Supporting Information - columbia.edu

1 Supporting InformationIn Situ Optical Imaging of the Growth of Conjugated PolymerAggregatesJaesungYang,HeungmanPar k, * Supporting Information Supporting Videos S1-3. Aggregates (S1) growing and (S2, S3) dissipating, consistent with Ostwald ripening. The videos are 2000 frames in length with an exposure time of s per frame, and playback speed is 200 frames per second (fps). Arrows point to the relevant aggregates at the beginning of each video. Supporting Video S4. Coalescence and approaching-receding processes between diffusing MEH-PPV aggregates.

2 The video is 2000 frames in length with an exposure time of s per frame, and playback speed is 200 fps. Supporting Video S5. Coalescing aggregates measured during quasi-real-time polarization anisotropy experiments. The video is 3000 frames in length with an exposure time of s per frame, and playback speed is 200 fps. Arrows point to the relevant aggregates at the beginning of the video. Methods Materials and sample preparation. MEH-PPV was synthesized as described previously. The MEH-PPV had Mw = 168 kDa with PDI = , with a single-peak trace measured by gel-permeation chromatography.

3 PMMA (Mw = 97 kDa and PDI = ) was purchased from Sigma-Aldrich. Sample films were prepared by spin casting a toluene solution of MEH-PPV (~ nM) containing wt% PMMA on the quartz crystal microbalance (QCM) sensor and the glass coverslip at ~ 2800 rpm to yield film thickness of 280 10 nm, as measured by the QCM-mounted film. Solvent vapor delivery and control. Details of the experimental apparatus are provided elsewhere.[1] Briefly, the system consists of a mass flow controller (Alicat Scientific, MCS-200 SCCM)-based solvent vapor control system, a QCM (Stanford Research Systems, QCM200) for assessment of film swelling, and a wide-field fluorescence imaging system.

4 The QCM- and coverslip- mounted sample films were placed at the lid and base, respectively, of the custom-built reaction chamber and exposed to dry nitrogen gas flow at volumetric flow rate, Qnit, of 400 standard cubic centimeter per minute (sccm) for 60 min to remove residual solvents. The films were swollen with solvent vapor using an acetone-chloroform solvent mixture with the liquid volume ratio of 50:50. Initial Qnit for film swelling was 170 sccm, which was decreased progressively to ~ 40 sccm after the film was fully swollen to maintain the plateau thickness.

5 Unless otherwise mentioned, films were swollen for ~ 55 min, after which films were de-swelled by the flow of dry nitrogen gas. In all experiments, temperature was held at 21 C. In situ optical tracking and spectroscopy of single MEH-PPV aggregates. For in situ optical imaging of growth of MEH-PPV aggregates, a 488 nm continuous-wave diode laser (Thorlabs, L488P60) was used. The laser beam was coupled into a multimode fiber, which was shaken mechanically to eliminate speckles and homogeneously illuminate the field of view (FOV).

6 The FOV was 47 m 47 m and 512 512 pixels. Circularly polarized light was produced by a quarter wave plate, passed through a laser line filter, collimating lens, and a removable motorized rotating linear polarizer, and focused onto the back-focal plane of an oil immersion objective (Olympus PlanApo N 60 , NA = ) via a dichroic beam splitter. Fluorescence was collected by the same objective, spectrally filtered with 514 nm long pass and 520 680 nm band pass filters and imaged onto an EMCCD camera (Andor, iXon DV885 KCS-VP).

7 To examine time-dependent aggregate growth kinetics, five aggregate tracking videos with duration of 200 s and exposure time of s were collected with an interval of 400 s, from 10 min into solvent vapor swelling of S2 sample films. Excitation power density at the sample was W/cm2. Each video was recorded at different positions on the film so photobleaching was minimal. For excitation polarization modulation depth (M) measurements, a motorized rotating linear polarizer was placed in the excitation laser beam path.

8 The measurements were performed by rotating the polarization of linearly polarized excitation light and monitoring fluorescence intensity as a function of polarization angle, . The rotation rate was 10 /s. Excitation power density at the sample was W/cm2. Data analysis. Data was analyzed using custom computer programs written in IDL, Igor, and Python. Number of Single MEH-PPV Chains per Aggregate. The number of single MEH-PPV chains per aggregate, NSM-AGG, was calculated using concentrated film-intensity analysis developed previously.

9 [2] In this analysis, NSM-AGG is calculated as = , , =1 , { , 1 ( , 1)} (S1) Here, NSM,B and NSM,D are the number of single chains within the full imaging area before and during SVA, respectively, and NAGG is the number of aggregates within the imaging area. ISM,B is the median fluorescence intensity of a single chain before SVA and was determined to be 4500 counts per second (cps) at the excitation power density employed. IFilm,B and IFilm,D are the total intensity of the fluorescence image before and during SVA, respectively.

10 C corrects for the decreased fluorescence intensity of single chains caused by SVA-mediated conformational changes and was previously determined to be [2] is the sum of fluorescence intensities from aggregates within an imaging area. These variables and resultant NSM-AGG are tabulated in Table S1. SVA time (min) IFilm,B ( 108 cps) IFilm,D ( 108 cps) ( 108 cps) NAGG NSM-AGG 0 - - - - 10 - 1085 60 235 115 20 - 590 25 595 195 30 - 465 10 715 245 40 - 360 35 940 320 50 - 325 5 1060 340 Table S1.