 C Meth: lactoseramp min.sao M(0): Change In Mass (%) - Dry Surface Adsorption Bulk Absorption and Surface Adsorption Glass Transition Target RH (%) Time/mins DVS - The Sorption Solution Surface Measurement Systems Ltd UK RH ramping experiment (similar to DSC temperature ramp) Gravimetric data clearly shows moisture-induced glass transition and crystallization 32

33 Spray Dried Lactose Spray dried Lactose powder at 25C shown at a range of humidities: A: 0%RH B: 50%RH C: 60%RH D: 90%RH The formation of a gel, a solution followed by crystallisation is clearly shown.

34 Color Video Microscope Colour Video Microscope The DVS colour vide microscope is fully detachable with improved specifications, coupling qualitative sample information with DVS isotherm data. The microscope shows visual sample changes including swelling, deliquescence events, cracking and phase changes. This optional feature can also be used in combination with some other DVS advantage modular features. Key Specifications 1.3 Megapixel colour images (1280x1024) Adjustable focus. Adjustable magnification of 50x to 200x Picture overlay information includes: date, sample info, experimental info, adjustable scale marker, and overlay grid. Images exportable to.bmp,.tiff, and.jpeg file formats 34

35 DVS-Microscope Accessory Maltodextrin 0% RH Maltodextrin 95% RH, 0 minutes Maltodextrin 95% RH, 30 minutes Maltodextrin 95% RH, 50 minutes 35

36 Vapor-Induced Transitions Humidity Induced Transitions for Spray-Dried Lactose Relative Humidity (%) Humidity at Glass Transition (%) Humidity at Crystallization (%) Unstable Amorphous Region Crystalline Region Stable Amorphous Region Temperature ( C) Ramping experiments at different temperatures 2-D stability map for meta-stable materials 36

37 Sorption Kinetics Bulk diffusion coefficients with fixed geometries Film geometry (one-sided/two-sided) Spherical (powder) geometry Packaging applications Payne style cell MVTR determination Electronic packaging 37

38 Kinetics of Transitions Fraction Dehydrated C 27.5 C 25 C 22.5 C 20 C 17.5 C 15 C 1 Fraction Dehydrated DVS - The Sorption Solution Time/mins Monitor mass loss as sample dehydrates Study and model drying conditions Surface Measurement Systems Ltd UK

39 Two-Sided Film Diffusion 1 Polyimide films % RH 20% RH (fitted) Mt 4 M d Dt M t /M infinity Previous Target Diffusion R-sq. (%) RH (%) RH (%) Coeff. (cm²/s) E E E E E E Sqrt(t)/d Moisture gain and loss with polymer film; moisture access from both sides 1-D Fickian Diffusion coefficient at each step change in RH 39

40 Payne-Style Cell Cell opening Upper O ring Cell Lid Test Specimen Temperature & RH controlled environment Lower O ring 0%RH 100%RH Cell Cup Drying Agent i.e. Zeolite, Silica Gel (a) (b) Payne-style cell allows MVTR determination Can be run in dry (a) or wet (b) mode 40

41 Payne-Style Cell Change In Mass (% w/dry w) %RH 80 %RH 50 %RH 30 %RH Time (min) Payne-style cell allows MVTR determination Investigate surrounding RH effects 41

42 DVS Vapor Permeability-Membranes 42

43 DVS-Organic Vapors Water and Organic Vapor Control Proprietary optical sensor allows for real-time measurement and control of organic vapors Does not predict organic vapor concentration like competitive products Allows accurate determination of BET surface area, solvate formation, surface energetics, porosity, solid-solvent interactions Ethanol, Methanol, IPA, Cyclohexane, Heptane, Octane, Nonane, DCM, Ethyl Acetate, and Toluene commonly used 43

44 DVS-Organic Vapors 100 DVS Octane Partial Pressure Plot Target % P/Po Actual % P/Po % Partial Pressure Time/mins 44

45 BET Surface Area for Hydrophobic Drug DVS BET Plot for Metformin Hydrochloride Fines (less thane 140 mesh) 70 BET Data Line Fit (P/Po) / [( 1 - (P/Po) ) * M] Octane P/Po (%) DVS - The Sorption Solution Surface Measurement Systems Ltd UK

46 Methanol Sorption on Nafion Methanol Sorption Isotherm at 25 C Net Change in Mass (wt%) N117 Sample N112 Sample NR112 Sample Methanol P/Po (%) Methanol sorption on different Nafion samples at 25 C 46

47 Amorphous Content by DVS Octane adsorption on mixtures of amorphous lactose and -lactose monohydrate DVS Isotherm Plot Temp: 25.0 C 100% Crystalline Lactose % Amorphous 6.017% Amorphous % Amorphous 100% Amorphous Change In Mass (%) - Dry DVS - The Sorption Solution Target p/po (%) Surface Measurement Systems Ltd UK

48 Amorphous Content by DVS Amorphous content for mixtures of crystalline and amorphous (spraydried) Salbutamol Sulfate 48

49 DVS-Raman Accessory 1. Raman spectroscopy is the measurement & detection of the wavelength and intensity of inelastically scattered light from molecules. When electromagnetic radiation passes through matter, most of the radiation continues in its original direction but a small fraction is scattered. Rayleigh Scattering Raman Scattering 2. Rayleigh scattering: Light that is scattered at the same wavelength as the incoming light. Sample 3. Raman scattering: Light that is scattered due to vibrations in molecules or optical phonons in solids. 4. The majority of scattered light is elastic and only one in 10 6 optical photons are scattered at frequencies different to the incident light This is the weaker Raman scattered light. Incident Laser Light 49

50 DVS Advantage Video and Raman 50

51 DVS-Raman Spectroscopy DVS water sorption/desorption results (a.) and in-situ Raman spectra (b.) for MCC at 25 C. 51

52 IGC Surface Energy Surface energy is the most commonly measured property by IGC Analogous to surface tension of liquids Defined as the excess energy at the surface of a material compared to the bulk Directly related to the thermodynamic work of adhesion Can be divided into dispersive, acidic, and basic components

53 Measuring Surface Energy of Solids

54 Comparisons to Contact Angle Contact angle measurements are a common surface energy method γ LV γ 0 SV θ Y γ SL Solid surface Clean surface Sessile drop contact angle performed on powder compacts High pressure causes surface deformation; Rough surface topography Porous surface leading to penetration of liquid; Swelling; Dissolution Fast penetration of water droplet into 400 MPa mannitol compacts.

55 What Does Surface Energy Affect? Wettability Cohesion Process-induced Disorder Adhesion Increasing Surface Energy

56 Animation by L. Teng, Surface Measurement Systems IGC Principles

57 igc-sea Instrument Overview Small footprint: 450 mm (18 ) x 450 mm (18 ) x 700 mm (27.5 ) Variable injection sizes; wider concentration range; 1:4000 injection ratio 12 vapor reservoirs (50ml) 2 column oven design: 20 to 180 C Flame Ionization Detector (FID) Humidity control (optional)

58 IGC Sample Preparation Sample Silane-treated glass tube 30cm long & 6 mm O.D. 2, 3, 4 and 10 mm I.D. 10 mg 500 mg of material typically 0.5 m 2 of surface area Glass wool 58

59 Schematic of IGC

60 IGC Principle: Retention Time Single pulse of probe molecule t 0 is the retention time for an inert molecule (distribution coefficient K R = 0, CH 4, Ar, N 2 & H 2 ) t R is the retention time for the interacting probe Net retention time t N = t R - t 0 Detector response t 0 t R,Hexane t R,Heptane t R,Octane Methane Hexane Heptane Octane Time

61 Isotherms Detector Response Detector Response Detector Response Time Time Time Amount Adsorbed Amount Adsorbed Amount Adsorbed Partial Pressure Partial Pressure Partial Pressure a) b) c) The retention time is directly related to the first derivation of the amount adsorbed The height is related to the partial pressure

62 Dispersive Surface Energy Dispersive Component of Surface Energy Sequential injection of alkanes with increasing C-chain length at specific surface coverage DG 0 RT lnv N Const N Plot RTlnV N vs. a(γ d L) 1/2 then γ d s = (slope/2n A ) 2 A a m 2 d S d L

63 Surface Energy Heterogeneity Decane Known sample BET surface area Nonane Known molecular size of probes Octane Amount/Mole of probes needed to achieve certain coverage can be determined Heptane 30% 60% 70% 75% Surface Coverage Retention volumes at this coverage can be used to determine surface energy

64 Surface Energy Methodology Specific Free Energy DG SP Measured Directly Use polar or acid-base probes Use probes of specific functional groups to probe interactions with the surface Apply Various Acid-Base Theories Allows determination of specific component of surface energy (using Good-van Oss Chadury approach) Measurement of the Lewis acidity and basicity of the surface (using Gutmann approach)

65 Origins of Surface Chemistry Heterogeneity Almost all solid surfaces possess heterogeneous properties Chemical heterogeneity Surface contaminants and impurities Different crystal planes can exhibit different chemistry Degree of crystallinity/amorphicity Morphological state: polymorphs, hydrates and solvates Surface groups/inhomogeneous surface modification Structural heterogeneity Crystals may have several defect sites Growth steps, crystal edges, surface pores, etc. Irregularities of crystal lattice Pore of different sizes and shapes Heterogeneous properties cause differences in adsorption energies, thus vapour sorption capacity and surface energies

66 Anisotropic Surface Chemistry of Crystals D-mannitol Crystallisation of macroscopic pharmaceutical crystal (Excipient) D-mannitol (AR as received D-mannitol) Silanised D-mannitol Characterisation of surface energy using sessile drop contact angle Following crystallisation of macroscopic crystals Preparation of D-mannitol powders with same particle size (45-63 m), density, shape but different surface chemistries and thus energies. OH OH (120) (010) HO OH (011) OH OH C 6 H 14 O 6 (D-mannitol) 5mm

67 Contact Angle Measurement on D-mannitol Crystals (120) (010) (011) γ LV Liquid drop γ SV θ Clean solid surface Surface Chemistry by XPS C 1s XP Signal (a.u.) Monographs of macroscopic β mannitol crystal. Size: mm C-OH 287 Facet 286 CH x 285 Binding Energy (ev) mm Young s equation: Owens-Wendt: Advancing Contact Angle, a ( ) Surface Energy (mj/m 2 ) Hydrophilicity 282 Facet (120) a DIM H 2 O d p p / Facet (011) b W A γ SL LV cos SL SV d d p p 2 LV SV 2 LV SV LV (cos C 1s XP Signal (a.u.) C-OH (010) CH x (120) (011) Binding Energy (ev) R. Ho, S.J. Hinder, J.F. Watts, S.E. Dilworth, D.R. Williams and J.Y.Y. Heng. Int. J. Pharm (2010) 387: 1-2 pp

68 SEA Dispersive Surface Energy 55.0 Dispersive S.E. [mj/m 2 ] Silanised D-Mannitol AR D-Mannitol D- Mannitol γ D max γ D min γ D 50 Silanised AR Surface Coverage [n/n m ] SEA surface energy profile measurements ability to distinguish homogeneity and heterogeneity in surface free energy

69 SEA Specific Surface Energy Profiles Specific S.E. [mj/m 2 ] Silanised D-Mannitol AR D-Mannitol D-Mannitol γ AB max γ AB min γ AB 50 Silanised AR Surface Coverage [n/n m ] Changes in surface chemical environment - To an isotropic hydrophobic surface property

70 Surface Modification: Silanisation Work required to reversibly separate an interface between two bulk phases. W Coh total = 2[( s D * sd ) ½ + ( s + * s- ) ½ +( s - * s+ ) ½ ]

71 Surface Modification for Improved Flow Properties Silanised D-Mannitol AR D-Mannitol Total Flow Energy [mj] Air Velocity [mm/s] Free flowing materials fully aerate when flow energy stabilises - Silanisation influences the dynamic flow properties, but not under consolidated conditions

72 Effect of Cleaning Process on Surface Energy Heterogeneity Surface energy distribution of Aluminum and Teflon measured using igc-sea film cell (sample area ~2 x 8 ) Investigated cleaning proceedures effects on surface energy Ability to measure heterogeneity of entire surface unique to igc-sea Even simple films can be highly energetically heterogeneous Contact angle would require numerous droplets across the film surface. Even this would only be a gross approximate measure of heterogeneity

73 Dispersive Surface Energy of Aluminium Acid-cleaned aluminium surface was energetically more active and heterogeneous, having higher mean γ sd.

74 Dispersive Surface Energy of Teflon Though bleached Teflon surface possessed higher mean γ sd, nitric acid solution has roughened the surface, inducing more surface defects and a variation of γ sd.

75 Surface Energy Values (γ 50 ) by igc SEA Planar Sample γ s d [ mj/m 2 ] γ s ab [ mj/m 2 ] γ s t [ mj/m 2 ] γ s ab / γ s t Aluminium Al Bleached Al Nitric Acid Teflon Teflon Bleached Teflon Nitric Acid

76 Isotherms-BET Surface Area P/[n(P0-P)] [g/mmol] P C 1 P n[ P0 P] nmc P nmc SEA Calculated Results : Selected P/P0 range 0.14 to 0.20 C constant BET Surface Area: m 2 /g CRM 171 BET Surface Area = 2.95 m 2 /g Selected linearization P/P 0 range P/P0

77 IGC-BET Surface Area Standards 0% RH: IGC value of 50% 2.95 RH: m 2 IGC /g value of % m 2 /g RH: IGC value of 1.45 m 2 /g As humidity increases, measured BET surface area decreases Water competing for sites or blocking available surface area Example AFM image on Graphene: JACS, 2011, 133(8),

78 Polyolefin-Challenges Various pretreatments used to improve adhesion to polyolefins Low pressure plasma Corona treatment Flame treatment UV irradiation Mechanical etching Priming techniques Adhesion promoters to introduce polar functionality to TPO Chlorine donors 78

79 Polyolefin-Challenges 79

80 Polymer Samples Thermoplastic polyolefins (TPO) and elastomers Different elastomer loadings (12 and 25 wt %) Different elastomer densities Polyolefin-Case Study Measure mechanical adhesion to paint and compare to IGC surface energies

81 Dispersive Surface Energy

82 Mechanical Testing TPO samples were painted with topcoat Comprehensive Shear Delamination Apparatus (SLIDO) as a measure of mechanical adhesion Traction force (or frictional force) measured by taking the peak load in compression

83 Sliding Frictional S= v 2 a Compressive Force Run Length Traction Force

84 Friction in Painted TPO Plowing Cohesive Failure

85 Mechanical Adhesion Versus Surface Energy

86 Polyolefin Case Study Summary Higher surface energies lead to higher practical adhesion to paint Higher surface energies lead to lower microhardness (lower crystallinity) Increase in amorphous content (lower crystallinity) allows greater penetration of paint into TPO, thus greater adhesion Thermodynamic adhesion agrees with practical adhesion

87 Surface Energy Analysis Dispersive, acid-base components & total surface energy Acid-base Free Energy of Desorption Analysis Heterogeneity Mapping Heterogeneity profiles, heterogeneity distributions Gutmann Acid/Base Properties Isotherm Analysis Vapour uptake, Henry s constant BET Specific Surface Area Thermodynamic Work of Adhesion/Work of Cohesion Heat of Sorption Bulk Solid Properties Glass Transition Temperature Solubility Parameter (Hildebrand 1D, Hansen 3D) Cross-linking Density Properties measured by IGC

88 Acknowledgements Thank you to SMS collaborators SMS Colleagues: current and former team members London Imperial College SPEL Group Thank you for your time and attention Head Office: United States Office: Surface Measurement Systems, Ltd. Surface Measurement Systems, Ltd, NA 5 Wharfside, Rosemont Road th Street SW, Suite 1 London HA0 4PE, UK Allentown PA, Tel: +44 (0) Tel: Fax: +44 (0) Fax: science@surfacemeasurementsystems.com